AOSpine Masters Series Volume 5 Cervical Spine Trauma

AOSpine Masters Series Cervical Spine Trauma

AOSpine Masters Series Cervical Spine Trauma

Series Editor:

Luiz Roberto Vialle, MD, PhD Professor of Orthopedics, School of Medicine Catholic Universit y of Parana State Spine Unit Curitiba, Brazil

Guest Editors: F. Cumhur Oner, MD Professor Spinal Surgery Universit y Medical Center Utrecht Utrecht, The Netherlands

Alexander R. Vaccaro, MD, PhD Richard H. Rothm an Professor and Chairm an Department of Orthopaedic Surgery Professor of Neurosurgery Co-Director, Delaware Valley Spinal Cord Injury Center Co-Chief of Spine Surgery Sidney Kimmel Medical Center at Thomas Je erson Universit y President, Rothman Institute Philadelphia, Pennsylvania

With 109 f gures

Th iem e New York • St u t tgar t • Delh i • Rio de Jan eiro

Th iem e Medical Pu blish ers, In c. 333 Seven th Ave. New York, NY 10001 Execut ive Editor: William Lam sback Man aging Editor: Sarah Lan dis Director, Editorial Ser vices: Mar y Jo Casey Editorial Assist ant: Haley Paskalides Product ion Editor: Barbara A. Ch ern ow In tern at ion al Product ion Director: An dreas Sch aber t Vice Presiden t , Editorial an d E-Produ ct Develop m en t: Vera Sp illn er In tern at ion al Market ing Director: Fion a Hen derson In tern at ion al Sales Director: Louisa Turrell Director of Sales, North Am erica: Mike Rosem an Sen ior Vice Presiden t an d Ch ief Operat ing O cer: Sarah Van d erbilt Presiden t: Brian D. Scan lan Com p ositor: Carol Pierson , Ch ern ow Editorial Ser vices, In c.

Librar y of Congress Cataloging-in -Pu blicat ion Dat a AOSpin e m asters series. V. 5, Cer vical spin e t rau m a / ed itors, Lu iz Roberto Vialle, F. Cum h u r On er, Alexan der R. Vaccaro. p. ; cm . Cer vical spin e t rau m a In cludes bibliograp h ical referen ces an d in dex. ISBN 978-1-62623-223-5 (alk. pap er) — ISBN 978-1-62623-224-2 (eBook) I. Vialle, Luiz Roberto. editor. II. On er, F. Cum h ur, editor. III. Vaccaro, Alexan der R., editor. IV. AOSpin e In tern at ion al (Firm ) V. Title: Cer vical sp in e t raum a. [DNLM: 1. Spin al Inju ries—diagn osis. 2. Cer vical Ver tebrae—inju ries. 3. Orth op edic Procedu res— m eth ods. 4. Sp in al Inju ries—th erapy. W E 725] RD594.3 617.4'82044—dc23 2015008433

Copyrigh t ©2015 by Th iem e Medical Publish ers, In c. Im po rtan t n ote: Medicin e is an ever-ch anging scien ce u n dergoing con t in u al develop m en t . Research an d clin ical experien ce are con t in ually expan ding ou r kn ow ledge, in par t icu lar ou r kn ow ledge of prop er t reat m en t an d drug th erapy. In sofar as th is book m en t ion s any dosage or ap plicat ion , readers m ay rest assu red th at th e au th ors, editors, an d publish ers h ave m ade ever y e ort to en sure th at su ch referen ces are in accordan ce w ith the state o f know ledge at the tim e o f productio n o f the bo o k. Never th eless, th is does n ot involve, im p ly, or express any gu aran tee or respon sibilit y on th e par t of th e pu blish ers in respect to any dosage in st ruct ion s an d form s of app licat ion s st ated in th e book. Every user is requested to exam in e carefully th e m an u fact u rers’ lea et s accom p anying each d rug an d to ch eck, if necessar y in con su ltat ion w ith a physician or sp ecialist , w h eth er th e dosage sch edu les m en t ion ed th erein or th e con t rain dicat ion s st ated by th e m an u fact u rers di er from th e st atem en t s m ade in th e presen t book. Such exam in at ion is part icularly im por t an t w ith drugs th at are eith errarely u sed or h ave been n ew ly released on th e m arket . Ever y dosage sch edu le or ever y form of app licat ion u sed is en t irely at th e u ser’s ow n risk an d respon sibilit y. Th e au th ors an d p ublish ers requ est ever y u ser to rep or t to th e p u blish ers any discrepan cies or in accuracies n ot iced. If errors in th is w ork are fou n d after pu blicat ion , errat a w ill be posted at w w w.th iem e.com on th e p rodu ct descript ion page. Som e of th e p rodu ct n am es, p aten t s, an d registered design s referred to in th is book are in fact registered t radem arks or p ropriet ar y n am es even th ough speci c referen ce to th is fact is n ot alw ays m ade in th e text . Th erefore, th e appearan ce of a n am e w ith ou t design at ion as prop rietar y is n ot to be con st ru ed as a represen t at ion by th e p u blish er th at it is in th e pu blic dom ain . Prin ted in Ch in a by Everbest Prin t ing Ltd. 5 4 3 2 1 ISBN 978-1-62623-223-5 Also available as an e-book: eISBN 978-1-62623-224-2

AOSpine Masters Series Luiz Roberto Vialle, MD, PhD Series Editor

Volum e 1

Met astat ic Spin al Tu m ors

Volum e 2

Prim ar y Sp in al Tu m ors

Volum e 3

Cer vical Degen erat ive Con dit ion s

Volum e 4

Adu lt Sp in al Deform it ies

Volum e 5

Cer vical Sp in e Traum a

Volum e 6

Th oracolu m bar Spin e Trau m a

Volum e 7

SCI an d Regen erat ion

Volum e 8

Back Pain

Volum e 9

Pediat ric Sp in al Deform it ies

Volum e 10

Sp in al In fect ion

Contents

Series Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix Luiz Roberto Vialle Guest Edito rs’ Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi F. Cum hur Oner and Alexander R. Vaccaro 1 An atom y of th e Cer vical Sp in e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 Ronald L.A.W . Bleys 2 Biom ech an ics of th e Cer vical Sp in e: From th e Norm al State to th e Injur y State . . . . . . . . . . 17 Ahm er K. Ghori, Dana Leonard, and Thom as Cha 3 Evaluat ion of an Inju red Cer vical Spin e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Richard Assaker, Fahed Zairi, and Xavier Dem ondion 4 Non op erat ive Man agem en t of Cer vical Sp in e Trau m a. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Peter Form by and Melvin D. Helgeson 5 Occipit al Con dyle Fract u res an d Occip itocer vical Dissociat ion . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Philipp Schleicher, Mat t i Scholz, and Frank Kandziora 6 Atlas Inju ries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 Matt i Scholz, Philipp Schleicher, and Frank Kandziora 7 Odon toid Fract u res, Hangm an’s Fract u res, an d C2 Body Fract u res . . . . . . . . . . . . . . . . . . . . . . 73 W ilco C. Peul and Carm en L.A. Vleggeert-Lankam p 8 Com pression (AO Typ e-A Inju ries) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 Nuno Neves 9 Su baxial Cer vical Spin e Inju ries: Dist ract ion (AO Typ e-B Inju ries) . . . . . . . . . . . . . . . . . . . . . . 94 W illiam A. Robinson, Kevin P. McCarthy, Alexander R. Vaccaro, and C. Cham bliss Harrod 10 Facet an d Lateral Mass Fract u res . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 Máxim o-Alberto Díez-Ulloa

viii

Contents 11 Cer vical Dislocat ion s (AO Typ e- C Inju ries) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 W illiam Muñoz, Michael J. Vives, and Saad B. Chaudhary 12 Cer vicoth oracic Ju n ct ion Inju ries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 Ripul Rajen Panchal 13 Cer vical Trau m a in Com bin at ion w ith An kylosing Spon dylit is or Di u se Idiopath ic Skelet al Hyp erostosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 Jorrit-Jan Verlaan and F. Cum hur Oner 14 Rh eu m atoid Ar th rit is an d Osteop orosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 David T. Anderson 15 Pediat ric Cer vical Sp in e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 Ahm et Alanay and Caglar Yilgor 16 Th e New AOSpin e Subaxial Cer vical Spin e Inju r y Classi cat ion System . . . . . . . . . . . . . . . . 169 Gregory D. Schroeder, Paul M. Millhouse, Alexander R. Vaccaro, F. Cum hur Oner, and Luiz Roberto Vialle Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177

Series Preface

Sp in e care is advan cing at a rapid pace. Th e ch allen ge for today’s sp in e care p rofession al is to qu ickly syn th esize t h e best available eviden ce an d exp er t op in ion in th e m an agem en t of sp in e p at h ologies. Th e AOSp in e Mast e r s Series p rovides ju st th at—each volu m e in th e series delivers p ath ology-focu sed exper t opin ion on procedu res, diagn osis, clin ical w isdom , an d pitfalls, an d h igh ligh ts today’s top research pap ers. To bring th e valu e of it s m asters level edu cat ion al cou rses an d academ ic congresses to a w ider audien ce, AOSpin e h as assem bled in tern at ion ally recogn ized spin e path ology leaders to develop volum es in th is Masters Series as a

vehicle for sharing their experiences and expert ise an d p roviding lin ks to th e literat u re. Each volum e focuses on a curren t com pelling an d som et im es con t roversial topic in spin e care. Th e u n iqu e an d e cien t for m at of t h e Masters Ser ies volu m es qu ickly focu ses t h e at ten t ion of t h e read er on t h e core in for m at ion crit ical to un derst an ding th e topic, w h ile en cou raging th e reader to look fu r th er in to th e recom m en d ed literat ure. Th rough th is ap p roach , AOSpin e is advan cing spin e care w orldw ide. Luiz Roberto Vialle, MD, PhD

Guest Editors’ Preface

Th e diagn osis an d t reat m en t of t rau m at ic cervical sp in e inju ries is a rapidly evolving eld . Advan ces in im aging an d crit ical care, togeth er w it h t h e d evelop m en t of sp eci c in st r u m en t at ion an d su rgical tech n iqu es, n ow en able p at ien t s to sur vive m any on ce-fatal injuries. How ever, th e failu re to recogn ize th ese inju ries an d t reat th em properly can h ave catast roph ic con sequ en ces. Many of th ese inju ries are associated w ith n eu rologic im pairm en t , an d advan ces in ou r un derst an ding of th e prim ar y an d secon dar y m ech an ism of spin al cord injuries h as m ade th e im por t an ce of early su rgical decom p ression an d stabilizat ion u n iversally accepted. Th us, it is param oun t th at all spin e su rgeon s be p repared to p rop erly diagn ose an d t reat p at ien t s w ith th ese inju ries rapidly. Alth ough in th e past spin al inju ries w ere u sually a result of h igh -en ergy t rau m a an d w ere relegated to a few specialized t reat m en t cen ters, w ith th e aging of th e populat ion , m any

elderly p at ien t s are presen t ing to com m u n it y h ospital em ergen cy room s w ith cer vical spin e injuries from low -en ergy falls. Th is book w ill h elp spin e surgeon s feel com for table in m an aging th ese com plex cases. Th is book o ers det ailed an alyses of th e essen t ial asp ect s of t h e m ost com m on inju r ies to both th e u pper an d low er (subaxial) cer vical spin e. World-ren ow n ed exper t s discuss th e anatom y, biom echanics, patient evaluation, and crit ical steps in th e decision -m aking process for th e t reat m en t of th ese com plex injuries. Th e au th ors of each ch apter both discu ss th e h istoric literat ure an d presen t a syn th esized an alysis of th e curren t literat ure an d th eir ow n clin ical exp erien ce. Th ey also p rop ose t reatm en t algorith m s th at are based on th e best available eviden ce. F. Cum hur Oner, MD Alexander R. Vaccaro, MD, PhD

Contributors

Ahm et Alanay, MD Professor Depar t m en t of Or th op ed ics an d Trau m atology Facult y of Medicin e Acibadem Un iversit y Istan bu l, Tu rkey David T. Anderso n, MD Or th opaedic Spin e Su rgeon Or th oCarolin a Ch arlot te, North Carolin a Richard Assake r, MD, PhD Professor Depar t m en t of Neu rosu rger y Cen t re Hosp italier Region al Un iversitaire de Lille Clin qu e de Neu roch iru rgie Lille, Fran ce Ronald L.A.W. Bleys, MD, PhD Professor of An atom y Depar t m en t of An atom y Un iversit y Medical Cen ter Ut rech t Ut rech t , Th e Neth erlan ds Tho m as Cha, MD, MBA Or th opaedic Spin e Cen ter Boston , Massach u set t s

Saad B. Chaudhary, MD, MBA Assist an t Professor Depar t m en t of Or th opaedics Moun t Sin ai Beth Israel New York, New York Xavie r Dem o ndio n, MD, PhD Professor Musculoskelet al Depar t m en t of Radiology Cen t re Hospitalier Region al Un iversitaire de Lille Lille, Fran ce Máxim o -Albe rto Díez-Ullo a, MD Associate Professor Doctor in Medicin e an d Surger y Un iversit y of San t iago de Com p ostela Or th opaedics an d Trau m atology Ser vice Un iversitar y Hosp italar y Com plex of San t iago de Com postela San t iago de Com postela, Sp ain Peter M. Fo rm by, MD Residen t Depar t m en t of Or th opaedics Walter Reed Nat ion al Militar y Medical Cen ter Beth esda, Mar ylan d

xiv

Contributors Ahm er K. Gho ri, MD Ch ief Residen t Har vard Or th op aedic Su rger y Residen cy Depar t m en t of Or th op aedic Su rger y Massach u set t s Gen eral Hospit al Boston , Massach u set t s

William Muñoz, MD Residen t Depart m en t of Or th opaedics Rutgers New Jersey Medical Sch ool Doctor’s O ce Cen ter New ark, New Jersey

C. Cham bliss Harro d, MD At ten ding Spin al Su rgeon Bon e an d Join t Clin ic of Baton Rouge Baton Rouge, Lou isian a

Nuno Neves, MD Orth opedic Su rgeon Spin e Group Orth opedic Depar t m en t Cen t ro Hospit alar São João Facult y of Medicin e, Un iversit y of Por to Por to, Por t ugal

Melvin D. Helgeso n, MD Ch ief Pediat ric an d Sp in e Su rger y Ser vice Depar t m en t of Or th op aedic Su rger y Walter Reed Nat ion al Militar y Medical Cen ter Or th opaedics Dep ar t m en t Beth esda, Mar ylan d Frank Kandzio ra, MD, PhD Head of Depar t m en t Cen ter for Spin al Surger y an d Neu rot rau m atology Zen t ru m fü r Wirbelsäu len ch iru rgie u n d Neu rot rau m atologie Beru fsgen ossen sch aftlich e Un fallklin ik Fran kfur t am Main , Germ any Dana Leo nard, BA Clin ical Research Coordin ator Depar t m en t of Or th op aedic Su rger y Brigh am an d Wom en’s Hospit al Boston , Massach u set t s Kevin P. McCarthy, MD Bon e an d Join t Clin ic Baton Rouge, Lou isian a Paul W. Millho use, MD Roth m an In st it u te Th om as Je erson Un iversit y Ph iladelp h ia, Pen n sylvan ia

F. Cum hur Oner, MD Professor Spin al Surger y Un iversit y Medical Cen ter Ut rech t Ut rech t , Th e Neth erlan ds Ripul Rajen Panchal, DO Assistan t Professor Depart m en t of Neu rological Su rger y Un iversit y of Californ ia Davis Medical Grou p Sacram en to, Californ ia Wilco C. Pe ul, MD, PhD Director Spin e In ter ven t ion Progn ost ic St u dy Grou p Leiden Un iversit y Medical Cen ter Med ical Cen ter Haaglan den Th e Hagu e, Th e Neth erlan ds William A. Ro binso n, MD Residen t Physician Depart m en t of Or th opaedic Surger y Th e Mayo Clin ic Roch ester, Min n esot a Philipp Schleicher, MD Fellow Cen ter for Spin al Su rger y an d Neu rot rau m atology Beru fsgen ossen sch aftlich e Un fallklin ik Fran kfur t am Main , Germ any

Contributors Matti Scho lz, MD Sen ior Con su ltan t Depar t m en t for Trau m a an d Orth opaedic Su rger y Beru fsgen ossen sch aftlich e Un fallklin ik Fran kfur t am Main , Germ any Grego ry D. Schro e de r, MD Roth m an In st it u te Th om as Je erson Un iversit y Ph iladelp h ia, Pen n sylvan ia Alexande r R. Vaccaro , MD, PhD Rich ard H. Roth m an Professor an d Ch airm an Depar t m en t of Or th op aedic Su rger y Professor of Neu rosu rger y Co-Director, Delaw are Valley Sp in al Cord Injur y Cen ter Co- Ch ief of Sp in e Su rger y Sidn ey Kim m el Med ical Cen ter at Th om as Je erson Un iversit y Presiden t, Roth m an In st it u te Ph iladelp h ia, Pen n sylvan ia Jo rrit-Jan Ve rlaan, MD, PhD Or th opaedic Surgeon Un iversit y Medical Cen ter Ut rech t , Th e Neth erlan ds Luiz Ro berto Vialle, MD, PhD Professor of Or th opedics, Sch ool of Medicin e Cath olic Un iversit y of Paran a State Spin e Un it Curit iba, Brazil

Michael J. Vives, MD Associate Professor Ch ief Spin e Division Depar t m en t of Or th opedics Rutgers New Jersey Medical Sch ool New ark, New Jersey Carm en L.A. Vleggee rt-Lankam p, MD Depar t m en t of Neu rosu rger y Leiden Un iversit y Medical Cen ter Leiden , Th e Neth erlan ds Caglar Yilgo r, MD Assist an t Professor Depar t m en t of Or th opedics an d Trau m atology Facult y of Medicin e Acibadem Un iversit y Istan bu l, Tu rkey Fahe d Zairi, MD Assist an t Professor Depar t m en t of Neu rosu rger y Lille Un iversit y Hospit al Lille, Fran ce

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1 Anatomy of the Cervical Spine Ronald L.A.W. Bleys

■ Introduction Th e cer vical sp in e is th e p ar t of th e ver tebral colu m n th at exten ds from th e sku ll to th e th orax. It h as seven ver tebrae, C1 to C7, w h ich are sm aller th an th e ver tebrae of th e in ferior region s due to th e fact th at th ey bear less w eigh t . Alth ough th e in ter ver tebral disks are also th in n er th an th e th oracic an d lum bar disks, th ey are relat ively th ick in com parison to th e h eigh t of th e ver tebral bodies. Th is con t ributes to th e m obilit y of th e cer vical sp in e, w h ich is th e m ost m obile p ar t of th e ver tebral colu m n p erm it t ing exion an d exten sion , lateral exion , an d rotat ion . Th e orien t at ion of th e ar t icular facets an d th e relat ively sm all t issue m ass surroun ding t h e cer vical ver tebrae add fu r th er to th e m obilit y. Ver tebrae C3 to C6 are t ypical cer vical ver tebrae. Th e atlas (C1) an d th e axis (C2) are at ypical, an d C7 is di eren t because of its long spin ou s process. In anterior and posterior surgical approach es to the cer vical spine, th e course of m any im portant struct ures should be taken in to accoun t. Mu scles are m ore abu n dan t in th e p osterior region because the center of gravit y of the head is an terior to th e cer vical spin e. Th e posterior m u scles are arranged in several layers. In th e u pperm ost posterior region th e deep su boccipit al m u scles are im p or tan t for p ost u re. Many n er ves an d blood vessels are closely related to th e cer vical sp in e. Th e spin al n er ves em erge from th e in ter ver tebral foram in a an d

th e ver tebral ar ter y passes t h rough th e foram in a in th e t ran sverse processes. Th is ch apter discusses th e gen eral feat ures of th e cer vical ver tebrae, th e associated ligam en t s, th e m u scles of th e back, an d th e vascu lar su p ply of th e cer vical sp in e, an d describes th e u p per cer vical sp in e an d th e su baxial cervical spin e in m ore detail.

■ General Features Cervical Vertebrae Ver tebrae C3 to C7, like th e th oracic an d th e lu m bar ver tebrae, con sist of a ver tebral body, a ver tebral arch , an d seven p rocesses (Fig. 1.1). Th e bodies are sm all bu t broad . Th e su perior su rfaces of th e bodies are saddle-sh aped, w ith th eir lateral m argin s p roject in g u pw ard as u n cin ate processes. Th e an terior m argin is depressed a bit. On the inferior surface the anterior m argin project s dow n an d p ar tly overlaps th e an terior aspect of th e in ter vertebral disk. Th ese p ar t icu lar sh ap es of th e su rfaces of th e bodies lim it lateral an d an teroposterior gliding m ovem en t s. Th e arch es are dorsal to th e bodies an d each on e is divided in to t w o pedicles an d t w o lam in ae. Th e ver tebral foram en bet w een th e body an d th e arch is big an d t riangular to accom m odate th e in t u m escen t ia cer vicalis. Th is is th e cer vical en largem en t of th e spin al cord, w h ich

2

Chapter 1

a

b

Fig. 1.1a,b (a) Superior and (b) anterior view of the rst, second, fourth, and seventh cervical vertebrae. (From Schuenke M, Schulte E, Schumacher U, eds.

Thieme Atlas of Anatomy. General Anatomy and Musculoskeletal System. New York: Thieme; 2006. © Thiem e, 2005. Illustration by Karl Wesker.)

Anatomy of the Cervical Spine is related to th e in n er vat ion of th e u pper lim b. Su p er ior an d in fer ior to t h e p ed icles are t h e su perior an d in ferior ver tebral n otch es, w h ich con t ribu te to th e bou n daries of th e in ter ver tebral foram in a th rough w h ich th e spin al n er ves pass. Th e seven processes are th e t w o t ran sverse processes, th e sp in ou s p rocess, an d fou r ar t icular processes. A dist in ct ive feat ure of a cer vical t ran sverse process is th at it h as a foram en —th e t ran sverse foram en . Th is re ects th e fact th at th ese processes are com posed of a ven t ral par t , w h ich is a rem n an t of a rib an lage, an d a d orsal p ar t , w h ich rep resen t s th e or igin al t ran sverse p rocess. Cor resp on d in gly, t h e t ran sverse p rocess en d s laterally in an ter ior an d posterior t ubercles. Th e ver tebral ar teries t ypically ru n th rough th e t ran sverse foram in a of th e upper six cer vical ver tebrae. For th is reason th e foram in a of C7 are sm aller. Th e spin ous processes of C3 to C6 are bi d an d th ose of C3 to C5 are sh or t . Race an d sex di eren ces h ave been reported becau se sh ort bi d spin ou s processes are especially foun d in w h ite m ales.1 Ver tebra C7 di ers from C3 to C6 becau se it h as a long sp in ou s p rocess th at is n ot bi d. Th is ver tebra is called ver tebra prom in en s because in m ost p eople it h as th e m ost p rom in en t sp in ou s process, w h ich according to m any descript ion s can be easily palpated, esp ecially w h en th e n eck is in exion . How ever, becau se th e spin ou s p rocesses of C6 an d T1 h ave alm ost sim ilar dim en sion s, it m ay be difcult to dist ingu ish am ong C6, C7, an d T1. Ver tebrae C1 an d C2 are discu ssed below (see Occipu t an d Upp er Cer vical Spin e).

Ligaments of the Vertebral Column Ver tebrae are con n ected by n u m erou s ligam en t s (Fig. 1.2). Th ey can be divided in to long ban ds, w h ich exten d along th e greatest par t of th e sp in e, an d sh or t s ban d s, w h ich con n ect adjacen t ver tebrae. Th e long ban d s com p r ise th e an terior longit udin al, th e posterior longit u din al, an d th e su praspin ou s ligam en t s. The anterior longitudinal ligam ent is a strong broad band that connects the anterolateral surfaces of th e ver tebral bodies. It exten ds from th e occip it al bon e to th e an terior t u bercle of C1 an d t h en con t in u es d ow nw ard to t h e fron t of

the sacrum . Its upperm ost part is relatively n arrow. Th e ligam en t is m ost adh eren t to th e in ter ver tebral disks an d th e adjacen t m argin s of th e ver tebral bodies. It lim it s exten sion of th e spin e. Th e p osterior longit u din al ligam en t ru n s in side th e ver tebral can al from C2 to th e sacru m an d con n ect s th e posterior surfaces of th e vertebral bodies. At low er levels it is broader over th e disks th an over th e bodies, giving it a den t icu lated ap pearan ce. How ever, in th e cer vical an d u p p er t h oracic region s, it is of u n ifor m w id t h . It s st ron gest at t ach m en t s are to t h e in ter ver tebral disks. From C2 it exten ds upw ard as th e tectorial m em bran e to th e sku ll base. Th e su praspin ou s ligam en t is a brou s cord th at con n ect s th e t ips of th e spin ou s processes from C7 to th e sacr u m . In th e cer vical region it exp an ds as th e n u ch al ligam en t . Th e n u ch al ligam en t is st r u ct u rally di eren t because it is com posed of broelast ic t issu e. It is a t riangu lar bilam in ar in term u scu lar sept u m th at r un s from th e extern al occipit al prot uberan ce to th e p oster ior bord er of th e foram en m agn u m an d from t h ere to t h e p oster ior t u bercle of C1 an d th e bi d spin ous processes of th e rem ain ing cer vical ver tebrae (Fig. 1.2). Bet w een th e lam in ae is a layer of loose con n ect ive t issue. Th e layers fuse at th e free posterior border of th e ligam en t. Th e n uch al ligam en t provides at t ach m en t for m u scles becau se th e spinous processes of C3 to C5 are short. In other an im als th e ligam en t is m u ch th icker an d is of im por t an ce for su sp en sion of th e h ead. Th e short bands are the interspinous and in tertransverse ligam en ts and th e ligam enta ava. Th e in tersp in ou s ligam en t s are th in ban ds th at con n ect adjacen t sp in ou s processes. Th e in tert ran sverse ligam en ts con n ect adjacen t t ran sverse processes. In th e cer vical region th ey are in con sp icu ous an d part ially replaced by in tert ran sverse m u scles. Th e ligam en t a ava are st rong yellow ish elast ic ban ds th at con n ect th e lam in ae of adjacen t ver tebrae an d th us con t ribute to th e posterior w all of th e ver tebral can al. Th ey are th ick in t h e t h oracic an d lu m bar region s. In th e cer vical region th ey are th in , long, an d broad, w h ich accom m odates th e great exten t of m obilit y of th e cer vical spin e. Th e ligam en ta ava

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Chapter 1

Fig. 1.2 Ligam ents of the cervical spine as seen in a midsagit tal section, left lateral view. (From Schuenke M, Schulte E, Schumacher U, eds. Thieme

Atlas of Anatomy. General Anatomy and Musculoskeletal System. New York: Thieme; 2006. © Thiem e, 2005. Illustration by Karl Wesker.)

lim it abr u pt exion of th e sp in e an d th u s resist separat ion of th e ver tebral arch es. Becau se of their elastic nat ure they assist in extension back to an erect p ost u re after exion . Sp eci c ligam en t s related to th e occip it al bon e an d th e upper t w o cer vical ver tebrae are discu ssed below (see Occip u t an d Up p er Cer vical Spin e).

an d Upper Cer vical Spin e an d Subaxial Cer vical Spin e). Th e d orsal m u scles (Fig. 1.3) form a greater m ass th an th e prever tebral m u scles becau se m ost body w eigh t is an ter ior to t h e sp in e. Mu scles on th e posterior side of th e spin e are n ot con n ed on ly to th e cer vical region . Th ey are best un derstood w h en th e m u sculat ure of th e back is con sidered as a w h ole. Th ese m u scles are organ ized in to su per cial, in term ediate, an d deep groups. On ly th e deep m u scles are t r u e in t rin sic back m u scles th at sp eci cally act on th e sp in e an d are su p p lied by d orsal ram i of t h e sp in al n er ves. Th e su p er cial an d in ter m ed iate m u scles are ext rin sic back m u scles. Su per cial ext rin sic m u s-

Muscles of the Back Th e m u scles of th e cer vical spin e are dist in guish ed in prevertebral m u scles an d th e m uscles of th e back. Prever tebral m u scles in clu de th e an terior an d lateral ver tebral m u scles, an d th ey are described below (see sect ion s Occip u t

Anatomy of the Cervical Spine cles act on th e p ectoral gird le an d th e sh ou lder join t . Th ey in clude t rapezius, levator scapulae, lat issim u s dorsi, an d rh om boids. In term ediate ext rin sic m u scles are th e su perior an d in ferior serrat u s posterior, w h ich m ay aid in resp iration . Of all extrin sic m uscles, only the trapezius an d levator scapulae are fou n d in th e cer vical region . Th e in t r in sic back m u scles also h ave a m u lt ilayered ar rangem en t an d are d ivid ed in to su p er cial, in ter m ediate an d d eep layers (Table 1.1). Th e super cial layer is foun d on ly in th e cer vical an d upper th oracic region an d con sists of th e splen ius capit is an d splen ius cer vicis. Th ese at an d th ick m u scles origin ate from th e m id lin e (sp in ou s p rocesses an d n u ch al ligam en t) an d exten d su perolaterally to th e t ran sverse p rocesses of C1 to C3 (or C4) (sp len iu s cer vicis) an d th e occipit al bon e an d m astoid process (sp len iu s cap it is). W h en left an d righ t m u scles act togeth er, th ey exten d th e h ead an d n eck. W h en act ing alon e, th ey draw an d rotate th e h ead to th e ipsilateral side an d are th ere-

fore syn ergist ic w ith th e con t ralateral stern ocleidom astoid. Th e erector spin ae form s th e in term ediate layer. It is a m assive m uscle com plex lying on eith er side of th e ver tebral colum n . It is divided in to th ree colu m n s, w h ich are, from lateral to m edial, th e iliocostalis, longissim u s, an d spin alis. Each colu m n is fu rth er region ally divided, based on th e levels of th eir su p erior at t ach m en ts (Table 1.1). Th e origin s an d in ser t ion s of th e variou s par ts are n ot discussed h ere in det ail. In th e cer vical region , deep to th e splen iu s m uscles, part s of all colum n s are foun d. Th e erector spin ae is th e ch ief exten sor of th e vertebral colu m n an d th e h ead. Act ing u n ilaterally, it ben ds th e sp in e laterally. Th e longissim u s capit is t u rn s th e h ead to th e ip silateral side. Th e deep m uscles are th e t ran sversospin alis group. Th ey lie deep to th e erector spin ae an d are su bd ivid ed in to sem isp in alis, m u lt i d u s, an d rot atores grou p s, w h ich are fu r t h er sp eci ed accord in g to t h e levels of t h eir su p er ior at t ach m en t s (Table 1.1). Th ese m u scles r u n from t ran sverse processes to sp in ou s p rocesses

Table 1.1 The Intrinsic Muscles of the Back Muscle Group

Name of Muscle

Regional Divisions

Super cial layer

Splenius

Intermediate layer (erector spinae)

Iliocostalis

Cervicis Capitis Lumborum Thoracis Cervicis Thoracis Cervicis Capitis Thoracis Cervicis Capitis Thoracis Cervicis Capitis

Longissimus

Spinalis

Deep layer (transversospinalis)

Semispinalis

Multi dus Rotatores

Short muscles

Interspinales Intertransversarii

Lumborum Thoracis Cervicis

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Chapter 1 of m ore superior ver tebrae, h en ce th e n am e t ran sversosp in alis grou p, an d occu py th e sp ace bet w een th e spin ou s an d t ran sverse processes. Sem ispin alis m u scles bridge fou r or m ore vertebrae, m ult i du s m uscles bridge t w o to four ver tebrae, an d rot atores m u scles bridge t w o ver tebrae or con n ect adjacen t ver tebrae. In th e cer vical region , th e sem ispin alis is w ell developed. Th e sem ispin alis capit is at tach es to th e occipit al bon e an d is visible as a longit udin al bulge in the neck next to the m idline. The sem ispinalis m uscles extend th e spin e and the head, an d, w h en act ing u n ilaterally, th e sem ispin alis cap it is t u rn s th e h ead sligh tly to th e con t ralateral side. Mu lt i du s m u scles are im p or t an t for segm en tal stabilizat ion d u ring m ovem en ts of th e spin e. Rot atores m u scles are gen erally n ot so w ell developed in th e cer vical region . Deep to the t ransversospin alis group a fourth group is fou n d th at con sist s of th e sm all in tersp in ales an d in ter t ran sversarii. Th ese sh or t m uscles connect the spinous and the transverse processes of adjacen t ver tebrae, respect ively, an d like th e m u lt i dus m uscles are im por t an t as segm en tal stabilizers. Th e in terspin ales an d in ter t ran sversarii are best developed in th e cervical region. Here th e intertransversarii consist of an terior an d p osterior m u scles, w h ich at tach to th e anterior and posterior tubercles of the transverse processes. As a con sequence, the ven t ral ram i of th e sp in al n er ves p ass bet w een th e an terior an d posterior in ter t ran sversarii. Deep to the sem ispin alis capitis, in the upper par t of th e n eck, th e su boccip ital m u scles are foun d. Th ese con sist of four m uscles, w h ich con n ect t h e occip it al bon e, C1 an d C2. Th ey occu py th e so-called su boccip it al region . Th ese m u scles are discu ssed below (see Occip u t an d Upp er Cer vical Spin e). In a posterior approach to th e cer vical spin e, from su p er cial to deep, th e follow ing m u scles are fou n d (Fig. 1.3; see also Fig. 1.5): • Trapezius • Sp len iu s cap it is/sp len iu s cer vicis • Sem ispinalis capitis/sem ispinalis cervicis and longissim us capit is • Mult i du s an d rotatores • In terspin ales an d in tert ran sversarii/suboccipit al m u scles

W h en th e com par t m en t bet w een th e layers of th e n u ch al ligam en t is op en ed, easy access to th e ver tebrae is obt ain ed.

Vascular Supply of the Cervical Spine Un like in th e th oracic an d lum bar region s, segm en t al ar teries h ave n ot p ersisted in th e cer vical region . Th e cer vical ver tebrae are su pp lied by spin al bran ch es from longit udin al ar teries th at d evelop ed from an astom oses bet w een th e segm en tal ar teries. Th ese are th e ver tebral, deep cer vical, an d ascen ding cer vical ar teries. Th e ver tebral ar ter y ar ises from t h e su bclavian ar ter y an d is discu ssed in th e n ext sect ion . Th e deep cer vical ar ter y origin ates from th e costocer vical t ru n k an d ascen ds beh in d th e transverse processes, bet w een the sem ispinalis cap it is an d sem isp in alis cer vicis. Th e ascen ding cer vical ar ter y is a bran ch of th e in ferior thyroid ar ter y an d ascen ds on th e an terior t u bercles of th e t ran sverse p rocesses. Spin al vein s form ven ous plexuses along th e en t ire ver tebral colu m n . Th ese p lexu ses are both outside and inside the vertebral canal, and because they are m ore abundant anteriorly and posteriorly, it h as becom e custom ar y to term th em an terior an d p osterior in tern al ver tebral ven ou s p lexu ses an d an terior an d p osterior extern al ver tebral ven ous plexuses. Th e in tern al ver tebral ven ou s p lexu s occu p ies th e ep idu ral space. It is discussed below (see Occiput an d Up p er Cer vical Sp in e). Th e p lexu ses an astom ose freely w it h each ot h er an d d rain in to segm en t al vein s in t h e t h oracic an d lu m bar region s an d in to, am ong oth ers, th e vertebral vein s on th e cer vical level.

■ Occiput and Upper Cervical

Spine Occipital Bone, Atlas, and Axis Th e occipit al bon e h as squ am ou s, basilar, an d lateral (con dylar) p art s. Th e squ am ou s par t is th e bony plate su p erop osterior to t h e foram en m agn u m . Th e m ost visible extern al fea-

Anatomy of the Cervical Spine

Fig. 1.3 Muscles on the posterior side of the cervical spine. On the left side all muscles are intact. The trapezius, splenius capitis, and semispinalis capitis cover the deep region of the neck. Rem oval of these muscles (right) gives access to the sub occipital region. Four suboccipital muscles connect

the occipital bone, the atlas, and the axis. (From Schuenke M, Schulte E, Schumacher U, eds. Thieme Atlas of Anatomy. General Anatomy and Musculoskeletal System. New York: Thieme; 2006. © Thieme, 2005. Illustration by Karl Wesker.)

t u res are th e extern al occip it al prot u beran ce an d t h e exter n al occip it al crest , w h ich r u n s dow n from t h e p rot u beran ce to th e foram en m agn u m . Many m u scles at t ach to th is p ar t of

th e occipit al bon e, in clu ding th e t rap eziu s, th e sp len iu s cap it is, an d th e sem ispin alis cap it is. Th e basilar p ar t exten ds su p eroan te riorly from t h e foram en m agn u m . It s in fer ior su rface

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Chapter 1 p rovid es at t ach m en t to t h e p h ar yn x an d a few m u scles. It s su p erior su rface con t ribu tes to th e clivu s in th e cran ial cavit y on w h ich th e m ed u lla oblongat a an d t h e p on s rest . Th e d ist al p ar t s of t h e ver tebral ar teries an d th e basilar ar ter y r u n h ere, too. Th e t w o lateral (con dylar) p ar t s lie on bot h sid es of th e foram en m agn u m . Th e occip it al con dyles are on t h eir in ferior su rfaces an d ar t icu late w ith th e su p er ior facet s of t h e at las. Th ey are oval or kid n eysh ap ed an d t h eir lon g a xes converge an terom edially. Above the condyles are the hypoglossal can als. Th e con dylar fossa, a dep ression beh in d each con dyle, m ay con t ain a con dylar can al for th e passage of an em issar y vein . Th is con dylar em issar y vein , if presen t , con n ect s th e sigm oid sin u s an d vein s in th e su boccip it al t riangle. Ver tebra C1, th e atlas (Fig. 1.1), h as n eith er a body n or a spin ous process. Th e ring-sh aped bon e con sist s of t w o lateral m asses con n ected by a sh or t an terior arch an d a longer posterior arch . Th e place of th e body is occupied by th e den s of C2. Du ring developm en t , th e body of C1 fu ses w ith th e body of C2 an d becom es th e den s. For th is reason th ere is n o in ter ver tebral d isk bet w een C1 an d C2. Th e lateral m asses ar t iculate w ith th e occipital bon e an d bear th e w eigh t of th e skull. Th e t ran sverse processes arise from th e lateral m asses, an d th erefore th ey are m ore laterally p laced th an th ose of th e oth er cer vical ver tebrae. Moreover, th e t ran sverse p rocesses th em selves are long. For th ese reason s, C1 is th e w id est of th e cer vical vertebrae, an d it s t ran sverse processes can even be palp ated bet w een th e ram u s of th e m an dible an d th e m astoid process. Th eir posit ion s m ake th em good levers for m u scles th at keep th e h ead balan ced. Each lateral m ass h as a kidn eysh ap ed su perior ar t icu lar facet , w h ich ar t icu lates w ith an occip ital con dyle. Th e in ferior ar t icular facet is at an d circular an d ar t icu lates w ith C2. Th e an terior arch h as an an terior t u bercle on it s extern al aspect to w h ich th e an terior longit u din al ligam en t is at t ach ed . It s in tern al aspect carries a facet for th e den s. Th e posterior arch h as a posterior t u bercle in th e m id lin e. Th is is a ru dim en t ar y sp in ou s p rocess to w h ich th e n uch al ligam en t is at tach ed. Th e su p er ior su r face of th e p oster ior arch h as a

groove for th e ver tebral ar ter y. Th e suboccip ital n er ve, w h ich is th e dorsal ram u s of spin al n er ve C1, em erges bet w een th e ver tebral arter y an d th e posterior arch . Th e st rong ver tebra C2, th e axis (Fig. 1.1), is ch aracterized by th e den s, w h ich p roject s u p w ard from its body an d ser ves as a p ivot arou n d w h ich th e atlas rotates. In adults, th e m ean length of th e den s is 15 m m . Th e an terior su rface h as a facet for th e an terior arch of th e atlas, w h ereas on th e p osterior su rface th ere is a groove for th e t ran sverse ligam en t of th e atlas. Th e body of th e axis con t ain s a r u dim en tar y disk, w h ich in dicates th e fu sion bet w een th e cen t ra of C1 an d C2. Th e pedicles an d th e m edial par t of th e t ran sverse p rocesses carr y at sup erior ar t icu lar facet s on w h ich th e atlas rot ates. Th e t ran sverse p rocess project s in feriorly an d laterally, an d as a con sequ en ce t h e t ran sverse foram en is d irected laterally. Th is perm it s th e ver tebral ar ter y to pursu e a lateral cou rse to th e t ran sverse foram en of th e atlas. Th e axis h as th ick lam in ae to w h ich th e ligam en t a ava at t ach , an d it h as a large bi d spin ou s process.

Joints and Ligaments Togeth er, th e join ts of th e upper cer vical spin e are called th e cran iover tebral join ts. Th ey con n ect th e occipital bon e, th e atlas, an d th e axis, an d p rovid e a w id e range of m ovem en t . Half of th e rot at ion , w h ich can occu r in th e cer vical spin e as a w h ole, takes place bet w een th e atlas an d th e axis. Th e join ts involved are th e atlan to-occipital join ts an d th e atlan toa xial join t s. Th ey are all syn ovial join t s. Th e atlan to-occipital join t s are ar t icu lat ion s bet w een th e occipit al con dyles an d th e superior ar t icu lar facet s of th e lateral m asses of th e atlas. Th e su rfaces on th e con dyles are convex, an d th ose on th e atlas are con cave. Th e join t cap su les are th in an d loose, an d th e join t a xes run in an an terom edial direct ion . Main m ovem ents are exion and extension (nodding of the h ead), but a few degrees of lateral exion an d rot at ion are possible as w ell. Th e occipit al bon e an d atlas are also con n ected by th e an terior and posterior atlanto-occipital m em branes. Th e an ter ior at lan to-occip it al m em bran e is broad

Anatomy of the Cervical Spine an d d en se an d con n ect s t h e an ter ior arch of C1 w ith th e an terior m argin of t h e foram en m agn u m . Medially it is con t in u ou s w ith th e an terior longit udin al ligam en t , an d laterally it blen ds w ith th e join t capsule. Th e posterior atlan to-occip ital m em bran e is also broad bu t th in , an d it con n ect s th e posterior arch of C1 w ith th e posterior m argin of th e foram en m agn um . It also blen ds w ith th e join t capsu les. Becau se th e ver tebral ar teries occu py grooves on th e posterior arch , th is m em bran e arch es over th e ar teries an d perm it s access to th e ar teries on th eir w ay to th e cran ial cavit y. Th e ar t icu lar su rfaces an d th e brou s st ru ct u res (join t cap su le, m em bran es, an d ligam en t s) are involved in m ain tain ing st abilit y. Th ere is a role for th e dorsal n eck m u scles as w ell, esp ecially th e su b occipit al m u scles, w h ich are involved in m ain tain ing p ost u re. Th e atlan toaxial join ts are th e th ree ar t iculat ion s bet w een t h e at las an d t h e a xis. Th ey are t w o lateral atlan toaxial join ts, bet w een th e lateral m asses of t h e at las an d th e su p er ior ar t icular facet s of th e axis, an d th e m edian atlan toaxial join t . Th e ar t icu lar su rfaces of th e lateral join ts are n early at , p erm it t ing gliding m ovem en t s. In th e m edian at lan toaxial join t th e d en s ar t icu lates w ith th e an terior arch of th e atlas in fron t an d w ith th e t ran sverse ligam en t of th e atlas beh in d. Th e groove on th e posterior su rface of th e den s h as a car t ilage covering for th is. Th is join t is a p ivot join t , an d it perm its rotation. As a consequence, the m ovem en t of th e th ree join t s togeth er is a rot at ion , th e den s being t h e axis. Th is resu lt s in a rot at ion of th e h ead of abou t 40 degrees. Join t cap su les of t h ese t h ree join t s are loose. Du r in g th e rot at ion th e den s is h eld in posit ion by th e st rong t ran sverse ligam en t of th e atlas, w h ich run s bet w een both lateral m asses an d form s th e posterior w all of th e socket for th e den s. It s length is ~ 20 m m . It is at tach ed on t u bercles on the m edial sides of the lateral m asses. W here it ar t icu lates w it h t h e d en s it is covered by car t ilage. From its u pp er an d low er m argin s m edian longit u din al ban ds ru n to th e occip it al bon e an d th e body of C2. Togeth er w ith th e t ran sverse ligam en t , th ese su p erior an d in ferior longit u din al ban ds con st it u te th e cru ciate ligam en t of th e atlas.

Th ere are m ore ligam en t s, w h ich con n ect th e axis an d th e occipit al bon e. Th ree of t h em at tach to th e den s. From th e sides of th e den s th ick alar ligam en t s ru n to th e lateral m argin s of th e foram en m agn um . Th ese ligam en t s lim it excessive atlan toaxial rot at ion . From th e ap ex of th e den s th e apical ligam en t of th e den s fan s out in to th e an terior m argin of th e foram en m agn u m . It lies bet w een th e an terior at lan tooccipit al m em bran e an d th e cruciate ligam en t (su perior longit u din al ban d) an d is separated from th ese st r uct u res by fat pad s. Th e tectorial m em bran e is th e cran ial con t in u at ion of th e posterior longit u din al ligam en t . From th e body of th e axis it r un s upw ard beh in d th e cr uciate ligam en t an d at t ach es to t h e occip it al bon e above t h e an ter ior m argin of t h e foram en m agn u m , w h ich act u ally is th e oor of th e p oster ior cran ial fossa. Here it blen d s w it h t h e cranial dura m ater. Bet w een the tectorial m em bran e an d th e cruciate ligam en t is a th in layer of loose connective tissue. Taken together, passing from ou tside th e an terior side of th e spin e in to th e vertebral can al, bet w een th e occipit al bon e an d t h e an ter ior arch of t h e at las/den s of th e axis com p lex, th e follow ing layers are crossed in th e m idlin e (Fig. 1.2): • An terior atlan to-occipital m em bran e an d an terior longit u din al ligam en t • Fat pad • Ap ical ligam en t of den s • Fat pad • Su p erior longit u d in al ban d of cr u ciate ligam en t • Loose con n ect ive t issue • Tectorial m em bran e • Ep idural space • Spin al du ra m ater Th e ligam en t s, especially th e t ran sverse ligam en t , are an im p or t an t factor for m ain t ain ing st abilit y in th e atlan toaxial join t s. Oth er factors are th e join t capsules an d th e suboccipit al m u scles. At th e level of th e atlas th e t ran sverse ligam ent divides the vertebral canal into t w o parts: th e an terior th ird, w h ich con t ain s th e den s, an d th e posterior t w o th irds, w h ich con tain s th e sp in al cord an d su rrou n ding m en inges. Th e cord it self occu p ies h alf of t h e p oster ior t w o

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Chapter 1 th irds, leaving m u ch sp ace arou n d it . Th is is n ecessar y to en able un com plicated rotat ion of th e h ead. Becau se th e a xis of rot at ion , th e den s, is eccen t r ically located , t h e con sequ en ce of rot at ion is th at th e area of th e ver tebral can al decreases. Abu n dan t sp ace arou n d th e spin al cord p reven t s com pression of th e cord. Mu ch of t h e sp ace arou n d t h e cord is occu p ied by t h e in tern al ver tebral ven ou s plexu s. Th is is a m assive ven ou s system in th e ep idu ral space, w h ich r un s dow nw ard from th e m argin al sin us an d h as con n ect ion s w ith n u m erou s vein s around the vertebral colum n as far as the pelvic cavit y. It h as been radiologically dem on st rated th at du ring atlan toa xial rot at ion disp lacem en t of blood from th is ven ous plexus t akes place at th e level of th e u p p er cer vical sp in e, th ereby preven t ing com p ression of th e du ral sac. W h en th e n eu t ral p osit ion of t h e h ead is restored, th e plexu s lls again . Th e in tern al ver tebral ven ou s plexu s seem s to act as a volu m e bu er in th is area.2

Suboccipital Region Th e su boccip it al region is a d eep m u scle com p ar t m en t in t h e su p er ior p oster ior cer vical region . It lies deep to th e t rapezius, stern ocleidom astoid, sp len iu s capit is, an d sem ispin alis m u scles. It is in ferior to th e extern al occip it al prot u beran ce an d in clu des th e p osterior aspect s of th e atlas an d th e axis. In a p osterior approach , th e n al m u scle, w h ich h as to be rem oved to en ter th e region , is th e sem ispin alis capitis. Its m ain conten ts are th e four suboccip ital m uscles, the vertebral artery, and the dorsal ram i of the upper three cervical spinal nerves. The suboccipital m uscles are four short m uscles th at con n ect th e occipit al bon e, th e atlas,

an d th e a xis. Th ey are n am ed th e rect us capit is posterior m ajor, rect u s cap it is posterior m in or, obliquu s capit is superior, an d obliqu us capit is in ferior (Table 1.2 an d Fig. 1.3). Th e obliquus cap it is in ferior is th e on ly on e w ith ou t an at tach m en t to th e occipit al bon e. Th ese m uscles exten d an d rot ate th e h ead an d are of great im por t an ce for p ost u re. Th ey h ave a h igh den sit y of m uscle spin dles, w h ich are sen sors of propriocept ion . It h as been stated th at th e rect u s m u scles an d obliqu u s cap it is su p er ior m ay be m ore im p or t an t as p ost u ral m u scles t h an as prim e m overs. Th e rect u s cap it is p osterior m ajor an d th e obliquu s capit is m uscles form th e bou n daries of th e suboccipit al t riangle (Fig. 1.4). Th e oor of t h is t r ian gle is for m ed by t h e p oster ior at lan to-occip it al m em bran e an d t h e p oster ior arch of t h e at las. Here th e ver tebral ar ter y is foun d, lying in a groove on th e posterior arch an d passing un dern eath th e posterior atlan tooccipit al m em bran e on it s w ay to th e ver tebral can al. Th e su boccip it al n er ve, w h ich is th e dorsal ram u s of spin al n er ve C1, em erges bet w een th e vertebral ar ter y an d th e posterior arch . It su p plies all fou r su boccipit al m u scles an d also sen ds a bran ch to th e sem ispin alis capit is. Th ere is n o in ter ver tebral foram en bet w een th e atlas an d t h e a xis. Spin al n er ve C2 em erges bet w een th e posterior arch of th e atlas an d th e lam in a of th e axis, below th e obliqu u s capit is in ferior. It s dorsal ram us, larger th an all oth er cer vical dorsal ram i, divides in to a large m edial bran ch an d a sm all lateral bran ch . Th e m edial bran ch is called the greater occipital nerve (Fig. 1.4). It ascen ds dorsal to th e obliqu u s cap it is in ferior an d pierces th e sem ispin alis cap it is w h ile supplying it . It th en pierces th e t rapeziu s and supplies the skin of the scalp as far for w ard

Table 1.2 The Suboccipital Muscles Muscle

Origin

Insertion

Rectus capitis posterior major Rectus capitis posterior minor

Inferior nuchal line of occipital bone Inferior nuchal line of occipital bone

Obliquus capitis superior

Spinous process of C2 Posterior tubercle of posterior arch of C1 Transverse process of C1

Obliquus capitis inferior

Spinous process of C2

Occipital bone above inferior nuchal lie Transverse process of C1

Anatomy of the Cervical Spine

Fig. 1.4 Dorsal view of the suboccipital region after removal of the super cial muscles. The dorsal branches of the cervical spinal nerves give rise to the suboccipital (C1), greater occipital (C2), and

third occipital (C3) nerves. The vertebral artery occupies a groove on the posterior arch of C1 and pierces the posterior atlanto occipital membrane.

as th e ver tex. Th e sm aller lateral bran ch sup plies th e sem isp in alis cap it is, splen iu s capit is, an d longissim us capit is. Th e dorsal ram u s of spin al n er ve C3 t urn s backw ard after em erging from th e in ter ver tebral foram en . It r un s dorsal to ver tebra C3 an d divides in to m edial an d lateral bran ch es. Th e m edial bran ch gives rise to th e t h ird occip it al n er ve, w h ich ascen d s n ext to th e m idlin e an d pierces th e t rapezius to su p ply th e skin of th e low er occip ital an d su boccipit al region s, m edial to th e greater occipital nerve (Fig. 1.4). All dorsal ram i m en tioned here h ave in tercon n ect ing bran ch es.

Th e vertebral arter y m ay be described in four par t s. Th e rst t w o (p rever tebral an d cer vical) par t s are discu ssed below (see Su baxial Cer vical Sp in e). Havin g p assed t h rough t h e t ran sverse foram en of C2, it t u rn s laterally to reach th e t ran sverse foram en of C1. Th en , as th e atlan t ic (t h ird) p ar t , it lies m ed ial to t h e rect u s cap it is lateralis, r u n s in a m ed ial d irect ion beh in d th e lateral m ass of C1 an d deep to th e obliquu s capit is su perior, occupies th e groove on t h e su p er ior su r face of t h e p oster ior arch of C1 covered by th e sem ispin alis capit is, an d en ters th e ver tebral can al below th e p osterior

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Chapter 1 atlan to-occip ital m em bran e (Fig. 1.4). Th e in t racran ial (fou r th ) p ar t p ierces th e du ra an d th e arach n oidea m ater, en ters th e cran ial cavit y th rough th e foram en m agn u m , an d u n ites w ith it s fellow to form th e basilar ar ter y. Usu ally th ere is som e tor t u osit y in th e ar ter y in its cou rse bet w een th e t ran sverse foram in a of C2 an d C1. Th is m ay provide slack, w h ich is n ecessar y to rot ate th e h ead w ith out com prom ising th e ar ter y.3 An oth er ar ter y th at sh ould be m en t ion ed h ere is th e occip it al arter y. Th is large an d tort u ou s arter y is a posterior bran ch of th e extern al carot id ar ter y. It ru n s on a groove on th e m edial side of th e m astoid p rocess an d con t in ues it s cou rse posterior to th e obliqu u s cap it is su perior an d sem isp in alis. It pierces th e fascia, w hich con n ects th e cran ial at tach m en t s of th e stern ocleidom astoid an d t rapeziu s; th is is th e invest ing layer of th e cer vical fascia. Tort u ous bran ch es supply th e scalp as far for w ard as th e vertex. Th e su boccipit al region con t ain s a ven ou s plexu s, w h ich receives t ribu t aries from , am ong oth ers, th e extern al vertebral ven ou s plexu s an d n eigh bor in g m u scles. Th e su boccip it al ven ou s p lexu s drain s via t h e left an d righ t p oster ior jugu lar vein s, w h ich join t h e exter n al jugular vein s. Alth ough th ey are n ot in th e suboccipital region , t w o oth er sh ort m uscles sh ou ld be m en t ion ed h ere becau se th ey also con n ect th e atlas to th e occipital bon e. Th e rect us capit is lateralis arises from th e t ran sverse p rocess of C1, an d th e rect u s cap it is an terior arises from th e an terior su rface of th e lateral m ass of C1. Th e lat ter m u scle exes th e h ead in th e atlan to-occipit al joint , an d th e rect u s capit is lateralis exes th e h ead laterally.

■ Subaxial Cervical Spine Joints From C2 dow nw ard, th e ver tebrae ar t icu late via facet join t s (zygapop hysial join ts) an d in ter ver tebral disks. At th e level of C3 to C7, sm all u n cover tebral join ts are presen t as w ell.

Facet joints are plane synovial join ts bet ween th e in ferior an d su p erior ar t icu lar processes of adjacen t vertebrae. In th e cer vical region th e ar t icu lar su r faces are obliqu e in su ch a w ay t h at th ey r u n from su p eroan ter ior to in fero p oster ior. Th u s, t h e in fer ior facet is directed in feroan ter iorly an d t h e su p er ior facet is directed su p erop oster iorly. Th e cer vical facet join t s allow free exion an d exten sion . Th ey also allow lateral exion an d rotat ion , w h ich are alw ays coupled due to the oblique joint surfaces. Th e join t capsules are th in an d loose, perm it t ing a w ide range of m ovem en t . Th e cer vical in ter ver tebral disks are th ick in com p arison to th e h eigh t of th e ver tebral bodies. Th ey are th icker an teriorly, w h ich con t rib u tes to th e cer vical lordosis. Th ey con sist of a w ell-developed n ucleus pu lposus an d an an ulu s brosu s. Th e lat ter is st r ikingly d i eren t from it s fellow s in oth er region s. It h as been d em on st rated t h at t h e ad u lt cer vical an u lu s brosu s is usually in com p lete posteriorly. In stead of con cen t ric lam in ae it form s a crescen t ic m ass an terior to th e n u cleu s, t ap ering laterally tow ard th e un cin ate processes. Posteriorly it con sist s of on ly a th in layer of ver t ically orien ted bers. Th e de cien cy is rein forced by th e posterior longit ud in al ligam en t .4 Usu ally after th e age of 10 ssu res develop in th e lateral part s of th e in ter vertebral disks. Th ese ssures give rise to the so-called uncovertebral join ts or clefts (of Lusch ka) bet w een th e un cin ate processes of vertebrae C3 to C7 an d th e corresp on ding in ferolateral su rfaces of t h e vertebral bodies su p erior to th em . Th ese ar t iculat ion s are un ique to th e cer vical spin e. Th e ssures and thus the joints develop in the upper th ree disks rst an d later in th e rem ain ing t w o disks. Th e join t su rfaces are covered w ith car t ilage, an d laterally th e join ts are bou n ded by connective tissue, w hich is con sidered a pseudocapsu le. Th e u n cover tebral join t s develop from rudim en tar y ar t iculat ion s in to m at ure join ts, w hich con t ribute to m obilit y an d stabilit y an d m ay becom e degen erated w ith age.5

Muscles Th e m uscles posterior to the cervical spin e w ere discu ssed above (see Gen eral Feat u res). Most

Anatomy of the Cervical Spine of th e an terior an d lateral ver tebral m uscles rem ain to be discussed. Th e an terior ver tebral m uscles are th e rectus capitis anterior (see Occiput and Upper Cervical Sp in e, above), th e longu s capit is, an d th e longu s colli. Th e longu s cap it is ru n s from th e basilar par t of th e occipital bon e to th e t ran sverse processes of C3 to C6. Th e several par t s of th e longu s colli r u n bet w een th e bodies an d t ran sverse p rocesses of C1 to C6 an d C3 to T1. Th e longu s colli an d longu s cap it is are im m ediately beh in d th e prever tebral layer of th e deep cer vical fascia. Th ey ex th e h ead an d th e n eck an d are supplied by bran ch es of th e cer vical spin al n er ves. Th e lateral ver tebral m uscles are th e rect us cap it is lateralis (see Occipu t an d Up per Cer vical Spin e, above), t h e levator scap u lae, an d th e scalen u s an terior, m ediu s, an d p osterior. Th e levator scap u lae arises from th e t ran sverse processes of C1 to C4 an d r u n s to th e su p erior par t of th e m edial bord er of th e scap u la. It acts on th e scapula. If th e sh oulder is xed, it assist s in lateral exion of t h e cer vical sp in e. Th e m u scle is su pp lied by th e dorsal scap u lar n er ve an d addit ion al bran ch es of th e cer vical plexus. Th e scalen u s m u scles h ave th eir origin s on th e t ran sverse processes—th e scalen u s an terior on C3 to C6, th e scalen u s m ediu s on C3 to C7, an d th e scalen u s p oster ior on C4 to C6—an d r u n to th e rst rib (scalen us an terior an d scalen us m ediu s) or th e secon d rib (scalen u s posterior). Th e scalen u s m u scles m ay act on th e cer vical spin e (lateral exion , an d if both an terior scalenus m uscles work together they ex the spine) or the ribs (elevation during forced inspiration). Th e scalen u s m u scles are su p plied by sh or t bran ch es of th e cer vical sp in al n er ves.

Topographical Relationships A good un derstan ding of th e position of th e cer vical spin e an d its m ajor topograph ical relat ion sh ip s can be obtain ed by st u dying t ran sverse sect ion s of th e n eck (Fig. 1.5). Th e n eck h as a system of fascias, w h ich , th rough th eir disp osit ion , create com p ar t m en ts. Th e clin ical sign i can ce of com p ar t m en ts is th at th ey determ in e an d lim it th e sp read of path ology, especially in fect ion , to a cer tain exten t .

Th e su p er cial cer vical fascia is th e su bcutan eous con n ect ive t issu e, w h ich con n ects th e derm is to th e deep fascia. It con tain s a variable am oun t of fat , an d an terolaterally it con t ain s th e p lat ysm a. Th e deep cer vical fascia con sist s of th ree layers: invest ing (or super cial), pret rach eal, an d p rever tebral. It also for m s t h e carot id sh eath . Th e w ell-visible invest ing layer su rrou n ds th e n eck like a collar an d splits to en close th e stern ocleidom astoid an d t rap eziu s. Posteriorly it is con n ected to th e periosteu m of spin ous process C7 an d to th e n uch al ligam en t . Th e p ret rach eal layer is th in an d p resen t on ly in th e an terior part of th e n eck. Tw o p ar t s are dist ingu ish ed. On e par t en closes th e in frahyoid m u scles or st rap m u scles an d is fu sed w it h t h e invest in g layer an ter iorly. Th e secon d p ar t form s an envelope for th e thyroid glan d. Th e prever tebral layer su rrou n ds th e cer vical spin e in cluding th e p re- an d post vertebral m u scles. Th erefore, th e term prevertebral is rath er u n for t un ate, an d perivertebral w ou ld h ave been m ore ap propriate. How ever, it h as to be m en t ion ed th at th e fascia becom es ver y th in laterally an d posteriorly, w h ere it is u n der th e cover of the trapezius. Anteriorly it is quite prom inent an d divides to form t w o layers, of w h ich th e an terior layer h as received it s ow n n am e, th e alar fascia. All th ree layers of th e deep fascia con n ect to th e carot id sh eath . Th is is a con den sat ion of th e deep fascia aroun d th e com m on an d in tern al carot id ar teries, th e in tern al jugular vein , an d th e vagu s n er ve. Th e disp osit ion of th e com p on en t s of th e deep cer vical fascia creates m u scu lar, visceral, an d n eurovascu lar com par t m en ts. Th e m uscular com par t m en t s are th e sp aces occu p ied by th e stern ocleidom astoid, in frahyoid, t rap eziu s, an d pre- an d post ver tebral m u scles. Th e visceral com partm ent lies anteriorly in the neck and con t ain s th e thyroid an d p arathyroid glan ds, th e lar yn x, th e p h ar yn x, an d th e u pp er p ar t s of th e t rach ea an d th e esop h agus. Posteriorly it is closed by a visceral fascia. Beh in d t h e ph ar yn x is th e bu ccoph ar yngeal fascia, w h ich con t in ues dow nw ard in to th e esop h ageal adven t it ia. Th e n eurovascular com par t m en t is th e space in side th e carot id sh eath . Sp ecial at ten t ion h as to be paid to t w o in terfascial spaces th at m ain ly con t ain loose con n ect ive t issu e. Th ey are t h e

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Chapter 1

Fig. 1.5 Transverse section of the neck at the level of vertebra C5. The deep cervical fascia has investing, pretracheal, and prevertebral layers, and also forms the carotid sheath. Their disposition

results in muscular, neurovascular, and visceral compartm ents. In an anterior approach the cervical spine can be reached bet ween the visceral and neurovascular compartments.

slit-like spaces bet w een th e visceral fascia an d t h e alar fascia, an d bet w een t h e alar fascia an d th e prever tebral layer proper. Th ese spaces allow m ovem en t of th e viscera relat ive to th e cer vical spin e during sw allow ing. Th e an terior space is term ed th e ret rovisceral space an d con sist s of ret roph ar yngeal an d ret roesop h ageal p ar t s. Th e p oster ior sp ace h as received t h e n am e “danger sp ace,” w h ich illu st rates th e clin ical sign i can ce of th ese sp aces. Becau se both spaces con t in ue dow nw ard in to th e m ediast in u m , t h ey for m im p or t an t rou tes for th e sp read of in fect ion s from t h e h ead an d n eck region to th e m ediast in u m . From th e t ran sverse sect ion it can be u n derstood th at an an terior ap proach of th e cer vical spin e m ay go bet w een th e n eu rovascular an d visceral com part m en t s (Fig. 1.5). W h en it is

perform ed carefu lly, im por tan t st ru ct u res are avoided. Tiny bran ch es of th e an sa cer vicalis are at risk, h ow ever. Th e an sa cer vicalis is a n eu ral loop of th e cer vical plexus th at is em bedded in th e carot id sh eath . Its bran ch es sup ply th e in frahyoid m u scles. An oth er st ru ct u re to keep in m ind, and functionally m ore im portan t , is th e sym path et ic t run k. It is em bedded in th e p rever tebral layer of th e deep cer vical fascia, posterom edial to th e carot id sh eath an d at th e level of th e t ran sverse p rocesses of th e vertebrae. Th e low er h alf of t h e cer vical p ar t of t h e sym p ath et ic t r u n k m ay con sist of several st ran d s, w h ich m akes it m ore di cu lt to iden t ify. Su periorly it form s a single bun dle. Here it con t ain s th e elongated su perior cer vical gan glion , w h ich lies on th e t ran sverse processes of C2 an d C3.

Anatomy of the Cervical Spine The cer vical plexus is form ed by ventral ram i of spin al n er ves C1 to C4. It is an terom edial to th e levator scap u lae an d scalen u s m ediu s. It s cu t an eou s bran ch es su p p ly t h e an ter ior an d lateral p ar ts of th e n eck. An im p or tan t m otor bran ch is th e ph ren ic n er ve, w h ich ru n s dow n on th e an terior surface of scalen u s an terior. In th e low er par t of th e n eck th e recu rren t lar yngeal n er ve ascen ds on it s w ay to th e laryn x. Tradit ion ally described as lying in th e groove bet w een th e t rach ea an d esoph agu s, t h is is gen erally t h e case on ly ju st below it s en t ran ce in to th e lar yn x. Fu r th er dow n it is em bedded in th e loose con n ect ive t issu e n ext to th e t rach ea an d th e esoph agus, m ore often parat rach eally th an paraesoph ageally.6 Th e ver tebral ar ter y com es from th e rst part of th e su bclavian ar ter y. It s rst part , th e prever tebral par t , ascen ds bet w een th e longu s colli an d scalen u s an terior. It lies an terior to th e t ran sverse p rocess of C7 an d ven t ral ram i of cer vical ner ves C7 and C8. It enters the transverse foram en of C6 an d from h ere is called th e vertebral (secon d) p ar t . It ascen d s th rough th e t ran sverse foram in a of th e rem ain ing ver tebrae an d is surroun ded by a plexu s of vein s, w hich low in th e n eck form s th e ver tebral vein th at join s th e brach iocep h alic vein . Th e ver tebral ar ter y m ay st ar t it s course th rough th e t ran sverse foram in a on a di eren t level, even as high as C3. Bet w een the transverse processes th e ar ter y lies an terior to th e ven t ral ram i of spinal n er ves C2 to C6. Th e th ird an d four th (atlan tal an d in t racran ial) par t s w ere discussed above (see Occipu t an d Up p er Cer vical Sp in e).

■ Chapter Summary Th e cer vical spin e is th e m ost m obile par t of th e ver tebral colu m n , p er m it t ing exion an d exten sion , lateral exion , an d rot at ion . It con sist s of seven relat ively sm all ver tebrae, of w h ich th e presen ce of a t ran sverse foram en for passage of th e ver tebral ar ter y is a dist in ct ive feat u re. Th e at las an d t h e a xis are at yp ical ver tebrae. Th e atlan to-occipital join t s are im portan t for the m ovem en t of n odding the head, w hereas

the atlantoaxial join ts perm it a rotation of about 40 degrees. Stabilit y in th ese cran iover tebral join t s, w it h t h eir w id e ran ge of m ovem en t , com es from join t cap su les, m em bran es, ligam en t s, an d t h e su boccip it al m u scles. Esp ecially th e st rong t ran sverse ligam en t of th e atlas sh ou ld be m en t ion ed as w ell as th e su b occipit al m uscles, w h ich are ver y im por t an t for post u re an d h ave a h igh den sit y of m u scle spin dles. Th ese m uscles lie in th e su boccipital region , deep to th e sem ispin alis capit is. Th ey have a close topographical relationship w ith the ver tebral ar ter y, th e suboccipit al n er ve th at su p plies th ese m u scles, an d th e greater occipital n er ve. From C2 d ow nw ard, th e cer vical ver tebrae ar t iculate via obliquely posit ion ed facet join ts an d relat ively th ick in ter ver tebral d isks. Th e ad u lt an u lu s brosu s of t h e d isks is u su ally in com p lete posteriorly. Th is de cien cy is rein forced by th e posterior longit udin al ligam en t . At th e level of C3 to C7 sm all un covertebral join ts develop in th e lateral par ts of th e in terver tebral disks after th e age of 10. Th ese join t s con t ribu te to m obilit y an d stabilit y. Th e p osterior relat ion sh ip s of th e cer vical spin e in clu de th e n uch al ligam en t an d th e dorsal m uscles. Th e n u ch al ligam en t is a bilam in ar in term u scular sept u m th at p rovides at t ach m en t for m u scles. Easy access to t h e ver tebrae is obtain ed bet w een th e layers of th e ligam en t . Th e dorsal m u scles form a greater m u scle m ass th an th e prever tebral m u scles becau se m ost body w eigh t is an terior to th e spin e. Th ey are divided into super cial, interm ediate, and deep grou ps, of w h ich on ly th e deep m uscles are t ru e in t rin sic back m u scles. Th ey h ave a m u lt ilayered arrangem en t an d are divided in to th e splen iu s m uscles, erector spin ae com pon en ts, an d t h e t ran sversosp in alis grou p . Th e lat ter grou p in cludes th e sem ispin alis capit is, w h ich is visible as a longit udin al bulge n ext to th e m id lin e. Im portant anterior relationships include the viscera of th e n eck, th e st ruct ures in side th e carot id sh eath , th e cer vical p lexu s, th e sym path et ic t ru n k, an d t h e recu rren t lar yngeal n er ve. An an ter ior ap p roach to t h e cer vical sp in e m ay go bet w een th e visceral an d n eu rovascu lar com p ar t m en ts.

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Chapter 1 Pearls Recognize that the cervical spine is the m ost m obile part of the vertebral column. Recognize the distinctive features of the cervical vertebrae, including those of the at ypical vertebrae. Be aware of the multilayered arrangement of the intrinsic back m uscles. Recognize the wide range of m ovement of the craniovertebral joints. Understand the importance of the suboccipital muscles as postural m uscles. Understand the disposition of the components of the deep cervical fascia and the creation of compartm ents.

Pitfalls Do not overlook the factors that maintain stabilit y in the craniovertebral joint s. Do not overlook the precise course of the vertebral artery and the nerves in the suboccipital region. Do not overlook the course of the neural structures anterior to the cervical spine.

Refere nces Five Must-Read Refe rences 1. Duray SM, Morter HB, Sm ith FJ. Morphological variat ion in cer vical spinou s processes: poten t ial applicat ion s in th e foren sic iden t i cat ion of race from th e skeleton . J Foren sic Sci 1999;44:937–944 Pu bMed 2. Reesin k EM, Wilm in k JT, Kingm a H, Lat aster LM, van Mam eren H. Th e in tern al ver tebral ven ou s p lexu s p reven t s com p ression of t h e du ral sac d u r ing at lan to-axial rot at ion . Neu rorad iology 2001;43:851– 858 Pu bMed 3. Wisem an O, Logan B, Dixon A, Ellis H. Tor t u osit y in th e cer vical par t of th e ver tebral ar ter y. Clin An at 1994;7:26–33

4. Mercer S, Bogdu k N. Th e ligam en t s an d an n u lu s brosu s of h u m an adu lt cer vical in ter ver tebral d iscs. Spine 1999;24:619–626, discussion 627–628 PubMed 5. Hart m an J. An atom y an d clin ical sign i can ce of th e un cin ate process an d u ncovertebral join t: a com prehensive review. Clin Anat 2014;27:431–440 PubMed 6. Lieberm an n -Me er t DM, Walbrun B, Hieber t CA, Siew er t JR. Recu rren t an d su p erior lar yngeal n er ves: a n ew look w ith im plicat ion s for th e esoph ageal su rgeon . An n Th orac Surg 1999;67:217–223 Pu bMed

2 Biomechanics of the Cervical Spine : From the Normal State to the Injury State Ahmer K. Ghori, Dana Leonard, and Thomas Cha

■ Introduction Cer vical sp in e inju ries are com m onp lace an d generally occur in a bim odal distribution: young pat ien ts in th e set t ing of h igh -en ergy t rau m a and elderly patients in the setting of low -energy falls. Cer vical t raum a can be categorized in to speci c injur y pat tern s result ing from ch aracteristic m ech anism s, m ost com m on ly involving com p ression , exion /exten sion , or rot at ion al force vectors. To un derst an d th e injur y state, on e n eeds to rst un derstan d th e an atom y of the cervical spine, in cluding th e num erous, varied st ruct ures th at stabilize it , an d th e biom ech an ics t h at allow for it s p hysiological range of m ot ion . Th is ch apter describes th e relat ion sh ip bet w een th e biom echanics of th e cervical spine an d cer vical t rau m a, an d review s t h e recogn izable inju r y p at tern s th at can occu r w h en st abilizing st r u ct u res in th e cer vical sp in e are disru pted by sp eci c force vectors. Alth ough at t ribu t ing speci c force vectors to inju r y p attern s is a sim pli cat ion of act ual t raum a, it en ables a greater understanding of cer vical traum a in th e set t ing of n orm al biom ech an ics.

■ Biomechanics: Functional

Anatomy and Stability Un derstan ding cer vical an atom y is cru cial to u n derst an ding cer vical biom ech an ics. Th e cer-

vical spin e con sist s of seven vertebrae align ed on average in 20 to 40 degrees of lordosis. Th e fu n ct ion al an atom y of th e cer vical sp in e can be divided in to u pper an d low er cer vical spin e, each w ith it s u n iqu e feat u res. A com plex set of osseous an d ligam en tou s st r uct ures m ain tain s t h e st abilit y of t h e cer vical sp in e w it h in t h e ran ge of p hysiological m ot ion , allow in g t h e sp in e to su p p or t t h e h ead at th e occip itocervical ju n ct ion ; to ex, exten d , an d rot ate; to ar t iculate w ith th e body at th e cer vicoth oracic jun ct ion ; an d to protect th e spin al cord, ver tebral ar ter y, an d n er ves.1

Functional Anatomy: Upper Cervical Spine Th e u pp er cer vical spin e is com p osed of th e C1 ver tebra, C2 ver tebra, an d th eir respect ive art icu lat ion s: th e occip itocer vical join t an d th e atlan toaxial join t . A com p lex set of ligam en ts st abilizes th e u p p er cer vical spin e an d facilitates physiological m ot ion .

C1 Vertebra Th e C1 ver tebra, also called th e atlas, is th e on ly purely ring st r uct ure in th e cer vical spin e. It is com p osed of an an ter ior an d p oster ior arch lin ked on eith er side by relat ively large lateral m asses. It has concave superior articular facets th at ar t iculate w ith th e convex occipit al con dyles; th is convex-on -con cave ar t icu lat ion

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Chapter 2 en ables exion -exten sion at t h e occip itocervical join t .2 Th e in ferior facet s of C1 are convex an d ar t iculate w ith th e convex su perior facet s of C2; th is convex-on -convex ar t iculat ion en ables rot at ion at th e C1- C2 join t .

C2 Vertebra Th e C2 ver tebra, also called t h e a xis, is a t ran sit ion al segm en t w it h bot h u n iqu e m or p h om et ric feat u res an d sh ared elem en ts w ith th e su baxial cer vical sp in e. An teriorly it h as an odontoid process that articulates w ith the anterior arch of C1. Th e su p erior an d in ferior facet s are o set in th e sagit tal plan e, w ith th e superior facet being m ore an terior th an th e in ferior facet . Th is o set gives rise to an elongated pars articularis that is oriented approxim ately 45 degrees in th e sagit tal plan e. Th is sagit tal o set places d isp rop or t ion ately h igh st ress on th e C2 pars, giving rise to th e poten t ial for inju r y an d in st abilit y, as discussed later in th is ch apter.

Occipitocervical Joint Th e occip itocer vical (OC) join t is devoid of a disk; th erefore, stabilit y is derived from th e ball-an d-socket join t for m ed by t h e convex occip it al con dyles ar t icu lat ing w ith th e con cave C1 su p erior facet s. Th is join t is t h e on ly w eigh t-bearing art iculat ion bet w een th e h ead an d th e spin e an d is suppor ted by a th ick join t . Mot ion in th e OC join t is p red om in an tly n u t at ion al (n odding) an d, w ith in th e physiological range of 50 degrees of m ot ion , does n ot resu lt in an terior to p osterior t ran slat ion d u e to con form it y of th e atlan tal socket an d st rong st abilizing rest rain t from th e tectorial m em bran e, w h ich is th e cran ial con t in uat ion of th e posterior longit u din al ligam en t (PLL) Th e cran ial con t in u at ion of th e an terior longit u din al ligam en t (ALL) also st abilizes th is join t , bu t to a lesser exten t . Th e alar ligam en t s, w h ich origin ate on th e odon toid an d in sert on each occip it al con dyle, are th e p rim ar y rest rain t to axial rot at ion in th e up p er cer vical sp in e.3,4

Atlantoaxial Joint Both th e in ferior facets of C1 an d th e su p erior facets of C2 are convex, w h ich en ables th e pre-

d om in an t ly rot at ion al m ot ion in t h e at lan toa xial join t; 50 d egrees of rot at ion is n orm al. As th e atlas rot ates aroun d th e odon toid, th e ipsilateral lateral m ass slides backw ard an d m edially w h ile th e con t ralateral lateral slides for w ard an d m edially.5 Th e prim ar y stabilizer for posterior displacem en t of th e atlas is th e odon toid process, w h ereas an terior displacem en t is resisted by th e t ran sverse atlan t al ligam en t ,6 w ith secon dar y con t ribu t ion s from th e C1–C2 join t capsule, an d th e apical ligam en t . Th e p rim ar y st abilizers to a xial rot at ion at C1–C2 in clu de th e alar ligam en t s (at t ach ing the skull to the odontoid process) and joint cap sule. Ext rin sic st abilizers in clu de th e p araspin al m uscles, th e ligam en t um n u ch ae, an d th e in terspin ou s ligam en ts.

Functional Anatomy: Subaxial Spine Th e C3 th rough C7 ver tebrae h ave sim ilar m orph ology an d stabilizing ligam en tou s st ru ct u res an d are d iscu ssed toget h er as t h e t yp ical cervical ver tebrae. Th ere are th ree m ain an atom ic st r u ct u res t h at con t r ibu te to st abilizat ion of th e ver tebrae in t h e su ba xial cer vical sp in e: th e u n cin ate p rocess, t h e facet join t s, an d t h e circu m feren t ial ligam en tou s bu t t ress of ALL an d PLL. The uncinate process, w hich is a bony projection on the dorsolateral-superior aspect of each ver tebral body, ar t icu lates w ith th e in ferior aspect of th e cran ial ver tebral body. Con cept ually, on e can con sider th em to be organ ized in a st acked ow er-pot fash ion . Th e u n cover tebral ar t icu lat ion adds stabilit y to th e cer vical sp in e by lim it ing lateral ben ding.7 Th e facet joints in the subaxial cer vical spine are oriented 45 degrees below horizon tal in the sagit t al plan e. Th is orien t at ion en ables exion exten sion of th e subaxial cer vical spin e, w h ich gen erates 50% of cer vical exion -exten sion . Th e facets also m ain ly resist a xial com pression forces, t ypically absorbing 20 to 30% of com pressive load s 8 w h ile also provid ing resist an ce to hyp er exion an d sh ear forces. Th e circum feren t ial ligam en tous but t ress is created by t h e ALL, PLL, an d in tersp in ou s ligam en ts.2 Th ese ligam en ts st abilize th e spin e by

Biomechanics of the Cervical Spine preven t ing m ot ion beyon d th e physiological range.

Functional Stability Th e n orm al cer vical sp in e is able to w ith st an d physiological loads, m ain tain a n orm al p osture, and protect n eural elem ents w ithout pain. Sp eci c st abilizing m ech an ism s in respon se to th ree t yp es of forces are discu ssed h ere.

Compression Th e st ru ct u res th at bear com pressive forces are th e ver tebral colu m n an d disks. Th e ver tebral en d p lates ten d to fail before th e disks w h en supranorm al com pressive forces are applied.9,10

Flexion and Extension Flexion forces are n eu t ralized by th e p araspin al m u scles, supraspin ous ligam en t , in terspinous ligam en t, facet joint/capsule com plex, and ligam en t u m avu m . Cadaveric st u d ies h ave sh ow n th at exion in stabilit y correlates best w ith injur y to th e in terspin ou s/su praspin ous ligam ents, and ligam entum avum , w hereas exten sion in st abilit y correlates best w ith disrupt ion of th e ALL, disrupt ion of th e disk’s en d plate, an d capsu lar injuries.11,12

Rotation In th e upper cer vical spin e, th e alar ligam en t s are th e prim ar y rot ator y rest rain t , w ith con t ri-

but ion s from th e OC join t capsule, tectorial m em brane, and transverse ligam ent. In the subaxial spin e, th e in ter ver tebral disk, facet join ts/ cap su le, an d posterior ligam en tou s com plex all ser ve as rotator y rest rain ts.

■ Biomechanics: De ning

Instability Th e com plex biom ech an ics of th e cer vical spin e m ake it di cult to h ave a un ifying system th at ch aracterizes in stabilit y. W h ite an d Panjabi13 described th e p hysiological m ot ion in a n orm al cer vical spin e (Table 2.1), an d den ed st abilit y as th e “abilit y of th e sp in e u n der physiologic loads to lim it pat tern s of disp lacem en t so as n ot to dam age or irrit ate th e sp in al cord or n er ve root s an d, in addit ion , to preven t in capacitat ing deform it y or p ain du e to st ruct u ral ch anges.” In th e occip itocer vical ju n ct ion , in st abilit y is suggested w h en axial rotat ion on on e side is greater than 8 degrees an d th ere is m ore th an 1 m m of t ran slat ion bet w een th e basion an d th e od on toid w ith exion /exten sion . At th e atlan toaxial ju n ct ion , in stabilit y is suggested w h en th ere is a com bin ed lateral overh ang of C1 on C2 in excess of 7 m m , u n ilateral rotat ion of C1- C2 of m ore th an 45 degrees, an atlan to– dens interval (ADI) greater than 3 m m , and space available for th e cord (SAC) less th an 13 m m .14 In th e suba xial cer vical spin e, in st abilit y is suggested w ith t ran slat ion in th e sagit t al p lan e

Table 2.1 Normal Motion of the Cervical Spine (in Degrees) Segment C0-C1 C1-C2 C2-C3 C3-C4 C4-C5 C6-C7 C7-T1

Flexion/ Extension

Lateral Bending

Rotation

25 20 10 15 20 17 9

5 5 10 11 11 7 4

5 40 3 7 7 6 2

Source: Adapted from White AA, Panjabi MM. Clinical Biom echanics of the Spine, 2nd ed. Philadelphia: Lippincot t; 1990.

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Chapter 2 greater than 3.5 m m or 20%on exion/extension rad iograp h s, or sagit tal plan e angu lat ion m ore th an 11 degrees on rest ing lateral radiograph s. Ot h er factors t h at suggest in st abilit y in clu d e d isr u pt ion of an ter ior or p oster ior colu m n s, spin al cord or n er ve root inju r y, congen ital cervical sten osis (SAC < 13 m m ), an d abn orm al disk sp ace n arrow ing.2 Determ in ing in st abilit y in th e case of ligam en t inju r y can be p ar t icu larly ch allenging. Cadaveric st u dies h ave sh ow n th at th rough ou t th e cer vical sp in e, st ru ct u ral in tegrit y is m ain tained as th e su praspin ous/in terspin ous ligam en t s are t ran sected , bu t becom es u n st able as th e PLL is t ran sected .14 Th erefore, it is im por tan t to iden t ify posterior ligam en tou s in tegrit y w h en evaluat ing th e stabilit y of th e t rau m at ic cer vical spin e. Tradit ion ally, exion /exten sion and open-m outh radiographs w ere used to help iden t ify ligam en tou s inju r y, bu t m agn et ic reson an ce im aging (MRI) has n ow replaced th ese m odalit ies, as it is far m ore sen sit ive an d sp eci c. Fur th erm ore, MRI is safer th an dyn am ic im aging in th e acu te set t ing.

■ Biomechanics: The Injured

Cervical Spine By di erentiating the t ypes of force vectors, cervical t rau m a can be categorized in to speci c injur y pat tern s th at can be un derstood based on th e biom ech an ics of th e cer vical spin e. Alth ough th is organ izat ion al app roach is a sim pli cat ion , as m ost sp in e t rau m a is th e resu lt of a com plex an d unpredictable force vectors, it h elps explain t rau m a in th e con text of n orm al biom ech an ics.

Flexion Injuries Flexion inju ries are th e resu lt of rapid accelerat ion or d ecelerat ion of th e sp in e as th e torso st ays in p lace w h ile th e h ead keep s m ovin g. W it h hyp er exion , t h e an ter ior elem en t s fail u n d er com p ression w h ile th e p oster ior elem en t s exp erien ce ten sile failu re. Depen ding on th e posit ion of th e axis of rotat ion , exion injuries can resu lt in exion -com pression or

exion -dist ract ion inju r y pat tern s. Th e spect ru m of injur y can range from a sprain to gross in st abilit y, w ith n eurologic com prom ise depen ding on th e am ou n t of en ergy im p ar ted in th e t rau m a. Th e p osterior ligam en tou s st ru ct u res p rogressively fail u n der ten sion , star t ing w ith the supraspinous ligam ent, then the interspinous ligam ent and the ligam entum avum , an d n ally th e PLL. Plain radiograph s can be deceivingly ben ign , as ligam en tou s st ru ct u res are n ot visualized an d on e m ust rely on subtle secon dar y m arkers of in st abilit y su ch as in terspin ou s w iden ing, local kyph osis, an d disk sp ace w iden ing. Flexion /exten sion im aging sh ou ld be avoided in th e set t ing of t raum at ic exion injuries as it can exacerbate an already u n st able sp in e. MRI is t h e im agin g m odalit y of ch oice to ch aracterize th e inju r y p at tern , as it is h igh ly sen sit ive an d speci c, an d h elps in guiding t reat m en t . Several t ypes of inju ries can be seen w ith a exion force, an d th e m ain on es are sum m arized in th e follow ing subsect ion s.

Clay-Shoveler’s Fracture Th is is an avu lsion p rocess of th e spin ou s p rocess, t ypically at C7.15 It result s w h en a exion m om en t overcom es th e ten sion ban d e ect of the in terspinous ligam en ts, leading to bony failure at th e t ip of th e spin ou s p rocess.

Posterior Ligamentous Injury A exion m om en t can lead to pure ligam en t inju r y on a scale from m in or n eck sprain to com p lete disru pt ion of posterior ligam en tou s st r u ct ures. In p urely ligam en tou s injur y, in it ial radiograp h s m ay sh ow n orm al align m en t . Th e on ly suggest ion of inju r y m ay be su bt le in tersp in ou s w id en in g, en d -p late an gu lat ion , or local kyp h osis. In som e cases th e ligam en tou s inju r y can p rogress if t h e p oster ior ten sion ban d is u n able to tolerate p hysiological load ing. Som e literat u re dem on st rates a 30 to 50% in cid en ce of d elayed in st abilit y.16 Th erefore, an MRI sh ou ld be obtain ed to ru le out posterior ligam en tous inju r y if it is suspected from the m echanism of injur y, the exam ination (posterior n eck pain ), or su btle n dings on plain radiograph s.17

Biomechanics of the Cervical Spine

Simple Wedge Compression Fractures Th e exion m om en t cau ses an terior ver tebral bodies im pingem ent, w hich can w edge the disk th rough th e en d plate.18 Th is gives rise to a com p ression fract u re w ith cen t ral disk d ep ression . Typically th e posterior elem ents are intact; h ow ever, a posterior ligam en tous injur y can n ot be exclu ded based on st at ic radiograph s.

Flexion-Compression (Teardrop Fracture) In th is pat tern of inju r y th e posterior elem en ts fail un der ten sion an d th e axis of rotat ion lies w it h in t h e ver tebral body, givin g r ise to t h e an terior-in ferior ver tebral body fract ure. Dep en d ing on t h e am ou n t of force, t h is inju r y m ay be st able or u n st able. In low er en ergy m ech an ism s, t h e PLL rem ain s in t act , t h e an ter ior an d p oster ior sp in al colu m n s m ain t ain th eir align m en t , an d t h e on ly suggest ion of p ath ology m ay be th e bony inju r y an d subtle in tersp in ou s w iden ing. With m ore en ergy, th e posterior in ferior ver tebral body m ay su blu x in to th e can al, an d th e m ost severe form of th is injur y occu rs w h en th e PLL is torn , leading to sign i can t fragm en t ret rop u lsion an d likely n eural inju r y.2

Flexion-Distraction Injury In th is injur y pat tern , th ere is a exion m om en t an d th e axis of rot at ion is an terior to t h e ver tebral body. Th e sp ect r um of inju r y ranges from posterior elem ent sprain to com plete posterior elem en t an d disk space disrupt ion , result ing in an terior posterior colum n in st abilit y. In early inju r y st ages, bilateral facet sublu xat ion m ay resu lt from th e exion dist ract ion force.2 With m ore force, th e inju r y m ay p rogress to bilateral “perch ed” face, as th e in ferior ar t icu lar facet is displaced su p erior an d an terior to th e superior ar t icular facet . Th e m ost severe instance of an injury caused by a exiond ist ract ion force is a bilateral facet dislocat ion , w h erein t h e in fer ior ar t icu lar p rocesses lie an terior to th e su perior ar t icular process. Th is injur y is often associated w ith a ten sile failu re of th e disk space an d fract u res of t h e lateral m ass, pedicle, lam in a, or spin ous process. In 50

to 60% of cases t h e ver tebral ar ter y is inju red as w ell.19 Excess of 50% an terior t ran slat ion of th e su p erior ver tebra, w h ich can t yp ically be seen on lateral radiograph s, m ay suggest a h igh likelih ood of n eurologic inju r y.2

Flexion-Translation Injury A exion -t ran slat ion vector force on th e cer vical spin e leads to bilateral facet inju ries. Th e inju r y pat tern m ay be p u re su p erior art icu lar process fract u res, p u re in ferior ar t icu lar p rocess fract ures, or a com bin at ion of both .20 Un like facet d islocat ion s, facet fract u res are n ot associated w ith capsular disrupt ion . Th e posterior ligam en tous com plex m ay be st retch ed but is n ot disrupted. How ever, if th e exion t ran slat ion force is cou p led w ith ten sile force, th en th e posterior ligam en tou s com plex m ay be torn an d associated ten sile fract u re, su ch as lam in ar or p edicle fract u res, can also occu r.21 If th ere is a sh ear com p on en t to th e force, it m ay also disru pt th e p osterior ligam en t s an d p rogress to disk disru pt ion as w ell.2

Flexion-Rotation Injury Flexion m om en t com bin ed w ith a rot at ion al torqu e can lead to eit h er u n ilateral facet fract u re or u n ilateral facet d islocat ion . Su p er ior facet fract u res are m ore com m on t h an in ferior facet fract ures.22 With dislocat ion , th e facet cap su le is disru pted, bu t w ith facet fract u re th e cap su le rem ain s in t act . How ever, th e in t act cap su le m ay recoil th e fract u red fragm en t in to th e n eu ral foram en , cau sing n eu rologic sym p tom s. Un ilateral facet dislocat ion s can be associated w ith t ran slat ion of th e cran ial ver tebrae, but th is is lim ited to 25% if th e injur y is t ruly un ilateral.2

Flexion-Lateral Bending Un cin ate process fract ures result from a pure exion -lateral ben ding force on t h e cer vical spin e.23 How ever, cer vical sp in e m ot ion is cou p led such th at lateral ben ding usu ally causes rot at ion; th us, pu re exion -lateral ben ding in ju ries are exceedingly rare.2

21

22

Chapter 2

Flexion Injuries of the Upper Cervical Spine Severe exion inju r y w ith h orizon t al sh eer or dist ract ion can disru pt th e ligam en tou s st ru ct u res stabilizing th e occip itocer vical ju n ct ion an d lead to an an terior occipitocer vical dislocat ion . Th is is often a fatal inju r y, an d even w h en n ot fat al it is often m issed du ring in it ial t rau m a evalu at ion . Th erefore, ever y cer vical spin e com puted tom ography (CT) scan sh ould in clu de th e occipitocer vical ju n ct ion , an d th e t reat ing su rgeon m u st pay close at ten t ion to rule ou t th is injur y using lateral radiograph s an d th e CT scan .

Extension Injuries Exten sion inju ries t yp ically are th e resu lt of rap id accelerat ion or decelerat ion w h en th e h ead stops an d th e body keeps m oving, or a fall in older in dividu als w ith fron t al h ead st rike. With hyperextension the posterior elem ents fail u n der com p ression , w h ereas an terior elem en t s exp erien ce ten sile failu re. Th e inju r y sp ect ru m m ay begin w ith an ALL tear. Addit ion al ten sile or sh eer force m ay lead to disru pt ion of th e disk space or com pressive fract u res of th e lam in a, facet s, or sp in ou s p rocess. Th e term in al en d of th is inju r y sp ect r u m is posterior t ran slat ion of t h e ver tebral body leading to cord com p ression . In cases of p u re ligam en tou s in jur y, in it ial inju r y p lain radiograph s m ay be deceivingly reassu ring, as th e on ly m arker of injur y m igh t be a sligh tly sh -m outh ed an terior disk sp ace. In cases of bilateral facet fract u res, th ere m ay be a disk sp ace inju r y, w h ich m akes th e overall pat tern u n st able an d m ay on ly be detectable w ith a MRI. Th e t reat ing su rgeon m u st m ain tain a h igh level of su spicion for th ese inju ries, par t icularly in pat ien ts w ith congen ital sten osis/degen erat ive spon dylosis or in p at ien ts w ith a fu sed cer vical spin e su ch as th ose w ith an kylosing spon dylit is or di u se idiop ath ic skeletal hyperostosis (DISH). Pat ien t s w ith congen it al sten osis are m ore likely to experien ce n eu rologic de cit s from direct com pression , or in com p lete cord inju r y such as cen tral cord syndrom e. In patien ts w ith fused cervical spines, hyperexten sion injur y can resu lt in an inju r y sim ilar to a long bon e frac-

t u re, resu lt ing in gross in st abilit y at th e inju r y level.24 Patients w ith ankylosing spon dylitis are also at h igh er risk for excessive bleeding from th e disk space inju r y, w h ich can result in p rogressive n eu rologic declin e.25

Lateral Mass Fracture -Separation Exten sion -rotat ion leads to a lateral m ass fract u re-sep arat ion ; th is is de n ed as an ip silateral pedicle an d lam in a fract u re leading to a oating lateral m ass. Depen ding on th e en ergy im p ar ted , t h e lateral m ass m ay be d islocated , w h ich w ould lead to in st abilit y at th e superior an d in ferior levels. Th e m ajorit y of in st abilit y occu rs at th e level of injur y or level in ferior to th e injur y.26

Hyperextension Injuries of Upper Cervical Spine Hyperextension leads to a com pressive force on the posterior arch of C1, as it is im pinged bet ween the occiput and posterior elem ents of C2. A pure hyperextension injury w ould lead to just a posterior arch fract ure of C2. If th e exten sion is coupled w ith axial load, then a bilateral anterior an d p osterior arch fract ure (Je erson fract u re) m ay be seen .27 Th is inju r y places ten sile st rain on th e t ran sverse ligam en t , an d can lead to a m idsu bst an ce tear of th e t ran sverse ligam en t or an avulsion fract ure o the lateral m ass. Th is can be an un stable injur y pat tern , an d a com bin ed lateral m ass overh ang of m ore th an 7 m m suggest s an u n st able biom ech an ical situation . Tensile force on the an terior C1 m ay lead to an anterior avulsion fract ure of C1, w here the ALL an d longu s colli in ser t . Th e hyperexten sion force m ay be com bin ed w ith oth er forces su ch as lateral ben ding, axial load, an d rot at ion . These com bined force vectors m ay result in any com bination of C1 anterior arch, posterior arch, lateral lass, or t ran sverse process fract u res.

Axis Fractures Axial load coupled w ith hyperextension leads to a shear stress on the pars interarticularis of C2.2 Th is can lead to bilateral C2 pars fract u re, also kn ow n as a h angm an’s fract u re. After th e in it ial inju r y, exion or dist ract ion m om en t s m ay

Biomechanics of the Cervical Spine lead to any com bin at ion of dist ract ion an d d isplacem ent, w hich can lead to neurologic injury. Hyperexten sion inju r y cou p led w ith severe sh eer or d ist ract ion can lead to a p oster ior at lan to-occipit al dislocat ion . As discu ssed earlier, th e t reat ing su rgeon m u st p ay close at ten t ion to r u le ou t t h is inju r y in t h e t rau m a set t ing.

Atlantoaxial Subluxation and Dislocation Disrupt ion of th e stabilizing ligam en t s aroun d th e C1- C2 join t can lead to several d i eren t injur y pat tern s th at result in sublu xat ion or dislocat ion of th e atlan toaxial join t . With hyper exion , th e t ran sverse ligam en t ser ves as th e rest rain t to an ter ior disp lacem en t of C1.2 If th is is torn or if th e odon toid fract ures below th e ligam en t , t h en t h e at las su blu xates an ter iorly an d w it h en ough force an an ter ior at lan toa xial dislocat ion m ay be seen . With a hyperexten sion force, a posteriorly displaced odon toid fract ure m ay resu lt , w ith a posterior atlan toaxial su blu xat ion or dislocat ion .2 Rotator y stabilit y of th e atlan toaxial join t com es prim arily from th e alar ligam en t s, w ith secon dar y con t ribut ion from th e t ran sverse ligam en t , tectorial m em bran e, an d facet capsu les. With en ough rotator y torqu e th ese st ru ct ures can fail, lead in g to rot ator y su blu xat ion or dislocat ion .28

■ Chapter Summary Understanding the anatom ic osseoligam entous st r u ct u res th at m ain t ain st abilit y in th e cer vi-

cal spin e th rough th e physiological range of m ot ion is im port an t in recogn izing th e inju ries th at can result from th e applicat ion of speci c force vectors an d t h e failu re of on e or m ore of th ose st abilizing st r uct u res. Depen ding on th e exten t of injur y, th e cer vical sp in e m ay n ot be able to su p p or t t h e h ead or tolerate p hysiological loads w h ile st ill p rotect ing th e sp in al cord. In it ial radiograp h s can be decept ively ben ign becau se severe ligam en tou s inju r y m ay n ot be d etected on p lain X-rays if t h e overall align m en t is m ain t ain ed . MRI p lays a large role in id en t ifyin g ligam en tou s in st abilit y an d h as becom e an in tegral part of evaluat ing cer vical t rau m a. To su ccessfu lly t reat p at ien ts, th e su rgeon m u st un derst an d th e fun ct ion al an atom y, th e role it plays in th e biom ech an ics th at m ain t ain th e stabilit y of th e cer vical sp in e, an d h ow sp eci c force vectors can lead to recogn izable inju r y pat tern s.

Pearls One needs to understand norm al cervical anatomy and biomechanics, because cervical traum a can be organized into discrete forces that disrupt the norm al biom echanics. Upright cervical spine radiographs serve as a useful tool to assess functional (with gravit y) stabilit y of osteoligam entous structures. Pitfall Plain radiographs can miss severe ligamentous injury if the overall alignm ent is maintained. MRI plays a large role in identifying ligamentous instabilit y and has becom e an integral part of evaluating cervical traum a.

Refere nces Five Must-Read Refe rences 1. Voo LM, Pin t ar FA, Yogan an dan N, Liu YK. St at ic an d dyn am ic ben ding respon ses of th e h um an cer vical spin e. J Biom ech Eng 1998;120:693–696 PubMed 2. Savas PE. Biom ech an ics of th e inju red cer vical spin e. In : Vaccaro AR, eds. Fract ures of th e Cer vical, Thoracic, an d Lu m bar Sp in e. New York: Marcel Dekker; 2003:23–44 3. Dvorak J, Panjabi MM. Fu n ct ion al an atom y of th e alar ligam en t s. Spin e 1987;12:183–189 Pu bMed

4. Dvorak J, Sch n eid er E, Sald inger P, Rah n B. Biom ech an ics of t h e cran iocer vical region : t h e alar an d t ran sverse ligam en t s. J Or t h op Res 1988;6:452–461 Pu bMed 5. Bogduk N, Mercer S. Giom ech an ics of th e cer vical sp in e. I: Norm al Kin em at ics. Clin Biom ech (Bristol, Avon ); 2000;15:633-648. 6. Fielding JW, Coch ran Gv, Law sing JF III, Hoh l M. Tears of th e t ransverse ligam en t of th e atlas. A clin ical an d

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Chapter 2 biom ech an ical st udy. J Bon e Join t Su rg Am 1974;56: 1683–1691 Pu bMed 7. Clausen JD, Goel VK, Trayn elis VC, Scifert J. Un cin ate processes an d Lusch ka join t s in uen ce th e biom ech an ics of th e cer vical spin e: quan t i cat ion using a nite elem en t m odel of th e C5- C6 segm en t . J Or th op Res 1997;15:342–347 PubMed 8. Maim an DJ, San ces A Jr, Myklebust JB, et al. Com pression injuries of th e cer vical spin e: a biom ech an ical an alysis. Neurosu rger y 1983;13:254–260 Pu bMed 9. Maim an DJ, Yogan an dan N. Biom ech an ics of cer vical sp in e t rau m a. Clin Neu rosu rg 1991;37:543–570 PubMed 10. Brow n T, Han son R, Yorra A. Som e m ech an ical test s on th e cer vical spin e w ith par t icu lar referen ce to th e inter vertebral discs. J Bone Join t Surg 1957;39:1135– 1141 PubMed 11. Panjabi MM, W h ite AA III, Joh n son RM. Cer vical spin e m ech an ics as a fun ct ion of t ran sect ion of com pon en t s. J Biom ech 1975;8:327–336 PubMed 12. Panjabi MM, Oxlan d TR, Parks EH. Quan t it at ive an atom y of cer vical spin e ligam en t s. Par t II. Middle an d low er cer vical sp in e. J Sp in al Disord 1991;4:277–285 PubMed 13. W h ite AA, Panjabi MM. Clin ical Biom ech an ics of th e Spin e, 2nd ed. Ph iladelph ia: Lippin cot t; 1990 14. W hite AA III, Panjabi MM. Update on th e evaluat ion of in st abilit y of th e low er cer vical spin e. In st r Course Lect 1987;36:513–520 Pu bMed 15. Can celm o JJ Jr. Clay sh oveler’s fract u re. A helpful diagn ost ic sign . Am J Roen tgen ol Radiu m Th er Nu cl Med 1972;115:540–543 Pu bMed 16. South ern EP, Pelker RR, Crisco JJ II, Panjabi MM. Posterior elem en t st rength six m on th s p ost inju r y in th e can in e cer vical sp in e. J Sp in al Disord 1993;6:155– 161 Pu bMed 17. Vaccaro AR, Falat yn SP, Flan ders AE, Balderston RA, Nor th r u p BE, Cotler JM. Magn et ic reson an ce evaluation of th e in ter ver tebral disc, spin al ligam en t s, an d spin al cord before an d after closed t ract ion reduct ion of cer vical spin e dislocat ion s. Spin e 1999;24:1210– 1217 Pu bMed

18. Crow ell RR, Sh ea M, Edw ard s W T, Clot h iau x PL, W h ite AA III, Hayes WC. Cer vical inju r ies u n der exion an d com p ression loading. J Sp in al Disord 1993; 6:175–181 Pu bMed 19. Willis BK, Grein er F, Orrison W W, Ben zel EC. Th e in cid en ce of ver tebral ar ter y inju r y after m idcer vical spin e fract ure or sublu xat ion . Neurosurger y 1994; 34:435–441, discu ssion 441–442 PubMed 20. Sh an m ugan ath an K, Mir vis SE, Levin e AM. Rot at ion al injur y of cer vical facet s: CT an alysis of fract ure pattern s w ith im plicat ion s for m an agem en t an d n eurologic outcom e. AJR Am J Roen tgen ol 1994;163:1165– 1169 Pu bMed 21. Yogan an dan N, Pin t ar FA, Maim an DJ, Cu sick JF, San ces A Jr, Walsh PR. Hum an h ead-n eck biom ech an ics un der axial ten sion . Med Eng Phys 1996;18:289– 294 Pu bMed 22. Levin e AM. Facet inju ries in th e cer vical sp in e. In : Cam in s MB, O’Lear y PF, eds. Disorders of th e Cer vical Spine. Baltim ore: William s & Wilkins; 1992:289–302 23. Lee C, Kim KS, Rogers LF. Triangu lar cer vical ver tebral body fract u res: diagn ost ic sign i can ce. AJR Am J Roen tgen ol 1982;138:1123–1132 Pu bMed 24. Kw on BK, Hilibran d AS. Man agem en t of Cer vical fract u res in p at ien t s w ith di u se idiop ath ic skelet al hyperostosis. Curr Opin Orthop 2003;14:187–192 25. Kw on BK, Vaccaro AR, Grauer JN, Fish er CG, Dvorak MF. Subaxial cer vical spin e t raum a. J Am Acad Orth op Su rg 2006;14:78–89 PubMed 26. Levin e AM. Facet fract ures and dislocat ion s. In : Levin e AM, Eism on t FJ, Gar n SR, Zigler JE, eds. Spin e Traum a. Ph iladelph ia: W B Saun ders; 1998:331–366 27. Jackson RS, Ban it DM, Rhyn e AL III, Darden BV II. Up p er cer vical sp in e inju ries. J Am Acad Orth op Su rg 2002;10:271–280 PubMed 28. Dvorak J, Panjabi M, Gerber M, Wich m an n W. CT-fu n ct ion al diagn ost ics of th e rot ator y in st abilit y of upper cer vical spin e. 1. An experim en tal st udy on cadavers. Spin e 1987;12:197–205 Pu bMed

3 Evaluation of an Injured Cervical Spine Richard Assaker, Fahed Zairi, and Xavier Demondion

■ Introduction In adult blun t t rau m a, cer vical spin e injuries rep resen t 2 to 6%of cases,1,2 an d on e th ird of all spin al injuries.3 For t y-th ree p ercen t of cer vical spin e injuries are considered clinically unstable. Ap p roxim ately 0.2%of th ese inju ries are m isd iagn osed an d m igh t resu lt in catast rop h ic n eu rologic lesion s. Evalu at ion of a t raum a pat ien t is crit ical to “r ule ou t” an d “clear” th e cer vical sp in e. Rapid discon t in u at ion of cer vical im m obilizat ion n eeds to be cou n terbalan ced again st th e risk of spin al cord inju r y as con sequ en ces of a m issed sp in e inju ries. Physician s in gen eral act defen sively an d ask for a com bin at ion of p lain radiograph s, com p u ted tom ograp hy (CT) scan s, an d m agn et ic reson an ce im aging (MRI) for th e evalu at ion of th e bony an d ligam en tou s st ruct ures of the cer vical spin e.4,5 On th e on e h an d , a m issed cer vical sp in e inju r y can lead to cat ast rop h ic con sequ en ces an d lit igat ion costs,6,7 bu t on th e oth er h an d m any com plicat ion s m ay occur if th e im m obilizat ion of pat ien t s by th e use of collars con t in ues for m ore t h an 72 h ou rs.8 Th e r isk of skin u lcers an d sores in creases by 66% for each day of addit ion al im m obilizat ion .9 To avoid m issin g cervical sp in e inju ries, clin ician s liberally order

advan ced im aging st udies th at , in th e m ajorit y of th e cases, t urn out to be n orm al. Th is policy in creases th e h ealth care costs an d th e u n n ecessar y exp osu re to ion izing radiat ion s.10,11 A p rop er evaluat ion (clin ical rst) m igh t clear th e cer vical spin e w ith n o n eed for fur th er in vestigat ions such as radiograph s or CT scans.12,13 Th is ch apter describes th e best cu rren t eviden ce-based cer vical sp in e clearan ce p rotocol, an d discusses a clin ical m eth od to iden t ify pat ien t s th at does n ot en tail im aging invest igat ion s. For p at ien t s w h o do requ ire im aging, th is ch apter discu sses th e t yp e of im ages th at are required in alert an d obt un ded pat ien t s.

■ Clinical Evaluation Th e goals of th e clin ical evalu at ion of a pat ien t w h o su st ain ed a blu n t cer vical t rau m a are to “clear” th e cer vical sp in e clin ically an d to id en t ify pat ien t s w h o require addit ion al radiograph ic invest igat ion s. In an alert p at ien t th is rst step sh ou ld be st raigh tfor w ard an d easy. In an u n con sciou s p at ien t w h o is clin ically n ot evalu able, th e clearan ce relies on im aging st udies on ly. Pat ien ts w ith severe h ead t raum a

26

Chapter 3 (low Glasgow Com a Scale [GCS] score) are at h igh risk of h aving cer vical spin e injuries, too. Su sp icion of a cer vical sp in e (C-sp in e) inju r y m u st be m ain t ain ed an d th e sp in e im m obilized u n t il fu ll clearan ce is p rovided by a p rop er clin ical an d radiograp h ic w orkup .

■ Radiological Assessment Plain Films Three -View Radiographs St an dard radiograp h s are often con sidered as th e in it ial screen ing rad iograp h ic evalu at ion in sym ptom at ic or obt u n ded t raum a pat ien t . Th e th ree-view p rotocol is u su ally th e st an dard exam : an teroposterior, lateral cer vical, an d odon toid view s (Fig. 3.1). In cer vical sp in e t rau m a, p lain lm s are accu rate en ough to detect 84% of all cer vical injuries.14 Lim itat ion s are tech n ical du e to in adequate exposure of th e cer vicoth oracic jun ction and the atlantoaxial com plex. In an obscured area, oblique view s or a CT is recom m en ded before discon t in uing cer vical im m obilizat ion .

Dynamic View s Adding to th e th ree-view radiograph , act ive exion exten sion view s in a sym ptom at ic an d aw ake pat ien t w ith n orm al plain stat ic lm s w ill in crease th e sen sit ivit y (99%) an d speci cit y (93%). Th ey are u su ally ordered to exclu de su sp ected diskoligam en tou s inju ries (Fig. 3.2). Th e valu e of t h ese view s in t h e acu te set t in g is debat able du e to p ossible false n egat ives becau se of m u scle sp asm s. In com atose patients w ith norm al three-view lm s, passive exion -exten sion radiographs are qu est ion able an d m igh t be d an gerou s. Pu re

ligam en tou s inju r ies are rare (0.4%), an d in alm ost all cases plain radiograph s an d CT are accurate for detect ing th ese injuries. In a series of 14,577 pat ien ts w ith cer vical t raum a, 2,605 pat ien ts w ere n ot evalu able an d 14 pat ien ts h ad isolated ligam en tous injur y detected on plain st at ic radiograph s or CT.15

Computed Tomography Scan High -qu alit y CT scan s su rpass radiograp h s in d etect ing cer vical sp in e inju r ies, esp ecially in obt u n d ed p at ien t s. Th e ease of access, t h e sp eed of t h e st u dy, an d t h e sen sit ivit y an d speci cit y of CT m akes it th e m odalit y of ch oice in m any t rau m a cen ters. In addit ion , CT evalu at ion h elps in de n ing th e p at tern , m orph ology, an d possible m ech an ism of th e fract u res, an d con sequen tly h elps to determ in e th e ap prop riate t reat m en t st rategies (Fig. 3.3). In a series of 1,199 patients evaluated by plain lm s an d CT, 41 pat ien ts w ere m issed by plain lm s an d detected on ly by th e CT; all 41 n eeded addit ion al t reat m en t .16 Com puted tom ography scan s out perform ed plain radiograph s in pat ien ts w ith cer vical t raum a, w ith h igh er p redictabilit y an d accu racy, and consequently CT scan is recom m ended as th e rst screen ing im aging for obt un ded clin ically u n evalu able p at ien t s (h igh -r isk p at ien t s).17–20 If h igh -qu alit y CT im aging is available, there is n o in dicat ion for ext ra plain radiograph s. A II m edical evid en ce st u dy Vangu ri et al21 con clu ded th at CT is 100% sen sit ive in d etectin g bon e an d ligam en tou s inju r ies in blu n t cer vical t rau m a. CT alon e is en ough to ru le ou t C-sp in e inju r ies w it h ou t t h e n eed for ad d it ion al im aging. In a ret rospect ive st u dy, Gargas et al22 foun d th at MRI is n ot su p erior to m u lt islice CT scan w ith sagit tal and coronal reconstructions in the pediat ric t rau m a populat ion .

Evaluation of an Injured Cervical Spine

27

Fig. 3.1a–c The classic three-view  lms:  (a) odontoid, (b) lateral, and (c) anteroposterior views. Note the obscured area at the cervicothoracic junction.

a

b

c

28

Chapter 3

a

b

Fig. 3.2a,b C1-C2 instabilit y detected on  exion views.

Magnetic Resonance Imaging In a sym ptom at ic pat ien t w ith n orm al radiograph s or CT scan , MRI can be u sed to exclu de diskoligam en tou s inju ries.23 Tim ing is im por tan t; it sh ou ld be p er for m ed w it h in 48 h ou rs to detect th e abn orm al signals of soft t issue inju r ies.24 Th e sh or t t au inversion recover y (STIR) sequ en ces are su it able to evalu ate t h e p osterior ligam en t s an d th erefore con rm th e t yp e an d pat tern of inju r y. In ad d it ion , MRI h as t h e ad van t ages of assessin g t h e sp in al cord p are n ch ym a in a p at ien t w it h sign s of t rau m at ic m yelop at hy (Fig. 3.4).

In a recen t st u dy, Kh an n a et al24 evalu ated MRI in obt u n d ed p at ien t s (GCS < 13), w ith ou t obviou s n eu rologic d e cit s an d n or m al CT scan n dings. Th ey con cluded th at “th e addit ion of a cer vical MRI to th e evalu ation p rotocol of obt u n ded or com atose p at ien t s w ith an oth er w ise n orm al n eu rologic exam in at ion an d a n orm al cer vical CT did n ot provide any addit ion al u sefu l in form at ion to ch ange th e m an agem en t of th ese p at ien t s.” Th e lim itat ion s of MRI are due to th e t im e n eeded to t ran sfer th e pat ien t to th e MRI suite an d to obt ain th e evaluat ion , an d to th e difcu lt ies involved in m on itoring com atose p at ien t s w h o are ven t ilated . In add ition , MRI’s

Evaluation of an Injured Cervical Spine

a

c

b

d

Fig. 3.3a–d High-qualit y computed tom ography (CT) scans detecting a lateral mass fracture of C3 that was  missed on plain radiographs.

29

30

Chapter 3

a

b

Fig. 3.4a,b  Magnetic resonance imaging (MRI) showing diskoligam entous injuries and cord contusion.

cost -e ect iven ess in t h ese cases h as n ot yet been p roven .

■ C-Spine Clearance

In 2001, St iell et al25 p rop osed an oth er decision -m akin g p rotocol, t h e Can ad ian C-sp in e r u le (CCR), based on a st u dy of 8,924 aw ake p at ien t s adm it ted to t raum a cen ters in Can ada. Th e h igh ly sen sit ive CCR ut ilizes th ree criteria (Fig. 3.5):

1. An aw ake, aler t pat ien t w ith ou t sym ptom s 2. An aw ake an d sym ptom at ic pat ien t 3. An obt u n ded clin ically u n evalu able p at ien t

1. Th e p resen ce of any h igh -risk factor th at m an dates radiography 2. Th e presen ce of low -risk factors th at allow safe assessm en t of range of m ot ion 3. Th e abilit y to act ively rot ate th e n eck 45 degrees to th e left an d righ t

In 1998, Ho m an et al10 publish ed th e decision -m aking r u les for NEXUS (Nat ion al Em ergen cy X-Radiography Ut ilizat ion St udy Group) to detect th e probabilit y of a C-spin e injur y follow ing t rau m a. Accord ing th e NEXUS protocol, clearan ce of t h e C-sp in e can be obt ain ed in cases w ith th e follow ing n dings:

In 2002, a st u dy grou p from th e Join t Sect ion on Disorders of the Spin e an d Periph eral Ner ves of th e Am erican Associat ion of Neurological Su rgeon s (AANS) an d th e Congress of Neu rological Su rgeon s (CNS) publish ed gu idelin es an d recom m en dat ion s for each clin ical scen ario follow ing a blu n t t raum a 26,27 :

• • • • •

1. For an aw ake an d asym ptom at ic p at ien t , radiological evaluat ion is n ot recom m en ded, an d th e im m obilizat ion is cleared if th e p at ien t m eets th e follow ing criteria: • Aler t , aw ake • Not in toxicated • No sym ptom s of n eck p ain or m idlin e ten dern ess • No associated inju ries th at dist ract from th e n eck p ain

On adm ission of a pat ien t follow ing a t rau m a, th ree clin ical scen arios m igh t be en cou n tered:

No cer vical pain an d tendern ess No n eurologic de cit Norm al aler t n ess No in toxicat ion No associated p ain fu l det ract ing injuries

Th e m ost im por tan t lim itat ion of th e NEXUS p rotocol is t h e rep rod u cibilit y of t h e cr iter ia “n o in toxicat ion ” an d “n o p ain fu l associated inju ries.”

Evaluation of an Injured Cervical Spine

The Canadian C-Spine Rule For alert (GCS=15) and stable trauma patients where cervical spine injury is a concern.

1. Any High-Risk Factor Which Mandates Radiography? Age ≥ 65 years or

Dangerous mechanism* or

Paresthesias in extremities No

Yes

2. Any Low-Risk Factor Which Allows Safe Assessment of Range of Motion? Simple rearend MVC**

No

or

Sitting position in ED

Radiography

or

Ambulatory at any time or

Delayed onset of neck pain***

Unable

or

Absence of midline c-spine tenderness Yes

3. Able to Actively Rotate Neck? 45° left and right Able

* Dangerous Mechanism: -

fall from elevation ≥ 3 feet / 5 stairs axial load to head, e.g. diving MVC high speed (>100km/hr), rollover, ejection motorized recreational vehicles bicycle collision

** Simple Rearend MVC Excludes:

No Radiography

-

pushed into oncoming traffic hit by bus / large truck rollover hit by high speed vehicle

*** Delayed: - i.e. not immediate onset of neck pain

Fig. 3.5 The Canadian C-spine rule. ED, emergency department; MVC, m otor vehicle collision.

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Chapter 3 2. For aw ake an d sym ptom at ic pat ien t , recom m en dat ion s are to radiologically evalu ate th e C-sp in e by th ree-view radiograp h s th at in clu de an terop osterior (AP) an d lateral cervical p lain radiograph an d an odon toid view. A CT scan is recom m en ded if th ere is a susp icious im age or h idden areas on th e p lain radiograp h s. In cases in w h ich th e th ree-view radiograph s an d th e CT (if n eeded) are n orm al, it is recom m en ded (level III) to p erform eith er dyn am ic view s or an MRI (w ith in 48 h ours). Th e cer vical spin e can be cleared if all th e above exam s are n orm al (level III). 3. In an obt u n d ed an d u n evalu able p at ien t , th ree- view rad iograp h s, su p p lem en ted if n eed ed by a CT scan , are system at ically ord ered . It is recom m en d ed (level III) t h at in an obt u n d ed p at ien t w it h n or m al rad iological evalu at ion th e C-sp in e is cleared on ly after: • Norm al dynam ic exion-extension view s, • Norm al MRI (w ith in 48 h ou rs), or • At th e discret ion of th e physician . In 2003, St iell et al28 com p ared th e sen sit ivit y of th e CCR versu s th e NEXUS an d con cluded w it h class I evid en ce th at CCR is m ore sen sit ive th an NEXUS criteria in th e detect ion of C-spin e inju ries an d resulted in low er rates of rad iography. In 2009, th e Eastern Associat ion for Su rger y of Trau m a (EAST) pu blish ed an u pdated p rotocol for clearing th e cer vical spin e after blun t traum a.29 The association concluded (class I evidence) that a CT scan is the m odalit y of choice for th e prim ar y im aging of th e cer vical spin e t rau m a cases, an d it is su perior (in sen sit ivit y an d speci cit y) to th e th ree-view plain radiograp h s protocol. In 2012, Rose et al30 con clu ded in a p rosp ect ive st udy th at even pat ien t s alert w ith “dist ract ing injuries” m ight be cleared clin ically w ith ou t th e n eed for addit ion al im aging. Dist ract ing injuries in th e con text of clearing th e C-spin e clin ically is a m yth an d th u s invalid . Th e Neck Pain Task Force graded th e blun t n eck inju ries to determ in e th e ap propriate m an agem en t 31 (see text box).

Grading of Blunt Neck Injuries (According to the Neck Pain Task Force) Grade I: neck pain with no signs of serious pathology and no or lit tle interference with daily activities Grade II: neck pain with no signs of serious pathology, but interference with daily activities Grade III: neck pain with neurologic signs of nerve  compression Grade IV: neck pain with signs of major structural  pathology

Th e recom m en dat ion s issu ed by th e Neck Pain Task Force are illu st rated in Fig. 3.6.

■ Plain Radiographs Versus

CT Scan Th e st u dy grou p of th e Join t Sect ion on Disorders of th e Sp in e an d Perip h eral Ner ves con clu ded, in it s 2002 recom m en dat ion s,32 th at th e th ree-view cer vical sp in e series is recom m en ded for th e evalu at ion of t h e C-spin e after t rau m a (level I recom m en dat ion based on class I eviden ce). It suggests th at th is radiograph ic evaluat ion sh ou ld be supplem en ted (class I eviden ce) by CT as n ecessar y on suspicious or n ot w ell-visualized areas (C1-C2, C7-T1). Th e sen sit ivit y of th e th ree-view series ranged from 60 to 84%. Th e n egat ive predict ive value ranged from 85 to 98%, in creasing to 100% w h en com bin ed w ith dyn am ic view s.33–36 Furth er st u dies dem on st rate th e superiorit y of CT com pared w ith plain radiograph ies in detect ing cer vical sp in e injuries.37–50 In 2001, Sch en ar ts et al39 reported a series of 1,356 patients selected prospectively according to th e EAST protocol from 2,690 t raum a pat ien ts an d w h o requ ired radiological assessm en t . Th ey con clu ded th at th e CT is su perior to plain lm s in th e assessm en t of a t rau m at ic cer vical spin e. In 2003, Gri en et al51 in a class I m edical eviden ce st u dy con rm ed th e su p eriorit y of th e CT over th ree-view lm s.

Evaluation of an Injured Cervical Spine

Fig. 3.6 Recommendations for assessment and management as proposed by the Neck Pain Task Force. CT,  computed tomography; ED, emergency departm ent; ROM, range of motion.

In 2005, Holm es and Akkinepalli37 perform ed a m eta-an alysis of st udies com paring CT to plain rad iograp h ies. Th e sen sit ivit y of plain radiograp h s w as 54% com pared w ith 98% for CT. Th ey con clu ded (class III eviden ce) th at th e CT is sup erior to plain radiograph s in detect ing C-sp in e t rau m at ic inju ries. In 2006, Da n er et al42 pu blish ed a class III m edical evidence (retrospective, loss of subjects) th at th e CT h as a sen sit ivit y of 99.2%com pared w ith plain lm s’ 44.1%. In over 245 fract u res, t w o inju ries w ere m issed by th e CT bu t iden t ied on th e plain radiograph s. Both of th ese fract u res w ere localized at C2 sp in ou s p rocess. Th e auth ors advocate, w ith n o st rong eviden ce, supplem en t ing CT w ith lateral plain X-rays. Th ey h igh ligh t th e n eed for proper tech n ical im aging m odalit ies on th e region of in terest .

In 2007, Math en et al41 p u blish ed a class I m ed ical evid en ce st u dy con clu d ing th at th e CT is su perior to p lain radiograp h s in acu te in ju ries, an d t h at p lain lm s ad d n o ad d it ion al d iagn ost ic in form at ion . Sen sit ivit y an d specicit y of th e CT w ere 100% an d 99.5%, resp ect ively, com p ared w ith 45% an d 97.4% for th e p lain radiograph s. In 2009, Bailit z et al40 p u blish ed a p rosp ect ive class I m edical evid en ce st u dy com p aring cer vical spin e radiographs to CT. Th e sen sit ivit y of th e CT w as 100% com p ared w ith 36% for spin e radiograph s. Th ey con cluded th at CT is su p erior an d sh ou ld be con sidered as th e m odalit y of ch oice. In 2010, Hen n essy et al,52 in a prospect ive st udy, evalu ated th e perform an ce of im aging m odalit ies in detect ing C-spin e injuries an d

33

34

Chapter 3 con clu ded th at “CT of th e C-sp in e is h igh ly sen sit ive in d etect ing th e vast m ajorit y (99.75%) of clin ically sign i can t C-sp in e inju ries. We recom m end that CT be used as the sole m odalit y to rad iograp h ically clear th e C-spin e in obt u n ded t rau m a p at ien t s an d do n ot su p p or t th e u se of exion -exten sion radiograph s as an an cillar y diagn ost ic m eth od.” In addit ion to th e su p eriorit y of th e CT over plain rad iograp h s, it h as been suggested th at CT h as t h e advan t ages also of being qu icker to obt ain th an p lain rad iograp h s (alm ost h alf th e t im e) 43,44 an d being m ore cost-e ect ive 45 in gen eral becau se of th e sh orter t im e for evaluat ion an d th e su p erior sen sit ivit y for detecting injuries w ith n o n eed for addit ion al im ages. Th ese advan t ages overcom e th e h igh er sh or tterm costs of th e CT. In sum m ar y, th e evalu at ion of a sym ptom at ic pat ien t requ ires h igh -qu alit y CT im aging, an d th ere is n o n eed for addit ion al im ages such as th ree-view or ve-view rad iograp h s.

■ Magnetic Resonance

Imaging An MRI scan is superior to any oth er im aging m odalit ies in d etect in g d iskoligam en tou s in ju r ies. So logically MRI m igh t be of great h elp in cases of n egat ive rst -lin e rad iological evalu at ion , especially if th e pat ien t cou ld n ot be assessed clin ically an d could n ot un dergo dyn am ic view s. An MRI scan , in clu ding th e STIR sequ en ces, is ver y h elpfu l in detect ing p osterior ligam en tous inju ries, disk h ern iat ion , spin al cord con t u sion , an d even t u ally ver tebral ar ter y inju ries. It is also h igh ly sen sit ive in t h e d etect ion of ligam en tou s inju ries of th e cran iocer vical jun ct ion . Many quest ion s m igh t be raised about th e n eed for an d value of an MRI scan in t raum a pat ien ts: • Does th e addit ion of MRI provide m ore in form at ion in detect ing C-spin e injuries?

• Does MRI im pact th e t reat m en t st rategy in obtunded or neurologically a ected patients? In 2002, Gh an t a et al53 p u blish ed a ret rosp ect ive st u dy of 124 con secu t ive t rau m a p at ien t s an d com pared th ree-view plain lm s, CT, an d MRI of th e C-sp in e. Th ey con clu ded th at 22% of obt un ded patien ts w ith n orm al p lain lm s an d CT h ad abn orm al MRI n dings (ligam en tous injuries). Im por t an tly, 6%of th ese injuries w ere un stable. In 2006, St assen et al54 p u blish ed a ret rospect ive series of 52 pat ien t s (class III eviden ce). Of th e 44 pat ien ts w ith n egat ive CT n dings, 13 h ad an abn orm al MRI dem on st rat ing ligam en tous injuries. Th ey con cluded th at CT evalu at ion alon e is in su cien t an d advocate sup plem en tal MRI. In 2008, Much ow et al55 perform ed a m et aanalysis and published a class I m edical evidence st udy that established MRI as the recom m ended im aging m iodalit y to clear th e C-spin e despite n orm al plain lm s an d CT im aging. In 2010, Men aker et al,56 in a ret rospect ive class III st u dy, also con clu d ed t h at 8.3% of ob t u n d ed p at ien t s an d 25.6% of sym ptom at ic p at ien t s w ith n orm al CT evalu at ion h ad an abn orm al MRI w ith im pact on th e t reat m en t st rategy. In 2010, Sim on et al57 con clu ded in a st udy th at th e addit ion of MRI to CT in creased th e detect ion of C-spin e inju ries of t rau m a pat ien ts. In 2010, Sch oen feld et al58 repor ted a m et aan alysis com paring CT alon e to CT w ith MRI in d etect ing t rau m at ic C-spin e injuries. Th e series con sisted of 1,550 pat ien t s w ith a n egat ive CT evalu at ion w h o also h ad u n dergon e MRI st u dies. In 12% of th e cases MRI sh ow ed abn orm al n dings, m ostly ligam en tous injuries. In 6%th e an om alies discovered on MRI h ad im p act on th e t reat m en t ch oice. Th e auth ors con cluded th at MRI is u sefu l for iden t ifying injuries in obt un ded or un evaluable pat ien t s w ith n orm al CT scan n dings. In sum m ar y, in an obt u n ded or u n evaluable patient w ith a norm al plain radiographs and/or norm al high-qualit y CT scan, the MRI scan seem s to be th e im aging m odalit y of ch oice based on class II an d class III m edical eviden ce st udies.

Evaluation of an Injured Cervical Spine

■ Chapter Summary In assessm en ts of C-spin e clearan ce protocols in t raum a cen ters in th e Un ited Kin dgom 59 an d th e Un ited States,60 it w as con cluded th at a sign i can t n u m ber of cen ters h ad n o clear policy, an d recom m en d ed bet ter d issem in at ion of t h e gu idelin es an d protocols th rough n at ion al societ ies. Th e u pdated level I recom m en dat ion s for clearing a C-sp in e inju ries are th e follow ing 61 : 1. Aw ake an d asym ptom at ic pat ien t: “Th e aler t , asym ptom at ic p at ien t w ith out a n eurologic de cit w h o can com plete a fu n ct ion al range-of-m ot ion exam in at ion an d is free from oth er m ajor dist ract ing in jur y m ay safely be released from cer vical spin e im m obilizat ion w ith out radiograph ic evalu at ion .” Th is recom m en dat ion is based on class I m edical evidence supporting a level I recom m endation for discontinuing cer vical spine im m obilizat ion in su ch a sit u at ion . 2. Aw ake an d sym ptom at ic p at ien t: High -qu alit y CT scan is th e m odalit y of ch oice for aw ake an d sym ptom at ic p at ien t . Th is is a level I recom m en dat ion based on class I m edical eviden ce. If CT is n ot available, a t h ree-view rad iograp h is recom m en d ed (level I). If CT is n or m al in a sym ptom at ic pat ien t , class II an d class III m edical eviden ce st udies recom m en d th ree di eren t st rategies: • Main t ain cer vical im m obilizat ion u n til p at ien t is asym ptom at ic. • Perform dyn am ic radiograph s an d/or MRI w ith in 48 h ou rs. • Clear th e C-spin e at th e discret ion of th e at ten ding p hysician .

3. Obt un ded, u n evalu able pat ien t: Th e level I recom m en dat ion in a pat ien t th at is n ot clin ically exam in able is to obt ain a h igh -qu alit y CT scan . If t h e CT is n ot available, a th ree-view plain radiograph is recom m en ded. In an obt u n d ed p at ien t w h o h ad n orm al CT or n orm al rad iograp h s, MRI seem s to be appropriate evaluat ion based on class II an d class III m edical eviden ce st udies. In such a scen ario, cer vical im m obilizat ion can be discon t in u ed if MRI w ith in 48 h ou rs is n orm al.

Pearls Rapid discontinuation, within 72 hours, of cervical imm obilization is recomm ended. The alert, asymptomatic patient without a neurologic de cit who can complete a functional range-  of-motion exam ination and is free from  other  m ajor distracting injury m ay safely be released  from  cervical spine immobilization without a radiological evaluation. In an awake and symptomatic patient, a high-  qualit y CT scan may rule out traum atic and unstable C-spine injuries. In an obtunded and unevaluable patient, highqualit y CT scan is  rst recomm ended in addition  to MRI if the CT is normal. Pitfalls Missed C-spine injuries might have catastrophic  consequences. Avoid prophylactically extended C-spine imm obilization (especially in comatose patients). Avoid excessive and unnecessary imaging studies  for fear of hidden injuries.

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2. Davis JW, Ph rean er DL, Hoyt DB, Mackersie RC. Th e et iology of m issed cer vical sp in e inju ries. J Trau m a 1993;34:342–346 PubMed 3. Goldberg W, Mu eller C, Pan acek E, Tigges S, Ho m an JR, Mow er W R; NEXUS Group. Dist ribut ion an d pat-

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Chapter 3 tern s of blun t t raum at ic cer vical spin e injur y. An n Em erg Med 2001;38:17–21 Pu bMed 4. Harris TJ, Blackm ore CC, Mirza SK, Ju rkovich GJ. Clear ing t h e cer vical sp in e in obt u n d ed p at ien t s. Spin e 2008;33:1547–1553 Pu bMed 5. Rich ards PJ. Cer vical spin e clearan ce: a review. Injur y 2005;36:248–269, discu ssion 270 Pu bMed 6. Lekovic GP, Harrington TR. Lit igat ion of m issed cer vical spin e injuries in pat ien t s presen t ing w ith blu nt t raum at ic injur y. Neu rosurger y 2007;60:516–522, discussion 522–523 Pu bMed 7. Widd er S, Doig C, Burrow es P, Larsen G, Hurlbert RJ, Kor tbeek JB. Prospect ive evaluat ion of com puted tom ograph ic scan n ing for th e spin al clearan ce of ob tunded t raum a patients: prelim in ar y results. J Traum a 2004;56:1179–1184 Pu bMed 8. Ajan i AE, Cooper DJ, Sch ein kestel CD, Laidlaw J, Tu xen DV. Optim al assessm en t of cer vical spine t raum a in crit ically ill p at ien t s: a p rospect ive evalu at ion . An aesth In ten sive Care 1998;26:487–491 Pu bMed 9. Acklan d HM, Cooper DJ, Malh am GM, Kossm an n T. Factors p red ict ing cer vical collar-related d ecu bit u s ulcerat ion in m ajor t raum a pat ien t s. Spin e 2007; 32:423–428 Pu bMed 10. Ho m an JR, Wolfson AB, Todd K, Mow er W R. Select ive cer vical spin e radiography in blu nt t rau m a: m eth odology of th e Nat ion al Em ergen cy X-Radiography Ut ilizat ion St u dy (NEXUS). An n Em erg Med 1998; 32:461–469 Pu bMed 11. Com m it tee on th e Biological E ect s of Ion izing Radiat ion s, Board on Radiat ion E ect s Research , Com m ission on Life Scien ces (BEIR V). Health E ect s of Exposure to Low Levels of Ion izing Radiat ion . Wash ington , DC: Nat ional Academ y Press; 1990:281 12. Ho m an JR, Schriger DL, Mow er W, Lu o JS, Zu cker M. Low -risk criteria for cer vical-spin e rad iograp hy in blun t t raum a: a prospect ive st u dy. An n Em erg Med 1992;21:1454–1460 PubMed 13. Mow er W R, Ho m an JR, Sch riger DL. Th e feasibilit y of select ive radiography in pat ient s w ith t raum ain duced n eck pain . Ann Em erg Med 1990;19(Suppl): 1220–1221 Abst ract 14. St reit w ieser DR, Kn opp R, Wales LR, William s JL, Ton n em ach er K. Accuracy of st an dard radiograph ic view s in detecting cervical spine fract ures. Ann Em erg Med 1983;12:538–542 PubMed 15. Ch iu WC, Haan JM, Cu sh ing BM, Kram er ME, Scalea TM. Ligam en tou s inju ries of th e cer vical sp in e in u n reliable blu n t t rau m a pat ien t s: in cid en ce, evalu at ion , an d ou tcom e. J Trau m a 2001;50:457–463, d iscu ssion 464 PubMed 16. Gri en MM, Fr ykberg ER, Ker w in AJ, et al. Radiographic clearance of blunt cervical spine injury: plain radiograph or com puted tom ography scan ? J Traum a 2003;55:222–226, discu ssion 226–227 Pu bMed 17. Holm es JF, Akkin ep alli R. Com p u ted tom ograp hy versus plain radiography to screen for cer vical spin e

injur y: a m et a-an alysis. J Traum a 2005;58:902–905 PubMed 18. Diaz JJ Jr, Gillm an C, Morris JA Jr, May AK, Carrillo YM, Guy J. Are ve-view plain lm s of th e cer vical spin e u n reliable? A prospect ive evaluat ion in blun t t raum a pat ien t s w ith altered m en t al st at us. J Traum a 2003; 55:658–663, discu ssion 663–664 PubMed 19. Gri en MM, Fr ykberg ER, Ker w in AJ, et al. Radiographic clearance of blunt cervical spine injur y: plain radiograp h or com puted tom ography scan ? J Traum a 2003;55:222–226, d iscu ssion 226–227 PubMed 20. Suzuki T, Morim ura N, Sugiyam a M, Kit ah ara T, Som a K. How often sh ould com puted tom ograph ic scan s follow ing cross-t able lateral cer vical lm s be perform ed ? J Or th op Su rg (Hong Kong) 2004;12: 40–44 PubMed 21. Vangu ri P, Young AJ, Weber W F, et al. Com puted tom ograph ic scan : it’s n ot just about th e fract ure. J Traum a Acute Care Surg 2014;77:604–607 22. Gargas J, Yaszay B, Kruk P, Bast rom T, Sh ellington D, Kh an n a S. An an alysis of cer vical sp in e m agn et ic reson an ce im aging n dings after norm al com puted tom ograp h ic im aging n d ings in p ediat ric t rau m a pat ien t s: ten -year exp erien ce of a level I p ediat ric t raum a cen ter. J Traum a Acute Care Surg 2013;74: 1102–1107 23. Rich ards PJ. Cer vical spin e clearan ce: a review. Injur y 2005;36:248–269, d iscu ssion 270 PubMed 24. Kh an n a P, Chau C, Dublin A, Kim K, Wisn er D. Th e valu e of cer vical m agn et ic reson an ce im aging in th e evaluat ion of th e obt un ded or com atose pat ien t w ith cer vical t raum a, n o oth er abn orm al n eurological n dings, an d a n orm al cer vical com puted tom ography. J Traum a Acute Care Surg 2012;72:699–702 25. St iell IG, Wells GA, Van d em h een KL, et al. Th e Can adian C-sp in e r u le for radiography in aler t an d st able traum a patients. JAMA 2001;286:1841–1848 PubMed 26. Radiograph ic assessm en t of th e cer vical sp in e in asym ptom at ic t rau m a p at ien t s. Neu rosu rger y 2002; 50(3 su pp l):S30–S35 27. Radiograph ic assessm en t of th e cer vical spin e in sym ptom at ic t raum a pat ien t s. Neurosurger y 2002; 50(3 su pp l):S36–S43 28. St iell IG, Clem en t CM, McKnigh t RD, et al. The Can adian C-sp in e ru le versu s th e NEXUS low -risk criteria in pat ien t s w ith t raum a. N Engl J Med 2003;349: 2510–2518 Pu bMed 29. Com o JJ, Diaz JJ, Du n h am CM, et al. Pract ice m an agem en t guidelin es for iden t i cat ion of cer vical spin e injuries follow ing t raum a: u pdate from th e eastern associat ion for th e su rger y of t rau m a p ract ice m anagem en t guidelin es com m it tee. J Traum a 2009;67: 651–659 PubMed 30. Rose MK, Rosal LM, Gon zalez RP, et al. Clin ical clearan ce of th e cer vical sp in e in p at ien t s w ith dist ract ing injuries: it is t im e to dispel th e m yth . J Traum a Acute Care Surg 2012;73:498–502

Evaluation of an Injured Cervical Spine 31. Gu zm an J, Haldem an S, Carroll LJ, et al; Bon e an d Join t Decade 2000–2010 Task Force on Neck Pain an d It s Associated Disorders. Clin ical pract ice im plicat ion s of th e Bon e an d Join t Decade 2000–2010 Task Force on Neck Pain an d It s Associated Disorders: from con cept s an d n dings to recom m endat ions. Spin e 2008;33(4, Su ppl):S199–S213 Pu bMed 32. Radiograph ic assessm en t of th e cer vical spin e in sym ptom at ic t raum a pat ient s. Neurosurger y 2002; 50(3, Su p pl):S36–S43 PubMed 33. Bern e JD, Velm ah os GC, El-Taw il Q, et al. Value of com plete cer vical helical com puted tom ograph ic scan n ing in iden t ifying cer vical spin e injur y in the un evaluable blu nt t raum a p at ien t w ith m ult iple in ju ries: a prospect ive st udy. J Traum a 1999;47:896– 902, d iscu ssion 902–903 PubMed 34. Ajan i AE, Cooper DJ, Sch ein kestel CD, Laidlaw J, Tuxen DV. Optim al assessm ent of cervical spine traum a in crit ically ill pat ien t s: a prospect ive evaluat ion . An aesth In ten sive Care 1998;26:487–491 Pu bMed 35. Davis JW, Parks SN, Detlefs CL, William s GG, William s JL, Sm ith RW. Clearing th e cer vical spin e in obt un ded pat ien t s: th e use of dyn am ic uoroscopy. J Trau m a 1995;39:435–438 Pu bMed 36. MacDon ald RL, Sch w art z ML, Mirich D, Sh arkey PW, Nelson W R. Diagn osis of cer vical sp in e inju r y in m otor veh icle crash vict im s: h ow m any X-rays are en ough ? J Traum a 1990;30:392–397 PubMed 37. Holm es JF, Akkinepalli R. Com puted tom ography versus plain radiography to screen for cervical spine injury: a m eta-analysis. J Traum a 2005;58:902–905 PubMed 38. Diaz JJ Jr, Gillm an C, Morris JA Jr, May AK, Carrillo YM, Guy J. Are ve-view plain lm s of th e cer vical spine un reliable? A prospect ive evaluat ion in blun t t raum a pat ien t s w ith altered m en t al st at u s. J Trau m a 2003; 55:658–663, discu ssion 663–664 PubMed 39. Sch en ar t s PJ, Diaz J, Kaiser C, Carr illo Y, Eddy V, Mor ris JA Jr. Prospect ive com parison of adm ission com puted tom ograph ic scan an d plain lm s of the upper cer vical spin e in t rau m a pat ien t s w ith altered m ental status. J Traum a 2001;51:663–668, discussion 668–669 Pu bMed 40. Bailit z J, St arr F, Beecroft M, et al. CT sh ou ld rep lace th ree-view radiograph s as th e in it ial screen ing test in pat ien t s at h igh , m oderate, an d low risk for blun t cer vical spin e injur y: a prospect ive com parison . J Traum a 2009;66:1605–1609 PubMed 41. Math en R, In aba K, Mun era F, et al. Prospect ive evaluat ion of m ult islice com puted tom ography versus plain radiograph ic cer vical spine clearan ce in t raum a pat ien t s. J Traum a 2007;62:1427–1431 PubMed 42. Da n er RH, Sciulli RL, Rodriguez A, Protetch J. Im aging for evaluat ion of suspected cer vical spin e t raum a: a 2-year an alysis. Injur y 2006;37:652–658 Pu bMed 43. Da n er RH. Cervical radiography for traum a pat ien ts: a t im e-e ect ive tech n ique? AJR Am J Roen tgen ol 2000;175:1309–1311 Pu bMed

44. Da ner RH. Helical CT of the cervical spine for traum a pat ien t s: a t im e st udy. AJR Am J Roen tgen ol 2001; 177:677–679 PubMed 45. Blackm ore CC. Eviden ce-based im aging evaluat ion of th e cer vical spine in t raum a. Neuroim aging Clin N Am 2003;13:283–291 Pu bMed 46. Padayach ee L, Cooper DJ, Iron s S, et al. Cer vical spin e clearan ce in un con scious t raum at ic brain injur y pat ien t s: dyn am ic exion -exten sion u oroscopy versu s com puted tom ography w ith th ree-dim en sion al recon st ruct ion . J Traum a 2006;60:341–345 Pu bMed 47. Spiteri V, Kot n is R, Singh P, et al. Cer vical dyn am ic screen ing in spin al clearan ce: n ow redun dan t . J Traum a 2006;61:1171–1177, discussion 1177 PubMed 48. Gri th s HJ, Wagn er J, Anglen J, Bun n P, Met zler M. Th e u se of forced exion /exten sion view s in th e ob t un ded t raum a pat ien t . Skelet al Radiol 2002;31:587– 591 Pu bMed 49. Bolinger B, Sh ar t z M, Marion D. Bedside uoroscopic exion an d exten sion cer vical spin e radiograph s for clearan ce of th e cer vical spin e in com atose t raum a pat ien t s. J Trau m a 2004;56:132–136 Pu bMed 50. Davis JW, Kaups KL, Cun n ingh am MA, et al. Rout in e evaluat ion of the cer vical spin e in head-injured pat ien t s w ith dyn am ic uoroscopy: a reappraisal. J Trau m a 2001;50:1044–1047 PubMed 51. Gri en MM, Fr ykberg ER, Ker w in AJ, et al. Rad iograp h ic clearan ce of blu n t cer vical sp in e inju r y: plain radiograph or com pu ted tom ography scan ? J Traum a 2003;55:222–226, discussion 226–227 Pu bMed 52. Hen nessy D, Widder S, Zygun D, Hurlbert RJ, Bu rrow es P, Kortbeek JB. Cer vical sp in e clearan ce in ob t un ded blun t t raum a pat ien t s: a prospect ive st udy. J Traum a 2010;68:576–582 PubMed 53. Ghan t a MK, Sm ith LM, Polin RS, Marr AB, Spires W V. An an alysis of Eastern Associat ion for th e Surger y of Trau m a p ract ice gu idelin es for cer vical sp in e evalu at ion in a series of pat ien t s w ith m ult iple im aging tech n iques. Am Surg 2002;68:563–567, discussion 567–568 PubMed 54. St assen NA, William s VA, Gest ring ML, Ch eng JD, Ban key PE. Magn et ic resonan ce im aging in com bin at ion w ith h elical com puted tom ography provides a safe an d e cient m eth od of cer vical spin e clearan ce in th e obt un ded t raum a pat ien t . J Trau m a 2006;60: 171–177 PubMed 55. Much ow RD, Resn ick DK, Abdel MP, Mun oz A, An derson PA. Magn et ic reson an ce im aging (MRI) in th e clearan ce of the cer vical spine in blu nt t raum a: a m et a-an alysis. J Trau m a 2008;64:179–189 PubMed 56. Menaker J, Stein DM, Ph ilp AS, Scalea TM. 40-slice m ult idetector CT: is MRI st ill n ecessar y for cer vical spin e clearan ce after blu n t t rau m a? Am Su rg 2010; 76:157–163 PubMed 57. Sim on JB, Sch oen feld AJ, Kat z JN, et al. Are “n orm al” m ultidetector com puted tom ographic scans su cien t

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Chapter 3 to allow collar rem oval in th e t rau m a pat ien t? J Trau m a 2010;68:103–108 Pu bMed 58. Schoen feld AJ, Bon o CM, McGuire KJ, Warh olic N, Harris MB. Com p u ted tom ography alon e versu s com pu ted tom ograp hy an d m agn et ic reson an ce im aging in th e iden t i cat ion of occult injuries to th e cer vical spin e: a m et a-an alysis. J Traum a 2010;68:109–113, discu ssion 113–114 PubMed 59. Mercer SJ, Gu ha A. Assessing th e im plem en t at ion of gu idelin es for th e m an agem en t of th e potent ially in ju red cer vical spin e in u n con scious t raum a pat ien t s in Englan d. J Trau m a 2010;68:1445–1450 Pu bMed

60. Th eologis AA, Dion isio R, Mackersie R, McClellan RT, Pekm ezci M. Cer vical sp in e clearan ce p rotocols in level 1 t rau m a cen ters in th e Un ited St ates. Spin e 2014;39:356–361 Pu bMed 61. Tim othy C. Gu idelin es for th e m an agem en t of acu te cer vical spin e and spinal cord injuries: 2013 update. Radiograph ic Assessm ent; Am erican Associat ion of Neurological Surgeons; Congress of Neurological Surgeon s. Neurosurger y 2013;72:54–72

4 Nonoperative Management of Cervical Spine Trauma Peter Formby and Melvin D. Helgeson

■ Introduction Cer vical fract u res are com m on inju ries en cou n tered in a t rau m a set t in g, an d fract u res to th is area can h ave dam aging con sequen ces, in clu ding t rau m at ic sp in al cord injuries. It is est im ated th at 150,000 cer vical sp in e inju ries occu r an n ually in Nor th Am erica. Th e subaxial spin e accou n ts for th e m ajorit y of cer vical in juries, m aking up 65% of fract ures an d m ore th an 75% of all dislocat ion s.1 Isolated fract u res of C1 an d C2 accou n t for 5% an d 20% of cer vical fract ures, respect ively, w h ereas fract u res of th e occipit al con dyles are est im ated to occu r in 1% of cran iocer vical t rau m as.2,3 A sign i can t n u m ber of t h ese inju r ies can be t reated n on op erat ively w ith im m obilizat ion .

■ Initial Assessment Upon th e pat ien t’s arrival at th e t reat ing facilit y, a h istor y is t aken to determ in e com orbidit ies an d th e m ech an ism of inju r y. If possible, a com plete radiographic evaluation of the patien t sh ou ld be p erform ed, w h ich sh ou ld in clu de a cross-table lateral view of th e cer vical spin e w ith visualizat ion of th e occiput-T1 levels. A sw im m er’s view m ay be n ecessar y if th e low er cer vical spin e is n ot com pletely visualized. A lateral view of th e en t ire sp in e sh ou ld also be obtain ed, as n on con t iguou s spin al injuries are

ver y com m on . Based on th ese in it ial im ages or on clin ical su spicion , th e pat ien t m ay be sch edu led for a com p uted tom ograp hy (CT) scan , w h ich h as dem on st rated a greater sen sit ivit y (100%) th an th at of lateral radiograph s (63%) in detect ing fract u res of th e cer vical sp in e.4 In th e p at ien t w ith n o n eu rologic de cit s or radicu lar p ain , m agn et ic reson an ce im aging (MRI) m ay n ot provide any additional inform at ion required for patien t m an agem en t. Although this is a cont roversial issue, Tom ycz an d colleagues 5 foun d th at MRI w as n ot useful in un covering unstable cer vical spin e injuries even in com atose an d obt un ded pat ien t s. How ever, MRI is rout in ely obtain ed in pat ien ts w ith t rau m at ic cer vical spin e inju ries.

■ Skeletal Traction Closed redu ct ion of th e cer vical spin e h as been perform ed in m odern practice sin ce 1929, w h en Taylor 6 rst u sed a h alter to redu ce a cer vical dislocat ion . Gardn er-Wells tongs w ere rst described in 1973, an d are th e m ost frequ en tly used device in th e m odern era for in it ial closed cervical skeletal traction. Reduction can restore osseous align m en t , decom press th e spin al cord and nerve roots, and m aintain stabilit y. Surgery can occasion ally, bu t rarely, be avoid ed follow ing successful closed reduct ion . Follow ing a t rau m at ic cer vical spin e fract ure w ith spin al

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Chapter 4 cord or n er ve im p in gem en t , d ecom p ression sh ou ld be p erform ed as soon a possible to p reven t fu r th er dam age an d to en able th e m a xim u m possible recover y. Th e t yp ical m eth od of redu ct ion involves th e ap plicat ion of Gardn erWells tongs to th e sku ll. Th e posit ion of th e pin s is t ypically 1 cm above each p in n a, below th e equ ator of th e sku ll. A m ore an terior pin placem en t resu lt s in cer vical exten sion , an d a posterior placem en t resu lt s in cer vical exion , w h ich m ay be necessar y depen ding on the fract u re p at tern an d displacem en t . Pin s sh ou ld be placed p erp en dicu lar to th e sku ll to ach ieve m axim al m echanical advantage and avoid pullou t an d toggling. Ideally, at tem pts at closed redu ct ion sh ou ld be perform ed in an aw ake an d orien ted pat ien t w h o can p ar t icip ate in a n eu rologic exam . Before ap p licat ion of w eigh t s, a cross-t able lat eral cer vical sp in e lm sh ou ld be t aken an d a baseline neurologic exam should be perform ed. Un der expert guidan ce, in crem en t s of 10 lb of dist ract ion force are applied. Con siderat ion sh ou ld be given to p oten t ial n asot rach eal in t u bat ion if redu cing a p osterior t yp e II den s fract u re, as th ere is a repor ted 40% in ciden ce of resp irator y deteriorat ion from air w ay obst ru ct ion if t h e cer vical sp in e is exed d u ring red u ct ion .7 After each dist ract ion even t , a repeat lateral view of th e cer vical sp in e is t aken an d a repeat n eu rologic evaluat ion is p erform ed. If th ere are in dicat ion s th at th e disk spaces are d ist ract ing, w eigh ted dist ract ion sh ou ld be decreased as overdist ract ion m ay occu r, w h ich risks fu rther n eu rologic inju r y. On ce red uct ion is achieved, th e low est am ount of w eigh t is used to m ain t ain redu ct ion . Th e safe app licat ion of w eigh ts up to 140 lb h as been docu m en ted to ach ieve redu ct ion in th e low er cer vical sp in e.8 Next , th e p at ien t sh ou ld receive an MRI to fu rth er evalu ate th e diskoligam en tou s in tegrit y of th e cer vical spin e. In t h e u n con sciou s or obt u n d ed p at ien t , it is gen erally agreed th at an MRI sh ould be ob tain ed on an u rgen t basis to search for n eurologic com pression , an d n o at tem pt at closed redu ct ion sh ou ld be perform ed given th e risk of further injur y. But there is signi cant controversy regarding obtaining an MRI prior to reduct ion of t h e cer vical sp in e in th e aler t , aw ake,

an d orien ted pat ien t . In on e repor t , an alert 54-year-old m an su ered acute qu adriplegia follow ing closed t ract ion of a bilateral cer vical facet dislocat ion . Th ere w as n o pre-redu ct ion MRI, an d h e h ad kn ow n ossi cat ion of t h e p osterior longit udin al ligam en t . He h ad full n eu rologic recover y, h ow ever, after open decom p ression an d st abilizat ion .9 Vaccaro an d associates 10 obt ain ed p re-redu ct ion MRIs on 11 pat ien ts prior to aw ake closed t ract ion redu ct ion an d fou n d th at t w o of th e 11 h ad disk h ern iat ion s prior to reduct ion an d ve h ad disk h ern iat ion s follow ing closed reduct ion , th ough n on e h ad neurologic deteriorat ion follow ing th e p roced ure. Gran t et al11 review ed 82 pat ien t s w ith cer vical spin e fract u re-dislocat ion s and found that pre-reduction MRI show ing disk h ern iat ion or disrupt ion con ferred n o w orse a neurologic outcom e follow ing closed reduction on aler t pat ien ts, an d th erefore th ey did n ot recom m en d pre-redu ct ion MRI.

■ Cervical Orthoses Cer vical or t h oses are a grou p of exter n ally ap plied devices th at fu n ct ion by rest rict ing m ot ion in directly an d act to st abilize an d su p por t th e sp in e. Th ey are u sed for early m ot ion rest rict ion after acute t rau m a, in th e postoperat ive p eriod for addit ion al stabilit y/com for t , an d as de n it ive t reat m en t in gen erally st able pat ien ts w ith ou t n eu rologic de cit s. Or th oses provide th e p arasp in al m u scles w ith p rop riocept ive feedback to lim it m ot ion an d m ain tain p rop er an atom ic p osit ion in g. Most cer vical or t h oses exer t exion /exten sion con t rol to var ying degrees, but are m ore lim ited in th eir rot ator y an d coron al lateral ben ding con t rol. Th ere is an inverse relat ion sh ip bet w een th e am ou n t of d iscom for t /r igid it y of an or th osis an d toleran ce by a p at ien t , so it im p or t an t to m atch t h e or t h osis to th e p rop er inju r y an d pat ien t . In th e cer vical sp in e, devices are com m on ly referred to as eith er cer vical orth oses (COs) or cer vical th oracic or th oses (CTOs) depen ding on th e levels to w h ich th e device exten ds. In general, studies regarding the stabilit y a orded

Nonoperative Management of Cervical Spine Trauma by various or th oses are di cult to in terpret as a w h ole, given th e var ying m ean s used to m easu re angu lar an d t ran slat ion al m ot ion s, ou t dated or discon t in u ed or th oses, as w ell as th e m easu red sp ecim en s th em selves (i.e., h ealthy volu n teers vs cadavers). Cer vical orth oses are th e m ost com for t able or th oses w h en com posed of soft m aterial such as foam , but th ey provide lim ited stabilit y to th e cer vical sp in e (Fig. 4.1). Th ey m ain ly fu n ct ion by p roviding tact ile feedback to th e p at ien t , lim it ing drast ic an d ext rem e volu n tar y cer vical m ot ion . Th ey are often used in cases of cer vical m uscle st rain or soft t issue sprain , or in t h e p ostop erat ive p er iod for com for t . In a recen t st udy com paring soft an d rigid collars in 15 act ivit ies of daily living (ADL), soft collars w ere foun d to lim it m ean exion /exten sion by 27.1%, lateral ben ding by 26.1%, an d rotat ion by 29.3%.12 Th e corresp on ding redu ct ion s in m ot ion w ith a rigid collar w ere greater at 53.7%, 34.9%, an d 59.2%, th ough n o sign i can t di eren ce in m ot ion bet w een th ese t w o devices w as n oted in 13 of 15 ADLs. Th ese n dings in dicate that patients likely self-regulate their neck m ovem en t s based on com for t , an d th at rigid collars are n ot alw ays n ecessar y, p ar t icularly p ostop erat ively if th e con st ru ct is stable. Rigid collars are one of the m ainstays of early cer vical t raum a im m obilizat ion an d often pro-

Fig. 4.1 An example of a soft cervical collar.

vide th e m ean s for de n it ive t reat m en t . Som e exam ples of rigid COs in clude th e Ph iladelph ia collar, th e Miam i-J, th e Aspen cer vical or th osis, th e PMT® Cer vMax™ Cer vical Orth osis Collar (PMT Corporat ion , Ch an h assen , MN), an d th e Vista collar (Figs. 4.2 and 4.3). In cont rast, CTOs extend dow n the thorax to var ying degrees and gen erally con fer a greater am oun t of stabilit y to th e cer vical sp in e. Som e com m on exam ples of CTOs include th e Lerm an Min er va cer vical or th osis, th e stern o-occipito-m an dibular im m obilizer (SOMI), th e Aspen 2- an d 4-post , an d th e Vista TS an d TS4 CTOs. A th ree-dim en sion al (3D) m ot ion an alysis of ve COs (Aspen , Aspen Vista, Ph iladelph ia, Miam i-J, an d Miam i-J Advan ced) foun d th at th e Aspen best rest ricted sagit tal, axial, an d coron al m ot ion .13 Th e Vist a collar w as fou n d to be th e least rest rict ive in all m ot ion s. Oth er st u dies h ave fou n d t h e Ph ilad elp h ia an d Miam i-J collars to be m ore rest rict ive th an th e Aspen collar.14 In a st udy com paring th e Miam i-J an d Aspen COs to t h e Asp en 4-p ost an d Asp en 2-post CTOs, th e auth ors foun d n o sign i can t di eren ce in angu lar C0- C7 m ot ion bet w een th e t w o COs, th ough th e Miam i-J allow ed m ore m ot ion at C5–6.15 Th e t w o CTOs lim ited exion to a sim ilar degree, but th e Aspen 4-post lim ited angu lar an d tran slat ion al m ot ion in exten sion to a greater d egree (38% vs 22% an d 50% vs 24%, respect ively). In a sim ilar st u dy u sing cadavers w ith exion -com pression fract u res at th e low er cer vical sp in e level an d exten sion com p ression at th e u p per cer vical spin e level, Ivan cic16 evalu ated t w o COs (Vist a collar an d Vist a m ult ipost collar) an d 2 CTOs (Vist a TS an d Vist a TS4). Predictably, su ccessively greater rest rict ion in exten sion an d exion in th e u pper and low er cer vical spin es, respect ively, w as obt ain ed u sing th e CTOs. Th e Vista collar and Vista TS4 collar show ed the least and greatest rest rict ion , respect ively. Sch n eider et al17 evaluated four COs an d th ree CTOs on h ealthy adult volu n teers in th e su pin e an d stan ding position s. Th e su bjects fou n d th e Miam i-J an d Aspen collars to be th e m ost com for t able, an d, in gen eral, all COs w ere rated m ore com for table th an CTOs. As expected, th e CTOs lim ited m otion at all levels to a greater degree than COs. Th e Min er va w as th e m ost e ect ive at lim it ing

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Chapter 4

Fig. 4.2 An Aspen rigid cervical orthosis.

Fig. 4.3 A Miam i-J rigid cervical orthosis.

in ter ver tebral m ot ion at all levels. Of t h e cervical or th oses, th e Ph iladelph ia w as th e m ost e ect ive cer vical or th osis at all levels except C6- C7, w h ere th e PMT p erform ed bet ter. Th e Ler m an h alo w as t h e m ost e ect ive at lim it in g overall axial rot at ion an d coron al ben ding, w h ereas th e Ph iladelph ia w as th e best CO in th ese sam e p lan es. In deed, alm ost all st u dies in dicate th at st abilit y in creases as th e level of or th osis rest rict ion in creases.18 W h en p rescr ibin g a cer vical or th osis, t h e ben e t s of it s m ot ion rest r ict ion m u st be w eigh ed again st th e com plicat ion s. On e m ajor com p licat ion is cer vical collar–related decu bitus ulceration, w hich has been found to increase 66% for ever y 1-day in crease in collar u se.19 In on e st udy com paring cran iofacial t issue pressu res bet w een fou r COs, Miam i-J collars con ferred less occipital an d m an dibu lar pressures com p ared w it h Ph ilad elp h ia an d Asp en collars.14 Oth er com plicat ion s in clu de dysp h agia, in creased in t racran ial pressu re, an d decreased m ou th open ing w ith sem irigid orth oses, w h ich could poten t ially lim it de n it ive air w ay placem en t in an un st able pat ien t. A draw back of

m any cer vical braces such as the Miner va brace is th e m ot ion seen in th e u p per cer vical spin e occiput–C4 level w ith m ast icat ion . To lim it th is ph en om en on , it is recom m en ded to p at ien ts th at t h ey tem porarily rem ove t h e m an dibu lar com pon en t w h ile ch ew ing.

■ Halo Immobilization Th e h alo xator is a versat ile in st r u m en t for m an aging cer vical sp in e fract u res. Th is device can be u sed for tem p orar y closed red u ct ion an d stabilit y prior to surger y, as th e de n it ive t reat m en t for m any cer vical spin e fract u res, an d as a supplem en t for addit ion al stabilit y after cer vical fusion s. Th e h alo xat ion vest is gen erally espou sed as on e of th e m ost rigid extern al stabilizing devices of th e cer vical spin e, lim it ing cer vical sp in e m ot ion to bet w een 30% an d 90%. On e of t h e rep or ted w eakn esses of th e h alo xat ion vest is it s in abilit y to ad equ ately im m obilize t h e occip u t–C1 in ter face, w ith on e repor t sh ow ing 8 degrees of angula-

Nonoperative Management of Cervical Spine Trauma t ion at th is level.20 An oth er in -vivo st udy foun d h alo xat ion lim ited m axim um m ot ion to 70% of n orm al m ot ion, th ough th e least rest rain t w as above th e C2 level.21 How ever, it h as been sh ow n to be safe an d e ect ive in t reat ing fract u res an d d islocat ion s in t h e u p p er cer vical sp in e C1- C2. Th e conven t ion al h alo vest itself con sists of a com p lete or U-sh ap ed m et al ring, fou r p in s, a vest w ith an terior an d posterior com pon en t s, fou r u p righ t st ru t s, an d fou r xat ion rods. To app ly th e device, th e p at ien t is placed in t h e supin e p osit ion w ith st acked tow els p laced beh in d th e torso, n eck, an d h ead . Th e h ead an d n eck are m an u ally st abilized in n eu t ral p osit ion by at least on e assistan t . Th e appropriately sized ring sh ou ld ideally allow < 1 cm of clearan ce from all asp ect s of t h e h ead, ju st below th e equator of th e skull, an d n o por t ion of th e ring sh ould con tact th e pat ien t’s skin . Th e an terior pin s sh ou ld be p laced in th e safe zon e, ~ 0.5 to 1 cm above th e lateral on e th ird of th e eyebrow s. A m ore m edial p lacem en t can inju re th e adjacen t supraorbit al an d suprat roch lear n er ves, an d m ore lateral placem en t can p ierce th e m asseter m uscle an d poten t ially pen et rate th e th in tem poralis fossa. Pin s sh ould be placed p er p en d icu lar to t h e sku ll to m a xim ize t h e p in –bon e in terface, an d pat ien t s sh ou ld be in st r u cted to close t h eir eyes to avoid ten t in g the orbicularis oculi m uscles. The posterior pins sh ould be placed ~ 180 degrees from th eir correspon ding an terior pin s. Th ere are n o m ajor con cern s w h en placing the posterior pin s due to th e th ickn ess of th e posterolateral sku ll in th is region (9.47 ± 1.12 m m ). A cadaveric st udy fou n d t h at t h e m a xim u m safe torqu e an terolaterally an d p osterolaterally w as 8 in ch -lb an d 18 in ch -lb, respect ively.22 A separate st udy sh ow ed a decreased com plicat ion t ren d w ith n o in creased pin loosen ing or in fect ion w h en 6-inch-lb torque was used instead of 8-inch-lb.23 No skin in cision is n ecessar y an d th e p in s are altern ately t igh ten ed un t il 8 in ch -lb of torqu e are obt ain ed. Th e posterior aspect of th e vest in th en p laced by logrolling th e p at ien t w h ile th e h ead is m an u ally h eld in n eu t ral posit ion . Th e pat ien t is again p laced su pin e an d th e an terior aspect of th e vest is clam ped in place an d

the upright st ruts are connected to th e vest and ring. A h an d sh ou ld be able to t sn ugly bet w een th e vest an d ch est to dem on st rate safe excu rsion for breath ing an d to preven t skin n ecrosis. A supin e an d u prigh t lateral of th e cervical sp in e is th en obtain ed to en su re adequate st abilizat ion w ith ou t fract u re disp lacem en t . Th e pin s are ret igh ten ed at 24 to 48 h ou rs an d again at 1 w eek to preven t loosen ing. In a review of h alo vest im m obilizat ion , View eg an d Sch ulth eiss 24 recom m en d ed th e utilit y of halo vest im m obilization for the treatm en t of p at ien t s w ith isolated Je erson fract u res, h angm an’s fract u res, an d odon toid t ype II an d t ype III fract ures, w ith a low dislocat ion rate. However, there was an unsatisfactory healing rate w h en it w as used to t reat com bin ed inju ries w ith an odon toid t ype II fract u re. Tash jian et al25 fou n d th at th ere w as a sign i can t ly h igh er m orbidit y an d m or t alit y rate (42% vs 20% m or t alit y rate) w h en t reat ing t ype II an d III den s fract ures in elderly pat ien ts (> 65 years of age) w ith h alo xat ion com pared w ith rigid cer vical or t h oses or op erat ive xat ion . In an in -vivo st udy com p aring exion an d exten sion radiograp hs in 20 p at ien t s im m obilized w ith eith er a m odi ed 12-pin h alo vest xat ion or a Ph iladelp h ia collar, th ere w as a sign i can t advan t age of th e h alo vest in lim it ing subaxial sagit tal plan e m ot ion , th ough th ere w as n o differen ce foun d bet w een exion/exten sion at the C1- C2 levels. Norm al atlan toaxial m ot ion w as rest ricted by 88.5%w ith th e Ph iladelph ia collar com p ared w it h 70.8% w it h t h e h alo vest xat ion .26 An in -vit ro st u dy of in t act an d sim u lated t yp e II den s fract ures foun d th at h alo vest im m obilizat ion w as su p er ior to soft collar, Miam i-J collar, an d Min er va brace in all plan es of m ot ion at th e C1–C3 levels.27 In a review of pat ien ts w ith t ype II an d t yp e III den s fract u res t reated w ith eith er a h alo vest or rigid cer vical collar, Polin et al28 foun d excellen t h ealing in t ype III fract ures regardless of im m obilizat ion m ean s an d n o sign i can t di eren ce in osseous u n ion d esp ite collar p at ien t s bein g old er (68 vs 44 years) in t ype II fract u res. A radiograp h ic st udy of 10 pat ien ts w ith various cer vical spin e fract u res in it ially t reated in a h alo xat ion vest for 6 to 8 w eeks an d th en t ran sit ion ed to a

43

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Chapter 4 Min er va brace fou n d a m ean ver tebral m ot ion average from th e occiput to C7 w as low er in th e Min er va th an in th e h alo (2.3 vs 3.7 degrees) an d th at eigh t of 10 pat ien ts preferred th e Min er va brace. Addition ally the “snaking” ph en om en on , in w h ich th ere are p aradoxical altern ate rot at ion s t h rough ou t t h e cer vical sp in e, w as seen in both or th oses, bu t to a larger degree in th e h alo device.29

Complications Nu m erou s com p licat ion s h ave been associated w it h h alo vest xat ion , in clu d in g fract u re n on u n ion , p in loosen ing, su p er cial in fect ion , p ressu re sores, n er ve inju r y, dysp h agia, p in d iscom for t , scar, in t racran ial p en et rat ion , ep id u ral abscess, an d allergic react ion s to t h e pin s. On e of th e m ost w idely rep or ted prob lem s w ith h alo vest xat ion is th e u n acceptable com plicat ion s associated w ith it s use in elderly p at ien t s. Majercik et al30 repor ted a 40% m or t alit y rate in 109 pat ien ts > 65 years of age com p ared w it h 2% in 289 you n ger p at ien t s desp ite a h igh er inju r y severit y score in t h e you n ger coh or t . Th e m ost com m on com p licat ion is p in loosen in g (36–60%). In a biom ech an ical an d in -vivo st u dy, th e com pressive force of th e pin s w as fou n d to decrease by 83% in cadavers an d 88% in vivo over a 3-m on th w ear period.31,32 Loose pin s sh ould be ret igh ten ed to 8 in ch -lb if p ossible; oth er w ise, replacem en t to an adjacen t site is in dicated. St u dies h ave also rep or ted th at th e sn aking ph en om en on can p oten t ially lead to delayed union or nonun ion. Biom echanical studies have show n that physiological m otion is largely m aintain ed w ith a properly t t ing vest , h ow ever. Su p er cial in fect ion s at p in sites are m an aged w ith local pin care an d oral an t ibiot ics. More severe in fect ion s requ ire pin rem oval, rep osition ing, incision and drainage, and possible paren teral an t ibiot ics. Kim et al33 recom m en ded obtaining supine and upright lateral lm s w hile th e p at ien t is in th e h alo vest after p lacem en t an d th en at 2 w eeks, 6 w eeks, an d 3 m on th s to aid in iden t ifying a ch ange in fract ure displacem en t ≥ 5 m m to iden t ify pat ien t s at risk for t reat m en t failu re. Dysp h agia is t ypically in -

du ced by cer vical exten sion , an d m ay n ecessitate adjust m en ts to th e u prigh t st ru ts.

■ General Treatment

Principles Cervical Sprains Cer vical sp rain s are frequ en tly du e to hyp erexten sion w h ip lash -t yp e inju ries su st ain ed in m otor veh icle collision s. Often th e soft t issu e suppor t st r uct u re of th e cer vical sp in e, in cluding th e m u scu lar, ligam en tou s, an d cap su lar st r u ct u res, is st retch ed or par t ially torn in th e t rau m at ic even t . W h en th e h ead is t u rn ed to th e righ t or left , th e con t ralateral stern ocleidom astoid h as been sh ow n to h ave th e greatest contraction, w hich potentially exposes this m uscle to dam age.34 Th e t reat m en t for w h iplash t ype injuries is gen erally a soft cer vical collar for p ropriocept ive lim it at ion of ext rem e n eck m ovem ent during the healing process. One study fou n d n o di eren ce, h ow ever, in clin ical recover y w h en com paring 3 w eeks of soft collar im m obilizat ion to early m obilizat ion follow ing soft t issue n eck injuries. In fact , th e im m obilized group h ad a stat ist ically longer ret urn to w ork after injur y (34 days vs 17 days).35

Upper Cervical Spine Non operat ive m an agem en t of th e u p per cer vical spin e (occip u t–C2 levels) is com m onp lace. Follow ing closed red u ct ion , m any fract u res at t h ese levels can be m an aged by r igid im m obilizat ion un less grossly un stable or w ith an associated n eurologic injur y requiring decom pression . Th e classi cat ion an d su rgical in dicat ion s for each fract u re pat tern are discu ssed in subsequen t ch apters. Th e m ajorit y of occipital con dyle fract ures can be t reated n on op erat ively w it h r igid or sem irigid im m obilizat ion u n less th ere are con com it an t fract u res or gross ligam en tou s in st abilit y. Maddox et al36 ret rospect ively review ed the nonoperative m anagem ent of Anderson and Mon tesan o t ypes I to III an d foun d n o associa-

Nonoperative Management of Cervical Spine Trauma t ion bet w een n eck disabilit y in dex scores an d fract ure t ype, displacem en t of fract ure, sex, bilateralit y, or p resen ce of h ead inju r y. Sim ilarly, m ost fract u res of th e atlas (7% of all cer vical spin e fract ures) can be t reated w ith rigid collar or halo im m obilization based largely on w h eth er or n ot th e t ran sverse ligam en t in in tact . Th ere is sign i can t con t roversy regarding t h e m eth od of im m obilizat ion , t h ough eith er m eth od h as docu m en ted su ccess. Th e den s fract ure is th e m ost com m on fract u re of th e a xis, occu rring in a bim odal dist ribut ion in th e young an d elderly popu lat ion s via h igh - an d low -im p act t rau m a, respect ively. An derson an d D’Alon zo t ype I to III fract u res have all been m anaged n onoperatively in either r igid cer vical or t h oses or h alo vest im m obilizat ion dep en ding on th e associated inju ries, t ran sverse ligam en t in tegrit y, th e Had ley t yp e IIA classi cat ion , an d th e direct ion an d degree of disp lacem en t (> 6 m m ) of th e den s. It is gen erally agreed t h at in t h e eld erly p op ulat ion , h alo im m obilizat ion is associated w ith increased m orbidit y and m ortalit y, though th ere h ave been good ou tcom es w ith h alo im m obilizat ion in p at ien t s over 65 years of age.37 Th e literat u re o ers con ict ing n dings regarding th e in creased m or t alit y rates in elderly pat ien ts w ith n on op erat ive m an agem en t com pared w ith op erat ive stabilizat ion . In a recen t st u dy by Molin ari et al,38 elderly pat ien t s w ith ≥ 50% disp lacem en t of th e den s w ere t reated w it h p oster ior fu sion an d t h ose w it h < 50% displacem en t w ere t reated w ith rigid cer vical collars. Th e au th ors fou n d a h igh er fu sion rate in op erat ive pat ien ts, bu t low er n eck disabilit y scores, less p ain , few er com p licat ion s, an d a low er m or t alit y rate (12% vs 20%) in th e n on operat ive grou p. Han gm an’s fract u res are also com m on ly t reated n on operat ively. In a ret rosp ect ive review of 27 t yp e II an d four t ype IIA h angm an’s fract u res, Vaccaro et al39 fou n d th at n on op erat ive t reat m en t w ith h alo im m obilizat ion led to un ion in 21 of th e t yp e II an d all of t h e t yp e IIA fract ures, th ough pat ients w ith in it ial angulation ≥ 12 m m required reapplication of traction before un ion . Li et al40 fou n d th at n on op erat ive m an agem en t w as accept able for m ost fract u re

pat tern s, th ough xat ion sh ou ld be con sidered for severely displaced Levin e-Edw ards t ype IIa an d III fract u res.

Subaxial Spine Trauma Like t h e u p p er cer vical sp in e, n on op erat ive t reat m en t of t h e su ba xial (C3- C7) sp in e is com m onp lace u n less th ere is gross in st abilit y or n eu rologic injur y requiring decom pression . Facet fract u res are on e exam p le of a fract u re for w h ich th e t reat ing physician m ay con sider su rgical in ter ven t ion , as pat ien ts t reated n on operat ively seem to experien ce greater pain an d disabilit y th an th ose m an aged operat ively. Un ilateral facet fract u res m ake u p 6 to 10% of all cer vical sp in e fract u res, w it h on e rep or t in dicat ing th at th e C7 facet is th e m ost com m only injured level (68%). Halliday et al41 suggested t h at t h ere m ay be u t ilit y in obt ain in g an MRI to evaluate th e facet region , th e interspin ous ligam en t , th e an terior longit udin al ligam en t , an d th e posterior longit udin al ligam en t . Inju r y to t h ree of th ese fou r ligam en t com p lexes con fer red a h igh er r isk for in st abilit y an d th e poten t ial n eed for surger y. A separate st u dy in d icated th at fract u re in st abilit y an d p ossible n on op erat ive failu re m ay be determ in ed if th e facet fract u re involves > 40%of th e absolute h eigh t of th e in t act lateral m ass or an absolute h eigh t > 1 cm .42

Gunshot Wounds Gun sh ot-related fract u res of th e cer vical sp in e are un com m on ly en coun tered an d are often treated nonoperatively, as these are usually stable injuries. Th ese injuries can be com plicated by em ergen t bleeding an d air w ay obst r uct ion th at m ay p reclu d e t yp ical sp in e im m obilizat ion . In a review of 10 p at ien t s w it h at lan toa xial gu n sh ot w ou n d s, all bu t t w o inju r ies involved th e ver tebral ar ter y. On ly on e pat ien t requ ired op erat ive fu sion of th e sp in e, on e received h alo im m obilizat ion , on e required fragm en t rem oval, an d on e requ ired em bolizat ion follow ing a st ula.43 All ult im ately h ad a m ech an ically st able sp in e. In a sep arate review of 81 pat ien t s w ith gu nsh ot w ou n ds to th e h ead

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Chapter 4 or n eck, 19 pat ien ts w ere iden t i ed as h aving cervical spine fractures.44 Of the alert and aw ake pat ien ts, on ly th ree w ere iden t i ed as h aving a cer vical spin e fract u re, an d n on e of th ese w ere u n st able. Th e au t h ors’ con clu sion s w ere t h at spin al precau t ion s sh ould n ot in terfere w ith lifesaving p rocedu res, par t icu larly in th e aler t an d orien ted p at ien t .

■ Chapter Summary Cer vical spin e fract u res are com m on inju ries seen in th e t rau m a set t ing, an d proper recogn it ion an d t reat m en t of inju ries to th is region are in tegral to p reven t fu rth er dam age. Im m obilizat ion follow ed by radiograp h ic an d often CT/ MRI scan s are th e m ain st ay of in it ial t reat m en t . Cer vical t ract ion w it h eit h er Gard n er-Wells tongs or a h alo device are m odalit ies used to redu ce fract u re dislocat ion s an d to relieve cord com p ression . Th e m ajorit y of cer vical sp in e t rau m a is m an aged n on op erat ively w ith cer vical im m obilizat ion . Th e rigidit y an d vertebral levels sp an n ed by th e or th osis is largely u p to th e t reat ing p hysician , w h o m u st con sider in -

creasing p at ien t d iscom for t an d com plicat ion s as stabilit y in creases.

Pearls The majorit y of cervical spine injuries occur in the subaxial cervical spine. Rigid im mobilization is required after injury to ensure that no additional dam age occurs. The m ajorit y of cervical spine injuries are m anaged nonoperatively. There remains signif cant controversy regarding perform ing an MRI prior to reduction of the cervical spine in the alert, awake, and oriented patient. Closed reduction should be performed under expert guidance in an awake and oriented patient who can participate in a neurologic exam . In general, stabilit y increases as the level of cervical orthosis restriction increases. Pitfalls Ensure proper plain X-ray im aging prior to any closed reduction at tempt. Decubitus ulceration is a m ajor but preventable complication of cervical imm obilization. Use caution when considering application of halo vest imm obilization for elderly patients.

Refere nces Five Must-Read Refe rences 1. Vaccaro AR, Hulbert RJ, Patel AA, et al; Spin e Traum a St u dy Grou p. Th e su baxial cer vical sp in e inju r y classi cat ion system : a n ovel approach to recogn ize th e im por t an ce of m orph ology, n eurology, an d in tegrit y of th e disco-ligam en tous com plex. Spin e 2007;32: 2365–2374 Pu bMed 2. Noble ER, Sm oker W R. Th e forgot ten con dyle: th e appearan ce, m orph ology, an d classi cat ion of occip it al con dyle fract ures. AJNR Am J Neuroradiol 1996; 17:507–513 PubMed 3. Sayadipour A, An derson D, Mlyavykh S, Perlm ut ter O, Vaccaro A. Su baxial cer vical spin e inju ries. In : Ben zel EC (ed). Sp in e Surger y: Tech niqu es, Com plicat ion Avoidan ce an d Man agem ent , vol 3. Ph iladelph ia: Elsevier; 2012:611–624. 4. Plat zer P, Jain dl M, Th alh am m er G, et al. Clearing th e cer vical spine in critically injured patients: a com prehen sive C-spine protocol to avoid unn ecessar y delays in diagnosis. Eur Spine J 2006;15:1801–1810 PubMed

5. Tom ycz ND, Ch ew BG, Ch ang YF, et al. MRI is u n n ecessar y to clear t h e cer vical sp in e in obt u n d ed / com atose t raum a pat ien t s: th e four-year experien ce of a level I t rau m a cen ter. J Trau m a 2008;64:1258– 1263 Pu bMed 6. Taylor AS. Fract ure dislocat ion of th e cer vical spine. An n Surg 1929;90:321–340 Pu bMed 7. Harrop JS, Vaccaro A, Przybylski GJ. Acute respirator y com prom ise associated w ith exed cer vical t ract ion after C2 fract u res. Spine 2001;26:E50–E54 Pu bMed 8. Cotler JM, Herbison GJ, Nasu t i JF, Dit un n o JF Jr, An H, Wol BE. Closed redu ct ion of t rau m at ic cer vical sp in e d islocat ion u sing t ract ion w eigh t s u p to 140 poun ds. Spin e 1993;18:386–390 Pu bMed 9. Wim berley DW, Vaccaro AR, Goyal N, et al. Acute quadriplegia follow ing closed t ract ion reduct ion of a cer vical facet dislocat ion in th e set t ing of ossi cat ion of th e posterior longit udin al ligam en t: case repor t . Spin e 2005;30:E433–E438 Pu bMed

Nonoperative Management of Cervical Spine Trauma 10. Vaccaro AR, Falat yn SP, Flan ders AE, Balderston RA, North ru p BE, Cotler JM. Magn et ic reson ance evaluat ion of th e in ter vertebral disc, spin al ligam en t s, an d spin al cord before an d after closed t ract ion reduct ion of cer vical spin e dislocat ion s. Spin e 1999;24:1210– 1217 PubMed 11. Gran t GA, Mirza SK, Chapm an JR, et al. Risk of early closed reduct ion in cer vical spine sublu xat ion injuries. J Neu rosurg 1999;90(1, Suppl):13–18 Pu bMed 12. Miller CP, Bible JE, Jeged e KA, W h ang PG, Grau er JN. Soft an d rigid collars provide sim ilar rest rict ion in cer vical range of m ot ion during fteen act ivit ies of daily living. Spin e 2010;35:1271–1278 Pu bMed 13. Evan s NR, Hooper G, Edw ards R, et al. A 3D m ot ion analysis st udy com paring the e ectiveness of cer vical spin e or th oses at rest rict ing spin al m ot ion th rough physiological ranges. Eu r Sp in e J 2013;22(Su p p l 1): S10–S15 Pu bMed 14. Tesch er AN, Rin d esch AB, Youdas JW, et al. Rangeof-m otion restriction and cran iofacial t issue-interface pressu re from fou r cer vical collars. J Trau m a 2007; 63:1120–1126 PubMed 15. Gavin TM, Caran dang G, Havey R, Flan agan P, Gh an ayem A, Pat w ardh an AG. Biom echan ical analysis of cer vical or th oses in exion an d exten sion : a com parison of cer vical collars an d cer vical th oracic orth oses. J Reh abil Res Dev 2003;40:527–537 PubMed 16. Ivan cic PC. Do cer vical collars an d cer vicoth oracic or th oses e ect ively st abilize th e inju red cer vical spin e? A biom ech an ical invest igat ion . Spin e 2013; 38:E767–E774 PubMed 17. Schn eider AM, Hipp JA, Nguyen L, Reit m an CA. Redu ct ion in h ead an d in ter ver tebral m ot ion p rovided by 7 con tem porar y cer vical or th oses in 45 in dividu als. Sp in e 2007;32:E1–E6 Pu bMed 18. San dler AJ, Dvorak J, Hu m ke T, Grob D, Dan iels W. Th e e ect iven ess of variou s cer vical or th oses. An in vivo com parison of th e m ech an ical st abilit y provided by several w idely used m odels. Spin e 1996;21: 1624–1629 Pu bMed 19. Acklan d HM, Cooper DJ, Malh am GM, Kossm ann T. Factors predict ing cer vical collar-related decubit us ulcerat ion in m ajor t rau m a pat ien t s. Spin e 2007; 32:423–428 Pu bMed 20. Anderson PA, Bu dorick TE, Easton KB, Hen ley MB, Salciccioli GG. Failure of h alo vest to preven t in vivo m otion in pat ients w ith injured cervical spines. Spine 1991;16(10, Suppl):S501–S505 Pu bMed 21. Lind B, Sih lbom H, Nordw all A. Forces and m ot ion s across th e n eck in pat ien t s t reated w ith h alo-vest . Spin e 1988;13:162–167 PubMed 22. Ebrah eim NA, Liu J, Pat il V, et al. Evalu at ion of skull th ickn ess an d in ser t ion torqu e at th e h alo p in in sert ion areas in th e elderly: a cadaveric st udy. Sp in e J 2007;7:689–693 Pu bMed 23. Rizzolo SJ, Piazza MR, Cotler JM, Hum e EL, Caut illi G, O’Neill DK. Th e e ect of torqu e p ressu re on h alo p in

com plicat ion rates. A ran dom ized prospect ive st udy. Spin e 1993;18:2163–2166 PubMed 24. View eg U, Sch ulth eiss R. A review of h alo vest t reatm en t of upper cer vical spin e injuries. Arch Or th op Trau m a Su rg 2001;121:50–55 PubMed 25. Tash jian RZ, Majercik S, Bi W L, Palum bo MA, Cio WG. Halo-vest im m obilizat ion in creases early m orbidit y an d m ort alit y in elderly odon toid fract ures. J Trau m a 2006;60:199–203 Pu bMed 26. Koller H, Zen n er J, Hit zl W, et al. In vivo an alysis of atlan toaxial m ot ion in individuals im m obilized w ith th e h alo th oracic vest or Ph ilad elp h ia collar. Sp in e 2009;34:670–679 PubMed 27. Rich ter D, Lat t a LL, Miln e EL, et al. Th e st abilizing effect s of di eren t or th oses in th e in t act an d un st able upper cer vical spin e: a cadaver st u dy. J Traum a 2001; 50:848–854 Pu bMed 28. Polin RS, Szabo T, Bogaev CA, Replogle RE, Jan e JA. Nonoperat ive m an agem en t of t ypes II and III odon toid fract u res: th e Ph ilad elph ia collar versu s th e h alo vest. Neurosurger y 1996;38:450–456, discussion 456– 457 Pu bMed 29. Ben zel EC, Hadden TA, Sau lsber y CM. A com parison of the Minerva an d halo jackets for stabilizat ion of the cer vical spin e. J Neurosurg 1989;70:411–414 PubMed 30. Majercik S, Tash jian RZ, Bi W L, Harrington DT, Cio WG. Halo vest im m obilizat ion in th e elderly: a death sen ten ce? J Trau m a 2005;59:350–356, discu ssion 356–358 Pu bMed 31. Flem ing BC, Huston DR, Krag MH, Sugih ara S. Pin force m easu rem en t in a h alo-vest or th osis, in vivo. J Biom ech 1998;31:647–651 PubMed 32. Flem ing BC, Krag MH, Huston DR, Sugih ara S. Pin loosen ing in a h alo-vest orth osis: a biom ech an ical st udy. Spin e 2000;25:1325–1331 PubMed 33. Kim DH, Vaccaro AR, A onso J, Jen is L, Hilibrand AS, Albert TJ. Early predictive value of supine an d uprigh t X-ray lm s of odon toid fract ures treated w ith h alovest im m obilization. Spine J 2008;8:612–618 PubMed 34. Kum ar S, Ferrari R, Narayan Y. Looking aw ay from w h ip lash : e ect of h ead rot at ion in rear im p act s. Spin e 2005;30:760–768 PubMed 35. Craw ford JR, Khan RJ, Varley GW. Early m an agem en t an d ou tcom e follow ing soft t issu e inju r ies of t h e neck-a random ised cont rolled t rial. Injur y 2004;35: 891–895 PubMed 36. Maddox JJ, Rodriguez-Feo JA III, Maddox GE, Gu llung G, McGw in G, Th eiss SM. Non operat ive t reat m en t of occipit al con dyle fract u res: an outcom es review of 32 fract ures. Spin e 2012;37:E964–E968 PubMed 37. Koech F, Acklan d HM, Varm a DK, William son OD, Malh am GM. Non op erat ive m an agem en t of t yp e II od on toid fract u res in t h e eld erly. Sp in e 2008;33: 2881–2886 Pu bMed 38. Molin ari W J III, Molin ari RW, Kh era OA, Gru h n W L. Fun ct ion al outcom es, m orbidit y, m or t alit y, an d fract ure h ealing in 58 con secut ive pat ien t s w ith geriat ric

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Chapter 4 odon toid fract ure t reated w ith cer vical collar or posterior fu sion . Global Sp in e J 2013;3:21–32 PubMed 39. Vaccaro AR, Madigan L, Bau erle W B, Blescia A, Cotler JM. Early halo im m obilizat ion of displaced t raum at ic spon dylolisth esis of th e axis. Spin e 2002;27:2229– 2233 PubMed 40. Li XF, Dai LY, Lu H, Ch en XD. A system at ic review of th e m an agem en t of h angm an’s fract ures. Eur Spine J 2006;15:257–269 Pu bMed 41. Halliday AL, Hen derson BR, Hart BL, Ben zel EC. The m an agem ent of unilateral lateral m ass/facet fract ures of th e subaxial cer vical spine: th e use of m agn et ic reson an ce im aging to predict in st abilit y. Spin e 1997; 22:2614–2621 Pu bMed

42. Spector LR, Kim DH, A on so J, Albert TJ, Hilibran d AS, Vaccaro AR. Use of com puted tom ography to predict failu re of n on op erat ive t reat m en t of u n ilateral facet fract u res of th e cer vical sp in e. Sp in e 2006;31: 2827–2835 Pu bMed 43. Syre P III, Rodriguez-Cruz L, Desai R, et al. Civilian gun sh ot w oun ds to th e atlan toaxial spin e: a report of 10 cases t reated using a m ult idisciplin ar y approach . J Neu rosu rg Sp in e 2013;19:759–766 Pu bMed 44. Medzon R, Roth en h aus T, Bon o CM, Grin dlinger G, Rath lev NK. St abilit y of cer vical spin e fract ures after gun sh ot w oun ds to th e h ead an d neck. Spin e 2005; 30:2274–2279 PubMed

5 Occipital Condyle Fractures and Occipitocervical Dissociation Philipp Schleicher, Matti Scholz, and Frank Kandziora

■ Introduction Injuries of th e cran iover tebral jun ct ion com p r ise occip it al con dyle fract u res (OCFs) an d at lan to-occipit al dissociat ion (AOD). Th e lat ter en t it y is also frequ en tly term ed occip itocer vical dissociat ion , craniocer vical dissociation , and cran iocer vical dislocat ion in th e literat u re. Th e relevan ce of both OCF an d AOD h as in creased in recen t decades for several reason s. Im p roved p reh osp it al t rau m a care h as in creased th e sur vival rate of pat ien ts w ith AOD, so th at th ey are n ow t reated in th e em ergen cy dep ar t m en t; in th e p ast th is inju r y w as n early 100% fatal. Fu rth erm ore, th e w ide im plem en tat ion of com puted tom ography (CT) scan n ing as th e p r im ar y im aging m odalit y in t rau m a p at ien t s h as im proved th e detect ion rate of AOD as w ell as th at of OCF, w h ich also h as a m u ch h igh er in ciden ce rate th an du ring th e X-ray era. Especially for AOD, due to it s in h eren t risk for severe n eurologic dam age or fat al outcom e, im m ediate diagn osis an d adequ ate t reat m en t are cru cial. Despite th e in creasing relevan ce of OCF an d AOD, th e eviden ce class of th e exist ing data st ill does n ot exceed class IV (case series), becau se th e in ciden ce of th ese inju ries, alth ough in creasing, is st ill ver y low.

Never t h eless, w it h an in creasin g n u m ber of cases p u blish ed in t h e literat u re, it is p ossible to ext ract som e recom m en dat ion s for t h e d iagn osis an d t reat m en t of t h ese t yp es of inju r ies.

■ Epidemiological Features and Pathomechanisms Th e exact ep idem iological occu rren ce of AOD is u n kn ow n , becau se th e literat u re en com passes on ly case rep or ts an d case series. As of 2014, w e foun d a tot al of 534 repor ted cases of AOD in th e Medlin e database, w ith abou t a th ird of cases (n = 182) h aving su r vived at least several days after th e inju r y. Th e largest case series in clu ded 69 p at ien t s (w ith seven su r vivors, yielding a 10% sur vival rate). Th e largest su r vival series repor ted on 33 p at ien t s AOD, 23 of w h om su r vived (70% su r vival rate). Recen t prospect ive st u dies revealed a ver y low in ciden ce of AOD in a Western t rau m a pop u lat ion . Mü ller et al fou n d on ly ve AODs in 2,162 t rau m a p at ien t s receiving a cer vical spin e CT scan , for an in ciden ce of 0.23%.1 Of th ese ve pat ien t s, th ree died w ith in 1 w eek after inju r y. In con t rast , AOD can be foun d in up to 18%of t rau m a fatalit ies.2 Th u s, th ese dat a

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Chapter 5 in dicate th at AOD is a rare bu t severe injur y, w ith a sh or t-term m or talit y of abou t 60%. Occip it al con dyle fract u res h ave been rep or ted in at least 393 cases as of 2014. Th e largest case series con sisted of 107 p at ien t s. Th e rep or ted in ciden ce varies greatly, depen ding on th e un derlying p op u lat ion of th ese case series. Maserat i et al fou n d ~ 200 OCFs in a populat ion of ~ 25,000 t raum a pat ien ts w h o w ere adm it ted to th eir level I t raum a cen ter, yielding an incidence of ~ 0.8%.3 A sim ilar OCF incidence (1.1%) w as found in 700 traum a patients treated in a level I traum a center intensive care unit (ICU) was reported by Krüger et al.4 Th e m or t alit y of OCFs is d i cu lt to determ in e, becau se th ere are ver y few rep or t s on fat al outcom e in th e literat ure. In on e of th e largest case series by Maserat i et al, th e m ortalit y w as 12%. A m ajor cause of death w as a con com it an t t rau m at ic brain inju r y (TBI).3 Ad dit ion ally, th e in ciden ce of OCF in t raum a fatalit ies is ver y sim ilar to th at in su r viving t raum a pat ien ts (1–4%). Th is im p lies th at OCF is n ot in itself a fatal inju r y, bu t rath er th at th e occasion al death of a p at ien t w ith OCF m igh t m ain ly be d ue to con com it an t inju ries su ch as TBI. In th e m ajorit y of cases, a m otor veh icle acciden t (MVA) is th e inju r y m ech an ism . Th is explain s w hy th e t ypical OCF p at ien t is a you ng m an (average age in th e early 30s); th e m ale/ fem ale rat io is 2:1. In con t rast , th e t ypical AOD pat ien t is m u ch you nger; 20% of all cases are rep or ted in ch ildren . Th is is often exp lain ed by th e sh allow er occipitoatlan t al join t su rfaces, h igh er h ead m om en t , an d laxer ligam en ts in ch ildren .

■ Anatomic Features and

Biomechanics Th e clin ician m u st be cogn izan t of several an atom ic feat ures of th e cran iocer vical jun ct ion . To assess the neurologic sym ptom s, it is im por tan t to kn ow th e exact locat ion of th e exit ing cran ial n er ves aroun d th e occipital con dyles. To determ in e th e in stabilit y of a fract ure, th or-

ough know ledge of the craniocer vical ligam ents an d th eir bony at t ach m en ts is h elpfu l.

Joints and Ligaments at the Craniocervical Junction Th e occip itoat lan t al join t com p lex con sist s m ain ly of t w o convex-sh ap ed occip it al con dyles at th e an terior rim of th e foram en m agn um an d th e correspon ding con cave-sh aped upper joint surfaces of the atlas. The joint’s surface topology, w h ich w as described as “som ew h at cuplike” by W h ite an d Panjabi,5 m akes it act as a roller join t , w ith 25 degrees of exion / exten sion an d 5 degrees of axial rotat ion an d lateral ben ding. Th is join t is called a “yes join t” becau se it is u sed w h en th e h ead is n odding “yes.” Th e ligam en tous stabilit y of th e cran iovertebral ju n ct ion is p rovid ed m ost ly by t h e in ter n al ligam en t s arou n d th e sp in al can al. From an terior to posterior, th e follow ing st r u ct u res are involved: • Th e apical odon toid ligam en t con n ect s th e t ip of th e odon toid w ith th e an terior rim of th e foram en m agn u m . • Th e p aired alar ligam en t s con n ect t h e t ip of t h e odon toid w ith eit h er t h e an terom ed ial bord er of t h e occip it al con dyle or t h e an terom ed ial p or t ion of t h e at lan t al lateral m ass. Th e accou n t for 30% of th e rot at ion al st abilit y of t h e C0- C1 join t an d m ay cau se an avu lsion fract u re of t h e occip it al con dyle. • Th e longit u d in al p ar t of t h e cr u ciate ligam en t con n ect s t h e p osterior ver tebral body of t h e a xis ver tebra to t h e foram en m agn u m . • Th e tectorial m em bran e ru n s from th e an terior foram en m agn um dow nw ard an d con t in ues to th e st rong posterior longit udin al ligam en t . Its m ain fun ct ion is th e lim itat ion of hyperexten sion . • Th e ou ter ligam en t system con sists of th e extern al an terior an d posterior atlan to-occipit al m em bran e, th e join t cap su les of th e C0- C1 join t , an d th e n uch al ligam en t .

Occipital Condyle Fractures and Occipitocervical Dissociation

The Low er Cranial Nerves and Their Exits In an d aroun d th e occipital con dyles, th ere are t w o bony can als th at ser ve as an exit rou te for various st r uct ures, m ostly n er ves. In th ese n arrow canals, the nerves and vessels are in danger of being dam aged by direct t rau m a or in direct com p ression du e to sw elling, bleeding, or scar t issu e develop ing even m on th s after an inju r y. Directly w ith in th e hypoglossal can al, th e hypoglossal n er ve exit s th e sku ll base an d run s to th e tongue. It is th e on ly st r uct ure r un n ing th rough th is can al. Sligh tly lateral of th e occipit al con dyle, th e jugular foram en is passed by th e glossoph ar yngeal, vagal, an d accessor y n er ves as w ell as th e in tern al jugu lar vein an d p osterior m en in geal ar ter y. Beh in d th e occipital con dyles, an em issar y vein con n ect s t h e sigm oid sin u s an d a ver tebral ven ous plexus th rough th e posterior con dylar can al.

■ Diagnosis Clinical Presentation Th e clin ical p resen t at ion of AOD an d OCF sh ow s great var iabilit y in sym ptom t yp e an d in th e t im ing of sym ptom occurren ce. In rare cases, th ese en t it ies are diagn osed after an asym ptom at ic in ter val of several m on th s! 6–8 Due to th e severit y of th e inju r y, p at ien ts w ho sur vive an AOD are often un con scious an d sh ow sign s of brain or sp in al cord inju r y (SCI). In OCF, t ran sien t or persisten t loss of con sciousn ess is repor ted in 80% of cases. Sudden cardiac arrest in a patient w ith blunt h ead t rau m a, esp ecially d u r in g t ran sfer an d m an ip u lat ion , sh ou ld raise t h e su sp icion for brain stem com pression due to cran iocer vical in st abilit y. In OCF, involvem en t of th e low er cran ial n er ves occu rs in 30% of cases. Th erefore, given th e above n dings, it is im port an t for clin ician s to kn ow th e fu n ct ion of

the relevant n er ves, because low er cranial ner ve p alsy m igh t be t h e m ajor sym ptom lead in g to t h e d iagn osis. In abou t a t h ird of p at ien t s, t h e cran ial n er ve palsies m igh t develop after several m on th s as a sequ ela of cran iocer vical t rau m a. Delayed n eu rologic im p airm en t m ay result from fragm ent m igration or the com pressive e ect of develop ing brou s t issu e arou n d th e n arrow n er ve can als. If th e pat ien t is con scious, th e careful exam in er sh ould also look for on e of th e follow ing sign s an d sym ptom s: • Tenderness in t h e p oster ior cran iocer vical t ran sit ion is rep or ted in n early ever y p at ien t w ith OCF, an d it seem s to be a sen sit ive sym ptom . In Th eodore et al’s 9 repor t on 64 pat ien ts, on ly fou r did n ot rep or t u pp er cervical ten dern ess, an d all four w ere eith er in toxicated or h ad severe facial or ext rem it y inju r y. • Dysphagia is an often -rep or ted sym ptom in d elayed d iagn osis. It is cau sed eit h er by glossop h ar yngeu s, vagal, or hyp oglossu s n er ve p alsy or, in ver y rare cases, by t h e develop m en t of a ret rop h ar yngeal p seu d o m en in gocele.10–12 • Hoarseness an d num bness in the anterior part of the ear as w ell as in th e extern al au d itor y can al (R. au ricu laris) are furth er sign s of a vagal n er ve lesion . • Tort icollis or w eakness in lift ing th e sh oulder or abdu ct ion of th e arm is seen w h en th e accessor y n er ve is dam aged, becau se it in n er vates th e stern ocleidom astoid an d th e t rapezius m u scle. • A deviat ion of the tongue in dicates a lesion of th e ipsilateral hypoglossal n er ve.

Imaging Blun t h ead t raum a h as a sign i can t associat ion w ith cer vical spine injuries, including the upper cer vical sp in e. With th e im proved preclin ical t reat m en t algorith m s, th e sur vival rate of t raum a vict im s w ith AOD is increasing. But these patients m ight die in th e em ergen cy dep ar t m en t if a diagn osis

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Chapter 5 of AOD is m issed or delayed. Th us, it is essen t ial to u se a set of diagn ost ic m easu res of ver y h igh sen sit ivit y. Several m eth ods to correctly recogn ize th is severe inju r y h ave been develop ed; th ey are of varied p ract icabilit y. Th eir sen sit ivit y an d speci cit y h ave been evaluated in large st ud ies. X-ray im aging is a less reliable m eth od becau se of it s p oorer visu alizat ion of speci c bony lan dm arks. Addit ion ally, th ese lan dm arks are quite dist an t from th e origin of th e occipitoatlan tal join t . Th erefore, on ly grossly displaced lesion s w ill be recogn ized by on X-ray. Now adays, w ith th e w idesp read availabilit y of CT scan n ers in th e t raum a set t ing, CT-based m eth od s are p referable. Th e available m eth ods are as follow s: • Th e W holey basion– dens interval (sen sit ivit y 61%, speci cit y 71%; Fig. 5.1) ser ved as a st an dard m easure for m any years because of its easy applicat ion . A lin e is draw n from th e t ip of th e basion to th e t ip of th e odon toid process. A value of m ore th an 10 m m in adu lt s an d 12 m m in in fan t s is con sid ered abn orm al. A valu e of m ore th an 16 m m

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•

Fig. 5.1 Wholey’s basion (B)–dens (D) interval. (From Gire JD, Roberto RF, Bobinski M, Klineberg EO, Durbin-Johnson B. The utilit y and accuracy of computed tom ography in the diagnosis of occipitocervical dissociation. Spine J 2013;13:510–519. Reproduced with perm ission.)

is associated w ith a sign i can tly in creased m or t alit y.13 Th e Harris basion-axis interval (sen sit ivit y 28.5%, sp eci cit y 84.5%) describes th e dist an ce from th e basion to a tangen t draw n th rough th e posterior w all of C2. Norm al range is –4 to 12 m m in adults an d 0 to 12 m m in ch ildren .14 Th e Pow ers rat io (sen sit ivit y 32%, sp eci cit y 78%) is th e ratio of the distance from the basion to th e C1 posterior arch divided by th e d ist an ce from th e opisth ion to th e an terior C1 arch . A rat io greater th an 1 is con sidered p ath ological. Th is m eth od yields false-n egat ive results w h en th ere are st rictly longit ud in al or posterior dislocat ion s.15 Lee’s X-line m ethod (sensitivit y 54%, speci cit y 38%) is sim ilar to the Pow ers ratio, w ith a line draw n from the basion to the spinolam in ar lin e of C2 an d an oth er lin e draw n from the opisthion to the posterior inferior edge of the C2 vertebral body. The lines should touch the tip of the dens or the highest edge of the C1 spinolam inar line, respectively. Otherw ise, an AOD is likely.16 For Sun’s interspinous rat io (sensitivit y 28.5%, sp eci cit y 77%), t h e in tersp in ou s d ist an ce bet w een C1-2 an d C2-3 is m easu red . If t h e rat io is greater t h an 2.5, AOD can be assu m ed.17 Th e Dublin m ethod m easures th e dist an ce bet w een th e m an d ible an d th e an terior arch of th e atlas an d th e odon toid, resp ect ively, w h ich sh ou ld n ot exceed 2 an d 10 m m . Th is m eth od is st rongly depen den t on proper p osit ion ing an d an in t act m an dible, an d it h as proven to be im p recise.18 Using CT scan s, Pang et al19 developed th e condyle–C1 interval (CCI), w hich is based on 16 m easured param eters in di eren t plan es, w h ich m akes it di cult to use in ever yday pract ice. It w as sim p li ed by Gire et al20 to th e revised CCI (sen sitivit y 100%, speci cit y 92%; Fig. 5.2), in w h ich t h e join t su r face d istan ce in th e m idsagit t al plan e at th e p oin t of greatest sep arat ion bet w een th e occipital con dyle an d th e C1 lateral m ass is m easu red. A value greater th an 2.5 m m is con sidered path ological. A derivat ive of this m easu rem en t is th e con dylar sum , w h ich is

Occipital Condyle Fractures and Occipitocervical Dissociation th e m ost crit ical step in th e diagn ost ic p rocess, an d it sh ould be don e if th e results of th e CT leave th e clin ician in dou bt abou t th e diagn osis (Figs. 5.1 and 5.2).

Classif cation

Fig. 5.2 Revised condyle–C1 interval (CCI). OC, occipital condyle. (From Gire JD, Roberto RF, Bobinski M, Klineberg EO, Durbin-Johnson B. The utilit y and accuracy of computed tomography in the diagnosis of occipitocervical dissociation. Spine J 2013;13:510–519. Reproduced with perm ission.)

th e su m of th e left an d righ t revised CCI an d sh ou ld n ot exceed 5 m m . • For OCF, t h e sen sit ivit y of convent ional X-rays is low. Recen t st u d ies fou n d a sen sit ivit y of bet w een 0 an d 3%. Occasion ally, a ret roph ar yngeal h em atom a can be a sign on th e lateral view, bu t th is is ver y u n sp eci c. Th u s, conven t ion al X-ray is n ot h elpfu l in im aging th ese t ypes of injuries. On e m ajor crit icism of both X-ray an d CT scan s is t h at a sp on t an eou s redu ct ion of th e severely u n st able AOD m ay p resen t falsen egat ive n ding, lead ing to t h e cat ast roph ic con sequ en ces of a m issed diagn osis. Th erefore, som e au th ors recom m en d m agn et ic reson an ce im aging (MRI) for all cases th at are doubtfu l on CT. On MRI, th e th eoret ically proposed criteria are in tegrit y of th e cru ciate ligam en t an d th e occipitocer vical (OC) join t capsule, an d u id en rich m en t on th e pericon dylar area as a sign for in t racap su lar h em atom a (see Fig. 5.5c, below ). How ever, n on e of t h ese cr iter ia h as proven to be an in dicator of a t r ue in st abilit y. Th erefore, w ith th e w ide availabilit y of CT, th e decision of w h eth er to requ est an MRI is

Due to th e rarit y of th e lesion , th ere are n ot m any classi cat ion system s for AOD. On e of th e oldest is th e classi cat ion publish ed by Trayn elis et al21 in 1986 (Fig. 5.3). Th ey classi ed th e inju r y according to th e vector of t ranslat ion as follow s: t ype I, an terior; t yp e II, a xial; an d t yp e III, p oster ior. Th e d ist r ibu t ion of t h ese t yp es is rep or ted as follow s: t yp e I, 40%; t yp e II, 40%; an d t ype III, 5%. Th e rem ain ing 15% are n ot classi able. Alth ough often applied, this classi cation is criticized becau se in t r u e AOD, th e severe in st abilit y m akes a dislocat ion in ever y direct ion likely, an d th e dislocat ion seen on X-ray is n o m ore th an a sn ap sh ot in t im e; th e sit uat ion m ay im m ediately ch ange. Fu r th erm ore, th is classi cat ion h as n o im plicat ion s in determ in ing th e appropriate th erapy, as all of th ese injuries h ave an urgen t n eed for su rgical stabilizat ion . Horn et al22 p rop osed a di eren t ap proach , w h ich t akes in to accou n t di eren t grades of abn or m al n d ings in CT an d MRI, an d h elp s d eter m in e t h e ap p rop r iate t h erapy. Th e au t h ors d i eren t iate t w o grad es AOD. Grad e I lesion s h ave n orm al n dings on CT an d on ly m oderately abnorm al n dings on MRI. Th ese injuries are regarded as st able an d can be t reated con ser vat ively in a h ard cer vical collar. Grade II lesion s h ave abn orm al n dings on CT an d grossly abn orm al n dings on MRI. Th ese lesion s sh ou ld be qu ickly stabilized surgically. Th ere are oth er classi cat ion system s for OCFs. On e of th e earliest w as in t roduced by Saternus in 1987,23 sum m arizing h is experience w ith au top sy st u dies of t ra c fat alit ies. He differen t iated six t yp es of con dylar fract ure: • • • • • •

Axial com p ression Axial t ract ion Rot at ion w ith a xial st rain Obliqu e-com p ression Obliqu e-t ract ion Tran sverse th rust

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a

b

c

Fig. 5.3a–c Traynelis classi cation for atlanto-  occipital dislocation. (a) anterior translation. (b) posterior translation. (c) longitudinal translation. The red arrows indicate the direction of translation.

(From Kandziora F, Schnake K, Ho mann R. [Injuries  to the upper cervical spine. Part 2: osseous injuries].  Unfallchirurg 2010;113:1023–1039, quiz 1040. Reproduced with perm ission.)

An d erson an d Mon tesan o (Fig. 5.4) in t rodu ced th eir classi cat ion system in 1988, based on on ly six p at ien t s.24 It is easy to ap ply an d it h elp s d eterm in e t h e ap p rop riate t reat m en t , so it h as gain ed w idespread u se. Th e au t h ors di eren t iate t h ree di eren t t yp es of OCF:

Jeanneret has added a fourth type, a ring-shaped avulsion of th e en t ire foram en m agn u m .25 Th e secon d m ost often u sed classi cat ion is th at of Tu li et al8 pu blish ed in 1997, based on a ret rospect ive review of 93 of th eir ow n cases. Th ey di eren t iate n on displaced (t ype I), disp laced bu t st able (t ype IIA), an d disp laced an d u n st able (t ype IIB). Pat ien t s are determ in ed to be u n st able if th ey h ave on e of th e follow ing criteria:

• Type I: im p ression s fract u re • Type II: skull base fract u re th at exten ds in to th e occip ital con dyle • Type III: avulsion fract ure of th e alar ligam en t , likely to be displaced (Fig. 5.5a,b).

a

b

Fig. 5.4a–c Anderson and Montesano classi cation  for occipital condyle fractures. (a) Type I injuries  are compression fractures of the occipital condyle. (b) Type II injuries are skull base fractrues extending  into the occipital condyle. (c) Type II injuries are 

1. > 8 degrees of a xial rot at ion of th e occipu t– C1 join t to on e side

c

avulsion injuries at the at tachment of the alar ligaments. (From Kandziora F, Schnake K, Ho mann R.  [Injuries to the upper cervical spine. Part 2: osseous  injuries]. Unfallchirurg 2010;113:1023–1039, quiz  1040. Reproduced with perm ission.)

Occipital Condyle Fractures and Occipitocervical Dissociation

a

b

c

Fig. 5.5a–e Case example of a young man who  was injured in a high-speed motor vehicle accident  (MVA). (a) Computed tomography (CT) scan shows a subluxation of the right OC joint (red arrow) and an avulsion fracture of the left occipital condyle (Anderson and Montesano t ype III). (b) A rotatory displacement of the occiput against the atlas can be

seen. Note the left occipital condyle fracture (Anderson and Montesano t ype III). (c) Magnetic resonance imaging (MRI) demonstrates  uid  enhancement of the OC joint capsule and widening  of the joint space, which constitutes an atlanto-  occipital dislocation according to the CCI rule. (continued on page 56)

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d

e

Fig. 5.5a–e (continued ) (d) CT holographic image bet ter fusion. (e) Twelve-month follow-up CT scans. following treatm ent with an occipitocervical fusion. Note the reduced and nearly fused OC joint and the  The C2 screws are placed as Magerl screws, adding bony bridge along the occipital plate. high stabilit y to the C1-C2 joint as well as facilitating 

2. > 1 m m of occip u t–C1 t ran slat ion 3. > 7 m m of overh ang of C1 on C2 4. > 45 degrees of a xial rot at ion of C1–C2 to on e side 5. > 4 m m of C1–C2 t ran slat ion 6. < 13 m m bet w een th e posterior body of C2 an d th e posterior ring of C1 7. Avu lsed t ran sverse ligam en t 8. Eviden ce of ligam en tou s disru pt ion on MRI

None of the above classi cation system s have undergone validit y testing (Figs. 5.3 and 5.4).

■ Treatment Treat m en t opt ion s for th e cran iocer vical ju n ct ion in clu de con ser vat ive th erapy w ith im m o-

Occipital Condyle Fractures and Occipitocervical Dissociation bilizat ion in a h ard cer vical collar or in a h alo jacket , an d operat ive th erapy w ith occipitocervical fu sion via a p osterior m id lin e ap p roach (Fig. 5.5d,e ). An oth er opt ion is direct t ran sar t icu lar screw osteosyn th esis of C0- C1. Du e to ver y u n st able n at u re of AOD w it h th e r isk of severe n eu rologic d e cit s, op erat ive st abilizat ion is t h e t reat m en t of ch oice in m ost cases. Review s h ave fou n d a n eu rologic d eter iorat ion in 27% of p at ien t s w h o w ere t reated w it h exter n al st abilizat ion alon e. In con t rast , t h ere w as on ly on e case fou n d w it h n eu rologic d eter iorat ion after su rgical in ter ven t ion . To preven t a fat al dislocat ion on th e w ay to th e op erat ing room , som e au th ors recom m en d applying a h alo device as soon as possible, alth ough th is can n ot com pletely p reven t th e cran iover tebral jun ct ion from displacing.6–10,26 Th erefore, m ost au th ors recom m en d a de n it ive open procedure as soon as possible. W h en redu cing an AOD, som e au th ors h ave obser ved a w orsen ing of n eu rologic fu n ct ion if axial t ract ion w as applied. Van de Pol et al26 foun d th at 10% of pat ien ts experien ced n eurologic w orsen ing u n der t ract ion , so if t ract ion is n ecessar y for redu ct ion , t h ey ap ply it w ith great cau t ion .

Conservative Treatment Con ser vat ive t reat m en t for OCF is suit able for An derson an d Mon tesan o t ypes I an d II an d Tu li t ypes I an d IIA. A rigid cer vical collar (e.g., Ph iladelp h ia collar) sh ou ld be w orn for at least 6 w eeks. For AOD, th ere is on ly on e sit u at ion th at is su itable for con ser vat ive t reat m en t in a cer vical collar: a Horn grade I lesion 10–12,22 in w h ich th ere are subtle ch anges seen on MRI w ith out any abn orm alit y seen on CT. All ot h er lesion s requ ire op en st abilizat ion . If t h is is im p ossible, t h en im m obilizat ion in a h alo d evice sh ou ld be p er for m ed . For d en it ive t reat m en t in a h alo, on e sh ou ld con sid er t h e com p licat ion rate associated w it h t h is p roced u re, w h ich is a h igh as 30% in som e st u d ies, an d in clu d es p in loosen in g an d in fect ion .

Surgical Options In case of severe in stabilit y, w h ich is th e case in n early all AODs an d in An derson an d Mon tesan o t ype III an d Tuli IIB OCFs, st abilizat ion an d fu sion of th e OC join t com p lex is in dicated. Th is is esp ecially valid for AOD, becau se Bellabarba et al27 h ave fou n d th at n eu rologic dam age m ay occur in u p to 29%of p at ien t s bet w een th e t im e of inju r y an d stabilizat ion . Th e stan dard procedure in th is sit uat ion is an occipitocer vical fusion , u sing a screw /rod system con n ected to an occip it al p late. Th e in st ru m en t ation m ay in clude th e C2 vertebra, because th e r upt ure of th e cr uciate ligam en t , w h ich at t aches to th e C2 ver tebra, m igh t cau se atlan toaxial in stabilit y as w ell. In severe p ost t rau m at ic pain or gross displacem en t w ith com pression of cran ial n er ves, an OC join t resect ion follow ed by a fusion procedu re is also possible. In hyp oglossal n er ve palsy du e to a com pressing fragm en t, decom p ression of th e hypoglossal can al m igh t be in dicated eith er as a sole procedure or as part of a fusion procedure. How ever, the success rates of this procedure are low.

Technical Recommendations Th e st an dard occipitocer vical fu sion from C0 to C2 or even low er leads to 50%loss of m ot ion of th e axial rotat ion an d of a h igh propor t ion of exion /exten sion in th e cer vical spin e, w h ich h as a sign i can t e ect on pat ien t com for t in act ivit ies of daily living. Th erefore, th is possibilit y sh ou ld be sp eci cally in clu ded in th e in form ed con sen t . Perioperat ively, th e pat ien t sh ou ld be posit ion ed w ith a sligh tly exed p osit ion in th e OC join t , so th e p at ien t w ill be able to look at th e oor several m eters in fron t of h im for bet ter com for t . An u pw ard d irected view sh ou ld be avoided, w h ich h as been repor ted to be ext rem ely un com for t able. To avoid excessive m ot ion loss, som e altern at ive opt ion s are possible: • In cases of bony avulsion s, w h ich u sually sh ow a good h ealing capabilit y, a tem p orar y st abilizat ion is perform ed, follow ed by early im p lan t rem oval 3 to 9 m on t h s after t h e

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•

•

•

•

in it ial operat ion . Prior to im plan t rem oval, a solid h ealing of th e fragm en t sh ould be dem on st rated on CT. If th e atlan toaxial m ot ion segm en t is fou n d to be st able, an occipitoatlan t al fusion eith er by direct t ran sar t icu lar screw p lacem en t 14,28,29 or by a C1–lateral m ass screw an d occipital plate con st r uct 15,30 is p ossible, p reser ving at least th e rotat ion al m ot ion of th e C1- C2 join t com plex. For direct t ran sar t icu lar screw p lacem en t , th e screw t rajector y is ~ 45 degrees upw ard, st rictly parallel to th e sagit tal plan e. Th e en t r y poin t is th e m idpoin t in th e atlan tal lateral m ass at th e ju n ct ion w ith th e posterior arch . Th e recom m en ded screw dim en sion s are 4 m m in d iam eter an d 30 m m in len gt h . Ext rem e care sh ou ld be t aken to assess t h e hyp oglossal can al an atom y p r ior to su rger y, becau se th is st ru ct ure is at h igh risk during th is procedure. Th e con st r uct m igh t be rein forced by a posterior iliac crest bon e graft sim ilar to a Brooks fu sion for p rom ot ing bony fusion .16,29 Th e screw t rajectories for C1 or C2 screw s in a screw -an d-rod con st ru ct sh all be based on th e com m on tech n iqu es for screw placem en t in th ese vertebrae (e.g., Goel/Harm s tech n iqu e, t ran slam in ar screw s, pars screw p lacem en t ). W hen placing the occipital plate, care should be t aken to place th e p late directly in th e m idlin e bet w een th e superior an d in ferior n uch al lin e, becau se h ere th e occipit al bon e sh ow s t h e greatest t h ickn ess an d t h ere is n o risk of injuring th e ven ous sin uses. Th e screw s sh ou ld be p laced bicor t ically. Major cerebrospinal uid (CSF) leakage through th e d rill h oles is avoided by placing th e screw qu ickly.

Due to th e severit y of AOD, th e ou tcom e repor t s m ain ly focu s on su r vival an d n eu rologic outcom e. (Sur vival rates w ere cited earlier; see Ep idem iological Feat u res an d Path om ech an ism s, above.) Horn et al22 report in th eir series of 33 pat ien t s an outcom e of 10 death s (30%), four tet raplegic pat ien t s (12%), t w o paraplegic pat ien ts (6%), t w o h em iparet ic p at ien ts (6%), an d 14 pat ien t s w ith out any n eu rologic de cit (42%). Bellabarba et al27 repor ted th eir ou tcom es based on t h e Am erican Sp in al Inju r y Associat ion (ASIA) im pairm en t scale, w ith sim ilar result s in 17 p at ien ts: 47% ASIA E, 39% ASIA D, 12% ASIA C, an d 12% ASIA A. Resu lt s con cern ing postop erat ive pain or social reh abilit at ion are n ot p rovided. Maserat i et al3 foun d post t reat m en t n eck p ain in on ly 2% of th eir 97 pat ien t s w ith OCF. A delayed in st abilit y requ iring su rgical st abilizat ion w as foun d in on ly 1% of th eir pat ien t s. Maddox et al31 evaluated th e Neck Disabilit y In dex score of 32 pat ien ts after con ser vat ive t reat m en t of OCFs. He fou n d m ild d isabilit y or n on e in 14 p at ien t s (44%). Severe d isabilit y w as fou n d in fou r pat ien ts (12.5%). In terestingly, An derson an d Mon tesan o grade I an d II inju ries sh ow ed w orse result s th an An derson an d Mon tesan o III inju ries. Han son et al 32 fou n d “good recover y,” d en ed as bein g in d ep en d en t of n u rsin g care after 1 m on th , in 32 of 35 pat ien ts (91%) w h o su stain ed OCF w ith ou t a con com itan t TBI. In th e sam e series, 30 of 85 su r viving pat ien t s (35%) h ad a “poor outcom e” after 1 m on th , st ill requ ir ing con t in u ou s n u rsing su p p or t , t u be feed ing, or t rach eostom y. Th ese resu lt s are predom in an tly du e to th e TBI. Dat a on p ostt raum at ic pain w ere n ot rep or ted.

■ Chapter Summary ■ Prognosis and Outcome As m en tioned above, AOD an d OCF are injuries of very di erent severit y and therefore they have di erent outcom es.

Th e eviden ce for th e diagn osis an d t reat m en t of AOD an d OCF is low an d d oes n ot exceed level IV (case ser ies) becau se of t h e low in cid en ce of t h ese lesion s, w h ich are foun d in 1% of all t rau m a vict im s.

Occipital Condyle Fractures and Occipitocervical Dissociation Both t ypes of injuries are usually su ered by patients in high-speed MVAs. The t ypical patient w ith an OCF is a 30-year-old m an, w hereas the t ypical pat ient w ith an AOD is a ch ild. An AOD is a p oten t ially fatal inju r y, w ith an est im ated m or t alit y of 50 to 60%. Th e rate of n eurologic dam age in cluding TBI an d SCI is h igh ; th ese injuries are th e m ajor determ in an ts of long-term outcom e. In con t rast , an OCF is a m ore ben ign injur y w ith a low er m or talit y an d m ore favorable outcom e. W h en n ot accom pan ied by severe TBI or cran ial n er ve de cit , p ost t raum at ic pain is th e m ajor, albeit in frequ en t , problem . Delayed diagn osis of both en t it ies is a com m on occu rren ce. Th e t yp ical sym ptom s th at lead to th e diagn osis are low er cran ial n er ve palsies or dysph agia an d persisten t n eck pain . Th e diagn osis can be m ade based on CT scan n dings in n early 100% of th e cases. In cases of un cer t ain n dings, th e addit ion of an MRI can be useful. Conven t ion al X-ray is in su cien t for both en t it ies. Atlan to-occipital dislocat ion is t reated w ith im m ediate st abilizat ion in a h alo device, follow ed by a de n it ive open occipitocer vical stabilizat ion as soon as possible. Most OCFs can be t reated con ser vat ively in a h ard cer vical collar, but th e lack of t reat m en t w ill lead to an un favorable ou tcom e of th is u sually ben ign lesion .

Pearls The incidence of OCF and AOD is increasing. Both injuries are likely to be missed due to their rarit y and poor visualization on conventional X-rays. Atlanto-occipital dislocation is an injury of high mortalit y; thus, immediate diagnosis and treatment is crucial for a good outcom e. An OCF can be treated in a hard cervical collar in the m ajorit y of cases. Standard treatm ent for unstable lesions is an occipitocervical fusion from C0 to C2 or lower. Pitfalls Do not rely on conventional X-rays for patients injured in high-speed MVAs. CT is the gold standard for diagnosis of AOD or OCF. Any doubt should trigger an MRI, because bony structures m ay be randomly reduced to a physiological position during the initial CT scan. Although conservative treatment is reasonable for m ost OCFs, no treatment at all will lead to an unfavorable outcome. For operative treatm ent, positioning should be performed with extrem e care not to further harm the spinal cord and brainstem. In occipitocervical fusion, positioning should create a slightly exed position of the OC joint for increased patient comfort. During follow-up in conservative treatm ent of OCFs, look for delayed development of cranial nerve lesions.

Refere nces Five Must-Read Refe rences 1. Mueller FJ, Kin n er B, Rosskopf M, Neum an n C, Nerlich M, Fu ech t m eier B. In ciden ce an d ou tcom e of atlan to-occip it al d issociat ion at a level 1 t rau m a cen t re: a prospect ive st udy of ve cases w ith in 5 years. Eu r Spin e J 2012;22:65–71 2. Lador R, Ben -Galim PJ, Wein er BK, Hipp JA. Th e associat ion of occip itocer vical dissociat ion an d death as a resu lt of blun t t raum a. Spin e J 2010;10:1128–1132 3. Maserat i MB, Steph en s B, Zoh ny Z, et al. Occip it al con dyle fract ures: clinical decision rule an d su rgical m an agem en t . J Neu rosurg Spin e 2009;11:388–395 PubMed 4. Krüger A, Kü h n e C, Oberkirch er L, Ruch h olt z S, Frangen T, Junge A. Fract ures of the occipit al con dyle clin ical spect rum an d course in eigh t pat ien t s. J Cran iovertebr Jun ct ion Spin e 2013;4:50

5. W h ite AA, Panjabi MM. Clin ical Biom echan ics of the Spin e. Ph iladelph ia: Lippin cot t William s & Wilkin s; 1990 6. Dem isch S, Lin dn er A, Beck R, Zierz S. Th e forgot ten con dyle: delayed hypoglossal n er ve palsy caused by fract ure of th e occipit al condyle. Clin Neu rol Neurosu rg 1998;100:44–45 Pu bMed 7. Schliack H, Sch aefer P. [Hypoglossal an d accessor y n er ve paralysis in a fract ure of the occipit al condyle]. Ner ven arzt 1965;36:362–364 PubMed 8. Tuli S, Tator CH, Feh lings MG, Mackay M. Occipit al con dyle fract ures. Neurosu rger y 1997;41:368–376, discu ssion 376–377 PubMed 9. Th eodore N, Aarabi B, Dh all SS, et al. Occip it al con dyle fract ures. Neurosurger y 2013;72(Suppl 2):106– 113 PubMed

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Chapter 5 10. Naso W B, Cure J, Cu ddy BG. Ret roph ar yngeal p seu dom en ingocele after atlan to-occipit al dislocat ion : report of t w o cases. Neurosurger y 1997;40:1288– 1290, discu ssion 1290–1291 PubMed 11. Reed CM, Cam pbell SE, Beall DP, Bui JS, Stefko RM. Atlan to-occipit al dislocat ion w ith t raum at ic pseudom en ingocele form at ion an d post-t raum at ic syringom yelia. Spine 2005;30:E128–E133 PubMed 12. Choi EH, Jun AY, Ch oi EH, Sh in KY, Ch o AR. Traum at ic atlanto-occipital dislocat ion presenting w ith Dysph agia as th e ch ief com plain t: a case report . An n Reh abil Med 2013;37:438–442 PubMed 13. W h oley MH, Br uw er AJ, Baker HL Jr. Th e lateral roen tgen ogram of t h e n eck; w it h com m en t s on th e atlan to-odon toid -basion relat ion sh ip . Radiology 1958;71:350–356 Pu bMed 14. Harris JHJ Jr, Carson GC, Wagn er LK, Kerr N. Radiologic diagn osis of t rau m at ic occip itover tebral dissociat ion : 2. Com parison of th ree m eth ods of d etect ing occipitovertebral relationships on lateral radiograph s of supin e subject s. AJR Am J Roen tgen ol 1994;162: 887–892 Pu bMed 15. Pow ers B, Miller MD, Kram er RS, Mart in ez S, Geh w eiler JAJ Jr. Traum at ic an terior atlan to-occipit al dislocat ion . Neu rosu rger y 1979;4:12–17 Pu bMed 16. Lee C, Woodring JH, Goldstein SJ, Dan iel TL, You ng AB, Tibbs PA. Evaluat ion of t raum at ic atlan tooccipit al dislocat ion s. AJNR Am J Neu rorad iol 1987;8:19–26 PubMed 17. Su n PP, Po en barger GJ, Durham S, Zim m erm an RA. Spectrum of occipitoatlantoaxial injury in young children. J Neurosurg 2000;93(1, Suppl):28–39 PubMed 18. Dublin AB, Marks W M, Wein stock D, New ton TH. Trau m at ic dislocat ion of th e atlan to-occip it al ar t icu lat ion (AOA) w ith sh ort-term sur vival. With a radiograph ic m eth od of m easu ring th e AOA. J Neurosurg 1980;52:541–546 Pu bMed 19. Pang D, Nem zek W R, Zovickian J. Atlan to-occipit al dislocat ion —par t 2: Th e clin ical u se of (occip it al) con dyle-C1 in ter val, com parison w ith other diagnost ic m eth ods, an d th e m an ifest at ion , m an agem en t , an d ou tcom e of atlan to-occipit al d islocat ion in ch ildren . Neu rosu rger y 2007;61:995–1015, discu ssion 1015 PubMed 20. Gire JD, Rober to RF, Bobinski M, Klin eberg EO, Durbin -Joh n son B. Th e u t ilit y an d accu racy of com pu ted tom ography in th e d iagn osis of occip itocer vical dissociat ion . Spine J 2013;13:510–519 Pu bMed

21. Traynelis VC, Maran o GD, Du n ker RO, Kau fm an HH. Trau m at ic atlan to-occip it al dislocat ion . Case report . J Neurosurg 1986;65:863–870 Pu bMed 22. Horn EM, Feiz-Erfan I, Lekovic GP, Dickm an CA, Son n t ag VKH, Theodore N. Sur vivors of occipitoatlan t al dislocat ion inju ries: im aging an d clin ical correlates. J Neurosurg Spin e 2007;6:113–120 PubMed 23. Satern us KS. Bruch form en des Condylus occipit alis. Z Rech t sm ed . 1987;99:95–108 24. Anderson PA, Mon tesan o PX. Morph ology and t reatm en t of occipit al condyle fract ures. Spin e 1988;13: 731–736. 25. Jean n eret B (1994) Obere Halsw irbelsäule. In: Wit t AN, Ret t ig H, Sch legel KF (Hrsg). Spezielle Orth opädie Wirbelsäu le-Th orax-Becken . St u t tgar t: Th iem e, S 3.1– 3.37 26. van de Pol GJ, Han lo PW, On er FC, Castelein RM. Redislocat ion in a h alo vest of an atlan to-occipit al dislocat ion in a ch ild: recom m en dat ion s for t reat m en t . Spin e 2005;30:E424–E428 Pu bMed 27. Bellabarba C, Mirza SK, West GA, et al. Diagn osis an d t reat m en t of cran iocer vical dislocat ion in a series of 17 con secu t ive su r vivors du ring an 8-year period . J Neurosurg Spin e 2006;4:429–440 PubMed 28. Grob D. Tran sart icular screw xat ion for atlan to-occip it al d islocat ion . Spin e 2001;26:703–707 Pu bMed 29. Feiz-Erfan I, Gon zalez LF, Dickm an CA. Atlan tooccip it al t ran sart icular screw xat ion for th e t reat m en t of t raum at ic occipitoatlan t al dislocat ion . Tech n ical n ote. J Neurosurg Spin e 2005;2:381–385 Pu bMed 30. An derson AJ, Tow n s GM, Ch iver ton N. Trau m at ic occipitocer vical disrupt ion : a new tech n ique for st abilisat ion . Case report an d literat ure review. J Bon e Join t Su rg Br 2006;88:1464–1468 Pu bMed 31. Maddox JJ, Rodrigu ez-Feo JA III, Maddox GE, Gullung G, McGw in G, Th eiss SM. Nonoperat ive t reat m en t of occipit al condyle fract ures: an outcom es review of 32 fract ures. Spin e 2012;37:E964–E968 Pu bMed 32. Han son JA, Deligan is AV, Baxter AB, et al. Radiologic an d clin ical sp ect r u m of occip it al con dyle fract u res: ret rospect ive review of 107 con secut ive fract u res in 95 p at ien t s. AJR Am J Roen tgen ol 2002;178:1261– 1268 PubMed

6 Atlas Injuries Matti Scholz, Philipp Schleicher, and Frank Kandziora

■ Introduction After fract ures of th e odon toid process, atlas fract ures represen t th e secon d m ost com m on t ype of bony lesion in th e u pp er cer vical sp in e, predom in an tly cau sed by axial com pression forces. Fract ures of th e atlas accoun t for 2 to 13% of cer vical spin e injuries an d 1 to 3% of spin e fract ures. Th ese fract ures occur m ore frequen tly w ith in creasing age. If th e fract ure is isolated, it can be t reated con ser vat ively. Bu t it is im p or tan t to determ in e if th ere are ad dit ion al fract u res of th e cer vical sp in e, su ch as an odon toid fract ure, w h ich m ay be presen t in 50% of pat ien t s w ith atlas fract ures. In th ese cases it is th e con com it an t fract u re th at determ in es th e t reat m en t st rategy.1 An isolated t raum at ic lesion of th e t ran sverse ligam en t is a rare en t it y, but it m ay cau se a p ersisten t atlan toaxial instabilit y requiring atlantoaxial fusion . A fract u re of th e rst cer vical ver tebra w as rst described by Sir Astley Cooper, in an au topsy rep or t in 1823. A cen t u r y later, Sir Geoffrey Je erson develop ed an in it ial classi cat ion system of atlas fract ures by evalu ating 42 cases in th e literat ure an d fou r of h is ow n cases. Jefferson w as t h e rst to d escr ibe a fou r-p ar t bu rst fract u re after ver t ical com p ression of th e atlas, w h ich becam e kn ow n as th e Je erson fract u re. Barker et al2 in 1976 w ere th e rst to

describe a bony avu lsion of th e t ran sverse atlan tal ligam en t (TAL) as an u n com m on fract u re en t it y en t ailing a fract u re of th e m ed ial w all of th e lateral m ass of C1. As th e fract u re m ech an ism w as u n kn ow n , th e auth ors post ulated th at “th e bon e fragm en t is produ ced by a com bin at ion of TAL st retch ing an d pressure on th e lateral m ass du e to con t ract ion of th e n eck m u scles.” Tw en t y years later, Dickm an et al3 evaluated lesion s of th e TAL an d assessed th eir relevan ce in d eterm in ing w h eth er to t reat th e pat ien t w ith su rgical st abilizat ion of th e poten t ially u n st able atlas fract ure. Several review s h ave addressed th e diagn osis an d t reat m en t of atlas fract u res.4,5 How ever, d ue to a lack of ran dom ized st u dies, on ly class IV eviden ce is available to establish treat m en t recom m en dat ion s for th is rare fract ure en t it y.

■ Clinical Presentation Pat ien t s su ering from a t raum at ic fract ure of th e at las p resen t w it h com p lain t s abou t p ain in th e upper cer vical spin e, h eadach e, an d difcu lt y w ith cer vical spin e rot at ion . A n eu rologic de cit lin ked to an atlas fract u re is rare.6 How ever, a t rau m at ic lesion to th e low er fou r cran ial n er ves (IX to XII), kn ow n as th e Collet-

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Chapter 6 Sicard syndrom e, was described by Dom enicucci et al.7 Furth erm ore, due to a potent ial unilateral or bilateral ver tebral ar ter y lesion or p ost t rau m at ic th rom bosis, sym ptom s associated w ith a hyp operfu sion of th e basilar su pp ly territor y can include nausea, vom iting, tinnitus, im paired vision , or drop at t acks.

■ Classif cation Th ere are several classi cation system s for atlas fract ures. Th e rst classi cat ion w as based on th e n d ings of Je erson in 1920. He categorized atlas fract u res in to th ree t yp es: t ype I, a bilateral fract ure of th e an terior or posterior ring; t yp e 2, a com bin ed an terior an d p osterior ring (fou r-p ar t) bu rst fract u re; an d t ype 3, a fract ure of th e lateral m ass. A m ore recen tly establish ed classi cat ion system is th at of Geh w eiler et al,8 w h o categorized th ese fract u res in to ve t ypes (Fig. 6.1): Type 1: a rare isolated fract u re of th e an terior arch of th e atlas p redom in an tly w ith t w o fract u re lin es. Hyperexten sion forces an d st rain of th e longus colli m uscle creates a t ypical bilateral fract ure at th e an terior atlas ring close to th e area of longus colli m uscle origin . Type 2: an isolated, p redom in an tly bilateral, fract u re of th e posterior atlas ring cau sed by hyp erexten sion forces, resu lt ing in a com p ression of th e posterior arch of th e atlas

bet w een th e occipu t an d th e p osterior arch of th e axis. Type 3: a com bin ed inju r y of th e an terior an d p osterior arch of th e atlas, th e so-called Jefferson fract u re. Th is t ype is fu r th er su bdivided in to stable an d un stable injuries. Type 3a: a st able inju r y in w h ich th e TAL is in t act . Type 3b: an u n st able inju r y in w h ich th ere is a severe lateral displacem en t of a lateral m ass, suggest ing a lesion of th e t ran sverse ligam en t .9 Type 4: a fract ure caused by axial com pression forces an d involving a predom in an tly u n ilateral m ass. Type 5: an ext rem ely rare isolated fract ure of th e C1 t ran sverse process, gen erally caused by a direct t rau m a, such as a p un ch . If th e p at ien t presen t s w ith an u n st able atlas inju r y (Geh w eiler’s t yp e 3b), it is im por tan t to determ in e th e t ype of t ran sverse ligam en t lesion u sing th e Dickm an 3 classi cat ion (Fig. 6.2). Dickm an d ist ingu ish es bet w een an in t raligam en tou s ru pt ure an d a bony avulsion of th e ligam en t . Th e in t raligam entous r upt ure (t ype 1) can be fur th er categorized as a cen t ral lesion (t ype 1a) oras a lesion close to th e lateral m ass (t ype 1b). Th e bony avu lsion of th e t ran sverse ligam en t from a lateral m ass (t ype 2) can be fu r th er categorized as an isolated bony avu lsion (t yp e 2a) or as a bony avulsion du e to a fract u re of th e lateral m ass (t ype 2b). Th ese fract u res are Geh w eiler’s t ype 4. Th e degree of d islocat ion of th e bony fragm en t is im p or t an t in d eterm in ing th e su rgical t reat m en t .

Fig. 6.1 Gehweiler classi cation of atlas fractures.8

Atlas Injuries Fig. 6.2 Dickman classi cation  of transverse ligament lesions.3

■ Imaging and Criteria for

Instability On conventional cervical spine radiogram s, nondisp laced atlas fract u res are often overlooked . In case of an atlas burst fract ure w ith severe dislocat ion , th e op en -m ou th an terop osterior (AP) or odon toid view can sh ow a un i- or bilateral overh ang of a C1 lateral m ass (Fig. 6.2) over a C2 superior ar t icular process. In th e case of a C1 overh ang, th e dist an ce bet w een th e lateral border of C1 an d th e lateral border of C2 sh ou ld be m easured. If th e dislocat ion is bilateral, both sides sh ou ld be m easu red an d su m m ed. Accordingly to th e “r u le of Sp en ce,” in st abilit y is diagn osed if th e overh ang of C1 is m ore th an 6.9 to 8.1 m m . An ad d it ion al criterion for in st abilit y is t h e w id en in g of t h e an ter ior at lan tod en t al in ter val to m ore t h an 3 m m . Bot h m easu res suggest a failu re of t h e t ran sverse ligam en t , w h ich is t h e st rongest st abilizing st r u ct u re for th e atlan toaxial join t . To evalu ate th e in tegrit y of th e atlas ring in det ail an d to classify an atlas fract u re, com pu ted tom ograp hy (CT) is recom m en d ed. Axial CT slices sh ould be carefully review ed to determ in e th e p resen ce of a bony avu lsion of th e t ran sverse ligam en t as a criterion for a poten t ial in st abilit y. If a dislocat ion of th e C1 lateral m ass is seen an d CT w as u n able to d etect a bony avulsion of th e t ran sverse ligam en t, th en

m agn et ic reson an ce im agin g (MRI) is recom m en ded to evalu ate th e in tegrit y of th e t ran sverse ligam en t 10 an d to dist inguish bet w een st able burst fract ures (Geh w eiler t ype 3a) an d u n st able burst fract ures (Geh w eiler t ype 3b). Fract u res of th e u p p er cer vical sp in e can com prom ise vascular st ruct ures. How ever, th e ver tebral ar ter y is m ost at risk, especially in Geh w eiler t ype 5 lesion s. In th ese rare cases, CT angiography or MRI angiograp hy sh ou ld be p erform ed to exclude lesion s of th e ver tebral ar ter y w ith in th e foram en of th e t ran sverse p rocess of C1.11

■ Therapy Algorithm

(Fig. 6.3) Gehw eiler Type 1, 2, and 5 Fractures Atlas fract u res of t ypes 1, 2, an d 5 are stable. Th ese fract u res can be t reated w ith cer vical spin e im m obilizat ion w ith a soft cer vical collar for 6 w eeks.

Gehw eiler Type 4 Fractures Most t yp e 4 fract u res are m in im ally disp laced an d can be t reated con ser vat ively in a soft cer-

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Chapter 6

Fig. 6.3 The authors’ preferred treatment algorithm for m anagement of atlas fractures.

vical collar. In th e rare case of a prim ar y or secon dar y sign i can t dislocat ion of th e fract u red lateral m ass, resu lt ing in in congru en ce of th e atlanto-occipital and atlantoaxial joint, a reduction u n der t ract ion an d reten t ion for 6 to 12 w eeks in a h alo xator is recom m en ded. Axial t ract ion in m ost cases leads to an adequ ate lateral m ass realign m en t by ligam en tot a xis, an d adequate bony h ealing can be ach ieved. How ever, after th e in it ial reduct ion an d after 6 an d 12 w eeks un der h alot ract ion , evaluat ion w ith a CT scan is n ecessar y to con rm an adequ ate join t realign m en t an d bony h ealing. In case of inadequate initial reduction under halotraction, resu lt ing in a sym ptom at ic n on u n ion , surger y is in dicated to relieve th e pat ien t of p ersisten t pain cau sed by post t rau m at ic ar th rit is of th e dest ru cted join ts. Du e to th e poten t ial ch allenges in achieving a good screw xation w ithin th e fract u red lateral m ass of C1, w h ich also affects the atlantoaxial an d atlan to-occipital joint, an occipitocer vical fusion is th e t reat m en t of ch oice in m ost cases. How ever, osteoar th rit is in disp laced t yp e 4 fract u res is a slow p rocess. Th erefore, th e t reat m en t algorith m sh ou ld be m od i ed in eld erly p at ien t s. To avoid com p licat ion s of h alot ract ion in eld erly p at ien t s,12 t reat m en t in a st i collar in stead of a h alo xa-

tor, even in cases of disp laced t yp e 4 atlas fract u res, can be con sidered.

Gehw eiler Type 3 Fractures In stable atlas t ype 3a fract ures, con ser vat ive th erapy in a Ph ilad elp h ia collar is p ossible. How ever, t h ese p at ien t s sh ou ld be carefu lly review ed regarding fur th er dislocat ion , n on u n ion , an d sign s for atlan toaxial in st abilit y. For u n stable t ype 3b fract ures w ith m in im ally displaced bony avulsion of the transverse ligam en t , direct osteosyn th esis of th e atlas or h alot ract ion for 6 to 12 w eeks is recom m en ded. How ever, m ore su rgeon s n ow prefer th e su rgical m an agem en t of t ype 3b lesion , becau se h alo t ract ion en tails poten t ial pat ien t discom for t , a h igh er com plicat ion rate, an d a h igh er n on un ion rate. An isolated atlas osteosyn th esis is n ot recom m en ded in elderly pat ien ts, du e to th eir red u ced capabilit y for bony h ealing,or in t ype 3b fract u res w ith severe dislocated bony avulsion of th e t ran sverse ligam en t (Dickm an t ype 2). Alth ough tem p orar y xat ion of th e atlan toaxial com p lex is a p ossible altern at ive in you ng p at ien t s, a de n it ive atlan toaxial fu sion is th e t reat m en t of ch oice for elderly p at ien t s su ering from unstable atlas t ype 3b fract ures.

Atlas Injuries For d isp laced t yp e 3b at las fract u res an d in t raligam en tou s r u pt u re (Dickm an t yp e 1), an at lan toa xial fu sion is recom m en d ed du e tot h e u n likelih ood of ligam en tou s h ealing an d t h e p oten t ial for p ost t rau m at ic t ran slat ion al at lan toaxial in st abilit y. Depen ding on th e p at ien t’s an atom y an d th e feasibilit y of in t raop erat ive reduction , a posterior atlan toaxial fusion u sin g t h e Magerl/Gallie or Goel/Har m s tech n ique is a viable t reat m en t opt ion .

atlas fract u res, except for disp laced Geh w eiler t ype 4 fract u res. In t h ese cases, especially in you ng p at ien t s, t h e m orbid it y of at lan to-occip it al xat ion /fu sion is avoided by ad equ ate redu ct ion an d h alo-vest t reat m en t .

■ Conservative Management

Indications

of Unstable Atlas Fractures Most pat ients w ith stable atlas fract ures do w ell w ith con ser vat ive t reat m en t . Th ere are on ly sm all case series available that address the successful con ser vat ive m an agem en t of u n st able atlas bu rst fract u res. How ever, som e au th ors of recen t review s advocate 6 to 12 w eeks of h alo- xator t ract ion to m an age th ese u n stable atlas fract u res, predom in an tly Dickm an t ype 2 lesion s. Th e advan tage of h alot ract ion is th e extern al st abilizat ion it provides w ith ou t th e n eed for su rger y, w h ich en t ails poten t ial com plications.13 An other advantage is th e avoidan ce of atlantoaxial fusion, w hich was predom inantly perform ed before th e in t rodu ct ion of isolated atlas osteosyn th esis. How ever, h alo t ract ion is an invasive form of con ser vat ive fract u re m an agem en t, an d th u s it is n ot w ith ou t risks. Com plicat ion s of h alot ract ion are docu m en ted by St roh m et al,14 w ho evaluated h alo- xator treatm en t in 41 p at ien t s w ith u p per cer vical sp in e fract ures. Th ey reported several com plicat ion s: screw loosen ing (15%), p in -screw in fect ion (10%), skin n ecrosis (5%), fract ure redislocat ion (20%), an d in t racran ial screw pen et rat ion after a fall in on e pat ien t (2.5%). Fur th erm ore, th e pat ien ts w ere asked to rate th e com for t of th e h alot ract ion ; 58% rated it as in tolerable, 32% used a rat ing in th e m iddle of th e con t in u um , an d on ly 10% rated it as tolerable. Du e to th e discom fort an d poten t ial com p licat ion of h alo-vest t reat m en t an d t h e availabilit y of m od er n op erat ive tech n iqu es, w e p refer t h e su rgical m an agem en t of u n st able

■ Operative Management Isolated Osteosynthesis of the Atlas Th e p rim ar y in d icat ion for an isolated osteosyn th esis is an u n st able bu rst fract u re of th e atlas (Geh w eiler t yp e 3b) w ith bony avu lsion of th e t ran sverse ligam en t (Dickm an t ype 2). An illust rat ive case is sh ow n in Fig. 6.4. Th e bony dislocat ion sh ould be m ild if a good fragm en t rep osit ion an d later bony h ealing of th e ligam en t avu lsion are to be ach ieved, to p reven t th e com p licat ion of post t rau m at ic in su cien cy of th e t ran sverse ligam en t w ith ch ron ic pain due to t ranslation al atlantoaxial instabilit y. For th e sam e reason , an u n stable atlas fract u re w ith an in t raligam en tous t ran sverse ligam en t lesion sh ou ld n ot be t reated w ith an osteosyn th esis of th e atlas. In cases of Geh w eiler t yp e 3b an d Dickm an t ype 1 lesion s, it is im possible to ach ieve ligam en tou s h ealing because bony st r u ct u res w ill con solidate. Th is m igh t lead secon dar ily to t ran slat ion al atlan toa xial in st abilit y, w h ich h as to be t reated as w ell by an at lan toa xial fusion .

Biomechanics Koller et al15 perform ed in vit ro biom ech an ical test ing to an alyze th e m ech an ical p rop er t y of a C1 osteosyn th esis w ith in com p eten cy of th e t ran sverse atlan t al ligam en t . Five specim en s (C0–C2) w ith an in t act C1-ring an d an in t act transverse ligam ent were tested regarding their atlantoaxial sublu xation and load displacem ent. After a bony osteotom y (sim u lat ing a Je erson fract u re), a u n ilateral left cap su lotom y, a cu t of th e t ran sverse ligam en t , an d a C1 osteosyn t h esis, t h e sp ecim en s w ere tested again . Th e

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Chapter 6

a

c

b

d

e

Fig. 6.4a–e Case example of a 59-years old patient with an unstable atlas fracture, Gehweiler t ype 3b, and bony avulsion of the transverse atlantal ligament, Dickman t ype 2. (a) Open-mouth lateral X-ray with overhang of the right lateral m ass. (b) Postoperative lateral and open-m outh radio-

grams. (c) Computed tomography (CT) shows moderate ligament bone avulsion. (d) Three months postoperative CT with adequate C1 ring restoration. (e) Six months postoperative CT shows bony healing of C1 ring and osseous integration of ligament bone avulsion.

au th ors foun d su cien t biom ech an ical C1–C2 st abilit y u n der p hysiological loads after a C1 osteosyn th esis an d con clu ded th at “C1 osteosyn th esis m igh t be a valid altern at ive for th e treatm en t of displaced Je erson burst fract ures in com p arison to fu sion of C1-2.” Bicortical lateral m ass screw s are highly recom m en ded because th eir pu llout st rength is sign i can tly h igh er th an th at of m on ocor t ical C1 lateral m ass screw s.16 Ma et al17 com pared t h e p u llou t resist an ce of C1 p ed icle screw s an d C1 lateral m ass screw s biom echan ically in vit ro. Th ey foun d equal pullout resist an ce w ith m on ocort ical C1 pedicle screw s an d bicort ical C1 lateral m ass screw s, but th ey recom m en ded m on ocort ical screw placem en t in case of C1 p edicle screw usage becau se of p oten t ial low er m orbidit y.

Surgical Procedure

a

b

An osteosyn thesis of the atlas can be perform ed by an an terior-t ran soral, an isolated posterior, or a com bin ed p oster ior/an ter ior- t ran soral ap p roach (Fig. 6.5). For each ap p roach , on ly sm all-series case repor t s are available (Table 6.1). After a st an dard p osterior m id lin e ap proach to th e upper cer vical spin e, C1 lateral m ass screw s are placed in ord er to perform a p osterior atlas osteosyn th esis. Th e dorsal root gan glion of C2 an d ven ou s p lexu s are carefu lly m obilized an d cau dally ret racted to id en t ify th e m id p oin t of t h e in fer ior lateral m ass at th e ju n ct ion w ith th e posterior arch , w h ich is an ideal en t r y poin t for lateral m ass screw s. Th e drilling t rajector y is determ in ed by th e

c

Fig. 6.5a–c Di erent treatment strategies for isolated atlas osteosynthesis. (a) Transoral anterior  xation. (b) Posterior  xation. (c) Combined posterior and anterior  xation.

Atlas Injuries Table 6.1 Case Reports Describing the Di erent Approaches to Atlas Osteosynthesis Patients/ Follow -Up

Author

Approach/ Implant

Ma W et al.28

Transoral screws + plate

20 patients/ 6 months

Sun SH et al.29

Transoral screws + plate

Hu Y et al.30

Transoral screws + plate

Ruf M et al.31

Transoral polyaxial screws + rod

8 patients/ 6–24 months 1 patient/ 6 months 6 patients/ 6.5 years

Abeloos L et al.32

Posterior polyaxial screws + rod Posterior polyaxial screws + plate

1 patient/ 7 months 22 patients/ 2–32 months

Posterior polyaxial screws + rod Posterior polyaxial screws + rod

12 patients/ 22 months 3 patients/ 14 months

Combined polyaxial screw + rod + transoral wiring

8 patients/ 38 months

He B et al.33

Hu Y et al.26 Bransford R et al.34

Böhm H et al.22

an atom y of th e lateral m ass an d th e fract ure lin es, w h ich m u st be carefu lly an alyzed p rior to surger y.18 Atlas rep osit ion ing is th e key poin t of th e osteosyn th esis, an d it is ach ieved eith er by using dedicated reposition tools or m anually by bilateral extern al n eck com pression . Th e redu ct ion is th en xed w ith th e screw -an d-rod con n ect ion . Th e anterior t ran soral atlas osteosyn th esis is p erform ed by a st an dard t ran soral app roach . Tran sorally in ser ted screw s sh ou ld be p laced in th e “safe zon e.” Detailed an atom ic st udies of th ese ideal en t r y poin t s are available in th e literat u re.19 Th e com bin ed p osterior-an terior C1 xat ion u ses a p osterior screw xat ion w ith longer bicort ical C1 lateral m ass screw s an d addit ion al t ran soral w iring bet w een th e screw t ip s to close th e gap w ith in th e an terior arch of C1. Th is com bin ed proced u re en ables a perfect C1-

Outcome Bony fusion in all 20 patients after 6 months, no instabilit y, no complications Bony fusion in all 8 patients, no postoperative complications Bony fusion,no instabilit y C1/2, physiological C1/2 rotation No approach-related complications, one screw-and-rod dislocation with re-dislocation of lateral mass and worst clinical outcom e (Dennis pain score 4) Bony fusion, normal physiological C1/2 rotation Bony fusion in all 22 patients, no complications, norm al physiological range of motion

One died after 14 days (associated injuries); bony fusion in the other 2 patients, normal physiological rotation One delayed union after anterior revision, no approach-related complications; all 8 patients had bony fusion at  nal follow-up

ring redu ct ion . How ever, d u e to th e in creased risk of u sing t w o ap proach es, th is procedu re should not be the treatm ent of rst choice. Only one case report is available describing this com bin ed approach (Table 6.1).

Potential Complications Ret ract ing th e ven ou s p lexu s an d C2 root gan glion often causes ven ous bleeding. Sign i can t ven ou s bleed in g is rare, an d it can be t reated w it h local soft com p ression or in ser t ion of th rom bin -soaked Gelfoam . If th e bleeding does n ot stop, th e in ser t ion of a com m ercially available gelat in -th rom bin preparat ion m igh t h elp. Inju ries of th e vertebral ar ter y are rare, bu t m igh t occu r becau se of th e drilling an d screw in sert ion w ith lateral t rajector y or du e to th e u se of reposit ion ing tools for an in direct C1ring com p ression . A lesion of th e p osterior C2

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Chapter 6 root ganglion is possible du e to ret ract ion pressu re, an d bip olar coagu lat ion sh ou ld be u sed in cases of ven ous bleeding. How ever, th ese lesion s are p redom in an tly ben ign an d do n ot en t ail clin ical im p air m en t . Th e m ain com p licat ion is an in com p lete red u ct ion w it h later n on u n ion an d slow ly d evelop in g at lan toa xial in st abilit y or at lan toa xial/at lan to-occip it al ar th rit is. Woun d in fect ion s are in frequen t but th ey can be life th reaten ing, especially after t ran soral proced ures.

an alyze th e ach ieved redu ct ion . If an adequate rep osit ion ing of th e an terior ring is im possible u sin g t h e p oster ior ap p roach , an ad d it ion al an ter ior t ran soral ap p roach is an opt ion to ach ieve a full recon st r uct ion of th e C1 ring.22 Th erefore, if an isolated posterior osteosyn th esis is p lan n ed , th e p ossibilit y of h aving to u se an addit ion al t ran soral approach sh ould be par t of th e in form ed con sen t .

Tips and Tricks

Indications

We p refer th e isolated p osterior ap proach du e to it s low er m orbidit y com pared w ith th e t ran soral an d com bin ed ap proach . Bleeding of th e C2 ven ous plexus can be redu ced by con sequ en t exp osu re close to th e C1 arch . If di u se bleeding occurs, avoid bipolar coagulat ion . It is bet ter to apply gentle com pression w ith Gelfoam and to start w ith preparation of th e opposite side. An altern at ive is t ran spedicu lar screw in ser t ion . How ever, an adequ ate pedicle diam eter an d carefu l prep arat ion w ith protect ion of ver tebral ar ter y are m an dator y, if su rgeon s con sider u sing th is tech n iqu e.20,21 To perform a safe an d adequate reposit ion ing of th e C1ring, det ailed an atom ic kn ow ledge about th e fract ure m orph ology an d about th e exact location of the vertebral arter y is of prim e im por t an ce. Du e to th e n ecessit y of adequ ate redu ct ion an d esp ecially th e realign m en t of th e t ran sverse ligam en t bony fragm en t , good in t raoperat ive visu alizat ion is of great im p ortance. In t raoperat ive CT or th ree-dim en sion al (3D) u oroscopy is h igh ly recom m en d ed to

A p oster ior at lan to-a xial fu sion is in d icated in cases of u n st able at las bu rst fract u res w it h in t raligam en tou s lesion of th e t ran sverse ligam en t (Dickm an t yp e 1). An ot h er in d icat ion is t h e on set of t ran slat ion al at lan toa xial in st abilit y after con ser vat ive m an agem en t of Dickm an t yp e 2 lesion s or failed isolated at las osteosyn t h esis.23

a

Posterior Atlantoaxial Fusion

The Harms and Magerl Surgical Techniques To perform a posterior C1–C2 fusion , t w o establish ed surgical tech n iques are available. On e opt ion is th e Magerl t ran sar t icular C1–C2 screw xat ion w ith an additional posterior sup por t u sing an iliac crest bon e graft an d w iring as perform ed by Gallie. Th e oth er opt ion is th e Harm s p osterior screw an d rod xat ion (Fig. 6.6). Th e tech n ical det ails of th ese p rocedu res are beyon d th e scope of th is ch apter. Th e m ajor advan tages an d disadvan t ages of th ese procedu res are listed in Table 6.2.

b

Fig. 6.6a,b Posterior atlantoaxial fusion. (a) Magerl/Gallie technique. (b) Goel-Harms technique.

Atlas Injuries Table 6.2 Advantages, Disadvantages, and Typical Complications of Magerl/Gallie Procedure Versus Harms Procedure for C1/2 Fixation Transarticular f xation according to Magerl/Gallie

Screw and rod f xation according to Harms

Advantages

• 3   point  xation with adequate  biom echanical stabilit y • Implants are cheap

Disadvantages

• Requires reposition before screw channel preparation •  3  point  xation is impossible in  case of bilateral posterior arch fracture • Technically demanding • Lesion of the atlantoaxial joint unfavourable for implant removal in case of temporarily  xation • Bone graft harvesting mandatory • Screw trajectory sometimes impossible due to individual anatomy (high riding vertebral artery, obese patients with short neck.) • Lesion of Vertebral artery (5%) by wrong drilling trajectory an/or high riding artery • Inadequate screw purchase in C1 lateral m ass in case of inadequate reposition

• Reposition after screw placement possible • No harm to the C1/2 joint and therefore ideal for temporarily xation of C1-2 •  Modi cations in case of anatomical  need possible (e.g. short isthm us screw, lam ina screw) • Implants are expensive • Technically demanding • Pedicle screw insertion sometimes impossible (high riding vertebral artery)

Typical complications

Tips and Tricks Magerl Procedure After drilling the rst screw hole, the drill should rem ain in sit u . Oth er w ise, drilling of th e second hole m ay cause a rotation bet w een the atlas an d th e axis. Th en it m igh t be im possible to realign C1 and C2 w hile inserting the rst screw. In cases of lateral or rot at ion al lateral m ass d isp lacem en t , t h e Magerl screw m igh t m iss th e C1 lateral m ass. Th erefore, adequate C1 reposit ion ing h as to be veri ed by AP an d lateral in t raoperat ive im aging p rior to t ran sart icu lar drilling. Even w ith a un ilateral “h igh -riding” ver tebral ar ter y, a Magerl screw can be used. How ever, in th ese cases th e screw h as to be placed ver y steep ly. Th e screw m u st leave t h e a xis p ed icle before en ter ing t h e ist h m u s area, an d

• Lesion of Vertebral artery by wrong drilling trajectory • Venous bleeding C2 plexus • Lesion C2 root ganglion

sh ou ld reen ter th e p osterior area of th e atlas lateral m ass. W h en u sing th is tech n iqu e, care m u st be t aken n ot to u se screw s th at are too long, to avoid a violation of the atlanto-occipital join t . A Gallie w ire can be replaced by n on absorb able th read, w h ich is easier to h an dle th an st i w ires. In cases of bilateral posterior arch fract u re, it is im possible to ach ieve an adequ ate posterior Gallie xat ion . In th ese cases, a sp in al fu sion can be ach ieved by direct p lacem en t of au tologous bon e in th e p osterior dorsal p ar t of th e lateral atlan toa xial join t s. How ever, w ith out adequate th ree-poin t xat ion , th e Magerl xat ion is less st able th an a Harm s con st r u ct . Th erefore, w e p refer th e Harm s tech n iqu e for t reat m en t of u n st able fou r-par t Je erson fractures (Gehweiler t ype 3b) and intraligam entous disr u pt ion of th e TAL (Dickm an t ype 1).

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Harms Technique Th e speci c ch oice of screw length facilit ates intraoperative repositioning. If atlas repositioning in th e posterior direct ion is n ecessar y, th e screw h eads in C1 sh ou ld be m ore ven t ral th an th ose in C2. Th e rep osit ion ing is p erform ed by a screw -an d-rod con n ect ion in C2 rst . Th e rod is th en located posterior to th e C1 screw h ead , w h ich can be easily elevated by pulling th e screw h ead u sing th e reposit ion ing tool. In cases of a bilateral posterior arch fract u re, it is im p ossible to xate an iliac crest bet w een th e p osterior arch an d th e C2 spin ou s process for p oster ior fu sion . In t h ese cases, a sp in al fu sion can be ach ieved by direct in t rodu ct ion of autologou s bon e in th e posterior dorsal p ar t of th e lateral atlan toaxial join ts. If t h e p at ien t ’s an atom y p reven t s u sin g a t ran sp ed icu lar screw in C2, sh or t ist h m u s screw s or lam in a screw s are an altern at ive for screw xat ion in C2.

of n eck p ain , as sh ow n on th e Visu al An alogu e Scale (in it ial scores of 7.52 ± 3.2; p ostoperat ive scores of 1.80 ± 2.12), an d a p ostoperat ive cervical range of m ot ion in th e n orm al physiological range w as also reported. Th e atlan toaxial rot at ion , as m easured by fu n ct ion al CT, w as 62 degrees on average (range, 36–75 degrees). Th ese n dings w ere sim ilar to th e clin ical resu lts of several oth er au th ors (Table 6.1). Pat ien t s w ith atlan toaxial fu sion also d o w ell, bu t h ead rotat ion is reduced due to C1/2 fu sion . Elliot t et al27 com p ared th e ou tcom e of t ran sarticular screw s (Magerl procedure) and screw an d -rod con st r u ct s (Goel/Har m s p roced u re) for C1/2 fusion . A h igh er in ciden ce of ver tebral ar ter y injur y (4%vs 2.0%), a h igh er rate of screw m alp osit ion (7.1%vs 2.4%), an d a sligh tly low er fu sion rate w ere evid en t w it h t h e u se of t ran slam in ar screw s.

■ Chapter Summary ■ Outcome As p reviou sly st ated, m ost pat ien t s w ith st able atlas fract u res do w ell w ith con ser vat ive t reatm en t . Bu t con ser vat ive t reat m en t of Je erson fract ures does n ot m ean th at pat ien ts w ill return to their preinjury physical condition. Dvorak et al24 reported a p oorer long-term ou tcom e (as assessed by Sh or t Form 36 an d by a pain score) for p at ien t s w ith displaced Je erson fract u res greater th an 7 m m (Geh w eiler t ype 3b) com p ared w ith m in or disp laced Je erson fract u res (Geh w eiler t yp e 3a). Lew kon ia et al25 p erform ed a literat u re review addressing th e ou t com e of con ser vat ive m an agem en t in cases of C1 burst fract ures. Th ey foun d th at 8 to 20% of p at ien t s com plain abou t st i n ess in th e n eck, 14 to 80%of p at ien t s exp erien ce m ild pain , an d a 34% of p at ien t s rep or t lim it at ion s in t h eir act ivit ies. Th ere are on ly case repor t s w ith a m axim um of 22 pat ien ts available in th e literat u re, d escribing th e ou tcom e after su rgical m an agem en t of u n st able at las fract u res. Hu et al 26 t reated 12 p at ien t s w ith isolated posterior C1 osteosyn t h esis. Pat ien t s rep or ted good relief

At las fract u res are t h e resu lt of com p ression or hyp erexten sion forces. Th ese fract u res are often com bin ed w it h fract u res of t h e a xis an d esp ecially t h e od on toid p rocess. Th e Geh w eiler classi cat ion of atlas inju ries requ ires CT im aging. To d ist ingu ish bet w een st able an d u n st able at las inju r y, it is n ecessar y to evalu ate t h e in tegr it y of t h e t ran sverse at lan t al ligam en t on MRI an d to u se t h e Dickm an classi cat ion of t h e p oten t ial lesion . Most at las fract u res are st able an d can be su ccessfu lly m an aged by im m obilizat ion in a soft or h ard collar. Un st able at las fract u res m ay be m an aged con ser vat ively by h alo xat ion , bu t m ore su rgeon s n ow p refer su rgical t reat m en t d u e to t h e p oten t ial d iscom for t of h alo t ract ion . At las fract u res w it h ligam en tou s d isr u p t ion of t h e t ran sverse at lan t al ligam en t or severe d islocat ion of bony ligam en t avu lsion should be treated by C1/2 fusion. Unstable atlas fract u res w it h m od erate d islocat ion of bony ligam en t avu lsion m ay be t reated by at las osteosyn t h esis. Th ere is lit tle eviden ce su p port ing th e differen t t reat m en t st rategies of at las fract u res. Few st u dies are available com p ar ing con ser-

Atlas Injuries vat ive an d operat ive m an agem en t of un st able atlas fract u res or com p aring th e di eren t op erat ive t reat m en t st rategies.

Pearls Modern imaging facilitates the diagnosis of transverse atlantal ligament lesions. By com bining the Gehweiler and Dickman classication system s, the stabilit y of an atlas fracture  can be predicted. Modern osteosynthesis techniques for unstable atlas fractures enable a safe atlas fusion with preservation of C1/2 m otion. For atlantoaxial fusion,the standard Goel-Harm s and Magerl techniques provide  xation for the  C1-C2 segm ent.

Pitfalls In cases of an atlas fracture, patients should be carefully examined for concomitant fractures. Before considering conservative therapy for a Gehweiler t ype 3 lesion, care should be taken to determine if a transverse ligament lesion is also present. It is impossible to perform a Magerl/Gallie fusion in cases of inadequate pre- and intraoperative reduction. Do not overlook a high-riding vertebral artery if a Harm s procedure or C2 pedicle screw is planned. Patients in halotraction should be regularly exam ined for pin and halo-vest complications.

Refere nces Five Must-Read Refe rences 1. Li-Jun L, Ying-Ch ao H, Ming-Jie Y, Jie P, Jun T, DongSh eng Z. Biom ech an ical an alysis of th e longit udin al ligam en t of u p per cer vical sp in e in m ain t ain ing atlan toaxial st abilit y. Spin al Cord 2014;52:342–347 PubMed 2. Barker EGJ Jr, Kru m p elm an J, Long JM. Isolated fract u re of th e m edial p or t ion of th e lateral m ass of th e atlas: a previously un described en t it y. AJR Am J Roen tgen ol 1976;126:1053–1058 PubMed 3. Dickm an CA, Green e KA, Son n t ag VK. Injuries involving the transverse atlantal ligam en t: classi cation an d treat m en t gu idelin es based u p on exp erien ce w ith 39 injuries. Neurosurger y 1996;38:44–50 PubMed 4. Joaqu im AF, Gh izon i E, Ted esch i H, et al. Up p er cervical inju ries—a rat ion al ap p roach to gu id e su rgical m an agem en t . J Sp in al Cord Med 2014;37:139–151 Pu bMed 5. Syre P, Pet rov D, Malh ot ra NR. Man agem en t of u p p er cer vical sp in e inju r ies: a review . J Neu rosu rg Sci 2013;57:219–240 PubMed 6. Det tling SD, Morsch er MA, Masin JS, Adam czyk MJ. Cran ial n er ve IX an d X im pairm en t after a spor t srelated Je erson (C1) fracture in a 16-year-old m ale: a case report. J Pediatr Orthop 2013;33:e23–e27 PubMed 7. Dom en icu cci M, Man carella C, Dugon i ED, Ciap p et t a P, Paolo M. Post -t rau m at ic Collet -Sicard syn drom e: p erson al obser vat ion an d review of t h e per t in en t literat u re w ith clin ical, radiologic an d an atom ic con siderat ion s. Eur Spin e J 2014 Aug 24. [Epu b ah ead of p rin t] Pu bMed 8. Geh w eiler JA, Osborn e RL, Becker RF. Th e Radiology of Vertebral Traum a. Philadelphia: WB Saunders; 1980

9. Kan dziora F, Sch n ake K, Ho m an n R. [Injuries to th e upper cer vical spin e. Part 2: osseous inju ries]. Un fallch iru rg 2010;113:1023–1039, qu iz 1040 Pu bMed 10. Dickm an CAC, Mam ou rian A, Son n t ag VKV, Drayer BPB. Magn et ic reson an ce im aging of th e t ran sverse atlan t al ligam en t for th e evalu at ion of atlan toaxial inst abilit y. J Neurosurg 1991;75:221–227 PubMed 11. Haged orn JCII, Em er y SE, Fran ce JC, Da n er SD. Does CT angiograp hy m at ter for p at ien t s w it h cervical sp in e inju ries? J Bon e Join t Su rg Am 2014;96: 951–955 Pu bMed 12. Daen t zer D, Flörkem eier T. Con ser vat ive t reat m en t of upper cer vical spin e injuries w ith th e h alo vest: an ap p rop riate opt ion for all pat ien t s in depen d en t of their age? J Neurosurg Spine 2009;10:543–550 PubMed 13. Longo UG, Den aro L, Cam p i S, Ma u lli N, Den aro V. Upper cer vical spin e injuries: in dicat ion s an d lim it s of th e con ser vat ive m an agem ent in Halo vest . A system at ic review of e cacy an d safet y. Injur y 2010; 41:1127–1135 PubMed 14. St roh m PC, Mü ller Ch A, Köstler W, Reising K, Sü dkam p NP. [Halo- xator vest—in dicat ion s an d com plicat ion s]. Zen t ralbl Chir 2007;132:54–59 PubMed 15. Koller H, Resch H, Tau ber M, et al. A biom ech an ical rat ion ale for C1-r in g osteosyn t h esis as t reat m en t for d isp laced Je erson bu rst fract u res w ith in com p eten cy of th e t ran sverse atlan t al ligam en t . Eu r Sp in e J 2010;19:1288–1298 PubMed 16. Eck JC, Walker MP, Currier BL, Ch en Q, Yaszem ski MJ, An K-N. Biom ech anical com parison of un icort ical versu s bicor t ical C1 lateral m ass screw xat ion . J Spin al Disord Tech 2007;20:505–508 Pu bMed

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Chapter 6 17. Ma X-Y, Yin QS, Wu Z-H, et al. C1 pedicle screw s versu s C1 lateral m ass screw s: com parison s of pullout st rength s an d biom ech an ical st abilit ies. Spine 2009; 34:371–377 PubMed 18. Son n t ag VKH. Lateral m ass screw xat ion of t h e atlas: im por t an ce of an atom y of C1 for lateral m ass screw p lacem en t . World Neu rosu rg 2010;74:270– 271 PubMed 19. Kan dziora F, Sch ulze-St ahl N, Kh odadadyan -Klosterm an n C, Sch röder R, Mit tlm eier T. Screw placem en t in tran soral atlan toaxial plate system s: an an atom ical st udy. J Neurosurg 2001;95(1, Suppl):80–87 Pu bMed 20. Tan M, Dong L, Wang W, et al. Clin ical applicat ion of t h e “p ed icle exp osu re tech n iqu e” for at lan toa xial in stabilit y pat ien t s w ith a n arrow C1 posterior arch . J Sp in al Disord Tech 2015;28:25–30 Pu bMed 21. Qian L-X, Hao D-J, He B-R, Jiang Y-H. Morph ology of th e atlas p edicle revisited: a m orp h om et ric CT-based st udy on 120 pat ien t s. Eur Spin e J 2013;22:1142– 1146 PubMed 22. Böh m H, Kayser R, El Sagh ir H, Heyde CE. [Direct osteosyn th esis of in st able Geh w eiler t ype III atlas fract u res. Presen t at ion of a dorsoven t ral osteosyn th esis

of in st able atlas fract ures w h ile m ain t ain ing fun ct ion ]. Un fallch irurg 2006;109:754–760 PubMed 23. Jacobson ME, Khan SN, An HS. C1- C2 posterior xat ion : in dicat ion s, tech n ique, an d result s. Or th op Clin North Am 2012;43:11–18, vii Pu bMed 24. Dvorak MF, Johnson MG, Boyd M, Johnson G, Kw on BK, Fisher CG. Long-term health-related qualit y of life outcom es follow ing Je erson -t ype bu rst fract ures of the atlas. J Neurosurg Spine 2005;2:411–417 PubMed 25. Lew kon ia P, Dip aola C, Sch ou ten R, Noon an V, Dvorak M, Fish er C. An eviden ce-based m ed icin e process to determ in e ou tcom es after cer vical sp in e t rau m a: w h at su rgeon s sh ou ld be telling th eir pat ien t s. Sp in e 2012;37:E1140–E1147 PubMed 26. Hu Y, Xu R-M, Albert TJ, et al. Fun ct ion -preser ving reduct ion an d xat ion of un st able Je erson fract u res using a C1 posterior lim ited con st ruct . J Spin al Disord Tech 2014;27:E219–E225 PubMed 27. Elliot t RE, Tanw eer O, Boah A, et al. Ou tcom e com parison of atlan toaxial fu sion w ith t ran sar t icu lar screw s an d screw -rod con st r uct s: m et a-an alysis an d review of literat u re. J Sp in al Disord Tech 2014;27: 11–28 PubMed

7 Odontoid Fractures, Hangman’s Fractures, and C2 Body Fractures Wilco C. Peul and Carmen L.A. Vleggeert-Lankamp

■ Odontoid Fractures Odon toid fract u res accou n t for 9 to 18% of all cervical spine fractures and are m ost frequently cau sed by eith er hyp erexten sion or hyper exion . In th e elderly, odon toid fract u res are th e m ost com m on cer vical sp in e fract u res.1 Moreover, as th e populat ion ages, th ese fract ures w ill be seen m ore often in clin ical pract ice. Fract ures of th e odon toid process occur in di eren t form s requ iring di eren t t reat m en ts. An derson an d D’Alon zo 2 proposed th e u se of th e follow ing classi cat ion system for odon toid fract u res, w h ich is st ill com m on ly u sed today: t yp e I, fract u re of th e t ip of th e odon toid p rocess; t yp e II, fract u re of th e n eck of th e odon toid process; an d t ype III, a fract ure th at r u n s th rough th e body of C2. Typ e I odon toid fract ures n eed n o surgical stabilizat ion . A rigid collar is su cien t to en able th e ligam en t s to h eal. Type II and t ype III fractures can be t reated eith er con ser vat ively or su rgically. A t yp e III fract u re is gen erally t reated by extern al im m obilizat ion if th e fract u re su rface is large en ough to allow sp on t an eou s h ealing. If dislocat ion is likely to take place, a surgical in ter ven t ion is often p rop osed. Deciding on surgical or con ser vat ive t reatm ent for patients w ith fractures of the odontoid p rocess is based on th e follow ing factors: fract u re p at ter n , p at ien t age, n eu rologic d e cit s, an d th e pat ien t’s m edical con dit ion .3 Surgical

in ter ven t ion is in m ost cases p er for m ed by an terior odon toid screw xat ion (on e or t w o screw s) or p osterior atlan toaxial ar th rodesis. Con ser vat ive m an agem en t of t yp e II an d III fract u res involves rigid (e.g., h alo vest , Min er va cast) or n on rigid (e.g., cer vical collar, cer vicoth oracic or th osis) im m obilizat ion . The optim al treatm ent of odontoid fractures in elderly p at ien t s is st ill a subject of con t roversy, as th is age grou p t ypically h as a h igh er risk of developing com plicat ion s w h en t reated surgically, such as nonunion, than w hen treated con ser vat ively.4–7 Con sequ en tly, m any factors m ust be t aken into accoun t to n d th e righ t balan ce bet w een fract u re h ealing an d t reatm en t com plicat ion s.

Anterior Screw Fixation Direct an terior screw xat ion provides im m ed iate st abilizat ion of t h e sp in e an d p reser ves u pper cer vical spin e m obilit y. How ever, n ot all t ypes of odon toid fract u res are suit able for th is approach . To adequately repor t on th e fract u re lin e in a t yp e II den s fract u re, Grau er et al8 adju sted th e An derson an d d’Alon zo classi cat ion (Fig. 7.1). Type II an d t ype III odon toid fract u res are less su itable for an terior screw xat ion if th e fracture line is oriented obliquely from anteriorin ferior to posterior-su perior (t ype IIC). How ever, if th e fract u re lin e is orien ted oth er w ise

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Chapter 7

Fig. 7.1 Anderson and d’Alonzo classi cation as adapted by Grauer et al.8  (Reproduced with permission.)

(t ype IIA or t ype IIB), th e pat ien t is appropriate for an an terior screw xat ion . A pooled m eta-an alysis of n on u n ion , reop erat ion, infection , and approach -related com plications after anterior odontoid screw xation w as recen tly pu blish ed .9 A tot al of 63 st u dies w ere in clu ded. Th e authors foun d a pooled n on un ion rate of 10% an d a reoperat ion rate of 5% (in cluding m alposit ion of screw s). Com plicat ion s in clu d ed in fect ion in 0.2%, dysp h agia in 10%, an d h oarsen ess in 1.2%. A m ult ivariate m et a-an alysis dem on st rated a h igh er rate of n on un ion in pat ien ts over 70 years of age. Ap felbau m et al10 dem on st rated an overall bon e fu sion rate of 88% in t yp e II d en s fract u res t reated w ith an an terior den s screw, but a sign i can tly low er rate of bon e fu sion (25%) in p at ien t s w ith late fract u res (> 6 m on th s after inju r y). It can be con clu ded th at direct an terior screw xat ion is an e ect ive an d safe m eth od for t reat in g recen t od on toid fract u res in p at ien t s you nger th an 70 years of age. Un for t u n ately, n on e of th e st udies correlated n on u n ion w ith th e w ell-being of th e pat ien t .

Surgical Versus Nonsurgical Treatment of Type II Fractures A recen t system at ic review of papers publish ed bet w een 1975 an d 2011 sum m arized th e outcom e of surgical and con ser vative interventions for t yp e II an d III od on toid fract u res in t h e elderly, focusing prim arily on clin ical outcom e an d secon dar ily on fract u re u n ion an d st abilit y rates.1 A tot al of 17 st u dies w ere iden t i ed th at m et t h e in clu sion criteria. Th ey w ere all retrospective studies. (Not in cluded w as a m ore recen t p rospect ive m ult icen ter st udy th at provided data on th is sam e topic.5 ) On ly t w o of th e 17 st udies com pared th e clin ical outcom es of su rger y w ith th ose of con ser vat ive t reat m en t . On e w as a ret rosp ect ive st u dy of 27 p at ien t s over 70 years of age, w h ich foun d less m orbidit y in th e surger y grou p (st at ist ically sign i can t; p = 0.037), bu t n o st at ist ically sign i can t di eren ce in n on u n ion at th e fract u re site (p = 0.64) except for t yp e II fract u res (p = 0.0063).11 Th e oth er st udy (n = 17) fou n d a sligh tly bet ter clin ical ou tcom e in su rgically com p ared w it h

 

Odontoid Fractures, Hangman’s Fractures, and C2 Body Fractures 

conservat ively t reated patients (average Sm ileyWebster [SW] score 1.25 an d 1.92, respect ively; 1 is excellen t , 4 is poor). St at ist ical an alysis of th ese resu lt s cou ld n ot be p erform ed du e to th e lim ited n u m ber of pat ien t s involved.12 In ve st udies evaluat ing th e clin ical outcom e u sing t h e SW score, both su rgically an d con ser vat ively t reated pat ien t s h ad an in term ediate ou tcom e. Th e average SW score w as 1.71 for surgically t reated pat ien ts an d 2.02 for conser vat ively t reated p at ien ts. Of 16 st u dies repor t ing ext ract able u n ion rates, four com pared surgery w ith conservative t reat m en t . Un ion w as ach ieved in 85% (29/34) of th e surgically t reated pat ien ts an d in 44% (16/36) of th e con ser vat ively t reated pat ien ts. Th e resu lt s w ere m ain ly based on X-ray n dings. In th e in dividu al st u dies, n o st at ist ical an alysis could be perform ed due to th e sm all n um ber of pat ien ts. In a com parison of all pat ien t s in clu ded in th e 16 st u d ies, u n ion w as achieved in 81%(218/269) of surgically t reated patien ts an d 44% (56/128) of con ser vat ively t reated pat ien ts. Again , in th e in dividu al st u dies n o stat ist ical an alysis could be p erform ed. All 17 st u dies repor ted ext ract able stabilit y rates, sh ow ing fract u re stabilit y in m ost p at ien t s regard less of th eir t reat m en t (dyn am ic X-ray). In a com parison of all pat ien ts in cluded in th e 17 st u dies, stabilit y w as ach ieved in 95% (245/258) of surgically t reated pat ien t s an d in 87% (94/108) of con ser vat ively t reated p at ien t s. In ve st u dies com p aring su rgically to con ser vat ively t reated pat ien t s, st abilit y w as achieved in 97% (35/36) an d 77% (36/47) of cases, resp ect ively.

Prospective Study Th ere w as on e recen t p rospect ive m u lt icen ter st u dy com p aring ou tcom es an d com plicat ion s of n on su rgical an d surgical t reat m en t of t ype II odon toid fract u res in p at ien t s 65 years of age or older.5 A tot al of 159 p at ien t s w ith a t ype II d en s fractu re w ere en rolled; 101 pat ien t s w ere t reated surgically, an d 58 p at ien t s w ere t reated n on su rgically, as d eterm in ed by th e t reat m en t p referen ces of t h e t reat ing p hysician s an d th e p at ien t s. Th e t w o grou p s w ere sim ilar w ith regard to baselin e ch aracterist ics. Th e m ost com -

m on surgical t reat m en t w as posterior C1- C2 ar th rodesis (79%), w h ereas th e m ost com m on nonsurgical treatm ent w as im m obilization w ith th e use of a h ard collar (81%). Th e overall m or talit y rate w as 18% over th e 12-m on th follow -u p p eriod ; it w as sligh t ly h igh er in th e n on su rgical group . Th is is a likely ou tcom e because th e pat ien ts w h o are in poor clin ical con dit ion are n ot su bjected to a surgical inter vention a priori. At 12 m onths, the Neck Disabilit y In dex (NDI) score h ad decreased by 14.7 p oin t s (ou t of 50) in th e n on su rgical cohort, w hich w as signi cantly m ore than the NDI decrease of 5.7 points in the surgical group. Th e su rgical group h ad a sign i can tly low er rate of n on un ion (5% versus 21% in th e n on surgical group; p = 0.0033). Fract u re st abilit y w as n ot evalu ated . Th ere w as n o di eren ce in th e overall rate of com plicat ion s.

Discussion Th e review dat a w ere in su cien t to determ in e the di eren ce on clinical outcom e bet w een surgical an d con ser vat ive in ter ven t ion s in th e elderly w ith isolated odon toid fract u res. Overall, it seem s th at th e repor ted di eren ces lack clin ical relevance. The prospective study claim s that su rgical t reat m en t can be ben e cial for th e pat ien t’s gen eral w ell-being (m easu red by NDI). But it is n ot un likely th at th e bet ter NDI st ate of th e su rgically t reated p at ien t s is du e to th eir con dit ion , w h ich is gen erally bet ter at baselin e th an is th e con dit ion of th e p at ien t s w h o are t reated con ser vat ively. Overall, it can be con clu ded th at it is safe to su rgically t reat elderly pat ien ts w ith t ype II odon toid fract u res w h o are h ealthy en ough for gen eral an esth esia. Surgically t reated pat ien t s appear to sh ow higher osseous union rates com pared w ith conser vat ively t reated p at ien t s, bu t th is does n ot lead to h igh er st abilit y rates in th e su rgically t reated p at ien ts. Moreover, th e u n ion an d st abilit y rates w ere n ever correlated w it h th e p at ien t s’ gen eral w ell-being an d th eir rep or t s of n eck p ain . Th e ou tcom es t h at are rep or ted are h igh ly d ep en d en t on t h e clin ician’s ch oice of th e in it ial t reat m en t . Prosp ect ive st u d ies focu sin g p r im ar ily on t h e cor relat ion bet w een clin ical ou tcom e an d fract u re u n ion /st abilit y

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Chapter 7 are n ecessar y to d eter m in e t h e opt im al t reat m en t in t h e eld erly. Moreover, t h e safet y of su rgical in ter ven t ion s for odon toid fract u res in pat ien ts over 80 years old sh ou ld be evalu ated separately.

■ Biomechanical Studies Anterior Screw Fixation Th ere is st ill con t roversy regarding w h eth er on e- or t w o-screw xat ion is m ore appropriate. In a cadaver st u dy, seven axes w ere t reated w it h on e-screw an d seven w it h t w o -screw xation. Shear and torsional sti ness were m easu red u sing a n on dest r u ct ive low -load test in six direct ion s before an d after t ran sverse osteotom y at th e base of th e odon toid . Mean st i n ess in all direct ion s after screw xat ion w as sim ilar in both grou p s. Th e st i n ess after on ean d t w o-screw xat ion w as n ot restored to n orm al; th e m ean sh ear st i n ess restored rat io w as less th an 50%, an d th e m ean torsion al st i n ess restored rat io w as less th an 6% in both grou p s. Bon e m arrow den sit y did n ot correlate w ith m ean st i n ess after screw xat ion in both group s.13 It is con clu ded th at on e screw is su fcient to perform an anterior odontoid xation.

Posterior Screw Fixation Th ere are several proced u res to xate th e C1- C2 com plex. In cadaver st u dies, th e p u llou t st rength of the m ost com m only described screw tech n iques are com pared: C1 lateral m ass to C2 pedicle screw xat ion , C1 lateral m ass to C2 isth m u s screw xat ion , C1 to C2 t ran sart icular screw xat ion , C1 lateral m ass to C2 t ran sar t icu lar screw xat ion , an d crossed lam in ar (in t ralam in ar) screw xat ion . In gen eral, su rgeon s ch oose t h e tech n iqu e t h ey are m ost fam iliar w it h , bu t som et im es t h e st ron gest con st r u ct is required. Biom ech anical studies dem onstrate th at p edicle screw xat ion is in gen eral m ore resistan t to pu llou t th an are oth er screw s. A pedicle screw is n ot alw ays th e safest ch oice. An in vit ro st u dy using h um an cadaveric spin e com p ared t h e biom ech an ical st abilit y of p ed -

icle screw s w ith th at of variou s est ablish ed p osterior atlan toaxial xat ion s u sed to m an age atlan toaxial in stabilit y. Seven h um an cadaveric cer vical spin es w ith th e occipu t at t ach ed (C0- C3) h ad th e n eu t ral zon e (NZ) an d range of m ot ion (ROM) evaluated in th ree m odes of loading.14 Th e follow ing tech niques w ere com pared: C1 lateral m ass and C2 sh ort pedicle screw xat ion (14- to 16-m m screw ), C1 lateral m ass an d C2 long pedicle screw xat ion , C1 lateral m ass an d C2 in t ralam inar screw xat ion, Son ntag’s m odi ed Gallie xat ion , an d C1-C2 t ran sart icular screw xat ion w ith posterior w iring. Th e C1-C2 t ran sart icular group allow ed th e m ost lateral ben ding, an d Son n tag’s m odi ed Gallie xat ion w as sign i can tly w eaker and allowed m ore m ovem ent than the other groups. The follow ing conclusion w ere draw n : th e C1- C2 t ran sart icu lar proced ure w ith w iring provided th e h igh est st abilit y; th e m odi ed Gallie m eth od alon e w as n ot adequ ate for atlan toaxial ar th rodesis, becau se it does n ot provide su cien t st abilit y in lateral ben d ing an d rot at ion m odes; an d th e C2 pedicle screw an d C2 in t ralam in ar tech n iques w ere biom ech an ically less st able th an th e t ran sart icu lar screw xat ion w ith w iring. Th us, it can be con clu ded th at in gen eral a t ran sart icular screw xat ion of C1-C2 w ith w iring is th e m ost st able con st r u ct , directly follow ed by a C1 lateral m ass–C2 p edicle screw xat ion , to w h ich th e use of a sh ort pedicle screw is con sidered a good alternat ive.

■ C2 Anatomy in Children Com puted tom ography (CT) plays a central role in th e d iagn osis of cer vical spin e fract u res. In ch ild ren , rad iolu cen t syn ch on d roses bet w een ossi cat ion cen ters can resem ble fract u res. How ever, w h en the C2 fract ures, it is m ost likely to fract ure at th e jun ct ion s th at w ere form er syn ch on droses. Recogn it ion of cer vical sp in e fract ures in ch ildren requires fam iliarit y w ith n orm al developm en t al an atom y an d com m on varian t s as th ey app ear on CT scan s. In a st u dy by Piat t an d Gr issom ,15 841 CT scan s of t h e at las an d a xis of ch ild ren w ere

 

Odontoid Fractures, Hangman’s Fractures, and C2 Body Fractures 

Fig. 7.2 Bar graph showing the incorporation of the  apical ossi cation center into the dentate process.  By “incorporation” we mean the disappearance of 

the apical center as a distinct process or nodule.  Numbers of Percent of observations at each age are  presented.15

exam in ed . Syn ch on d roses w ere grad ed as rad iolu cen t , n ot tot ally rad iolu cen t bu t st ill visible, or n o longer visible. Th eir locat ion s an d sym m et ries w ere n oted . Th e p resen ce or ab sence of th e t ubercles of the transverse ligam ent w as n oted as w ell. It w as obser ved th at th e th ree com m on ossi cation centers of the atlas arose in the paired n eu ral arch es an d t h e an ter ior arch , bu t in as m any as 20% of cases t h e an ter ior arch d evelop ed from p aired sym m et r ical ossi cat ion cen ters. Th e ve com m on ossi cat ion cen ters of th e axis arose in th e paired n eural arch es, in th e basal cen ter, in th e d en t ate cen ter (from w h ich m ost of th e den tate process develops), an d in th e ver y apex of th e den tate process. The appearance of each synchondrosis was noted at sequ en t ial ages (Fig. 7.2). Th e t ubercles for th e t ran sverse ligam en t gen erally did n ot appear un t il th e ossi cat ion of th e syn ch on droses of th e atlas w as far advan ced. An om alies of th e atlas in clu ded an terior and posterior spina bi da, absence of sectors of th e posterior arch , an d an om alous ossi cat ion cen ters an d syn ch on droses. An om alies of th e a xis w ere m u ch less com m on . It w as con clu ded th at th ere is su bst an t ial variat ion in th e t im e course an d pat tern of developm en t of th e at las, an d an om alies are com m on . Som e fract u res of t h e atlas m ay escap e

recogn it ion w it h ou t m an ifest sequ elae. Var iat ion in th e t im e cou rse of th e develop m en t of th e axis is n otable as w ell, but an om alies seem m u ch less com m on .15

■ Hangman’s Fracture Hangm an’s fract ure, or traum atic cer vical spon dylolisth esis, is th e result of hyperexten sion t rau m a in com bin at ion w ith a xial loading, reboun d exion , rebou n d exten sion , or dist ract ion . Th e fract u res are assessed by th e Levin e an d Edw ards classi cat ion , w h ich is an adapt at ion of E en di et al’s 16 classi cat ion (Fig. 7.3): • Type 1: n on displaced fract ure w ith n o an gu lat ion bet w een C2 an d C3 an d a fract u re d islocat ion of less th an 3 m m • Type 2: fract u re w ith sign i can t angulat ion (> 11 degrees) an d displacem en t (> 3.5 m m ) • Type 2A: fract u re w ith m in im um displacem en t an d sign i can t angu lat ion (> 11 d egrees) • Type 3: fract u re w ith severe angulat ion an d d isplacem en t associated w ith u n ilateral or bilateral C2–3 facet dislocat ion Hangm an’s fract ures can be m an aged eith er con ser vat ively, w ith im m obilizat ion , or surgi-

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Chapter 7

a

b

Fig. 7.3a,b Hangman’s fractures can be classi ed  by the Levine and Edwards classi cation 25 (a), which  is an adaptation of the E endi classi cation 16 (b).  Type 1: nondisplaced fractures with no angulation  bet ween C2 and C3 and a fracture dislocation of less  than 3 mm. Type 2: fracture with signi cant angu-

lation (> 11 degrees) and displacement (> 3.5 mm).  Type 2A: fracture with minimum displacem ent and  signi cant angulation (> 11 degrees). Type 3:  fractures with severe angulation and displacement  associated with unilateral or bilateral C2–3 facet  dislocation. 

cally. Most h angm an’s fract u res can be t reated w ith cer vical im m obilizat ion . Extern al im m obilizat ion w ith a collar is regularly applied for th e t reat m en t of p at ien t s w ith t yp e I fract u res. Som e au th ors also recom m en d in it ial extern al im m obilizat ion , u su ally w ith a h alo vest , for t ypes 2 an d 2A. Type 3 an d long-term n on fu sion pat ien ts are u su ally t reated w ith su rger y. Th e m ost com m on su rgical ap p roach is a C1- C3 posterior xat ion , bu t an an terior C2- C3 ap proach is also pop ular.16 With th e in t roduct ion of n avigat ion system s for th e spin e, th e n avigated screw placem en t in th e C2 pedicle h as m ade th e C1- C2 pedicle xat ion a safe p rocedu re to su rgically t reat a h angm an’s fract u re.17 Th e xat ion w ith pars screw s (th rough th e isth m u s, crossing th e fract ure lin e) h as been reported previously; it

is m ore app rop riate to perform it w ith th e cu rren t n avigat ion system s.

Surgical Versus Conservative Treatment of Hangman’s Fracture Th ere are few st u dies on th e con ser vat ive versu s su rgical t reat m en t of pat ien ts w ith a h angm an’s fract u re. Li et al18 perform ed a system at ic review of th e literat ure from 1966 to 2004 an d foun d 32 repor ts on th e m an agem en t of h angm an’s fract u res. Regarding a prim ar y th erapy for h angm an’s fract ures, 20 papers (62.5%) advocated con ser vat ive t reat m en t, an d 11 of th e rem ain ing 12 p ap ers suggested t h at con servat ive t reat m en t w as su itable for som e st able fract ures. Most h angm an’s fract ures can be m anaged successfully w ith traction and extern al

 

Odontoid Fractures, Hangman’s Fractures, and C2 Body Fractures 

im m obilization, and surgical stabilization is recom m en ded in u n st able cases w h en th ere is th e possibilit y of later in stabilit y, su ch as t ype IIa an d III fract ures w ith sign i can t dislocat ion . An oth er system at ic review of th e literat u re from 1980 to 2010 covered on ly con ser vat ive t reat m en t . It , too, fou n d th at t ract ion is a good tool for realign m en t .19 In th at review, fou r retrospective studies w ere identi ed that assessed t h e ou tcom e of h an gm an’s fract u res. Th ese st u d ies in clu d e a m ix of p at ien t s w it h an d w ith out n eurologic injur y m an aged prim arily w ith early t ract ion an d a rigid extern al or th osis. Neck pain an d both ersom e st i n ess are n ot reported at long-term follow -u p, alth ough n o object ive pain scores w ere collected .

Biomechanical Study Un icort ical or bicort ical posterior screw s can be placed. Th e use of bicor t ical screw s en tails a h igh er risk of dam aging th e spin al n er ve or th e ver tebral ar ter y, becau se th e screw t rajector y h as to be prepared w ith a drill in stead of a probe. Th erefore, th ere w ou ld clearly be in terest in determ in ing w h eth er th ere is a di eren ce in th e p u llou t st rength of th e screw s. A biom echanical study using 11 hum an cadaveric cer vical spin es w as con ducted to determ in e w h eth er th e cer vical stabilit y ach ieved w ith lateral m ass xat ion u sing u n icor t ical 14-m m long screw s is com parable w ith th at obtain ed w ith lateral m ass xation using bicortical screw s. Cer vical sp in al sect ion s bet w een C3 an d C5 w ere tested in exion -exten sion , torsion , an d lateral ben ding m odes, both w ith an d w ith ou t lam in ectom y, w ith u n i- an d bicor t ical 14-m m screw s. An alysis dem on st rated th at bicor t ical con st r u ct s w ere, on average, st i er t h an u n icor t ical con st r u ct s in m ost ben d in g m od es after a w id e lam in ectom y w as p er for m ed . No sign i can t d i eren ces w ere fou n d , h ow ever, bet w een bicor t ical con st r uct s an d un icor t ical con st r uct s w ith ou t lam in ectom y. 20 Th ese resu lt s w ere n ot con r m ed by an ot h er p u blicat ion , w h ere t h e sam e resu lt s in both u n i- an d bicor t ical lateral m ass screw pu llou t st rength w as rep or ted, even in com bin ation w ith a lam in ectom y.21

■ C2 Body Fractures Th e C2 body is th e region th at lies below th e odon toid process (den s) an d bet w een th e pars in terar t icu laris of each side. Fract u res of th e C2 body are un com m on . Ben zel’s grou p 22 p roposed a classi cat ion sch em e th at id en t i ed th ree t yp es of C2 body fract u res: (1) vert ical, coron ally orien ted (t yp e 1); (2) ver t ical, sagittally orien ted (t ype 2); an d (3) t ran sverse, axially orien ted (t ype 3). Th e ver t ical, coron ally or ien ted t yp e 1 C2 body fract u re h as been described by oth ers as eith er an at yp ical t raum atic spondylolisthesis of the axis or an unusual t ype of h angm an’s fract u re. Th e t ype 3 C2 body fract u re is iden t ical to th e An derson an d D’Alon zo t ype III odon toid fract u re. Fujim u ra an d colleagu es 23 p roposed th e follow ing classi cat ion sch em e: Type I is an avu lsion fract u re du e to hyp erexten sion (teardrop fract u re). Type II is a t ran sverse fract u re ru n n ing horizontally through the C2 vertebral body caudal to th e superior en d of th e atlan toaxial join t . Th e fract u re lin e is caudal to th at in th e t ype III den s fract ure. Type III is a burst fract ure, or com m in uted fract ure of th e C2 body w ith m u lt ip le fragm en t s dislocated an terop osteriorly, often w ith ret rop ulsion in to th e spin al can al. Trau m at ic spon dylolisth esis is presen t in all cases. Typ e IV is a sagit tal or p arasagit t al fract u re exten ding from a p oin t lateral to th e d en s vert ically or diagon ally to th e in ferior su rface of C2.

Classif cation A t reat m en t algor it h m is d esirable, esp ecially for rare d iseases. To t h at en d , classi cat ion s of th e obser ved inju r y can be h elp fu l. It is t h erefore relevan t to st u dy w h eth er t h e classi cat ion s proposed by Ben zel an d by Fujim u ra correlate w ith th e ou tcom e in su rgical an d n on surgical t reat m en t . Germ an et al22 evalu ated 18 p at ien t s w h o w ere classi ed, based on th e Ben zel classi cat ion , as h aving a ver t ical C2 body fract ure. Sixteen coron ally orien ted t ype 1 ver t ical C2 body fract ures an d ve sagit t ally orien ted t ype 2 ver t ical C2 body fract ures w ere iden t i ed. All p at ien t s w ere m an aged n on op -

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Chapter 7 erat ively (w ith extern al or th oses) an d sh ow ed evidence of fusion (union of fracture fragm ents) at th e t im e of th e last follow -u p . Th e au th ors con clu de th at ver t ical C2 body fract u res are am enable to nonoperative treatm en t from both a n eurologic an d an osteological view poin t . Th ey also rep or t th at ver t ical C2 body fract u res are n ot rare injuries, as th ey accou n ted for 10% of th e upper cer vical spin e fract ures iden t i ed over th e st udy period . No rep or t s w ere iden t i ed on th e t reat m en t of Ben zel t ype III h orizon t al C2 body fract u res. Th erefore, th e Ben zel classi cat ion is n ot h elp fu l in determ in ing w h at t reat m en t sh ou ld be applied. As a ru le of th um b, w e can on ly suggest th at th e ver t ical body fract ures can be t reated con ser vat ively. Fujim ara 2 3 also p roclaim s n on op erat ive t reat m en t of a xis body fract u res as th e p rim ar y th erapy. Fujim ara claim s to app ly a cer vical cast if n o d islocat ion of t h e at lan to -a xial join t or C2/3 is recogn ized . If h ow ever a d islocat ion of t h e at lan to-a xial join t or C2/3 is p resen t , sku ll t ract ion or t ract ion w it h t h e h alo-ring sh ou ld be perform ed. Su bsequ en tly, upon ach ieving reduced p osit ion , a cer vical cast or h alo-vest sh ou ld be p u t on an d kept in a place for 8–16 w eeks. Fujim ara suggests a su rgical in ter ven t ion if it w ou ld be di cu lt to obtain or m aintain th e reduced posit ion due to som e associated inju ries. Again , n o correlat ion w as m ade bet w een th e t ype of inju r y an d th e selected m eth od of t reat m en t . Bot h t h e Fujim ara an d t h e Ben zel classi cat ion s are n ot h elp fu l in deciding w h eth er to perform a su rgical in ter ven t ion . Th e sam e logical ru le of thu m b th at app lies to all cer vical t rau m a cases is valid: if th e d islocat ion is severe, surgical in ter ven t ion is advisable. Zh ang et al24 provide in dicat ion s for w h en a su rgical st rategy sh ou ld be ap p lied. Th ey rep or t on a ret rospect ive an alysis of 28 cases p resen t ing w ith axis body fract u res. Th ey suggest the follow ing indications for surgical treatm ent: (1) fract u res associated w ith in st abilit y of adjacen t join t s; (2) irredu cible disp laced su perior articular facet fract ure; and (3) fract ures resultin g in sp in al cord com p ression . Th e su rgical p rocedu res t h ey ap plied w ere posterior C1-C2

p ed icle screw ap p licat ion . Com p licat ion s of m alp osit ion of screw s an d n eu rologic d e cit d id n ot occu r in t h ese 28 cases. Sat isfactor y reduct ion an d bony un ion w ere dem on st rated on postoperat ive radiograph ics. Th e auth ors con clu de th at con ser vat ive t reat m en t is st ill advocated as the prim ar y m anagem ent for m ost axis body fract ures, bu t th at surgical in ter ven t ion is n ecessar y for p at ien t s w ith obviou s adjacen t join t in st abilit y or irreducible displaced su p erior ar t icu lar facet fract u re. No classi cat ion , n eith er Ben zel’s n or Fujim ara’s, is u sed to illu st rate th eir con clu sion .

■ Chapter Summary In th is ch apter, th e an terior an d posterior surgical t reat m en t of C2 odon toid fract u res is described, an d at ten t ion w as p aid to th e balan ce bet w een surgical an d con ser vat ive t reat m en t of C2 odon toid fractures. Furtherm ore, C2 anatom y in ch ildren is described an d th e varian ce in an atom y an d develop m en t speed is st ressed. Th e Hangm an’s fract u re t reat m en t of th e differen t t ypes of fract ure is discu ssed. Fin ally, C2 body fract ures are discussed an d it w as con clu ded th at in gen eral con ser vat ive t reat m en t is adequ ate, an d th at classi cat ion of th is t yp e of fract u re is n ot h elpful in m aking decision s on t reat m en t .

Pearls In anterior screw  xation, a 10% nonunion rate is  reported in the literature; nonunion is signi cantly higher when patients are over 70 years of  age. For t ype II/III odontoid fractures, surgically treated  patients appear to show higher osseous union  rates compared with conservatively treated patients, but this does not lead to higher stabilit y  rates in the surgically treated patients (retrospective data, subjected to at trition bias). Most hangman’s fractures can be managed successfully with traction and external im mobilization, and surgical stabilization is recom mended  in unstable cases when there is the possibilit y of  later instabilit y, such as t ype IIa and III fractures  with signi cant dislocation.

 

Odontoid Fractures, Hangman’s Fractures, and C2 Body Fractures  Pitfalls C2 fractures in children are di cult to distinguish  from  synchondroses; the C2 fractures in children  are likely to occur at the line of the form er  synchondrosis.

Bicortical lateral mass screws do not have more  pullout strength than unicortical screws. Vertical C2 body fractures are not rare injuries;  they account for 10% of upper cervical spine fractures. They generally heal well with conservative  treatm ent with a sti  collar.

Refere nces Five Must-Read Refe rences 1. Huybregt s JG, Jacobs WC, Vleggeer t-Lan kam p CL. Th e opt im al t reat m en t of t ype II an d III od on toid fract ures in th e elderly: a system at ic review. Eur Spin e J 2013;22:1–13 PubMed 2. Anderson LD, D’Alon zo RT. Fract u res of th e od on toid process of th e axis. J Bon e Join t Su rg Am 1974;56: 1663–1674 Pu bMed 3. Hsu W K, An derson PA. Odon toid fract ures: update on m an agem en t . J Am Acad Or th op Su rg 2010;18: 383–394 PubMed 4. Huybregts JG, Jacobs WC, Peul WC, Vleggeert- Lankam p CL. Rat ion ale an d design of th e INNOVATE Trial: an in tern at ion al cooperat ive st udy on su rgical versus con ser vat ive t reat m ent for odon toid fract ures in th e elderly. BMC Musculoskelet Disord 2014;15:7 PubMed 5. Feh lings MG, Aru n R, Vaccaro AR, Arn old PM, Ch ap m an JR, Kopjar B. Predictors of t reat m en t outcom es in geriat ric pat ien t s w ith odontoid fract u res: AOSpin e North Am erica m u lt i-cen t re prospect ive GOF st udy. Spin e 2013;38:881–886 PubMed 6. Robin son Y, Robin son AL, Oler u d C. System at ic review on surgical an d n on surgical t reat m en t of t ype II odon toid fract ures in th e elderly. Biom ed Res In t 2014;2014:231948 PubMed 7. Sm ith JS, Kepler CK, Kopjar B, et al. E ect of t ype II odon toid fract ure n on un ion on outcom e am ong elderly p at ien t s t reated w ith ou t su rger y: based on th e AOSpin e Nor th Am erica geriat ric odon toid fract ure st udy. Spin e 2013;38:2240–2246 Pu bMed 8. Grau er JN, Sh a B, Hilibran d AS, et al. Prop osal of a m odi ed, t reat m en t-orien ted classi cat ion of odon toid fract ures. Spin e J 2005;5:123–129 PubMed 9. Tian NF, Hu XQ, Wu LJ, et al. Pooled an alysis of n on un ion , re-operat ion , in fect ion, an d approach related com plicat ions after an terior odon toid screw xat ion . PLoS ONE 2014;9:e103065 PubMed 10. Apfelbau m RI, Lon ser RR, Veres R, Casey A. Direct an terior screw xat ion for recen t an d rem ote odon toid fract ures. J Neurosurg 2000;93(2, Suppl):227– 236 PubMed 11. Kam in ski A, Gst rein A, Mu h r G, Mü ller EJ. [Tran sart icu lar C1- C2 screw xat ion : resu lt s of un st able odontoid fractures and pseudarth rosis in the elderly]. Un fallch iru rg 2008;111:167–172 PubMed

12. Molin ar i RW, Kh era OA, Gr u h n W L, McAssey RW. Rigid cer vical collar t reat m en t for ger iat r ic t yp e II od on toid fract u res. Eu r Sp in e J 2012;21:855–862 Pu bMed 13. Feng G, Wen dlan dt R, Spu ck S, Sch u lz AP. On e-screw xat ion provides sim ilar st abilit y to th at of t w oscrew xat ion for t ype II den s fract ures. Clin Or th op Relat Res 2012;470:2021–2028 Pu bMed 14. Sim HB, Lee JW, Park JT, Min d ea SA, Lim J, Park J. Biom ech an ical evalu at ion s of var iou s C1- C2 p oster ior xat ion tech n iqu es. Sp in e 2011;36:E401–E407 Pu bMed 15. Piat t JH Jr, Grissom LE. Develop m en t al an atom y of th e atlas an d axis in ch ildh ood by com pu ted tom ography. J Neurosurg Pediat r 2011;8:235–243 PubMed 16. E en di B, Roy D, Cornish B, Du ssau lt RG, Lau rin CA. Fract ures of th e ring of th e axis. A classi cat ion based on th e an alysis of 131 cases. J Bon e Join t Su rg Br 1981;63-B:319–327 Pu bMed 17. Singh PK, Garg K, Saw arkar D, et al. Com puted tom ography-guided C2 pedicle screw placem ent for t reat m en t of un st able h angm an fract ures. Spin e 2014;39:E1058–E1065 Pu bMed 18. Li XF, Jiang W M, Yang HL, et al. Surgical t reat m en t of ch ron ic C1-C2 dislocat ion w ith absen ce of odon toid process u sing C1 h ooks w ith C2 p edicle screw s: a case repor t an d review of literat ure. Spin e 2011;36: E1245–E1249 PubMed 19. Lew kon ia P, Dipaola C, Sch outen R, Noon an V, Dvorak M, Fish er C. An eviden ce-based m ed icin e p rocess to determ in e ou tcom es after cer vical sp in e t rau m a: w h at surgeon s sh ould be telling th eir pat ien t s. Spin e 2012;37:E1140–E1147 PubMed 20. Mu olet to AJ, Yang J, Vadhva M, Hadjip avlou AG. Cer vical st abilit y w ith lateral m ass plat ing: u nicor t ical versu s bicor t ical screw purch ase. Spin e 2003;28: 778–781 PubMed 21. Papagelopoulos PJ, Currier BL, Neale PG, et al. Biom ech an ical evalu at ion of p oster ior screw xat ion in cadaver ic cer vical sp in es. Clin Or t h op Relat Res 2003;411:13–24 PubMed 22. Germ an JW, Hart BL, Ben zel EC. Non operat ive m an agem en t of vert ical C2 body fract u res. Neurosurger y 2005;56:516–521, discu ssion 516–521 Pu bMed

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Chapter 7 23. Fujim ura Y, Nish i Y, Kobayash i K. Classi cat ion an d t reat m en t of axis body fract ures. J Orthop Traum a 1996;10:536–540 PubMed 24. Zh ang YS, Zh ang JX, Yang QG, Sh en CL, Li W, Yin ZS. Surgical m an agem en t of th e fract ures of axis body:

indicat ion s an d surgical st rategy. Eur Spin e J 2014; 23:1633–1640 Pu bMed 25. Levin e AM, Edw ards CC. Th e m an agem en t of t raum at ic spon dylolisth esis of th e axis. J Bon e Join t Su rg Am 1985;67:217–226 PubMed

8 Compression (AO Type -A Injuries) Nuno Neves

■ Introduction Th e cer vical sp in e is inju red in 2 to 3% of p at ien t s w h o su stain blu n t t rau m a, an d th e vast m ajor it y of t h ese fract u res an d d islocat ion s occu rs in th e su baxial sp in e.1,2 Th e su baxial cer vical spin e is an atom ically an d biom ech an ically sim ilar to t h e t h oracolu m bar sp in e, in bot h it s osseou s an d ligam en tou s elem en t s, bu t it s sm aller d im en sion s an d h igh er ran ge of m ot ion in all p lan es m akes it m ore p ron e to inju ries. Alth ough com p ression injuries are th e m ost com m on t yp e in th e th oracolu m bar sp in e, in th e cer vical spin e th ey are relat ively rare an d accou n t for less th an 15% of all inju ries.3 Ch aracterist ically, A-t yp e com pression fract u res resu lt from axial com p ression w ith or w ith out exion , h ave reduced ver tebral body h eigh t , an d h ave an in t act posterior ligam en tous com plex. Th is ch apter review s th e classi cation, clin ical an d diagnostic feat ures of A-t ype com p ression fract u res of th e su baxial cer vical spine, an d discusses th eir m an agem en t .

■ Methods A literat ure search w as perform ed on th e Nat ion al Librar y of Medicin e (Pu bMed) dat abase, u sing th e follow ing as th e m ajor search term s: cervical spine, fractures, injuries, burst fract ures,

an d com pression fract ures. Origin al papers an d review s w ere selected based on th eir relevan ce. Oth er art icles w ere fou n d th rough th e referen ces of th e selected papers.

■ Classi cation of Injuries of

the Subaxial Cervical Spine An e ect ive classi cat ion system establish es easy-to-rem em ber, st an dardized term in ology th at both facilit ates com m u n icat ion bet w een h ealth care providers an d gu ides t reat m en t .4 Furth erm ore, in t ra- an d in terobser ver reliabilit y sh ou ld be h igh . Th e AO (Arbeitsgem ein sch aft fü r Osteosyn th esefragen ) classi cat ion for sp in e inju ries, as described by Magerl et al,5 w as origin ally developed for th e th oracolu m bar spin e, an d is a com preh en sive system prim arily based on th e m orph ology an d m ech an ism of inju ries. Th is system h as th ree m ain t yp es: t ype A, ver tebral body com p ression ; t yp e B, disru pt ion of th e an terior an d p osterior elem en t s w ith dist ract ion ; an d t ype C, disrupt ion of th e an terior an d p osterior elem en t s w ith rotat ion . Each t ype is fu rth er divided in to th ree groups an d th ree subgroups, for a com plete descript ion of ever y injur y. Alth ough sp eci cally develop ed for th e th oracic an d lu m bar spin e, th e idea of expan ding it s u se for th e cer vical spin e h as been m et w ith

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Chapter 8 Table 8.1 AO Classi cation of Subaxial Cervical Spine Compression Injuries A—Compression A1—Impaction fractures

A2—Split fractures

A3—Burst fractures

A1.1—end-plate impaction A1.2—wedge impaction A1.3—vertebral collapse

A2.1—sagit tal or coronal A2.2—sagit tal and coronal A2.3—pincer fracture

A3.1—incomplete burst A3.2—burst-split A3.3—complete burst

Source: From Blauth MKA, Mair G, Schm id R, Reinhold M, Rieger M. Classi cation of injuries of the subaxial cervical spine. In: Aebi M, Arlet V, Webb JK, eds. AOSpine Manual: AOSpine International. New York: Thiem e; 2007:21–38. Reproduced with permission.

in terest , because it rep resen t s a u n i ed, com prehen sive classi cat ion for the w hole subaxial m obile spin e. In a ret rospect ive st u dy of 448 pat ien ts, Blau th et al3 ap p lied th e AO th oracolu m bar classi cat ion to th e cer vical sp in e, w h ich th e au th ors felt di ered ver y lit tle from its thoracolum bar counterpart (Table 8.1). Com p uted tom ograp hy (CT) is m an dator y for th e full classi cat ion of a cer vical sp in e inju r y, an d exion -extension X-rays or m agnet ic reson ance im aging (MRI) m ay also be requ ired to iden t ify p ossible inju ries to th e posterior ligam en tou s com plex. In t raoperat ive n dings m ay m odify even fu r th er th e in it ial classi cat ion . Alth ough it is com p reh en sive, th is system m ay becom e too com plex beyon d th e t ype (A, B, or C) an d group classi cat ion to apply in ever yday pract ice, m akin g it m ore u sefu l for acad em ic d escr ipt ion of inju r ies. Th e AO is in t h e p rocess of re n ing th e AO subaxial cer vical spin e classi cat ion , com bin ing elem en ts of th e Th oracolu m bar Inju r y Classi cat ion an d Severit y Score (TLICS) system along w ith th e p rin ciples of th e origin al AO Magerl system . A w id ely u sed classi cat ion system is t h e Allen -Fergu son system , w h ich is based on th e m ech an ism involved in each lesion in ferred from th e radiograph ic im ages.6 Th ere are six categories: (1) exion -com pression, (2) vertical com p ression , (3) exion -dist ract ion , (4) extension -com p ression , (5) exten sion -d ist ract ion , an d (6) lateral exion . Th ese system s rely on m orphological ch aracter ist ics an d in fer red m ech an ism s, w h ich poses several qu est ion s regarding th eir validit y. Th e sam e m ech an ism m ay produ ce di er-

en t pat tern s of injur y, an d iden t ifying a sp eci c m ech an ism from a cer t ain inju r y m ay be t rou blesom e. Addit ion ally, th e classi cat ion fails to consider ligam entous stabilit y or neurologic involvem ent, so its clinical applicabilit y is lim ited. More recen tly, based on m odern im aging, t w o n ew classi cat ion system s h ave been developed, en abling a con t in u ou s qu an t i cat ion of st abilit y an d aiding in decision m aking. Th e Cer vical Sp in e Inju r y Sever it y Score (CSISS) in depen den tly an alyzes fou r colum n s (an terior, posterior, righ t lateral colu m n , an d left lateral colu m n ) an d scores each u sing a 0 to 5 an alogue scale.7 Scores in crease proport ion ally to eith er disp lacem en t of fract u re fragm en t s or sep arat ion as a resu lt of soft t issu e inju r y. Each colum n is scored in depen den tly an d su m m ed, yielding a score range of 0 to 20. Excellen t in t ra- an d in terobser ver reliabilit y w as obt ain ed using this scale. Pat ien ts w ith a score ≥ 7 are t reated surgically. AO A-t yp e com pression inju ries score low on th e CSISS (0–3), as th ey are lim ited to th e an terior colum n . Th e Suba xial Cer vical Spin e Injur y Classi cat ion (SLIC) system evalu ates th ree param eters: fracture m orphology, the discoligam entous com p lex (DLC), an d n eu rologic fu n ct ion .4 Each is assign ed a speci c n um ber of poin t s, creating a score th at aids t reat m en t decision m akin g. An inju r y t h at scores below 4 can be t reated n on op erat ively, w h ereas su rger y is recom m en ded w ith a score above 4. Inju ries scoring equ al to 4 can be m an aged eith er w ay. AO A-t yp e com pression inju ries score low in th e SLIC system (1–2) un less a n eu rologic de cit is presen t .

Compression (AO Type-A Injuries)

■ Epidemiology According to Blauth et al,3 A-t yp e fract u res represen t 14.7%of all su ba xial sp in e inju ries. In th is st u dy, A3 w ere th e m ost com m on (9.8%) an d A1 an d A2 accou n ted for on ly 2.9% an d 2.0%, respect ively. Th is is in stark con t rast w ith th e th oracolum bar spin e, w h ere com pression an d bu rst fract u res are largely p red om in an t . In a st u dy of 203 ver tebral fract u res in 127 p at ien t s, bu rst fract u res accou n ted for 38% of th e fract u res, bu t on ly 10% w ere located in t h e cer vical spin e.8 Im por t an tly, all p at ien ts w ith a single spin e fract u re sh ou ld u n dergo im aging of th e en t ire axis, as at least 10% of pat ien ts m ay h ave a n on con t igu ou s sp in al fract u re.8,9 Axial com pressive cer vical spin e fract ures are t ypically obser ved in th e th ird an d fou rth decades of life, an d m en are p redom in an tly affected, w ith falls an d spor t s act ivit ies (e.g., diving h ead rst in sh allow w ater) being th e m ain causes of inju r y.9,10 Sp in al cord inju ries (SCIs), eith er com p lete or in com plete, are frequen tly associated w ith burst fract ures. According to Blauth et al,3 n eurologic injuries (ranging from radicular sym p tom s to severe com plete SCI) w ere obser ved in 54.5% of all cer vical spin e bu rst fract u res. On ly 15.3% an d 22.2% of n eu rologic inju r ies w ere associated w ith A1 an d A2 t yp es, respect ively, rep resen t in g t h e grou p s w it h t h e least com p licat ion s. You n g m en in t h eir early 30s are t h e grou p at h igh er risk of su stain ing SCI, bu t th e dem ograph ics are variable th rough out th e w orld, an d a recen t sh ift tow ard m ore w om en an d older age h as been described.11

■ Diagnostic Features A-t ype fract u res ch aracterist ically result from axial com pression . Th ey are usually associated w ith variable degrees of exion , an d th ey h ave redu ced ver tebral body h eigh t an d an in t act posterior ligam en tou s com plex. Im p act ion fract u res (grou p A1) are rare in juries th at result from axial loading forces in exion. The disc is pressurized, leading to w edg-

ing of th e ver tebral body, w h ich usu ally occu rs along th e su p erior en d plate. Becau se th e p osterior body cor tex is in t act , an d com m on ly th ere is n o injur y to th e posterior ligam en tous com plex (PLC), th e risk of n eurologic injur y is low. However, dam age to the PLC can occur w ith A1-t yp e fract u res creat ing an u n st able lesion , an d th e associat ion of a ver tebral com pression fracture w ith interspinous space w idening, vertebral sublu xation , and loss of cervical lordosis, in d icates a p robable ligam en tous disrupt ion , th e so-called h idden exion inju r y.12 A h igh level of su spicion is n ecessar y to iden t ify th ese inju ries, as th ey can be sp on tan eously redu ced in su pin e lateral X-rays, an d exion -exten sion im ages u n der uoroscopic con t rol or advan ced im aging m odalit ies m ay be in dicated . Sp lit fract u res (grou p A2) are rare lesion s. Because p ure coron al or sagit t al p lan e fract u re lin es are u n com m on , th is grou p presen ts a m inor change from its thoracolum bar classi cat ion cou n terpar t , in clu ding com bin ed sagit tal an d coron al plan e fract u res. In th e pin cer-t ype fract u re (A2.3), th ere is m arked displacem en t of t h e an ter ior fragm en t an d sm all com m in u t ion zon es, lead in g to red u ced resist an ce to com p ression an d in creased su scept ibilit y to n on un ion . Bu rst fract u res (grou p A3) resu lt from severe axial loading, a ect ing both th e an terior an d m iddle colu m n s of th e cer vical ver tebrae an d usually occur at C6 an d C7 rath er th an th e m id dle or u p per cer vical spin e.4,6 With axial loading, p ressu re in creases rap idly in side th e disc, pu sh ing th e su p erior en d p late in side th e ver tebral body, w h ich fails w it h ret rop u lsion of fragm en t s to th e spin al can al. Th e p osterior ver tebral body cor tex is inju red, leading to decreased an terior an d posterior ver tebral h eigh t an d a variable degree of segm en tal kyph osis. In com p lete bu rst fract u res are less com m on th an in t h e t h oracolu m bar sp in e, as u su ally th e w h ole posterior w all of th e vertebral body bulges in to th e spin al can al. Because th e h ead is often sligh tly exed, p osterior ligam en tou s com p lex disru pt ion can occu r an d m u st be ruled out by appropriate m eth ods. In an terop oster ior (AP) view s (Fig. 8.1a), X-rays reveal a ver t ical fract u re lin e, p ed icle

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Chapter 8

a

b

Fig. 8.1a–e A 48-year-old man su ered an injury in a motor vehicle accident. He was adm it ted to the hospital with neck pain and an incomplete spinal cord injury (American Spinal Injury Association [ASIA] grade B). (a,b) X-rays and (c) com puted tomography (CT) scan revealed a C5 complete burst fracture with vertebral body comm inution and retropulsion of the posterior cortex. The patient was put in skull traction for immediate reduction and indirect spinal cord decompression and underwent a C5 corpectomy, C4-C6 fusion with iliac crest bone graft, and plate xation.

c

w idening, and variable degrees of com m inution an d displacem en t of fragm en t s of th e ver tebral body. On lateral view s (Fig. 8.1b), th ere is soft tissue sw elling, shorten ing of both anterior and posterior ver tebral body h eigh t s, variable kyph osis, an d convexit y of th e p osterior ver tebral body w all as com pared w ith th e n orm al ver tebrae. As the pedicles are pushed laterally, vert i-

cal fractures in the lam inae or spinous processes can also be seen . Failu re of th e an terior colu m n , severe kyph osis, in terspin ous w iden ing, for w ard su blu xat ion of th e adjacen t ver tebral body, facet sublu xation, fract ure, or dislocation, are h igh ly suggest ive of disru pt ion of th e DLC. A CT scan can p recisely de n e bon e com m in u t ion , p osterior w all ret rop u lsion , an d facet

Compression (AO Type-A Injuries)

d

87

e

Fig. 8.1a–e (continued) (d,e) One year later the fusion has healed uneventfully and the neurologic status improved to ASIA grade D.

su blu xat ion or fract u res, w h ich are d i cu lt to visu alize in conven t ion al rad iograp hy (Fig. 8.1c). How ever, because ret ropulsed fragm en ts often h ave recoiled from th e m ost displaced posit ion , th e CT scan can sign i can tly u n derest im ate th e am ou n t of can al n arrow ing t h at occu rs d u r in g t h e im p act , an d so t h ere is n o d irect cor relat ion bet w een p ost inju r y occlu sion an d n eu ral dam age.13 Moreover, CT scan can easily im age th e occipitocer vical an d cervicoth oracic spin e, w h ich are di cult to assess w ith plain radiograph s. Magn et ic reson an ce im aging is used to evalu ate ongoing n eurologic com pression an d soft t issu e inju r ies, an d is in d icated in all p at ien t s w it h a n eu rologic de cit u n less obt ain ing t h e st u dy w ou ld lead to a su bst an t ial d elay in t reat m en t . A hyperin ten se sign al th rough ligam en tou s region s on T2 or sh ort tau inversion recover y (STIR) im ages is in dicat ive of a ligam en tou s inju r y. St ill, th ere is n o de n it ive clin ical correlat ion bet w een in creased ligam en tou s sign al an d m ech an ical in st abilit y.4

■ Initial Management Pat ien t s w ith A-t ype inju ries are kept im m obilized w ith a h ard cer vical collar w ith th e sp in e in a n eu t ral p osit ion . A cadaveric st u dy dem on st rated th at exion or exten sion can decrease can al diam eter in a pat ien t w ith a bu rst fract u re of th e cer vical spin e.14 On ce th e n eck h as been properly im m obilized, periodic neurologic exam s sh ould be perform ed. Although there is lit tle high-qualit y evidence on closed reduct ion of cer vical burst fract ures by sku ll t ract ion , it can be perform ed as a m ean s of ach ieving in direct n eu ral decom pression in an em ergen t set t ing.15 Even if su rgical t reat m en t h as already been decided, th is tem porizing m easure m ay help restore the anatom ic align m en t an d m ake surger y easier. Gardn erWells tongs are in it ially app lied w ith 5 kg to coun ter th e w eigh t of th e h ead; sequ en t ially, an d un der close su per vision , 2 kg for each segm en t is added, an d radiograph s or u oroscopy are used to control reduction. For burst fractures,

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Chapter 8 addit ion al w eigh t is rarely n eeded to ach ieve accept able align m en t an d reduct ion . Altern at ively, a h alo m ay be u sed both for redu ct ion an d de n it ive n on operat ive t reat m en t .

■ De nitive Management Th ere are th ree m ain factors to con sider w h en deciding w h eth er or n ot to su rgically stabilize a suba xial cer vical spin e injur y: spin al stabilit y, n eu rologic stat u s, an d in divid u al pat ien t factors.16 A sign i can t por t ion of A-t ype injuries h as n eith er n eurologic com prom ise n or m ech an ical in st abilit y, so th ese inju ries can be t reated n on operat ively. Th e AO subaxial spin e classi cat ion system does n ot con sider th e n eu rologic st at u s of th e p at ien t , bu t rat h er relies on m orph ological ch aracterist ics an d th e m ech an ism of injuries to est ablish th e severit y of th e fract u re. How ever, de n ing in stabilit y h as been a ch allenge an d a m at ter of in ten se debate an d con fu sion . W h ite an d Panjabi’s grou p 17 d e n ed stabilit y as “the abilit y of the spine under physiologic loads to lim it p at tern s of displacem en t so as n ot to dam age or irrit ate th e sp in al cord or n er ve root s an d, in addit ion , to preven t in cap acitat ing deform it y or p ain du e to st ru ct ural ch anges,” an d d evelop ed a ch ecklist to assist in th e determ in at ion of sp in al stabilit y. Th ey identi ed radiographic param eters for subaxial cer vical spin e in st abilit y in clu ding m ore th an 3.5 m m h orizon t al disp lacem en t of on e ver tebra in relat ion to an adjacen t vertebra, or m ore than 11 degrees of rotation di erence from that of eith er adjacen t ver tebra. Alth ough h elp fu l an d reliable in ext rem e cases, th is de n it ion m ay be in adequate in subtle cases, as in st abilit y is a con t in uu m of sit u at ion s rath er th an a d ich otom ous con dit ion . Th e SLIC system carefully an alyzes each of th ree com pon en ts of th e injur y: fract ure m orp h ology, in tegrit y of th e DLC, an d n eurologic fu n ct ion .4 For m or p h ology, A1- an d A2-t yp e inju r ies are assign ed on e p oin t an d A3 fract u res are assign ed an ad d it ion al p oin t . Th e SLIC system th en evalu ates th e in tegrit y of th e

DLC (in ter ver tebral disc, an terior an d posterior longit udinal ligam ents, interspinous ligam ents, facet capsu les, an d ligam en t um avum ). An in tact DLC is de n ed as n orm al spin al align m en t, n orm al disc space, an d ligam en tous appearan ce, an d is aw arded zero poin t s. Disru pt ion of th e DLC m ay be in ferred by th e presen ce of abn orm al facet align m en t (ar t icu lar apposit ion < 50% or d iast asis > 2 m m t h rough t h e facet join t ), w id en ing of t h e an ter ior d isc sp ace, t ran slat ion or rotat ion of th e ver tebral bodies, kyph ot ic align m en t of t h e cer vical sp in e, or h igh sign al in ten sit y seen h orizon tally th rough a disc involving th e n ucleus an d an ulus on T2 or STIR sagit tal MRI, an d is assign ed t w o poin ts. An in d eter m in ate inju r y exist s w h en rad iograp h ic d isr u pt ion of t h e DLC is n ot obviou s, bu t a hyp erin ten se sign al is fou n d t h rough eith er th e disc or th e posterior ligam en t s on MRI; th is is assign ed on e poin t . Fin ally, n eu rologic st at u s is assessed, an d zero to fou r p oin ts are assign ed. Injuries scored above fou r sh ou ld be t reated surgically, an d n on operat ive t reatm en t can be recom m en ded for t h ose scoring below four. Inju ries scoring equal to 4 can be m an aged eith er operat ively or con ser vat ively. In an ter ior colu m n inju r ies (im p act ion , sp lit , or bu rst ), t h e in tegr it y of t h e DLC m u st be carefu lly evalu ated before deciding bet w een th e t reat m en t opt ion s. On ly on e st u dy h as sp eci cally com pared th e resu lt s of n on op erat ive an d an terior op erat ive t reat m en t of cer vical spin e com p ression injuries.18 Sixt y-n in e con secut ive pat ien ts w ith both cer vical bu rst an d exion teardrop fract ures w ere review ed ret rospect ively. Th ir t yfou r w ere t reated w ith sku ll t ract ion or h alo vest, and 35 w ith anterior decom pression, bon e graft ing, an d plate xat ion . Surgically t reated p at ien ts had sign i can tly bet ter n eu rologic recover y, and h ad less n arrow ing of th e sp in al can al an d kyph ot ic deform it y at th e en d of th e follow -u p p eriod . Th ese resu lt s sh ou ld be carefully analyzed, because no distinction w as m ade bet w een th e t w o fract u re t ypes or bet w een neurologically intact and injured patients. Moreover, th e st u dy w as perform ed before th e SLIC system w as in use, an d so th e in tegrit y of th e DLC w as n ot reported.

Compression (AO Type-A Injuries)

Nonoperative Treatment Becau se A1 an d A2 t yp e fract u res are u n com m on , t h ere is n o st u dy com p ar in g su rgical versu s con ser vat ive t reat m en t in th ese speci c t ypes of inju ries. Neverth eless, th ey are in h eren tly st able lesion s th at h ave a low SLIC score, an d a st rong recom m en dat ion can be m ade for n on op erat ive m an agem en t in n eu rologically in tact p at ien ts. Th e associat ion of in tersp in ou s space w idening, vertebral sublu xation, and loss of cer vical lordosis in dicates a possible ligam en tou s disru pt ion , an d th ese pat ien t s requ ire close follow -u p, as th ese inju ries m ay disp lace later on . Pin cer-t ype fract u res (A2.3) w ith ou t disru pt ion of th e DLC sh ou ld u n dergo in it ial nonoperative m an agem ent, and sim ilarly m any burst fract u res w ith out injur y to th e DLC can be t reated n on su rgically. Th e use of braces or a h alo vest im m obilizes th e sp in e d u r ing h ealin g, m ain t ain in g sp in al align m en t , an d con t rols p ain by rest r ict ing m ovem en t . St able im p act ion or split fract u res can be t reated w it h a cer vical collar. Bu rst fract ures m ay n eed a h ard cer vical th oracic orth osis (CTO) or a h alo vest , esp ecially in th ose cases w h ere p rior redu ct ion w as p erform ed. Frequ en t radiograp h s m u st be obt ain ed to closely m on itor th e redu ct ion an d align m en t u n t il un ion is ach ieved, w h ich can t ake u p to 12 w eeks. Dyn am ic exion -exten sion radiograph s sh ou ld be t aken at th e en d of th e im m obilizat ion period to detect any residu al dynam ic instabilit y. Inabilit y to m aintain alignm ent and reduction m ay predispose to late pain or de n ovo n eurologic de cits, an d m ay w arran t su rgical st abilizat ion . Physical th erapy is u sually prescribed at th e en d of t reat m en t . Non op erat ive t reat m en t can resu lt in signi can t com plications.19 Cervical orthoses m ay be associated w ith discom for t , in adequ ate im m obilization, m uscle atrophy, psychological depen den ce, pain , skin breakdow n , an d w orsen ed p ulm on ar y fu n ct ion . Opt im ized t an d adequate, soft m aterials at skin contact sites can enh ance com fort and com pliance w ith treat m ent. Halo vest use can sign i can tly im pair daily life an d resu lt in m ultiple com plicat ion s, su ch as pin loosening, penetration and infection, pres-

su re sores, su bdu ral abscess, n er ve palsies, an d fract u re overdist ract ion . Th e u se of a h alo vest is relat ively con t rain dicated in th e presen ce of severe cach exia, in pat ien t s w ith severe deform it y (an kylosing spon dylit is or scoliosis), in m orbid obese pat ien ts, in th e elderly, an d in n on com p lian t or tet rap legic pat ien ts.

Surgical Treatment Accepted in dicat ion s for surger y in an terior colu m n com p ression inju r ies are as follow s: (1) neurologic de cit; (2) disruption of the DLC; an d (3) in abilit y to proceed w ith con ser vat ive t reat m en t (e.g., fract u red skull precluding h alo applicat ion ) or to m ain tain sat isfactor y reduct ion an d align m en t. As m en t ion ed above, in th e on ly st u dy available th at com pared n on operat ive m an agem en t w ith anterior operative m anagem ent of cervical spin e com pression injuries, th e resu lt s favored su rgical t reat m en t .18 How ever, n o d e n it ive in d icat ion s can be draw n from t h is st u dy, becau se resu lt s w ere rep or ted w it h ou t clear dist in ct ion bet w een neu rologically in t act an d inju red pat ien ts, an d th e DLC w as n ot speci cally assessed. No class I or II eviden ce addressing th e surgical approach in com pression an d burst fract u res is available, an d on ly eigh t class III st u dies were identi ed.20–27 Reports include m ixed fract u re pat tern s an d sm all n um bers of pat ien ts, an d m ost w ere p erform ed before con tem p orar y classi cat ion system s w ere in use. Brod ke et al20 com p ared t h e resu lt s of an terior versu s posterior surger y in 57 pat ien ts w ith un stable cer vical spin e lesion s an d associated spin al cord injuries, but on ly seven h ad isolated bu rst fract ures (fou r in th e an terior group an d th ree in th e posterior grou p). Tw elve pat ien ts h ad a burst fract u re associated w ith a clear dist ract ion injur y. Neu rologic im provem en t an d a h igh fu sion rate w ere obser ved in each grou p , w it h n o sign i can t d i eren ces; h ow ever, in th e an terior group, 70% im proved at least on e Fran kel grade, com p ared w ith 57% in th e posterior grou p. Toh et al21 review ed th e su rgical t reat m en t of 31 pat ien t s w ith burst or exion dist ract ion

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Chapter 8 injur y in th e m iddle an d low er cer vical sp in e w h o w ere t reated w it h an ter ior in st r u m en t at ion , p osterior in st r u m en t at ion , or bot h . Becau se all bu rst fract u res w ere ap p roach ed an teriorly, a com parison of t reat m en ts for th is speci c t ype of inju r y is n ot possible. Neverth eless, an terior d ecom p ression an d fu sion restored th e sp in al can al diam eter sign i can tly bet ter, an d im proved n eurologic fun ct ion in n in e of 24 pat ien ts, w h ereas n o im provem en t w as obser ved in th ose t reated p osteriorly. Com plicat ion s an d overall align m en t w ere evalu ated in a st u dy of 29 pat ien ts w ith an u n st able cer vical ver tebral fract u re or a fract u redislocat ion t reated w ith posterior sp in e fu sion and lateral m ass instrum entation.22 There w ere seven ver t ical com pression bu rst fract u res. A m ean loss of 2 degrees in sagit t al align m en t at th e n al follow -u p exam in at ion w as obser ved, w ith n o di eren ces bet w een th e various t ypes of inju r y pat tern s. Six com plicat ion s w ere repor ted : fou r w ou n d in fect ion s, on e h ardw are failu re, an d on e C5 n er ve root inju r y. Lam biris et al23 p erform ed a ret rospect ive st u dy of pat ien ts w ith di eren t su ba xial cer vical sp in al inju r ies to su m m ar ize t h e com p licat ion s of in st ru m en ted an terior or p osterior stabilizat ion of cer vical spin e injuries. No differen ce in th e com plicat ion rate bet w een an terior (74 pat ien t s) an d posterior (23 pat ien t s) xat ion w as obser ved. Neverth eless, n early all eigh t com p ression w edge inju ries an d 13 burst fract ures w ere t reated an teriorly, as p rop osed by th eir t reat m en t algorith m . Th e use of pedicle screw in st rum en tat ion w as also evalu ated in a ret rospect ive series of 144 un stable cer vical injur y pat ients.24 An overall low rate of instrum entation-related and other com p licat ion s w as obser ved w ith th is su rgical tech n ique. Kasim at is et al25 rep orted on 74 pat ien t s w ith un stable low er cer vical spine injuries w ho u n d er w en t an ter ior su rger y over a 15-year p eriod. Th ere w ere seven com pression w edge an d 13 bu rst fract ures, an d th e resu lt s w ere n ot st rat i ed according to inju r y t yp e. Overall, 90% of in com p lete lesion s im proved, th ere w as n o n eu rologic deteriorat ion an d n o in st ru m en t at ion failu re, an d all fu sion s h ealed.

Belirgen et al26 ret rospect ively an alyzed th e result s of an terior versus posterior su rger y in a group of 33 pat ien t s w ith reducible cer vical su baxial fract u res. Th ere w ere on ly fou r com p ression -t yp e inju r ies, an d t h e resu lt s w ere n ot rep or ted sp eci cally for t h is su bgrou p . Posterior su rger y w as associated w ith longer operat ive t im es and m ore blood loss, an d en tailed a larger n um ber of fused segm en t s. Th e auth ors con cluded th at an terior in st rum en tat ion w ith in terbody graft ing can be th e in it ial ch oice of t reat m en t for st abilizat ion of th ese pat ien ts, an d th at posterior su rger y is in dicated if radiograph s sh ow failu re after an terior in st ru m en tat ion . Th e Spin e Traum a St udy Group developed an eviden ce-based algor it h m for su rgical ap proach es to th e m an agem en t of su baxial cer vical sp in e inju ries based on a system at ic review of th e literat ure, exper t opin ion , an d an t icipated p at ien t preferen ces.27 Th e algorith m is d er ived from t h e SLIC system an d ad d resses bot h t h e in d icat ion for su rger y as w ell as t h e su rgical ap p roach . Com p ression an d bu rst fract u res w ith ou t disru pt ion of th e DLC are aw arded on e or t w o poin ts an d com m on ly zero for an in t act DLC. Hen ce, th e n eu rologic st at u s an d th e p resen ce of residu al com p ression of th e spin al cord are th e st rongest determ in an ts of treatm en t. With com plete or incom plete neurologic inju r y, th e SLIC system w ill add t w o to fou r p oin t s to t h e m or p h ology score, lead in g to an overall score of fou r to six. Su rger y is p referred w ith scores of ve or above. Scores of fou r sh ou ld be decided case by case, dep en ding on th e su rgeon’s preferen ces an d exp erien ce, an d th e pat ien t’s factors an d expect at ion s. Th e authors recom m ended anterior decom pression an d st abilizat ion for su rgically t reated bu rst fract u res. From th e aforem en t ion ed st u dies w e can con clu de th at an terior decom pression an d stabilizat ion is favored w h en surger y is in dicated for bu rst fract u res. Pat ien t posit ion ing is safe an d st raigh tfor w ard for an an terior ap proach , an d su rgical dissect ion is perform ed w ith m in im al soft t issu e dam age. Becau se spin al cord com pression is ventral, optim al decom pression of n eu ral elem en t s can be don e u n d er direct

Compression (AO Type-A Injuries) visualization. Corticocancellous autogenous strut graft , allograft , or a cage can be in serted an d su p plem en ted by a p late (Fig. 8.1d,e ). Because of it s ready availabilit y, low cost , an d predictable fusion rate, w e usu ally prefer iliac bon e autograft . After su rger y, a cer vical collar can be w orn , especially in m ore un stable cases, but th ere are n o st rict in dicat ion s on eith er it s u se or th e du rat ion of im m obilizat ion . Im paction wedge and split fractures w ith surgical indicat ion can be stabilized by anterior or posterior xat ion . Posterior m on osegm en tal fu sion w ith lateral m ass screw s is an easy, reliable, an d biom ech an ically valid surger y for th e t reat m en t of th ese inju ries. How ever, w e p refer an terior stabilizat ion . A w edge-sh aped graft is in serted an d a variable-angle screw p late is ap plied to t ake p u rch ase in th e in t act low er p ort ion of th e ver tebral body. With con tem p orar y im plan t s an d a correctly fash ion ed graft , th e risk of su bsiden ce is p robably m in im al.

■ Treatment

Recommendations Neurologically Intact Patients • A-t ype fract ures w ith out disrupt ion of th e DLC can be t reated n on op erat ively w it h a collar, a h ard cer vical th oracic or th osis, or a h alo vest , depen ding on th e severit y of th e inju r y. • Im pact ion an d split fract ures w ith disrup t ion of t h e DLC can be t reated con ser vat ively, bu t careful, frequ en t m on itoring of redu ct ion an d align m en t is n eeded, as th ese inju ries m ay displace. • Burst fract ures w ith disrupt ion of th e DLC can be t reated eith er con ser vat ively or surgically. Su rgical t reat m en t m ay be preferred becau se of th e risk of displacem en t , n eu rologic com p rom ise, late p ain , an d th e m in im al risks of an terior st abilizat ion . How ever, becau se th e long-term m orbidit y of losing t w o m obile levels m ay be sign i can t , st rong con siderat ion m ust be given to con ser vat ive t reat m en t , especially in th e you ng pat ien t .

• In abilit y to ach ieve or m ain t ain correct red uct ion an d align m en t is an in dicat ion for su rger y.

Neurologically Injured Patients • Neu rologic injur y w arran ts im m ediate red uct ion an d in d irect decom pression using sku ll tongs or h alo t ract ion , par t icu larly if su rger y is delayed. • Surger y is in dicated, especially in in com plete spinal cord lesions and continuous cord com pression , by direct an terior decom pression , in terbody graft ing, an d plat ing.

■ Chapter Summary A-t ype com pression fract ures (im pact ion , split an d burst fract ures) ch aracterist ically result from axial com pression , an d com m on ly h ave a reduced ver tebral body h eigh t an d an in t act p oster ior ligam en tou s com p lex. Con t rar y to w h at h ap p en s in th e t h oracolu m bar sp in e, w h ere com p ression fract u res are t h e m ost com m on t yp e, in th e cer vical spin e th ey are relat ively rare an d accou n t for less th an 15% of all injuries. Typically, th ese injuries occu r in young m en , an d falls an d spor t s act ivit ies are th e m ain cau ses of inju r y. More th an h alf of cer vical burst fract ures can be associated w ith eith er com plete or in com plete spin al cord injur y. A-t yp e fract u res, w ith ou t n eu rologic dam age can be t reated n on op erat ively w ith a collar, a h ard cer vical th oracic or th osis, or a h alo vest , depen ding on th e severit y of th e injur y, as long as th e DLC h as been th orough ly evaluated. Disru pt ion of th e DLC is n ot an absolute operat ive in dicat ion , as com p ression an d sp lit fract u res w ith disrupt ion of th e DLC can st ill be t reated conservatively. Im portantly, patients w ith a possible DLC disru pt ion requ ire frequ en t m on itoring, as th ese injuries m ay displace. Burst fract ures in n eurologically in t act patients w ith disruption of the DLC can be treated eith er con ser vat ively or surgically. Becau se of th e risk of disp lacem en t , n eu rologic com p ro-

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Chapter 8 m ise, an d late p ain , an d con sid er in g safet y an d e cacy of an terior stabilizat ion , surgical t reat m en t m ay be p referred. How ever, st rong con siderat ion m u st be given to con ser vat ive t reat m en t , becau se th e m orbidit y of losing t w o m obile levels m ay be sign i can t in th e long term , especially in a young pat ien t . Neurologic injury warrants im m ediate closed or open redu ct ion , an d surger y is in dicated for all pat ien ts w ith a persisten t n eurologic de cit . Ou r p referred app roach is a direct an terior decom p ression , in terbody graft ing, an d p lat ing. In ad d it ion to n eu rologic inju r ies, t h e failu re to ach ieve or m ain tain correct reduct ion an d align m en t is also an in dicat ion for surger y.

Pearls A-t ype compression fractures represent less than 15% of all subaxial spine injuries. Axial compressive cervical spine fractures are t ypically observed in m en in the third and fourth decades of life, and falls and sports activities are the m ain causes of injury. Burst fractures usually a ect the lower cervical spine (C6 or C7), and neurologic injuries are present in m ore than half of the patients. Skull traction can be perform ed for indirect neural decompression in an emergent set ting, even if surgical treatm ent has already been decided, as this will enable anatomic alignment and an easier

surgery, especially in those patients where coexisting injuries delay de nitive intervention. Most A-t ype fractures in neurologically intact patients can be treated nonoperatively, provided that DLC disruption has been appropriately ruled out. If feasible and adequate, conservative treatment of burst fractures with disruption of the DLC in neurologically intact patients can be used, considering the long-term m orbidit y of losing t wo mobile levels. Anterior decompression, interbody grafting, and plate stabilization are the preferred treatm ent in neurologically injured patients. Pitfalls A high level of suspicion is necessary to identify ligam entous disruption in compression injuries, as they can be spontaneously reduced in supine lateral X-rays, and exion-extension images under uoroscopic control or advanced im aging m odalities may be indicated. Patients with burst injuries should be kept im mobilized with a hard cervical collar, with the spine in neutral position, because either extension or exion has been associated with an increase in the occlusion of the spinal canal. If conservative treatm ent is undertaken, frequent radiographs should be obtained to closely monitor the reduction and alignm ent until union is achieved. Loss of reduction or alignment m ay warrant surgical stabilization.

Refere nces Five Must-Read Refe rences 1. Goldberg W, Mueller C, Panacek E, Tigges S, Ho m an JR, Mow er W R; NEXUS Group. Dist ribut ion an d pattern s of blun t t raum at ic cer vical spin e injur y. An n Em erg Med 2001;38:17–21 Pu bMed 2. Low er y DW, Wald MM, Brow n e BJ, Tigges S, Ho m an JR, Mow er W R; NEXUS Group. Ep idem iology of cervical spin e injur y vict im s. An n Em erg Med 2001;38: 12–16 PubMed 3. Blauth MKA, Mair G, Schm id R, Reinhold M, Rieger M. Classi cation of injuries of the subaxial cervical spine. In : Aebi M, Arlet V, Webb JK, eds. AOSpin e Manu al: AOSpine International. New York: Thiem e; 2007:21–38 4. Vaccaro AR, Hulbert RJ, Patel AA, et al; Spin e Traum a St u dy Grou p. Th e su baxial cer vical sp in e inju r y classi cat ion system : a n ovel approach to recogn ize th e im por t an ce of m orph ology, n eurology, an d in tegrit y of th e disco-ligam en tous com plex. Spin e 2007;32: 2365–2374 Pu bMed

5. Magerl F, Aebi M, Gert zbein SD, Harm s J, Nazarian S. A com prehen sive classi cat ion of th oracic an d lum bar inju ries. Eur Spin e J 1994;3:184–201 Pu bMed 6. Allen BL Jr, Ferguson RL, Leh m ann TR, O’Brien RP. A m ech an ist ic classi cat ion of closed, in direct fract ures an d dislocat ion s of th e low er cer vical spin e. Spin e 1982;7:1–27 PubMed 7. An derson PA, Moore TA, Davis KW, et al; Spin al Traum a St udy Group. Cer vical spin e inju r y severit y score. Assessm en t of reliabilit y. J Bon e Join t Su rg Am 2007;89:1057–1065 Pu bMed 8. Ben sch FV, Kiu r u MJ, Koivikko MP, Koskin en SK. Sp in e fract u res in fallin g accid en t s: an alysis of m u lt idetector CT n d ings. Eur Radiol 2004;14:618– 624 Pu bMed 9. Ben sch FV, Koivikko MP, Kiuru MJ, Koskin en SK. Th e inciden ce an d dist ribut ion of burst fract ures. Em erg Radiol 2006;12:124–129 PubMed

Compression (AO Type-A Injuries) 10. Blackm ore CC, Man n FA, Wilson AJ. Helical CT in th e prim ar y t rau m a evaluat ion of th e cer vical spin e: an eviden ce-based approach . Skelet al Radiol 2000;29: 632–639 PubMed 11. Wyn daele M, Wyn daele JJ. In ciden ce, prevalen ce an d epidem iology of spin al cord injur y: w h at learn s a w orldw ide literat u re su r vey? Spinal Cord 2006;44: 523–529 PubMed 12. Webb JK, Brough ton RB, McSw een ey T, Park W M. Hidden exion injur y of th e cer vical spin e. J Bon e Join t Surg Br 1976;58:322–327 Pu bMed 13. Carter JW, Mirza SK, Ten cer AF, Ch ing RP. Can al geom et r y ch anges associated w ith axial com pressive cer vical spine fract ure. Spine 2000;25:46–54 PubMed 14. Ch ing RP, Wat son NA, Carter JW, Ten cer AF. Th e e ect of post-injur y spin al posit ion on can al occlusion in a cer vical spin e burst fract ure m odel. Spin e 1997;22: 1710–1715 Pu bMed 15. Grant GA, Mirza SK, Ch ap m an JR, et al. Risk of early closed reduct ion in cer vical spin e sublu xat ion injuries. J Neurosurg 1999;90(1, Su ppl):13–18 Pu bMed 16. Kw on BK, Vaccaro AR, Grau er JN, Fish er CG, Dvorak MF. Subaxial cer vical spin e t raum a. J Am Acad Orth op Su rg 2006;14:78–89 Pu bMed 17. W h ite AA III, Joh n son RM, Panjabi MM, Sou th w ick WO. Biom ech an ical an alysis of clin ical st abilit y in th e cer vical sp in e. Clin Or th op Relat Res 1975;109: 85–96 Pu bMed 18. Koivikko MP, Myllyn en P, Karjalain en M, Vorn an en M, San t avir t a S. Con ser vat ive an d op erat ive t reatm en t in cer vical burst fract u res. Arch Or th op Traum a Su rg 2000;120:448–451 Pu bMed 19. Lauw er yn s P. Role of con ser vat ive t reat m en t of cervical sp in e inju r ies. Eu r Sp in e J 2010;19(Su p p l 1): S23–S26 PubMed

20. Brodke DS, An derson PA, New ell DW, Grady MS, Ch apm an JR. Com parison of an terior an d posterior approach es in cer vical spin al cord injuries. J Sp in al Disord Tech 2003;16:229–235 Pu bMed 21. Toh E, Nom ura T, Wat an abe M, Moch ida J. Surgical t reat m en t for inju ries of th e m iddle and low er cer vical spine. In t Orthop 2006;30:54–58 PubMed 22. Pateder DB, Carbon e JJ. Lateral m ass screw xat ion for cer vical spin e t rau m a: associated com plicat ion s an d e cacy in m ain t ain ing align m en t . Spin e J 2006; 6:40–43 Pu bMed 23. Lam biris E, Kasim at is GB, Tyllian akis M, Zouboulis P, Pan agiotop ou los E. Treat m en t of u n st able low er cervical spin e inju ries by an terior in st ru m en ted fu sion alon e. J Spinal Disord Tech 2008;21:500–507 PubMed 24. Yukaw a Y, Kato F, Ito K, et al. Placem en t an d com plicat ion s of cer vical pedicle screw s in 144 cer vical traum a patients using pedicle axis view techn iques by uoroscope. Eur Spine J 2009;18:1293–1299 PubMed 25. Kasim at is GB, Pan agiotopoulos E, Gliat is J, Tyllian akis M, Zouboulis P, Lam biris E. Com plicat ion s of an terior surger y in cer vical spin e t rau m a: an overview. Clin Neurol Neurosurg 2009;111:18–27 PubMed 26. Belirgen M, Dlouhy BJ, Grossbach AJ, Torn er JC, Hitch on PW. Su rgical opt ion s in th e t reat m en t of sub axial cer vical fract ures: a ret rospect ive coh or t st udy. Clin Neurol Neurosurg 2013;115:1420–1428 PubMed 27. Dvorak MF, Fish er CG, Feh lings MG, et al. Th e su rgical ap p roach to su baxial cer vical sp in e inju ries: an eviden ce-based algorith m based on th e SLIC classi cat ion system . Spin e 2007;32:2620–2629 PubMed

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9 Subaxial Cervical Spine Injuries: Distraction (AO Type -B Injuries) William A. Robinson, Kevin P. McCarthy, Alexander R. Vaccaro, and C. Chambliss Harrod

■ Introduction Of t h e 150,000 cer vical sp in e inju r ies t h at occu r an n u ally in Nor t h Am er ica, 7 to 8% are associated w ith spin al cord inju ries, w h ich are m ore frequen t am ong Cau casian s, th e elderly, an d m ales.1,2 Su baxial (C3–C7) inju ries accou n t for 75%of spin al cord inju ries. Th e AO (Arbeit sgem ein sch aft fü r Osteosyn th esefragen ) classies subaxial cer vical fract ures in to com pression (t yp e A), dist ract ion (t ype B), an d rot at ion (t yp e C) injuries. Dist ract ion inju ries t ypically occu r from excessive exion (m ore com m on ) or exten sion m ech an ism s an d m ay rep resen t 25 to 30% of su baxial inju ries an d are m ost com m on at C5–C6 ( exion ) an d C6–C7 (exten sion ).3 Flexion - dist ract ion inju ries (FDIs) often en t ail com pression of th e an terior colum n an d d ist ract ion of th e posterior elem en ts, w h ereas exten sion -dist ract ion injuries (EDIs) com press p oster iorly an d d ist ract t h e an ter ior colu m n . Pat ien t s w it h an kylosing sp in al d isord ers (ASDs) [an kylosing sp on dylit is (AS) an d di u se id iopath ic skeletal hyp erostosis (DISH)] h ave u n ique diseases th at are often associated w ith m issed fract ures, in creased n eurologic injuries, ep idu ral h em atom as, an d poorer ou tcom es.4 Treat m en t depen ds on t im ely in it ial evalu at ion an d diagn osis of sp in al an d n on sp in al in juries, u se of diagn ost ic st u dies, an d in tegrat ion of fract ure m orp h ology, spin al st abilit y, n eu rologic stat u s, an d com orbidit ies. Classi cat ion of subaxial fract u res h as been con t roversial,

bu t th e goal is to est ablish a clin ically relevan t , reliable, progn ost ic system th at guides t reatm en t . Neu rologic st at u s (as d eter m in ed by th e Am er ican Sp in al Inju r y Associat ion [ASIA] scale), radiographs, com puted tom ography (CT), and m agnetic resonance im aging (MRI) are vital diagn ost ic tools to accu rately classify su baxial fract ures.5–7 Closed reduct ion w ith cran iocervical t ract ion is often perform ed p rom ptly, an d operat ive in ter ven t ion is n ecessar y to m ain tain redu ct ion an d st abilize inju red segm en ts w h ile protect ing or decom pressing th e n eural elem en ts. Th is ch apter review s th e m an agem en t of cer vical subaxial exion an d exten sion dist ract ion inju ries, focu sing on evalu at ion , im aging, an d eviden ce-based t reat m en t recom m en dat ion s regarding closed redu ct ion , n on op erat ive versu s op erat ive t reat m en t , t h e select ion of t h e opt im al app roach , an d sp ecial issu es in th e m an agem ent of ASD pat ien t s.

■ Evidence -Based Medicine :

Literature and Clinical Recommendations Level of eviden ce rat ings h ave been establish ed using criteria set by the Journal of Bone and Joint Surgery, Am erican Volum e.8 Ideally, eviden cebased protocols are developed using th e overall body of evidence w ith respect to each clinical

Distraction (AO Type-B Injuries) qu est ion an d t h e p recept s ou t lin ed by t h e Grades of Recom m en dat ion Assessm en t , Developm en t an d Evalu at ion (GRADE) Working Grou p 9 an d recom m en dat ion s m ad e by t h e Agen cy for Healt h care Research an d Qu alit y (AHRQ).10 Th e st rength of eviden ce grade for each outcom e or clin ical quest ion , w h ich is categorized as h igh , m oderate, low, or in su cien t , is described in fu r th er det ail in Spine system at ic review s th at h ave proven in st ru m en t al in review ing con t roversial sp in e top ics.11 In con tem porar y system at ic review st udy grou ps, clin ical recom m en dat ion s or con sen su s st atem en t s are often m ade th rough a m odi ed Delph i app roach by ap plying t h e GRADE/ AHRQ criteria th at im par t a deliberate dist in ct ion bet w een th e st rength of th e eviden ce (i.e., h igh , m oderate, low, or in su cien t) an d th e st rength of t h e recom m en dat ion . W h en app ropriate, recom m en dat ion s or statem en ts “for” or “again st” are given “st rong” or “w eak” design ation s based on th e qualit y of th e eviden ce, th e balan ce of ben e t s/h arm s, an d valu es an d patien t preferen ces.11 Typ ically, t h ese system at ic review s lim it st udy in clu sion to level I, II, an d III st u dies (p rospect ive ran dom ized con t rolled t rials an d coh ort st u dies w ith exclusion of case series, case reports, cadaver studies, and studies w ith fewer t h an 10 cases). Un for t u n ately, t h e literat u re regard ing cer vical d ist ract ion inju r ies is essen t ially level IV or V (case series, case repor ts, cadaver st u d ies, an d st u dies w ith few er th an 10 cases); th erefore, w e w ill h igh ligh t im por tan t papers th at are th ough t to in uen ce decision m aking an d to guide t reat m en t .

Classif cations and Morphology Dist ract ion injuries occu r in exion or exten sion pat terns. Hyperextension injuries t ypically occu r in pat ien ts w ith st i spin es such as th e elderly (spon dylosis) or in patients w ith DISH or AS. Failu re of th e an terior an d m iddle colu m n s (EDI st age I) occurs w ith or w ith ou t posterior elem en t disru pt ion an d possible su blu xat ion / dislocat ion (stage II) w ith cen t ral cord syn drom es often associated. FDIs a ect p rim arily posterior elem en ts, w ith a broad array of inju ries ranging from facet su blu xat ion (st age I), to

unilateral perch/dislocation (stage II), to stage III (≤ 50%) and stage IV (> 50%) bilateral dislocation w ith anterior cord syndrom es often associated. Th ere are m u lt iple classi cat ion sch em es for subaxial cer vical spin e inju ries. Th e lack of a un iform ly accepted classi cat ion system h as greatly h in dered both h igh -qu alit y research an d e or ts to establish opt im al eviden ce-based t reat m en t algorith m s. Th e evid en ce is lim ited to ret rospect ive review s regarding dist ract ion injuries. Earlier classi cations such as the AllenFergu son an d th e AO focu s on m ech an ism of injur y (dist ract ion , com pression , rotat ion ) versus fracture m orphology (com pression, distract ion , rot at ion ), m aking it di cu lt to in corporate spin al st abilit y an d n eurologic st at u s an d to determ in e th e ap propriate t reat m en t . Cer vical spin e in stabilit y is best de n ed, by W h ite an d Panjabi,12 as the loss of the abilit y of the spine to m aintain, under physiological loads, its pattern of displacem en t so th at th ere is n o in it ial or add it ion al neu rologic de cit , n o m ajor deform it y, an d n o in cap acit at ing p ain . Su baxial in st abilit y h as been ch aracterized by 3.5-m m h orizon t al d isplacem en t or 11 degrees of adjacent vertebrae angulat ion on lateral radiograph s. The Suba xial Cer vical Sp in e Inju r y Classi cat ion (SLIC) in tegrates fract u re m orp h ology (com pression , distraction, rotation), the diskoligam entous com p lex (DLC) in tegrit y (st abilit y), an d n eu rologic stat us (in tact , root , com plete, or in com plete in ju ries).13 It h as been sh ow n to be reliable an d valid, an d to gu ide t reat m en t ap p rop riately 14,15 (Table 9.1). All th ree ch aracterist ics h ave su b group s, assign ing poin t s to guide t reat m en t; pat ien ts w ith scores ≤ 3 are t reated n on op erat ively, an d pat ien ts w ith scores ≥ 5 are t reated operat ively. For p at ien t s w ith a score of 4, th e t reat m en t is gu ided by th e su rgeon’s exp erien ce an d p referen ce as w ell as th e pat ien t’s com orbidit ies an d oth er injuries.

Evaluation Th e evalu at ion of a pat ien t w ith sp in e t rau m a sh ou ld follow th e Advan ced Trau m a Life Su p por t (ATLS) protocol, w ith im m ediate at ten t ion to a life-th reaten ing air w ay com prom ise, ven t ilat ion (su ch as p n eu m oth orax), an d cardiovascu lar inju r y. Su bsequ en t id en t i cat ion of

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Subaxial Cervical Spine Injury Classif cation (SLIC) System Finding Points

Morphology No abnormalit y Compression Burst Distraction (e.g., facet perch, hyperextension)    Rotation/translation  (e.g.,  facet  dislocation,  unstable  teardrop,  or  advanced  staged exion  compression injury) Diskoligamentous complex (DLC) Intact Indeterminate (e.g., isolated interspinous widening, MRI signal change only) Disrupted (e.g., widening of disk space, facet perch, or dislocation) Neurologic status Intact Root injury Complete cord injury Incomplete cord injury  Continuous  cord  compression  in  set ting  of  neurologic  de cit  (neurologic  m odi er)

0 1 +1 = 2 3 4

0 1 2 0 1 2 3 +1

Source:  Adapted  from   Vaccaro  AR,  Hulbert  RJ,  Patel  AA,  et  al.  The  subaxial  cervical  spine  injury  classi cation  system.  A  novel approach to recognize the importance of morphology, neurology, and integrit y of the disco-ligam entous complex. Spine 2007;32:2365–2374

add it ion al inju r ies, p ar t icu larly n eu rologic or spin al inju r y, sh ou ld be n oted. A focu sed h istor y sh ould in clu de iden t ifying th e t raum a m ech an ism , determ in ing th e locat ion of pain , an d n ot ing th e presen ce of urin ar y in con t in en ce, spon dyloar th ropathy (AS or DISH), or a pacem aker or oth er m etallic foreign body th at w ou ld con t rain dicate th e u se of MRI. Th e h istor y sh ould also n ote if th e pat ien t h ad u n dergon e earlier sp in e su rger y. Pat ien ts w ith ASD often h ave m in im ally displaced, n on displaced, or m issed fract u re(s) th at are often h igh ly un st able (long lever arm s from m u lt ifu sed segm en t s) as a resu lt of an exten sion -d ist ract ion m ech an ism . Su ch a fract u re often is m issed in th e in it ial clin ical an d radiograp h ic evalu at ion , bu t in st abilit y, n eu rologic com p ression , an d sym ptom at ic ep idu ral h em atom a (esp ecially in a pat ien t w ith coagulopathy) can lead to h igh rates of n eurologic declin e. Th e physical exam in at ion begin s w ith com plete exp osu re of th e pat ien t’s sp in e u sing a logroll tech n iqu e. Th e dorsal sp in e is exam in ed for ecchym osis, in durat ion , or any oth er in dicators of sign i can t spin e in st abilit y. Com p lete n eu rologic exam in at ion involves m otor m an u al st rength test ing, sen sor y pinp rick an d ligh t

tou ch evalu at ion , an d re exes w it h a carefu l rectal exam in at ion (for volun t ar y rect al ton e, bulbocavern osu s re ex, an d an al w in k re ex) to assess sacral n er ve root fun ct ion . Th e ASIA scale is th e preferred n eu rologic exam in at ion tool, as it provides a m eth od to ch aracterize any residual fun ct ion below th e level of a spin al cord inju r y (SCI), w h ich is de n ed as th e m ost cau dal level w ith n orm al m otor an d sen sor y fu n ct ion . Th e m ost im p or t an t p redictor of a favorable n eu rologic ou tcom e is reten t ion of sacral (S4-S5) sen sat ion 72 h ours to 1 w eek after th e injur y. In tact sacral p inprick sen sat ion suggest s a favorable p rogn osis for recover y of bladder fu n ct ion . In con t rast , p riapism cau sed by loss of sym path et ic ton e w ith u n regu lated parasym path et ic inp ut suggest s a com p lete SCI. Neu rologic st at u s can be u n cer t ain in polyt raum a pat ien t s w h o are in t ubated, ob t u n ded, or u n able to follow com m an ds. Serial n eu rologic exam s are m an dator y, w ith docum en t at ion of th e n eu rologic exam in at ion as soon as possible. Com plete disru pt ion of n eurologic fun ct ion an d n eural im pulse t ran sm ission in th e torso and extrem ities can cause accid paralysis after SCI or can occur transiently during spinal shock.

Distraction (AO Type-B Injuries) Sp in al sh ock en ds w ith th e ret u rn of t h e bu lbocavern osu s re ex, w h ich in dicates th at th e arc bet w een th e pelvic a eren t n er ves an d sacral cord e eren t n er ves is on ce again fu n ct ion ing. Hem odyn am ic stat u s sh ou ld be carefu lly assessed to di eren t iate n eu rogen ic from hyp ovolem ic sh ock. To t reat n eurogen ic sh ock an d m ain t ain m ean ar terial pressu re above 85 m m Hg, volu m e resu scit at ion is follow ed by th e u se of vasopressors an d ch ron ot rop ic agen t s. Th e use of cor t icosteroids for a closed acute t rau m at ic SCI is con t roversial. High rates of m edical com plicat ion s, th e lack of con sisten t eviden ce, an d a record of in con sisten t n eurologic recover y h ave lim ited th e abilit y to form u late gu idelin es for th e u se of cor t icosteroids. Additionally, elderly patients w ith m ultiple com orbidit ies, m orbidly obese p at ien t s, revision cases, p olyt rau m a pat ien t s, an d p at ien t s w ith su bopt im al bon e qu alit y create m ore ch allenging su rgical environ m en t s. Pat ien ts w ith SCIs m u st be p rom ptly iden t i ed to decom press an d realign spin al elem en ts w ith preven t ion of secon dar y SCI du e to isch em ia. Flexion an d exten sion d ist ract ion inju r ies are opt im ally m an aged by exp er ien ced sp in al su rgeon s w h o are qu ali ed to p er for m m u lt ip le xat ion tech n iqu es an d bailou t st rategies. In addit ion , opt im al m an agem en t requires facilit ies w ith th e ap prop riate su pport st a t rain ed in t rau m a su rger y, an esth esia, n eu rom on itoring, an d in ter ven t ion al n eu roradiology, an d th at h ave an in ten sive care u n it (ICU) w h ose sta is experien ced in h an dling th ese t ypes of cases.

as injuries can often be m issed u sing on ly rad iograp h s. CT an d MRI are invalu able in id en t ifying an d u n d erst an d ing osseou s fract u re pat tern s, DLC an d p osterior ligam en tou s com plex (PLC) in tegrit y, degree an d locat ion of n eurologic com pression , an atom ic varian t s, h em atom a, an d prior surger y (Figs. 9.2, 9.3, 9.4) Com p lete radiograp h ic evalu at ion in ligh t of th e clin ical scen ario aids in form ulat ing a fu ll t reat m en t p lan . CT angiograp hy (CTA) or m agnetic resonance angiography (MRA) should be perform ed if a ver tebral arterial injur y is su sp ected an d in pat ien ts w ith C1 an d C2 fractures requiring surgical treatm ent, patients w ith fract u re dislocat ion s, an d p at ien t s w ith fract u res exten ding in to th e foram en t ran sversarium given th e h igh er rates of vertebral arter y injuries. CT m yelogram s are u sefu l in evaluating bony an d n eu ral an atom y w h en MRIs are con t rain dicated, an d can give excellen t det ail of n eu ral st ru ct ures.

Imaging Cer vical sp in e inju ries requ ire im m ediate evalu at ion an d coordin at ion w ith m ult iple ser vices to adequately follow ATLS protocols. On ce lifeth reaten ing inju ries are d iagn osed an d st abilized, fu r th er cer vical radiograp h ic evalu at ion can proceed. Tradit ionally, anteroposterior (AP), lateral (Fig. 9.1), op en -m ou th od on toid , an d sw im m er’s lateral rad iograp h ic view s w ere com m on ly ordered, bu t th ey h ave been largely rep laced by in it ial cross-sect ion al im aging via m u lt id etector h elical com p u ted tom ograp hy (CT) an d m agn et ic reson an ce im aging (MRI),

Fig. 9.1 Lateral cervical radiograph demonstrating a C5–C6 exion-distraction  injury  with  50%  anterolisthesis in a patient with bilateral facet dislocation.

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Fig. 9.3 Midsagit tal T2-weighted magnetic resonance imaging (MRI) demonstrating a C6–C7 exion-distraction  injury  with  anterior  longitudinal  ligament disruption, prevertebral edem a, disk, posterior longitudinal ligament, and posterior ligamentous complex disruption.

Fig. 9.2 Midsagit tal computed tom ography (CT) image  demonstrating  a  C6–C7 exion-distraction  injury with anterior subluxation, C7 superior end plate, and vertebral body fracture.

■ Flexion-Distraction Injuries Flexion -dist ract ion inju ries (FDIs) rep resen t severe inju ries of th e su baxial sp in e th at begin w ith th e PLC an d facet join t an d th en lead to an terior disk disrupt ion . Subsequen t an terior su blu xat ion of th e cran ial ver tebrae (t yp e I), w ith uncovering of the articular surfaces (naked facet sign on CT), progresses to un ilateral (t ype II) or bilateral (t ype III, 50%) dislocat ion , w ith > 50% (t ype IV) dislocat ion being th e last step. Many au t h ors suggest t h at p oster ior lon git u d in al ligam en t (PLL) an d disk disru pt ion are

Fig. 9.4 Midsagit tal CT reconstructed image in a patient with a C6–C7 extension-distraction injury in  a  patient  with  di use  idiopathic  skeletal  hyperostosis  (DISH)  with owing  ossi cation  of  m ore  than  four consecutive vertebrae dem onstrating anterior disk space widening, anterior column distraction, retropharyngeal widening, and hyperlordosis.

Distraction (AO Type-B Injuries) requ isite for dislocat ion .6 Radiograph s often dem onstrate variable facet or interspin ous process w idening, disk space narrow ing, facet fracture, sublu xat ion , or dislocat ion (Fig. 9.1). CT best dem on st rates th e osseou s an atom y an d fract ures, w h ereas MRI facilit ates assessm en t of blood, th e DLC (w ith sh or t tau inversion recover y [STIR] sequ en ce), an d n eu ral elem en t s (cord sign al ch ange on T1 or T2 sequ en ces) (Figs. 9.2 an d 9.3). Progressive ver tebral arterial occlu sion an d inju r y is related to in creasing degrees of in st abilit y (rot at ion , t ran slat ion , dist ract ion ) an d are best evalu ated w ith MRA or CTA. Due to th e h igh degree of ligam en tous inju r y, cer vical FDIs are am ong t h e m ost u n st able t rau m at ic con dit ion s, w ith n eu rologic inju r y ranging from 10 to 84%. Neu rological m an ifest at ion s in clu de Inju ries ranging from rad iculopathy (in 70% u n ilateral p erch ed facet s, stage II) to com plete SCI (up to 84%in bilateral dislocat ion , t yp e IV). Spin al cord con t u sion (ed em a) or h em or rh age is best seen on MRI. In pat ien t s w ith FDIs, it is often di cult to ob tain a closed reduct ion as w ell as m ain tain redu ct ion via n on operat ive m easu res (bedrest in t ract ion , h alo). Op erat ive in ter ven t ion is su perior to n on op erat ive t reat m en t u n less pat ien t s can n ot tolerate an operat ion .

Is Closed Reduction Safe? Closed redu ct ion for cer vical fract u re su blu xat ion s h as long been advocated in th e t reatm en t of su baxial FDIs du e to early redu ct ion an d decom p ression of t h e n eu ral elem en t s. Class III eviden ce (coh ort an d case series) su p por t s closed t ract ion redu ct ion in aw ake, aler t , n eu rologically in t act p at ien t s w h o can p ar t icip ate in ser ial n eu rologic exam in at ion s.16,17 How ever, n eu rologic w orsen ing can occu r in pat ien ts w ith bilateral facet fract u res or st age IV FDI due to cord st retch or exacerbat ion due to un recogn ized h ern iated n ucleus pulposus (HNP).18 How ever, Vaccaro et al,17 in a p rospect ive st u dy w it h MRI p re- an d p ost red u ct ion , dem on st rated n o n eu rologic w orsen in g, alth ough t h e in ciden ce of disk h ern iat ion s in creased after closed reduct ion s. Pre-reduct ion MRIs are recom m ended in patien ts w ho are unable to be exam ined or in obtunded patients.

MRI is recom m en ded after failed closed redu ct ion or p rior to su rgical in ter ven t ion . Based on m od erate evid en ce, a st rong recom m en dat ion for closed reduct ion is given for su baxial EDIs.

Is There a Role for Nonoperative Treatment in FDIs? Essen t ially th ere is n o m edical eviden ce to su p por t extern al im m obilizat ion for cer vical d ist ract ion inju ries. A ret rosp ect ive review (level IV evid en ce) of cer vical fract u re d islocat ion s suggest s th at extern al im m obilizat ion m ay be su cien t for < 1 m m disp lacem en t . In a prospect ive obser vat ion al st udy, Lin d u t ilized h alo im m obilizat ion in 31 FDIs w ith 10 un ilateral an d seven bilateral dislocat ion s, w h ich u lt im ately resulted in four of 17 late su blu xat ion s requiring late surger y.19 Beyer’s ret rospect ive com parat ive st udy sh ow ed better ou tcom es w ith su rger y in u n ilateral facetd islocat ion s.20 Delay in de n it ive t reat m en t an d in abilit y to obt ain an d m ain t ain a reduct ion are com m on in pat ien ts t reated extern ally. Ver y low qualit y eviden ce exists to suppor t n on operat ive m an agem en t of FDIs; th erefore, th ere is a w eak recom m en dat ion for n on op erat ive m an agem en t of su baxial FDIs w ith a h alo vest in h igh ly m on itored set t ings.

How to Approach: Anterior, Posterior, or Combined? Alth ough exten sive repor ts exist , th e qualit y of the publish ed clinical evidence is low. Traditionally, FDIs w ere treated w ith posterior w iring an d fusion after successful closed reduct ion s.21 Failu res w ere often related to fract u red p osterior elem en t s (spin ou s p rocess, lam in a, or facet fract u res). Biom ech an ically, lateral m ass xat ion is st ronger th an w iring tech n iqu es an d less dep en d en t on in t act p oster ior elem en t s. In irredu cible injuries, an terior or posterior redu ct ion w ith graft ing an d th en p osterior xat ion w ith or w ith ou t h alo im m obilizat ion can be ut ilized. In gen eral, expedien t closed reduct ion is recom m en ded for p at ien t s w ith cer vical FDIs as described above. MRI sh ou ld be ob tain ed prior to operat ive in ter ven t ion .17,18

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Chapter 9 If n o HNP exists, posterior open redu ct ion w ith or w ith out par t ial rem oval of th e caudal su p erior ar t icu lar process follow ed by lateral m ass xat ion an d fu sion is ap propriate, as p osterior xat ion w ith screw s an d rods h as been sh ow n to be biom ech an ically advan t ageou s com p ared w ith an terior xat ion . Late kyp h osis an d n eck pain can occur after posterior on ly xat ion an d su p p lem en t al an terior cer vical diskectom y an d fu sion (ACDF) m ay be con sidered. In a ran dom ized prospect ive st udy, 24 pat ien ts w ith FDI an d SCI w ere t reated w ith eith er ACDF (n = 6) or posterior in st rum en tat ion w ith fu sion (n = 18), yielding n o d i eren ce in com plicat ion s an d in n eu rologic or radiograp h ic ou tcom es.22 If an HNP is p resen t , th en an ter ior cer vical d iskectom y follow ed by an terior open reduct ion w ith eith er Caspar dist ract ion pin s or lam in ar sp readers is at tem pted (Fig. 9.5). If accept able red u ct ion is obt ain ed in st age I an d II injuries w ith out en d-plate or facet fract ures, ACDF enables perform ing singlelevel con st ru ct s an d m ay be p referable to p osterior approaches.22 If anterior reduction cannot be obt ain ed, th en posterior redu ct ion , lateral m ass xat ion , an d fusion follow ed by subsequ en t an ter ior graft ing an d in st r u m en t at ion is perform ed. In st age III or IV inju ries, th e PLL is d isru pted an d th e in st an t an eou s axis of rot at ion (IAR) sh ifts an teriorly. An terior-alon e xat ion is in adequate, as n o ten sion ban ds exists; h ow ever, posterior-only xation entails the risk of addit ional an terior procedures being required d ue to kyph osis an d late disk h ern iat ion . Overall, a st ron g recom m en dat ion for op erat ive over n on op erat ive (h alo, bed rest ) t reat m en t is given for cer vical FDIs. Approach select ion (an terior, posterior, or circu m feren t ial) is often dictated by su rgeon an d pat ien t p referen ce w h en closed redu ct ion can be ob t ain ed. In st age I or II inju ries w ith ou t associated HNPs, it is a strong recom m en dat ion th at p osterior-on ly t reat m en t is safe an d e ect ive. In st age I or II inju ries w ith HNPs bu t w ith ou t facet or en d-p late fract u res, an terior cer vical d iskectom y an d fu sion w ith p lat ing is safe an d e ect ive. In st age III an d IV inju ries w it h ou t associated HNPs or ver tebral body fract ures, it is a w eak recom m en dat ion th at p osterior-on ly t reat m en t is safe and e ect ive. In stage III an d

Fig. 9.5 Intraoperative lateral radiograph demonstrating  lam inar  spreader  used  to  e ect  anterior  open  reduction  of  a  C4–C5 exion  distraction  injury.

IV injuries w ith associated HNPs or ver tebral body fract u re, circu m feren t ial t reat m en t is st ron gly recom m en ded (Fig. 9.6).

■ Extension-Distraction

Injuries Exten sion -dist ract ion inju ries (EDIs) disru pt th e an terior longit u din al ligam en t (ALL) an d disk w ith or w ith ou t th e PLL or PLC. According to th e Allen -Fergu son classi cat ion , th ese injuries are categorized as t ype I or t ype II based on w h eth er th ere is an terior angulat ion /w iden ing or su blu xat ion , resp ect ively. Th e PLL (act in g as a ten sion ban d) h as been t h ough t to be t h e key st r u ct u re d i eren t iat in g t h e t w o t yp es, alth ough recen t cadaveric st udies suggest th e facet capsules m ay be m ore im por tan t . Subsequ en t posterior t ran slat ion of th e cran ial ver te-

Distraction (AO Type-B Injuries) th e t reat m en t of su baxial FDIs an d EDIs. Class III eviden ce (coh or t an d case series) suppor ts th e u se of closed redu ct ion m an euvers so long as excessive exion posit ion ing is n ot required. Alth ough closed reduct ion h as been foun d to be safe for pat ien ts w ith EDIs, a h igh failure rate h as been n oted in p at ien t s w ith facet fract u res du e to p ossible overdist ract ion .16,17 Neu rologic w orsen ing h as been p ost ulated to be du e to overdist ract ion , n on con t igu ou s un recogn ized cran ial injuries, h ern iated n ucleus pulposu s, h em atom a, an d cord edem a. Based on m od erate eviden ce, a st rong recom m en dat ion for closed reduct ion is given for su baxial EDIs.

Is There a Role for Nonoperative Treatment in EDIs? Fig. 9.6 Postoperative intraoperative lateral radiograph demonstrating circumferential fusion of  a  C4–C5 exion-distraction  injury.

brae results in can al sten osis w ith or w ith out cord com p ression . Rad iograp h s often d em on st rate an ter ior ret rop h ar yn geal soft t issu e sw elling, disk sp ace w iden ing, an d an terior osteophyte avulsion fract ures. Often , radiograph s an d CT m ay n ot dem on st rate any radiological abn orm alit ies an d sublu xat ion or dislocat ion . CT best determ in es osseou s an atom y an d fractures, w hereas MRI facilitates assessm ent of the DLC (on STIR sequen ces) an d n eu ral elem en t s (cord sign al ch ange on T1 or T2 sequ en ces) (Fig. 9.4). In pat ien t s w ith AS or DISH, MRI is essen t ial to iden t ify su btle fract u res or h em atom as, even in n eurologically in t act pat ien ts, w h ich greatly a ect m anagem ent. Hyperextension inju ries com m on ly cau se sign i can t n eurologic inju r y (often cen t ral cord syn drom e) du e to sagit t al can al n arrow ing du ring exten sion , often in elderly p at ien ts w ith u n derlying cer vical sten osis.

Is Closed Reduction Safe? As d escr ibed above, closed red u ct ion for cervical fract u re su blu xat ion s h as been u t ilized in

Halo im m obilizat ion after closed redu ct ion h as been sh ow n to be safe an d e ect ive in selected w ell-reduced EDIs.16 Ver y low qualit y eviden ce sup por t s h alo im m obilizat ion of EDIs; th erefore, th ere is a w eak recom m en dat ion for h alo m an agem en t of subaxial EDIs if n eut ral cervical exion can be obt ain ed an d m ain tain ed w ith avoidan ce of hyper exion . A key poin t m ust be em ph asized: th e above review s an d subsequ en t recom m en dat ion exclu de p at ien t s w ith AS or DISH (see below ).

How to Approach: Anterior, Posterior, or Combined? Ret rospect ive repor t s (low overall qu alit y of evidence) support anterior or posterior xation as w ell as com bin ed approach es depen ding on th e overall st abilit y of th e inju r y prim arily related to PLC disru pt ion . Vaccaro et al23 repor t th at p at ien t s w ith st age I EDIs (disr u pt ion of th e ALL, disk, an d PLL w ith ou t PLC or p osterior elem en t disru pt ion or t ran slat ion ) can be successfu lly m an aged w ith an terior ten sion ban d p lat ing or xat ion on ly due to isolated an terior or m iddle colu m n disru pt ion . Type II inju ries are m ore com plex an d t yp ically requ ire p osterior xat ion to obt ain st abilit y. A w eak recom m en dat ion for an terior-alon e xat ion in t ype I injuries is ap propriate. A st rong recom m en dat ion again st an terior-alon e xat ion for t ype II

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Chapter 9 inju r ies w it h th e u se of p oster ior in st r u m en t at ion to p rovid e ad equ ate st abilizat ion is appropriate.

■ Ankylosing Spondylitis and

Di use Idiopathic Skeletal Hyperostosis An kylosin g sp on dylit is is a ch ron ic in am m ator y disease w ith progressive sacroiliac an d axial skeletal join t involvem en t th at is m ost prevalen t in m ales (3:1) often p resen t ing in th e secon d or th ird decades. Nin et y percen t of AS are associated w ith th e h um an leukocyte an t igen (HLA) B27 laborator y m arker (com pared w ith 7% of th e gen eral popu lat ion ). Ext raar t icular m an ifest at ion s in clude an terior uveit is, cardit is, aor t it is, con du ct ion defect s, rest lu ng disease or brosis, ileitis/colit is, an d ren al failure. It a ects car t ilage, bon e, an d syn ovial join ts, often progressing from en th esit is an d syn ovit is to ch on d r it is an d osteit is. AS ossi cat ion (m argin al syn desm ophytes) occu rs t yp ically caudally to cran ially (sacroiliac join ts in it ially, cer vical lastly) w it h t h e br idgin g bet w een ver tebrae occu r r ing in lin e w ith t h e m argin s of th e body (“bam boo sp in e”). Di use idiopathic skeletal hyperostosis (DISH) is a com m on disorder of u n kn ow n et iology (affect ing up to 28% of pat ien t s aged > 60 years). Given t h e in creasing size of th e aging popu lat ion com bin ed w ith th e in creasing occu rren ce of t yp e 2 d iabetes m ellit u s an d obesit y, DISH is m ore frequen tly being diagn osed. Poten t ial sequ elae of hyperostosis in th e cer vical sp in e in clu de sten osis, dysph agia, cer vical m yelopathy, an d SCI result ing from even m in or t rau m a. Th e in cid en ce of d elayed n eu rologic inju r y d u e to fract u re is h igh as a resu lt of u n recogn ized in stabilit y. Ext raspin al m an ifestat ion s are n um erous an d in clude an in creased risk of h eterotopic ossi cat ion after tot al h ip arth roplast y. DISH is m ore com m on in p at ien t s w ith diabetes m ellit u s an d gou t . DISH is recogn ized rad iograp h ically by th e presen ce of “ ow ing” ossi cat ion along th e an terolateral m argin s of

at least fou r con t igu ou s ver tebrae an d th e ab sence of changes of spondyloarthropathy or degen erat ive spon dylosis. A recen t system at ic review by Wester veld et al24 repor ted sim ilar n dings bu t also em ph asized th at surgical or n on operat ive t reat m en t d id n ot alter th e n eurologic prospect ive for m ost pat ien t s. Th ey foun d th at th e com plicat ion rate w as 51.1% in AS pat ien ts an d 32.7% in DISH pat ien t s. Th e overall m ort alit y w ith in 3 m on ths after injury w as 17.7%in AS an d 20.0% in DISH. Th is review m irrors th e exist ing ret rosp ect ive literat u re suggest ing th at th e clin ical ou tcom e of p at ien t s w ith fract u res in previou sly an kylosed spin es, du e to AS or DISH, is considerably w orse com pared w ith th e gen eral t raum a popu lat ion .25

Do All AS or DISH Patients Need Advanced Imaging? Pat ien t s w ith ASD m ost com m on ly also h ave AS or DISH. Both disorders create a st i spin e th at is often fu sed an d fu n ct ion ally rest ricted w ith underlying osteoporotic bone. Fractures are u p to th ree to four t im es m ore p revalen t th an in th e gen eral pop ulat ion . Delay in diagn osis is u n fort un ately com m on an d can be cat ast rop h ic d u e to n eu rologic inju r y an d d eter iorat ion often resu lt ing from epidural h em atom a. Plain radiograp h s alon e are n ot appropriate. CT is m an dator y in evaluat ion of th ese pat ien t s, an d MRI best iden t i es su btle t ran sverse fract u res associated w ith edem a an d posterior elem en t disru pt ion . Alth ough m any report s advocate caution an d judicious evaluat ion, diagnosis, an d t reat m en t of p at ien t s w ith ASD, th e qu alit y of th e literat u re is low to ver y low, as th ese repor t s are ret rospect ive case series an d review s. Caron et al’s 26 ret rospect ive review of 112 ASD pat ien ts w ith fract u res fou n d th at a delay in diagn osis, n eurologic d eclin e (81%), an d a h igh r isk of com p licat ion s an d d eat h (t h reefold in crease or 20 to 30%) are u n for t u n ately com m on . Du e to th e in creased risk of n eu rologic declin e an d m or talit y, a st rong recom m en dat ion is given th at p at ien t s w ith ASD u n dergo CT an d MRI (un less con t rain dicated).

Distraction (AO Type-B Injuries)

Do All AS or DISH Patients Need Operative Treatment for Cervical Fractures? Alt h ough a few older case rep or t s or case ser ies su p p or t n on op erat ive m an agem en t of cer vical fract u res in pat ien t s w ith ASD, m odern rep or t s, th ough ret rosp ect ive (low overall qu alit y of evid en ce), over w h elm in gly favor op erat ive m an agem en t .25,27 As described above regarding th e opt im al op erat ive ap proach to EDIs, AS an d DISH pat ien ts are best stabilized w ith a posterior approach w ith m ult iple xat ion poin ts above an d below th e fract ure. Sh ort segm en t in st r u m en t at ion to sp are segm en t s is n ot of con cer n . We st ron gly recom m en d op erat ive in ter ven t ion via m u lt ilevel posterior segm en t al con st ru ct s to p rovide adequ ate st abilizat ion to allow fract u re h ealing w ith su p p lem en tal an terior void graft ing as n eeded.26

■ Chapter Summary Cer vical su baxial exion an d exten sion dist ract ion fract u res are t yp ically u n stable an d severe inju ries th at are often associated w ith h igh rates of n eurologic inju r y, m orbidit y, an d m or t alit y. Delay in d iagn osis is com m on in p at ien t s w ith an kylosing spin al disorders, an d advan ced im aging is required. Prom pt closed

redu ct ion follow ed by surgical m an agem en t is t ypically requ ired to provide a stable environ m en t to en able fract u re h ealing, to m axim ize n eurologic recover y an d fun ct ion , an d to m in im ize com plicat ion s.

Pearls Integration of fracture morphology and diskoligam entous and neurologic status is necessary to guide treatment of subaxial fractures. Magnetic resonance imaging is necessary for appropriate diagnosis of cervical distraction injuries, especially in patients with DISH or AS, because missed injuries can have dire consequences. Closed reduction is recommended for cervical subaxial distraction injuries in awake, alert patients who can participate in serial neurologic exam inations. Cervical distraction injuries are highly unstable, and operative treatment is recom mended for m ost cervical distraction injuries. The selection of an approach is a com plex process, often inuenced by the presence or absence of disk  herniation. Pitfalls Failing to identify and decompress cervical disk herniations prior to reduction in patients failing closed, awake reductions. Missing extension distraction injuries in DISH or AS patients.

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5. Fran ce JC, Bon o CM, Vaccaro AR. In it ial radiograph ic evaluat ion of th e spin e after t raum a: w h en , w h at , w h ere, an d h ow to im age th e acu tely t rau m at ized spin e. J Or th op Trau m a 2005;19:640–649 Pu bMed 6. Vaccaro AR, Madigan L, Sch w eit zer ME, Flanders AE, Hilibran d AS, Albert TJ. Magn et ic reson an ce im aging an alysis of soft t issu e disr u pt ion after exion -dist ract ion injuries of th e subaxial cer vical sp ine. Spin e 2001;26:1866–1872 Pu bMed 7. St assen NA, William s VA, Gest ring ML, Ch eng JD, Ban key PE. Magn et ic resonan ce im aging in com bin at ion w ith h elical com puted tom ography provides a safe an d e cient m eth od of cer vical spin e clearan ce in th e obt un ded t raum a pat ien t . J Trau m a 2006;60: 171–177 PubMed

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Chapter 9 8. Wrigh t JG, Sw ion tkow ski MF, Heckm an JD. In t roducing levels of evidence to th e journ al. J Bon e Join t Surg Am 2003;85-A:1–3 PubMed 9. Atkin s D, Best D, Briss PA, et al; GRADE Working Group. Grading qualit y of eviden ce an d st rength of recom m en dat ion s. BMJ 2004;328:1490 PubMed 10. West S, King V, Carey TS, et al. System s to Rate th e St rength of Scien t i c Eviden ce. Eviden ce Repor t/ Tech n ology Assessm en t No. 47 (Prepared by th e Research Triangle In st it ute–Un iversit y of Nor th Carolin a Eviden ce-Based Pract ice Cen ter, Con t ract No. 290–97–0011). Rockville, MD: Agen cy for Health care Research an d Qu alit y; 2002 11. Nor vell DC, Det tori JR, Skelly AC, Riew KD, Ch apm an JR, An derson PA. Meth odology for th e system at ic review s on an adjacen t segm en t pathology. Spin e 2012;37(22, Suppl):S10–S17 Pu bMed 12. W h ite AA 3rd, et al., Biom ech an ical an alysis of clin ical st abilit y in th e cer vical spin e. Clin Or th op Relat Res 1975;109:85–96 13. Vaccaro AR, Hulbert RJ, Patel AA, et al; Spin e Traum a St u dy Grou p. Th e su baxial cer vical sp in e inju r y classi cat ion system : a n ovel approach to recogn ize th e im por t an ce of m orph ology, n eurology, an d in tegrit y of th e disco-ligam en tous com plex. Spin e 2007;32: 2365–2374 Pu bMed 14. Dvorak MF, Fish er CG, Feh lings MG, et al. Th e surgical ap p roach to su baxial cer vical sp in e inju ries: an eviden ce-based algorith m based on th e SLIC classi cat ion system . Spin e 2007;32:2620–2629 PubMed 15. W h ang PG, Patel AA, Vaccaro AR. Th e developm en t an d evalu at ion of th e su baxial inju r y classi cat ion scoring system for cer vical spin e t raum a. Clin Or th op Relat Res 2011;469:723–731 PubMed 16. Rocksw old GL, Bergm an TA, Ford SE. Halo im m obilizat ion an d surgical fu sion : relat ive in dicat ion s an d e ect iven ess in th e t reat m en t of 140 cer vical spin e injuries. J Traum a 1990;30:893–898 PubMed 17. Vaccaro AR, Falat yn SP, Flan ders AE, Balderston RA, North ru p BE, Cotler JM. Magn et ic reson ance evaluat ion of th e in ter vertebral disc, spin al ligam en t s, an d spin al cord before an d after closed t ract ion reduct ion of cer vical spin e dislocat ion s. Spin e 1999;24:1210– 1217 PubMed

18. Eism on t FJ, Aren a MJ, Green BA. Ext ru sion of an in ter ver tebral disc associated w ith t rau m at ic su blu xat ion or d islocat ion of cer vical facet s. Case rep or t . J Bon e Joint Surg Am 1991;73:1555–1560 PubMed 19. Lin d B, Sih lbom H, Nordw all A. Halo-vest t reat m en t of un st able t raum at ic cer vical spin e injuries. Spin e 1988;13(4): 425–432 20. Beyer CA, Caban ela ME, Berquist TH. Un ilateral facet dislocat ion s an d fract u re-dislocat ion s of th e cer vical spin e. J Bon e Join t Surg Br, 1991;73(6):977–981 21. Boh lm an HH. Acute fract ures an d dislocat ion s of the cer vical spin e. An an alysis of th ree h un dred h ospit alized p at ien t s an d review of th e literat u re. J Bon e Join t Su rg Am 1979;61:1119–1142 PubMed 22. Brodke DS, An derson PA, New ell DW, Grady MS, Ch apm an JR. Com parison of an terior and posterior ap p roach es in cer vical sp in al cord inju ries. J Sp in al Disord Tech 2003;16:229–235 PubMed 23. Vaccaro AR, Klein GR, Th aller JB, Rush ton SA, Cotler JM, Alber t TJ. Dist ract ion extension injuries of th e cer vical sp in e. J Sp in al Disord 2001;14:193–200 PubMed 24. Wester veld LA, Verlaan JJ, On er FC. Sp in al fract u res in pat ien t s w ith an kylosing sp in al disorders: a system at ic review of th e literat ure on t reat m en t , n eurological st at us an d com plicat ion s. Eur Spin e J 2009;18: 145–156 PubMed 25. W h ang PG, Gold berg G, Law ren ce JP, et al. Th e m an agem en t of sp in al inju ries in p at ien t s w it h an kylosing spon dylit is or di use idiopath ic skelet al hyperostosis: a com parison of t reat m en t m eth ods an d clin ical outcom es. J Spin al Disord Tech 2009;22: 77–85 PubMed 26. Caron T, Bran sford R, Nguyen Q, Agel J, Chapm an J, Bellabarba C. Spin e fract ures in pat ien t s w ith an kylosin g sp in al d isord ers. Sp in e 2010;35:E458–E464 PubMed 27. Bran sford RJ, Koller H, Caron T, et al. Cer vical spin e traum a in di use idiopath ic skeletal hyperostosis: injur y characteristics and outcom e w ith surgical treatm ent . Spin e 2012;37:1923–1932 PubMed

10 Facet and Lateral Mass Fractures Máximo -Alberto Díez-Ulloa

■ Introduction Fract u res of th e lateral m ass an d facet s m ay occu r in com plex injuries an d lead to ver y un st able scen arios, w h ich are addressed in oth er ch apters. Th is ch apter d iscu sses isolated lat eral m ass an d facet fract u res of t h e su baxial (C3- C7) cer vical spin e. Th e atlas an d th e axis h ave t w o lateral m asses each , bu t inju r y to th ese st r u ct u res is m ore relevan t to th e occipito-atlantoaxial com plex, has been described previou sly.

■ De nition Bon o et al,1 in th eir subaxial cer vical inju r y descript ion (SCID) system , describe a lateral m ass fract u re as “th e fract u re of any p or t ion of th e lateral m ass com plex, in clu ding th e art icu lar p rocesses an d th e p edicle.” Th is categorizat ion in clu des th e so-called oat ing lateral m ass, in w h ich ipsilateral fract u res of th e lam in a an d p edicle result in th e w h ole lateral m ass, w ith bot h facet join t s, in d iscon t in u it y t h e rest of t h e ver tebra, bringing abou t a facet su blu xat ion w ith both th e u pp er an d low er ver tebrae an d a m ech an ically ver y u n st able scen ario. Bon o et al’s st udy focused on th e discrepan cies in th e descript ion of cer vical inju ries by exper t surgeon s. Th e m ain con clusion w as th at sp in e su rgeon s often disagree in th e evalu at ion

of the sam e im ages. Lateral m ass fracture, how ever, w as ran ked h igh est in surgeon agreem en t am ong 11 proposed entities, reaching 70%, w hich is quite good, bu t n ot com p lete agreem en t .

■ Cervical Spine Anatomic

Considerations An atom ically, eith er of th e t w o lateral m asses at a speci c fu n ct ion al sp in al segm en t , in clu ding its t w o facet join ts, is con sidered on e of th e four colum n s (on e on each side) of th e cer vical spin e.2 Th is colu m n ar st ru ct u re sh ou ld n ot be seen in th e sam e w ay of th e Den is con cept of colum ns, but refers in stead to th e bony arch itect u re, w it h t h e fou r colu m n s bein g t h e vertebral body, t h e t w o lateral m asses, an d t h e p osterior arch (lam in ae an d spin ou s process). In t h e Cer vical Sp in e Inju r y Sever it y Score (CSISS) system , inju ries to a lateral m ass th at are equal in sp eci c w eigh t to th e inju ries to ver tebral body an d th e t w o lateral m asses accou n t for 50% of th e total score. In bet w een th e u pp er cer vical sp in e (occip it al-C1-C2) th at w orks m ain ly in rot at ion (besides exten sion at occiput- C1), an d th e low er cer vical spin e (C4- C7) th at does it m ostly in exion exten sion ; a m idd le cer vical spin e (C3C4) h as been d escr ibed .3 . Th e p ath oan atom y of su ch m iddle segm en t of th e cer vical spin e w ou ld be ch aracterized by sh ear inju ries w ith

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Chapter 10 soft t issu e involvem en t bu t scarcit y of bon e in jur y, w h ereas inju ries from C4 to C7 gen erally involve bony st ru ct ures, especially th e vertebral body an d th e lateral m asses.

in th e con text of a exion -dist ract ion inju r y.5 Facet fract u res, in con t rast , are u su ally th e resu lt of a exion inju r y w ith a rotat ion al com p on en t , alt h ough som et im es t h ey m ay occu r in axial-com pression injuries 6 (Figs. 10.1, 10.2, 10.3).

■ Mechanism of Injury It is n ecessar y to di eren t iate bet w een lateral m ass fract u res an d facet inju ries. Inju r y to th e pars in terar t icu laris or th e m ain body of th e lateral m ass is gen erally of th e exten sion t ype, in com bin at ion w ith eith er com p ressive 4 or distract ive forces. Infrequently, it m ay also occu r

■ Classi cation Th ere is a lack of clarit y regarding th e de n it ion of cer vical inju ries. Bon o et al1 pu blish ed th e results of an exper t con sen su s on specifying th e t yp e of injur y as a rst step in m aking

a

b

c

d

Fig. 10.1a–d Patient who was injured in a m otor vehicle accident was diagnosed with (a) a C4 left lateral mass, (b) a C5 burst fracture with a sagit tal fracture line, (c) a C4 listhesis, with (d) the characteristic horizontalization of the oating lateral mass.

In addition, there is a C3 inferior left facet fracture. Both an extension t ype (C4) and a exion t ype (C5) injuries occurred at adjacent segm ents, probably from a global C-spine axial compression injury. The patient had no neurologic symptom s.

Facet and Lateral Mass Fractures

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as spon dylolysis (un i- or bilateral) or as split , com m in u ted , an d oat in g lateral m ass (bot h p ed icle an d ip silateral lam in a fract u res, also refer red to as “sep arat ion t yp e”), w h ereas a facet fract ure can be fu r th er categorized based on w h eth er or n ot th e facets are dislocated 4,7 (see text box).

Classi cation of Lateral Mass/ Facet Fractures

Fig. 10.2 Magnetic resonance imaging of the sam e patient as in Fig. 10.1.

m an agem en t recom m en dat ion s. Tran sit ion al form s of inju r y also exist . Lateral m ass injuries h ave been classi ed in t w o m ajor t ypes 7 : lateral m ass an d facet injur y. Lateral m ass injuries can be furth er categorized

1. Lateral mass a. Spondylolysis i. Unilateral ii. Bilateral b. Com minuted c. Split i. Sagit tal ii. Coronal iii. Transverse d. Separation ( oating mass) 2. Facet joint a. Facet fracture b. Facet dislocation 3. Mixed or other type Example: lateral mass with contralateral lam ina fracture Modi ed from Kotani et al4 and Lee and Sung.7

a

b

Fig. 10.3a,b Patient was treated with anterior cervical diskectomy and fusion C3-C6. (a,b) Postoperative radiographs. She has a 5 years follow-up with an excellent clinical outcome

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a

b

Fig. 10.4a,b (a) Intraoperative im age of a unilateral approach for a unilateral facet fracture-dislocation with radiculopathy C7 at left C6-C7. Note the

amount of dissection that was needed. (b) Postoperative radiograph. He has a 6-year follow-up with an excellent outcome.

Th ere are sligh t di eren ces in th e descrip t ion s of th ese inju ries in th e literat u re. Kotan i et al4 do n ot in clude isolated facet inju ries in th eir st u dy, an d con cept of sp lit inju ries refers on ly to th e coron al p lan e w ith im p act ion of fragm en t s. Lee an d Su ng,7 on th e oth er h an d, consider only unilateral spondylolysis. We therefore use a com poun d classi cat ion , adding th e alw ays u sefu l “m ixed” or “oth er” t yp e to accoun t for injuries th at a surgeon m igh t con sider to be a lateral m ass fract u re bu t th at do n ot en t irely m atch any of th e p roposed t ypes. Th ese facet fract ures, especially of th e superior facet , m ay be associated w ith soft t issue inju r y at th e an n ulu s of th e disk, t h e ip silateral facet join t capsu le, an d th e avu m , giving rise to a u n ilateral facet fract u re d islocat ion , w ith m ainly a rotational com ponen t. It m ust be noted th at rotat ion an d lateral exion are a coupled m ot ion in th is an atom ic region (suba xial cer vical spin e); on e can n ot occur isolated from th e oth er: w h en ever th ere is a rot at ion , som e lateral exion takes place and vice versa. Th ese fract u re dislocat ion s m ay be som ew h at m ore st able th an th e un ilateral facet dislocat ion s, as th e injur y to th e an n ulus m igh t be less pron ou n ced. How ever, it is n ot alw ays clear h ow to d i eren t iate bet w een th ese t ypes of injuries. Th eoret ically, th ey can be con sidered as som ew h at di eren t en t it ies, w ith th e p u re u n ilateral dislocat ion being th e m ore u n st able inju r y, requ ir in g m ore en ergy d issip at ion an d t h en m ore exten sive inju r y to th e d isk an d ot h er

st r u ct u res (even t h e con t ralateral facet cap su le) ren d er ing it less st able on ce it is red u ced th an t h e facet fract u re-d islocat ion an d less st able on p resen t at ion , bu t w ith less soft t issu e dam age, an d t h erefore easier to m an age w ith on ly un ilateral osteosyn th esis 8 (Fig. 10.4).

■ Pathoanatomy Musculoskeletal Level of Injury Lateral m ass an d facet fract u res are t yp ically a low er cer vical spin e injur y. Th ere is, again , som e di cu lt y in review ing th e cases from several series in th e literat u re, as som e inju ries are described based on th e fun ct ion al spin al u n it t h at w as a ected an d fu sed , an d ot h ers are d escr ibed based on t h e sp eci c ver tebra th at w as inju red . As w e w ill d iscu ss below, m ost of t h e t im e a C6 lateral m ass fract u re requires C6- C7 surger y, bu t if w e are dealing w ith a su perior ar t icu lar facet fract u re it m ay requ ire C5- C6 surger y. As a gen eral r ule, th e low er th e level, th e h igh er th e in ciden ce of lateral m ass fract ure in th e su baxial cer vical sp in e.4,5,8 Never th eless, Lee an d Su ng,7 in th eir clin ical series th at in clu ded isolated facet fract u res, report a p eak in ciden ce at C4. Th is is in con t rast w ith th e con cept of th e m iddle cer vical sp in e segm en t

Facet and Lateral Mass Fractures in w h ich Torg et al3 foun d n o bon e inju r y but on ly soft t issu e injur y, w h ich p erh ap s can be explain ed by th e fact th at th eir repor t is a st u dy of a cadaveric m odel, n ot a clin ical series. Th ey also rep or t th at th is inju r y occu rred in axial com pression , w h ereas as st ated above, th ese injuries occur m ostly from an exten sion t ype of m ech an ism , but also som et im es from exion d ist ract ion forces 4,5

Soft Tissue Involvement at the Injured Level Kot an i et al4 repor t th at in lateral m ass fract ures, th e in stabilit y an d th e soft t issu e injur y m ain ly occu r in t h e cau dal fu n ct ion al sp in al u n it (C6C7 for a C6 lateral m ass fract ure); th us, in th ese lateral m ass fract ures th e in st abilit y u sually h appen s opposite to isolated facet fract ures (gen erally th e cran ial cran ial on e in th e m ass: C5C6 for a C6 facet fract ure). So, th ere is som e degree of an terolisth esis in m ore th an 75% of cases of lateral m ass inju ries (in ferior level in st abilit y) bu t in on ly 33% of facet fract ures; in th is lat ter injur y scen ario (facet fract ure), th e superior level is displaced in stead m ost frequently (50% of cases), superior level in st abilit y. Sim ilarly, in lateral m ass fract u res u p to 75% of cases h ad an an terior longit u din al ligam en t (ALL) inju r y, an d th e sam e percen tage h ad a disk inju r y, as seen on m agn et ic reson ance im aging (MRI), w ith an terolisthesis of the fract u red vertebra; 25% of cases also sh ow ed som e ALL involvem en t an d an terolisth esis of th e ver tebra above th e fract ure level. Th e ALL w as inju red in all sp lit-t yp e cases an d in a h igh p ercen t age of ever y oth er t ype of lateral m ass fracture; com m inution and separation occurred less often (50% an d 60%, resp ect ively). Th e disk w as a ected in 50% of each t ype of inju r y; it w as a ected th e least in u n ilateral sp on dylolysis (30%). Th e posterior longit u din al ligam en t (PLL) w as injured in 30 to 50% of cases, m ostly in split an d facet fract u res w ith ou t dislocat ion , w ith t h e except ion of th e com m in u t ion t ype, in w h ich th e PLL w as n ever inju red. In facet fract u res, t h e d isp lacem en t (an d t h u s t h e in st abilit y) is m ost ly at t h e cran ial adjacen t ver tebra, w ith a h igh (80%) in ciden ce of disk inju r y an d th e absen ce of inju r y in th e

posterior ligam en tou s com plex. Never th eless, th ese data sh ou ld be con sidered caut iously becau se an inju r y to th e t issu e does n ot im p ly th at th ere is m ech an ical in stabilit y n ecessit ating su rgical st abilizat ion . A rotational instabilit y (> 10 degrees) entails a split an d un ilateral facet fract ure-dislocat ion ; a sagit tal in st abilit y (kyp h ot ic segm en t > 10 degrees) en tails a split fract ure an d t ran slat ion al in st abilit y (> 3.5 m m ) in split , u n ilateral facet fract ure-dislocat ion an d com m in ut ion , an d som et im es in th e separat ion t ype of in jur y.7 It is n otew or thy th at th e split t yp e refers to a coron al sp lit w ith im p acted facet s in th is series, bu t even in a sagit t ally orien ted split lateral radiograph s dem on st rate spin e m alalign m en t in up to 66% of pat ien ts.9 Yetkin et al10 rep orted th at in p illar fract u res th e un cover tebral join t appear w iden ed on an teroposterior view s, w h ich cou ld be explain ed by rot at ion al m alalign m en t at th e segm en t . Th us, lateral m ass fract ures m ay frequen tly lead to u n stable con gu rat ion s even w ith ou t concom itan t soft tissue injury, carr ying the risk of m ech an ical in st abilit y in th e form of bony st r uct u ral failu re. In separation -t ype injuries (such as a oating m ass), there is not only a lateral sublu xation of th e a ected m ass bu t also a h orizon t alizat ion of it (rot at ion in th e sagit t al plan e, w ith th e cran ial facet lean ing for w ard (ven t rally) an d th e cau dal facet dorsally). Th ese con siderat ion s explain w hy surgical m an agem en t is usu ally n ecessar y (see below ).

Associated Neurovascular Injuries Th ese fract ures frequently have associated neurovascular injuries, especially root sym ptom s, both paresth esias an d w eakn ess,5 an d less frequen tly ver tebral ar ter y injuries, du e to th e close proxim it y of both th e n er ve root an d th e ver tebral ar ter y to th e lateral m ass. As th e foram en th rough w h ich th e root leaves th e spin al can al is form ed partly by th e lateral m ass an d th e facet , even m in or in t ru sion by bon e fragm en ts m ay cause im pingem en t an d radicular dam age. Th e vertebral arter y courses th rough a canal bet ween the vertebral body and the transverse p rocesses, so d isp lacem en t s t h at en t ail

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Chapter 10 listh esis alw ays p ose a risk. Fu r th erm ore, th e bony foram en transversarium is also quite sn ug aroun d th e vessel, so th at any invasion or displacem en t in to it m ay cau se vascu lar inju r y.

Root and Spinal Cord Injury In a series of un displaced facet fract ures,5 70% of pat ien t s h ad referred pain “at th e level of th e n eck, sh oulder, arm or ch est ,” an d 56% com p lain ed of som e sen sor y radicu lop at hy an d 40% of som e m u scle w eakn ess. In t h e series of Lee an d Su n g,7 t h ere w as a 36% in cid en ce (14/39) of con com it an t cord inju r y (h alf of t h em in p at ien t s w it h fract u red facet ), t w o t h ird s of w h ich w as Am er ican Sp in al Inju r y Associat ion (ASIA) grad e C or m ore severe; radicu lopathy w as presen t in 44% of p at ien t s. It is easy to u nderstan d th at in displaced cases, esp ecially if th e su p erior facet is in volved, th e in ciden ce of radicu lopathy w ou ld in crease dram at ically. In m y ow n experien ce, som e form of root involvem en t w as presen t in alm ost ever y pat ien t w ith facet inju r y.

Vertebral Artery Injury Th e ver tebral ar ter y lies in close an atom ic relat ion sh ip w ith th e lateral m ass, side by side w ith th e lateral w all an d t ied to th e spin e w h en it crosses th rough th e foram en t ran sversariu m , bet w een th e rem n an t s of th e rib an d th e t ran sverse process itself. For t un ately, th ere is a low in ciden ce of clin ically sign i can t injuries of th e vertebral arter y. Th e overall in ciden ce of blu n t t raum a is 17% in pat ien t s w ith cer vical inju ries (as seen on m ult idetector com puted tom ography [CT] angiogram ). Th e in ciden ce of secon dar y n eurologic even t s is 14% in p at ien t s w ith a ver tebral ar ter y inju r y (VAI), an d th e in ciden ce of st roke-related m or t alit y is 5% (t w o of 42 p at ien t s w it h VAIs am on g a tot al series of 253 m u lt id etector CT an giogram -tested p at ien t s after cer vical injur y from blu n t t raum a). Lee an d Sung 7 reported t w o cases of vertebral arter y d issect ion am ong 39 pat ien t s. Th ere w as a correlat ion bet w een VAI an d fract ure displacem en t in to th e foram en t ran sversarium > 1 m m (adju sted odds rat io [OR], 3.29; p = 0.026) by

m u lt ivariate regression m od el (togeth er w ith a basilar skull fract ure), but m ore relevan t to our discussion w as th e associat ion bet w een facet su blu xat ion /dislocat ion an d n eu rologic even t (cr u d e OR, 9.0; p = 0.004). In ad d it ion , th e diagn osis of an kylosing spon dylit is/di u se id iop at h ic skelet al hyp erostosis h ad a h igh associat ion w it h VAI (OR, 8.04; p = 0.034) by u n ivariate an alysis an d an associat ion w ith n eu rological even ts (OR, 40.67; p < 0.001).11 An an alysis of th e pat tern s of cer vical spin e fract ure-dislocat ion s in VAI foun d th at dist ract ion w as th e m ain et iopath ogen ic factor, w ith facet d islocat ion , w it h or w it h ou t fract u re, being th e m ost com m on pat tern , an d C5 being th e m ost frequ en tly inju red level. Again , displacem en t in to th e foram en t ran sversariu m w as p resen t in alm ost h alf of th e pat ien ts.12 In a series of 69 suspected VAIs in pat ien t s w ith facet dislocat ion or fract ures exten ding to th e foram en t ran sversarium in th e cer vical sp ine, 19 (27.5%) h ad an act ual inju r y. Th ere w as a 21% in ciden ce of vertebrobasilar isch em ia (4/19), w ith t w o death s at 4 an d 21 days. Alm ost h alf of t h e p at ien t s h ad a sp in e in ju r y t h at w as d eem ed u n st able an d requ ired su rger y.13 Most VAI pat ien t s rem ain asym ptom at ic (Fig. 10.5). Th e m ajor m ech an ism s of inju r y are distract ion (eith er exten sion or exion ) an d lateral exion . Th e vascu lar inju r y p at tern u sually is dissect ion or occlusion . Digit al subt ract ion angiograp hy (DSA) is th e m ost sen sit ive im aging tech n iqu e for th ese cases, bu t it s invasiven ess m akes it qu est ion able as a screen ing m eth od. Magn et ic reson an ce angiography can also diagn ose VAI, w ith out en t ailing th e invasiven ess of DSA. Man agem en t in clu des (1) in ter ven t ion al n euroradiology for h em orrh agic VAI an d p rogressive ver tebrobasilar st roke, an d (2) system ic an t icoagu lat ion w ith h eparin for m ild ischem ia. Controversy exist about the m anagem en t of asym ptom at ic p at ien t s becau se th e n at ural h istor y of VAI h as n ot been described in th is con text; h ow ever, both p rophylact ic h ep arin and ant iplatelet agents h ave been advocated, w hich m igh t in terfere w ith perform ing early su rger y.14 Th e in cid en ce of VAI can in crease to 50% in m id cer vical sp in e fract u re or su b lu xat ion,15 probably related to th e tenden cy for

Facet and Lateral Mass Fractures

Fig. 10.5 A 19-year-old patient who was injured in a motor vehicle accident presents with a fracture at C3 and a left lateral mass with involvement of the pedicle and left unciform facet with a rotational shear transverse component. The patient remained asymptomatic and was treated with antiaggregants and rigid external im mobilization.

t ran slat ion al inju ries in th is area du e to soft t issu e dam age, as p reviou sly described.3 As for th e top ograp hy of th ese lesion s, occlu sion at it s origin or at th e inju red level is th e m ost frequen t injur y pat tern . Th e ar ter y on th e left side is m ore frequ en tly a ected.15 Th e n dings in a series of six cases suggest th at early su rger y m igh t st abilize th e clot after em bolizat ion .16 Th is can be an ad dit ion al argu m en t for su rgical st abilizat ion .

■ Treatment Treat m en t is guided by th e t yp e of inju r y, th e p resen t ing sym ptom s (n ote t h e p resen ce of root inju r ies or VAIs), an d t h e associated inju ries in th e m u scu loskelet al system (cer vical spin e, oth er areas of th e spin e, long bon es, pelvis, etc.) or in oth er system s. Th ere is a con siderable in ciden ce of con com itan t inju ries to th e cen t ral n er vous system , respirator y system , an d in t ra-abdom in al organ s.5 Lateral m ass fract u res en t ail a dou ble-join t injur y, w h ich im plies a ch ain inju r y in w h ich t w o con secu t ive lin ks are dam aged , an d fou r

ar t icu lar su r faces are com p rom ised for su b sequen t in congr uit y. Th us, th e rst priorit y of t reat m en t is m ech an ical stabilit y, an d th e secon d is th e m ain ten an ce of th e key spat ial relat ion sh ip bet w een th e ar t icu lar car t ilages in th e syn ovial join t to avoid p ost t rau m at ic degen erat ive ch anges. Surgical t reat m en t is usu ally preferred for th ese inju r ies, except for som e u n d isp laced facet fract u res (see below ) an d for u n ilateral u n displaced spon dylolysis. Float ing m ass (separat ion ) (Fig. 10.6) an d com m in u t ion -t yp e lateral m ass fract u res are th e m ost u n st able sit u at ion s. St abilit y of spon dylolysis-t yp e fract u res d ep en d s on t h e rem ain ing soft t issu e inju r y (com p arable to th e h angm an t ype of a xis fract ures). Th e split t yp e of fract ure m ay lead to a pain ful join t , depen ding on th e displacem en t, w ith resu lt ing su b lu xat ion an d join t in congr u en cy. Depending on the instabilit y pat tern, caudalevel stabilizat ion is u sually n ecessar y. Th ere is, h ow ever, n o con sen sus on w h eth er th is sh ould be d on e th rough an an ter ior or a p osterior ap proach . Th e posterior ap proach h as som e biom ech an ical advan tages an d provides direct access to th e root decom pression , w h ereas th e an terior approach elim in ates any problem arising from th e disk t issue an d gen erally resu lts in a m ore lordot ic sp in e align m en t an d a low er in ciden ce of local pain from m u scle dissect ion . In th e oat ing m ass (separat ion ) (Fig. 10.6) and com m inution t ypes of injuries, a t w olevel ar th rodesis is preferable, alth ough if th e com m in u t ion is sligh t an d w ith ou t displacem en t , or if MRI sh ow s a p rist in e u p per level, on e-level (in ferior) surger y m igh t be con sidered 4 ; h ow ever, w ith an terior fu sion , on e-level su rger y in separat ion t ypes of inju ries som et im es yields an u n sat isfactor y outcom e.7 As a gen eral ru le, su rgical t reat m en t is preferred in isolated facet injuries, even in u n disp laced facet fract u res.5 In ad d it ion to local in st abilit y, t h ere is ar t icu lar in con gr u en ce if th e ar t icular surfaces are dam aged (split t ype, sagit tal or coron al, or com m in u t ion t yp e). Never th eless, con ser vat ive treat m en t can be con sidered in sup erior facet fract ures (th e m ost com m on ) if th ere is en ough of th e facet join t left to p reven t d isp lacem en t . Sp ector et al17

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a

b

c

d

Fig. 10.6a–d Patient presented with a separationt ype fracture ( oating mass) at C4 on the left side at the caudal level. Treatment entailed one-level surgery (C4-C5). (a) Admission lateral radiograph.

(b) Computed tom ography axial scan. (c) Anteroposterior radiograph at 5-year follow-up. (d) Lateral radiograph at 5-year follow-up.

suggest th at if th e fract u re lin e lies h igh er th an 40%of the facet height, this is, the fracture fragm en t is less th an 60%of th e facet h eigh t or if it s absolute ver t ical h eigh t is less th an 1 cm , th en th e facet rem n an t th at rem ain s at t ach ed to th e

lateral m ass is su cien t to m ain t ain segm en tal stabilit y. How ever, one sh ould consider th at th e ALL an d th e disk are inju red at th e in ferior level in abou t t w o th irds of pat ien t s an d at t h e up per level in on e fou r th to on e th ird of pat ien ts.4

Facet and Lateral Mass Fractures In ch oosing bet w een an an terior or a posterior ap proach , a carefu l evalu at ion of th e disk is m an dator y. If th ere is radiculopathy at th e level of inju r y, an terior dist ract ion h as been reported to op en th e foram en , bu t if th ere is a displaced facet fract u re it m igh t be m ore con ven ien t to perform a direct root decom p ression via a posterior app roach .8

■ Chapter Summary Th e lateral m ass as an an ch orage colu m n of th e cran ial an d caudal facet join t s is a cr ucial load-bearing st r u ct u re. We can categorize th e injuries in t h ese st ru ct u res as lateral m ass body or pars in terar t icu laris fract ures an d facet injuries. Th e form er are cau sed m ostly by exten sion m ech an ism s, w h ereas th e lat ter are caused by rot at ion m ech an ism s. Som e u n displaced facet fract ures, such as a sm all “t ip” fract u re or u n ilateral stable sp on dylolysis, can be t reated n on su rgically. Usually th ere are accom panying soft t issue injuries, esp ecially at th e cau dal fu n ct ion al sp in al un it (e.g., C6- C7 for a C6 lateral m ass fracture), that render the segm ent unstable to som e exten t . In th ese cases su rgical st abilizat ion is in dicated. Surger y can be perform ed from eith er an an terior or a posterior approach . In gen eral, an terior recon st r uct ion ach ieves bet ter kyph osis cor rect ion an d h as few er com p licat ion s en tailing p ain or in fect ion , w h ereas p osterior in st r um en t at ion s (screw s an d rods) ren der a m ore m ech an ically st able scen ario an d can in clu de a root decom p ression u n d er direct visu alizat ion if n eeded. Th e ch oice of approach also

dep en ds on th e inju red st ru ct u res. If th ere is a severe d isk inju r y, t h e an ter ior ap p roach is preferable. On e-level su rger y is possible eith er from an anterior (som e separation and alm ost any other lateral m ass t yp e except com m in u t ion ) or a posterior app roach . In com m in u t ion or displaced split t yp es of inju ries, t w o-level su rgical st abilizat ion sh ou ld be con sidered.

Pearls For the majorit y of lateral m ass fractures, surgical stabilization is indicated. If there is substantial injury to the caudal level, consider surgery even in nondisplaced facet fractures. Asym metry bet ween joints as seen on anteroposterior radiographs or coronal CT reconstructions are signs of mechanical instabilit y. A superior facet fracture with radicular symptoms and an intact contralateral joint can be treated posteriorly and unilaterally. If there is a clear and serious disk injury, choose an anterior approach. Carefully review the injury pat tern and the dam aged structures to decide whether surgery is needed; if it is, determine which approach to use and how m any levels need to be treated. Consider the possibilit y of a vertebral artery injury, especially if the foramen transversarium is involved or in ankylosing diseases. Pitfalls Failure to diagnose facet and lateral m ass fractures in a polytrauma patient. Initial radiograms should include lateral projections. If the radiograms are inconclusive, obtain CT scans with m ultiplanar reconstructions. Consider a facet fracture as stable just because it is undisplaced.

Refere nces Five Must-Read Refe rences 1. Bon o CM, Sch oen feld A, Gu pt a G, et al. Reliabilit y an d reproducibilit y of subaxial cer vical injur y descrip t ion system : a st an dardized n om en clat ure sch em a. Spin e 2011;36:E1140–E1144 PubMed 2. Patel AA, Vaccaro AR, An derson PA. Classi cat ion of cer vical spine injur y. In: Bridwell KH, DeWald RL, eds.

Th e textbook of spin al surger y, 3rd ed. Philadelph ia: Lippin cot t William s & Wilkin s; 2011:1381–1389 3. Torg JS, Sen n et t B, Vegso JJ, Pavlov H. Axial loading injuries to th e m iddle cer vical spin e segm en t . An an alysis an d classi cat ion of t w en t y- ve cases. Am J Spor t s Med 1991;19:6–20 Pu bMed

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Chapter 10 4. Kot an i Y, Abu m i K, Ito M, Min am i A. Cer vical sp in e injuries associated w ith lateral m ass and facet join t fract ures: n ew classi cat ion an d surgical t reat m en t w ith pedicle screw xat ion . Eur Spine J 2005;14:69– 77 Pu bMed 5. Aarabi B, Mir vis S, Sh an m uganath an K, et al. Com parat ive e ect iveness of su rgical versus n on operat ive m an agem en t of un ilateral, n on displaced, subaxial cer vical spin e facet fract u res w ith ou t eviden ce of spin al cord injur y: clin ical ar t icle. J Neurosurg Spin e 2014;20:270–277 PubMed 6. Ivan cic PC. Biom ech an ics of sport s-in duced axialcom pression injuries of th e n eck. J Ath l Train 2012; 47:489–497 Pu bMed 7. Lee SH, Su ng JK. Un ilateral lateral m ass-facet fract u res w ith rot at ion al inst abilit y: n ew classi cat ion an d a review of 39 cases t reated con ser vat ively an d w ith single segm en t an terior fusion . J Trau m a 2009;66: 758–767 PubMed 8. Ulloa MA. Un ilateral facet dislocat ion s w ith radiculopathy: on e sid e is en ough . Proc Global Spin e Con gress 2013;A222 9. Lee C, Woodring JH. Sagit t ally orien ted fract ures of th e lateral m asses of th e cer vical ver tebrae. J Trau m a 1991;31:1638–1643 PubMed 10. Yet kin Z, Osbor n AG, Giles DS, Haugh ton VM. Un cover tebral an d facet join t dislocat ion s in cer vical art icular pillar fract ures: CT evaluat ion . AJNR Am J Neuroradiol 1985;6:633–637 PubMed

11. Lebl DR, Bon o CM, Velm ah os G, Metkar U, Nguyen J, Harris MB. Vertebral arter y injur y associated w ith blu n t cer vical spin e t rau m a: a m u lt ivariate regression analysis. Spin e 2013;38:1352–1361 PubMed 12. Gupt a P, Kum ar A, Gam angat t i S. Mech an ism an d pat tern s of cer vical sp in e fract u res-dislocat ion s in ver tebral ar ter y inju r y. J Cran iover tebr Ju n ct ion Spin e 2012;3:11–15 Pu bMed 13. Mueller CA, Peters I, Podlogar M, et al. Ver tebral arter y injuries follow ing cer vical spin e t raum a: a prospect ive obser vat ion al st udy. Eur Spin e J 2011;20: 2202–2209 Pu bMed 14. In am asu J, Guiot BH. Vertebral arter y injur y after blun t cer vical t raum a: an update. Surg Neurol 2006; 65:238–245, discussion 245–246 Pu bMed 15. Willis BK, Greiner F, Orrison W W, Ben zel EC. Th e in ciden ce of vertebral arter y injur y after m idcer vical spin e fract u re or su blu xat ion . Neu rosu rger y 1994; 34:435–441, discussion 441–442 Pu bMed 16. Veras LM, Pedraza- Gu t iérrez S, Castellanos J, Capellades J, Casam itjan a J, Rovira-Cañ ellas A. Ver tebral arter y occlusion after acute cer vical spine t raum a. Spin e 2000;25:1171–1177 PubMed 17. Spector LR, Kim DH, A on so J, Albert TJ, Hilibran d AS, Vaccaro AR. Use of com puted tom ography to predict failu re of n on op erat ive t reat m en t of u n ilateral facet fract u res of th e cer vical spin e. Spin e 2006; 31:2827–2835 PubMed

11 Cervical Dislocations (AO Type -C Injuries) William Muñoz, Michael J. Vives, and Saad B. Chaudhary

■ Introduction Cer vical facet dislocat ion s are p ar t of a sp ect ru m of inju ries th at in clu d e ligam en tou s in ju r y, facet su blu xat ion an d d islocat ion , an d fract ure. Th ese su baxial cer vical spin e injuries are m ost frequen tly seen in young m en w h o su ered a h igh -en ergy t rau m a, su ch as a m otor veh icle acciden t , a fall from a h eigh t , or a sp or t s injur y. How ever, th is inju r y can also occu r in th e elderly after a low -en ergy t rau m a, especially in th ose w ith preexist ing degen erat ive path ology, spin al sten osis, an d osteop orosis. Cer vical facet dislocat ion s are serious injuries th at m u st be d iagn osed qu ickly an d t reated u rgen tly. Th e goals of t reat m en t for cer vical facet dislocations are protecting the spinal cord, decom p ressing th e n eu rologic elem en ts, an d restoring m ech an ical stabilit y to th e sp in al colu m n . Th e d e n it ive t reat m en t of th ese inju ries t ypically involves su rgical m an agem en t by an an terior, posterior, or com bin ed approach , depen ding on th e t yp e of inju r y, th e n eurologic st at u s, an d th e p at ien t’s m edical com orbidit ies an d con com itan t inju ries.

■ Classif cation Th e m ost w idely u t ilized classi cat ion system of cer vical fract u res an d dislocat ion s w as orig-

in ally d escr ibed in 1982 by Allen et al.1 Th is classi cat ion system in corp orates th e m ech an ism of injur y as w ell as th e posit ion of th e sp in e at th e t im e of inju r y, both in ferred by static post injur y radiograph s. Facet dislocat ions are classi ed as dist ract ive exion inju ries an d su bclassi ed as follow s: stage I, facet su blu xat ion ; stage II, u n ilateral facet dislocat ion (Fig. 11.1); stage III, bilateral facet dislocat ion s w ith 50% displacem en t (Fig. 11.2); st age IV, com plete dislocat ion . Desp ite th e w id espread u se of th is classi cat ion system , it h as been recogn ized th at sim ilar injur y pat tern s could be produced by di ering m ech an ism s. Th e Suba xial Cer vical Spin e Injur y Classi cat ion (SLIC) w as d escr ibed m ore recen tly by Vaccaro et al.2 Th is system focu ses on t h ree m ajor injur y characterist ics th at are crit ical to clin ical decision m aking: inju r y m orph ology, th e in tegrit y of th e diskoligam en tous com plex, an d th e p at ien t’s n eu rologic st at u s. A severit y scale is applied w ith in each categor y (Table 11.1), w ith th e sum of th e th ree scores being th e com posite score. SLIC scores below 4 u su ally can be m an aged con ser vat ively. A score ≥ 5 in dicates surgical m an agem en t , w h ereas a score of 4 can be t reated eith er con ser vat ively or surgically. Th e AO (Arbeit sgem ein sch aft fü r Osteosyn thesefragen) Spine Foundation has recently prop osed a n ew classi cat ion system for cer vical injuries. Prim ary injur y t ypes are categorized

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Chapter 11

a

b

c

d

Fig. 11.1a–d (a) Lateral radiograph of a patient in traction for a unilateral facet dislocation. Note the 25% translation of C5 on C6. (b) Sagit tal m agnetic resonance im aging (MRI) of the same patient after an unsuccessful at tempt at closed reduction. Note

the extruded disk material posterior to the C5 vertebral body. (c) Lateral intraoperative uoroscopy during open reduction after diskectomy. (d) Lateral uoroscopy after structural bone grafting and anterior plating.

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Cervical Dislocations (AO Type-C Injuries)

a

b

c

d

Fig. 11.2a–d (a) Lateral radiograph of an elderly wom an with bilateral facet dislocation after a fall. (b) Because the patient was neurologically intact, MRI was performed. It showed stripping of the

posterior longitudinal ligament but no associated disk herniation. (c) Lateral radiograph after awake closed reduction. (d) Postoperative lateral radiograph after posterior C5–C6 fusion.

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Chapter 11 Table 11.1 Subaxial Cervical Spine Injury Classif cation (SLIC) and Severity Scale Category

Subcategory

Morphology

No abnormalit y Compression Burst Distraction (e.g., facet patch, hyperextension) Rotation/translation (e.g., facet dislocation, unstable teardrop, or advanced-stage exion compression injury) Intact

Diskoligam entous complex (DLC)

Neurologic status

Points

Indeterminate (e.g., isolated interspinous widening, MRI signal change only) Disrupted (e.g., widening of disk space, facet patch, or dislocation) Intact Root injury Complete cord injury Incomplete cord injury Continuous cord compression in set ting of neurologic de cit (neurologic m odi er)

0 1 2 3 4 0 1 2 0 1 2 3 +1

Source: Adapted from Vaccaro AR, Hulbert RJ, Patel AA, et al. The subaxial cervical spine injury classi cation system . A novel approach to recognize the importance of m orphology, neurology, and integrit y of the disco-ligamentous complex. Spine 2007;32:2365–2374.

as com pression (t ype A), distraction (t ype B), and t ran slat ion (t ype C). Dislocat ion s are th erefore classi ed as C t yp e inju ries, becau se dislocat ion of th e facet t ypically resu lt s in t ran slat ion of on e ver tebral body relat ive to an oth er (Table 11.2). Facet inju ries are also in dicated after th e prim ar y inju r y is stated by app en ding an “F” to level 1 to 4 in p aren th eses. Facet su blu xat ion , perch ing, or dislocat ion s are F4. A “BL” m odier in dicates bilateral inju r y. For exam ple, a C6–7 bilateral facet dislocat ion resu lt ing in an terolisth esis of C6 on 7 w ou ld be classi ed as C6–7:C (F4 BL) If th ere are di eren t facet injuries at th e sam e level, th e righ t is described rst , an d th en th e left . For exam ple, a C6- C7 t ran slat ion al in jur y (t ype C) w ith righ t-sided facet dislocat ion (F4) an d a left-sided displaced facet fract ure (F2) w ould be classi ed as C6-C7:C (F4, F2)

■ Clinical Presentation Facet join t inju ries are u su ally cau sed by h igh en ergy t rau m a, su ch as a m otor veh icle accid en t , a fall from a h eigh t , or a sp or t s inju r y. Pat ien t s often com plain of axial n eck pain , an d m ay h ave paresth esia, p alsy, or w eakn ess at th e level of th e exit ing n er ve root .3 Pat ien ts m ay also h ave in com p lete or com p lete spin al cord injur y.4

■ Imaging Pat ien t s w ith suspected cer vical sp in e t raum a w ere t radit ion ally evaluated w ith radiograph s, w h ich in clude an teroposterior (AP), lateral, an d open -m outh odon toid view s.5 Th e en t ire cer vical spin e from occiput to th e top of T1 sh ou ld be visu alized an d evalu ated for inju r y. Com puted tom ography (CT) in creasingly is accepted as th e rst-lin e im aging for pat ien ts w ith cervical spine injur y, due to its w idespread

Cervical Dislocations (AO Type-C Injuries) Table 11.2 AO Cervical Spine Classif cation System Primary Injury Compression injuries

Type

Subtype

Description

A0

A1

A2

A3 A4 Distraction injuries

Translational injuries

B1 B2

Posterior tension band injury (bony) Posterior tension band injury (bony capsuloligamentous, ligamentous)

B3

Anterior tension band injury

C

No bony injury or minor injury such as an isolated lam ina fracture or spinous process fracture Compression fracture involving a single end plate without involvement of the posterior wall of the vertebral body Coronal split or pincer fracture involving both end plates without involvement of the posterior wall of the vertebral body Burst fracture involving a single end plate with involvement of the posterior vertebral wall Burst fracture or sagit tal split involving both end plates Physical separation through fractured bony structures only Complete disruption of the posterior capsuloligamentous or bony capsuloligamentous structures together with a vertebral body, disk, and/or facet injury Physical disruption or separation of the anterior structures (bone/disk) with tethering of the posterior elem ents Translational injury in any axis displacement or translation of one vertebral body relative to another in any direction

Subgroup Facet injuries

F1 F2 F3 F4 BL

Nondisplaced facet fracture with fragment < 1 cm in height, < 40% of lateral m ass Facet fracture with fragment > 1 cm, > 40% lateral m ass, or displaced Floating lateral mass Pathologic subluxation or perched/dislocated facet Bilateral injury

availabilit y an d in creased abilit y over conven t ion al rad iograp h s to id en t ify inju r y of t h e cer vical sp in e.6 CT provides excellen t osseous det ail of th e cer vical sp in e, esp ecially if th e pat ien t is obese or w h en evalu at ing th e low er cer vical spin e w h ere radiograph s can be subopt im al. Axial im ages facilitate detect ion of associated fract u res of th e lam in a, lateral m ass, or pedicles.7 Reform at ted im ages in th e sagit t al an d coron al plan es en able evalu at ion of th e relat ive posit ion of th e facet join t s an d di eren tiate sublu xation from dislocated facets. Magnetic reson ance im aging (MRI) provides opt im al

evaluat ion of th e soft t issues, in cluding th e spin al cord an d n er ve roots, in ter ver tebral disks, an d posterior ligam en t s. MRI also can be used to assess t h e exten t of sp in al sten osis.8 Th e t im ing of obt ain ing MRI is d iscu ssed below (see Treat m en t).

■ Injury Pathomechanics Th e facet join t s are th e on ly t r u e syn ovial join t s in t h e cer vical sp in e. Th e facet cap su les are

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Chapter 11 Fig. 11.3 Axial computed tomography (CT) showing dislocated right-sided facet joint with “reverse ham burger bun” appearance.

sign i can t stabilizers of th e in dividual m ot ion segm en t s. Tran slat ion al inju ries are t ypically th e en d resu lt of forces th at cau se disru pt ion of th e facet com p lex an d in ter ver tebral disk. Th e spect r um of facet dislocat ion s in cludes sublu xat ion s, p erch ed facets, u n ilateral an d bilateral dislocat ion s, an d fract u re dislocat ion s. Facet dislocat ion , w ith associated t ran slat ion of th e ceph alad ver tebra w ith respect to th e caudad ver tebra, is con sid ered t h e m ost severe for m of exion dist ract ion inju r y. Failu re of th e p osterior ligam en tous com plex (PLC) an d in terver tebral disk are seen in th e over w h elm ingly m ajorit y of cases.9 Th e inju r y forces of dist ract ion an d t ran slat ion of th e in ferior facet resu lt in it s com ing to rest an terior to th e su perior facets of th e low er level. Th is h as th e appearan ce of a “reverse ham bu rger bun ” on axial CT (Fig. 11.3). W h en th ere is n o associated fract u re of th e ar t icu lar p illar, th e facets are locked in th e dislocated p osit ion . Un ilateral injuries often resu lt in 25%t ran slat ion (spon dylolisth esis). Th e app aren t t ran slat ion of th e ver tebral body is actually due to rotational displacem en t. Sm all fract u res of eith er t h e su perior or in fer ior facet m ay be p resen t .10 Bilateral facet d islocat ion s h ave less rot at ion al d efor m it y bu t m ore t ran slat ion (50%). Pat ien t s w ith n orm al can al diam eters st ill experien ce 35%can al n arrow ing, w hereas those w ith stenotic canals m ay exp erien ce u p to 88% can al occlusion .11

■ Treatment Initial Management Pat ien t s sh ou ld be m edically stabilized according to th e Advan ced Trau m a Life Su p por t (ATLS) protocol. On ce th e p at ien t is h em odyn am ically st able, t h e sp in al inju r y can be assessed an d t reated . Pat ien t s sh ou ld be p laced on sp in al precau t ion s w ith ou t excessive m an ipu lat ion . Neurologic evaluation should be perform ed and docum en ted in it ially, an d con t in u ously m on itored th rough out th e course of t reat m en t . Th e p at ien t is assessed as n eu rologically in t act , com p lete sp in al cord inju r y, or in com p lete sp in al cord inju r y, w ith or w ith ou t a n er ve root injur y. Initial m anagem ent goals include prevention of fur th er spin al cord dam age an d m in im izing secon dar y inju r y du e to p rolonged com p ression . Tract ion h as gen erally been recogn ized as a safe tech n ique for closed reduct ion in aw ake an d cooperat ive pat ien ts.12 Th e use of MRI to screen for ext r u ded d isk m ater ial p r ior to closed red u ct ion h as been recom m en d ed by som e au th ors.13 Th is recom m en dat ion stem s from a repor t in w h ich a pat ien t su st ain ed a spin al cord injur y from a disk h ern iat ion th at w as presum ed to displace in to th e can al during pron e, open operat ive red u ct ion . To ou r kn ow ledge, h ow ever, n o cases of p erm an en t n eu ro-

Cervical Dislocations (AO Type-C Injuries) logic de cit h ave been reported in aw ake an d aler t p at ien t s w h o h ave u n d ergon e closed red u ct ion . Fu r t h er m ore, t h e in ter p ret at ion of h ern iated disks by MRI in th e con text of facet dislocat ion s is som ew h at su bject ive. A su r vey of m em bers of th e Spin e Traum a St udy Grou p by Grauer et al14 fou n d poor agreem en t (kap pa valu es 0.068–0.159) on w h et h er to p roceed w it h closed or open reduct ion after review ing t h e MRI in var iou s clin ical scen ar ios. After review ing th e MRI, orth op edic su rgeon s w ere sign i can tly m ore likely th an n eu rosu rgeon s to ch oose a closed versus open redu ct ion . Darsau t et al12 rep or ted a p rosp ect ive series of 17 pat ien t s w ith cer vical fract ure dislocat ion s t reated w ith closed redu ct ion u n der serial MRI gu idan ce. Pret ract ion disk disru pt ion w as foun d in 88% of pat ien ts, w ith posterior h ern iat ion in 23% of cases. Tract ion caused a ret u rn of h ern iated d isk m aterial tow ard th e disk space in all cases. As dist ract ing force w as in creased, sequ en t ial MRIs sh ow ed th at can al dim en sion s did n ot d im in ish at any t im e in any pat ien t . Th e auth ors con cluded th at closed redu ct ion of subaxial cer vical fract u re dislocation s is a safe and e cient m ethod to decom p ress t h e sp in al cord t h at d oes n ot resu lt in w orsen ing of h ern iated d isk m aterial or d ecrease th e dim en sion of th e spin al can al. Given th e above n dings, m any au th ors recom m en d early closed red u ct ion of facet d islocat ion s, w ith out delay for MRI, in aw ake an d cooperat ive p at ien t s w ith spin al cord inju ries to redu ce ten sion on th e cord as quickly as possible.15 W h en t ract ion redu ct ion is u n su ccessfu l or n ot preferred du e to an u n coop erat ive or u n con sciou s p at ien t , MRI sh ou ld be p er for m ed to investigate the presence of disk herniation prior to open redu ct ion .

■ Surgical Management Historical Perspective Becau se facet dislocat ion s p rim arily a ect th e posterior bony and ligam entous structures, they h ave t radit ion ally been st abilized using a posterior approach w ith posterior w iring, plate an d screw, h ook plate, an d recen tly rod an d screw

segm ental xation.16 Concerns about associated d isk h ern iat ion 13 an d im proved an terior p late design s h ave led to an in terest in t reat ing th ese inju ries via an anterior ap proach . Nat u ral an atom ic plan es used during th e anterior approach perm it less exten sive m u scle st ripp ing, p oten tially leading to reduced infection rates and less p ostop erat ive p ain .17 Sign i can t con t roversy exists regarding opt im al su rgical t reat m en t for th ese injuries, w ith biom ech an ical an d clin ical dat a being discrep an t (Table 11.3).

Biomechanical Studies Nu m erou s biom ech an ical st u dies h ave sh ow n th at posterior st abilizat ion p rovides in creased st abilit y w h en com p ared w it h an ter ior xat ion . Coe et al18 used a h um an cadaver biom ech an ical m odel to evalu ate variou s st abilizat ion techniques. A distractive exion injury w as sim ulated by disrupting the supraspinous ligam ent, in tersp in ous ligam en t , ligam en t u m avu m , posterior longit udinal ligam ent, facet joint cap su les, an d disrupt ion of th e in ter ver tebral disk to en able bilateral facet dislocat ion . Mult iple constructs were tested biom echanically, including posterior w iring, lateral m ass plates, p osterior h ook p lates, an d an terior n on locked plates. Flexu ral st i n ess an d torsion al st i n ess w ere n ot sign i can t ly d i eren t for all con st r u ct s; h ow ever, t h ere w as a sign i can t in crease in th e posterior st rain during exion an d axial loading, w ith an terior plates com p ared w ith posterior con stru ct s. Th e au th ors con clu d ed th at an terior n on locked p lates are an in ferior m eth od of t reat ing d ist ract ive exion inju ries of th e cer vical spin e w h en com pared w ith posterior xat ion tech n iques. Duggal an d colleagu es 19 st udied variou s xat ion techniques for unilateral facet dislocation s. Rep rodu cible u n ilateral facet dislocat ion s w ere created an d th en reduced in a h um an cadaver m odel. During all m odes of loading, posterior lateral m ass p lates perform ed sign i can tly bet ter th an an terior cer vical diskectom y an d fu sion (ACDF) w ith an an terior n on locking plate in th e m u ltip le m ot ion param eters. Th e auth ors con cluded th at lateral m ass xat ion provides bet ter im m obilization than ACDF w ith an terior n on locking plate for th ese injuries.

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Chapter 11 Table 11.3 Biomechanical and Clinical Studies Study Type

Authors

Experimental Design

Conclusion

Biomechanical

Coe et al18

Cadaver; posterior ligaments, PLL and disk sectioned to create bilateral dislocation; tested posterior wiring, lateral mass plates, and anterior nonlocked plate Cadaver; unilateral dislocation, then reduced Cadaver: tested intact, then after complete diskectomy/ PLL section, then ACDF with locked plate, then complete posterior release (simulated bilateral dislocation) Retrospective, 14 pts; CFS 4-5 or DFS 2–3; Caspar plate and structural bone graft Retrospective, 22 pts; bilateral dislocations–closed reduced; anterior structural graft, with locked unicortical plate Prospective, randomized; 52 pts with unstable cervical injuries and SCI; closed reduced; pat terns amenable to either anterior or posterior approach Retrospective, 41 consecutive pts; traum atic dislocations; all treated with anterior approach

Flexural and torsional sti ness similar for all constructs; increased posterior strain with anterior plate compared with posterior m ethods

Duggal et al19 Paxinos et al20

Clinical

Garvey et al23

Razack et al24

Brodke et al25

Reindl et al22

Song et al26

Johnson et al27

Retrospective, 50 pts with unilateral or bilateral dislocations; 38 treated anterior alone; 12 combined anterior-posterior Retrospective, 87 pts; unilateral or bilateral dislocation or fracture-dislocation; all treated with anterior structural graft/plate

Posterior lateral mass plating > ACDF with nonlocking plate With preload (follower load), ACDF with locked plate e ectively stabilized simulated DFS3 injury

Avg f/u 30 months; no loss of xation; all solid fusion by X-ray Avg f/u 32 months; all pts rated as solid fusion; one instrum entation failure No clinical di erence in outcomes based on approach; 100% fusion in posterior group, 90% in anterior group (not signi cant) Anterior approach successful m ost cases; 25% irreducible by anterior approach and necessitated posterior procedure No signi cant di erence in fusion rate/time, complication rate or clinical results; 3 instrumentation failures in anterior alone group Loss of postoperative alignm ent in 13%; no correlation unilateral vs bilateral; failure correlated with end-plate and facet fractures

Abbreviations: ACDF, anterior cervical diskectomy and fusion; Avg f/u, average follow-up; CFS, compressive exion stage; DFS, distractive exion stage; PLL, posterior longitudinal ligam ent; pts, patients; SCI, spinal cord injury.

Alth ough m any biom ech an ical st udies su p por t p osterior con st ru ct s as being su p erior to an terior procedures, oth er st u dies suggest th at physiological preload h as an im p or tan t stabilizing a ect in th e cer vical sp in e th at is n ot al-

w ays accou n ted for in biom ech an ical st u dies.20 Physiological p reload from m u scle act ivat ion is th ough t to be an im p or t an t st abilizing m ech anism after distraction- exion injuries.21 Results of biom ech an ical st udies th at accoun t for pre-

Cervical Dislocations (AO Type-C Injuries) load sh ow com parable stabilizat ion of an terior an d posterior procedures, w h ich is con sisten t w ith clin ical experien ce.20

Clinical Studies Despite biom ech an ical st u dies su p por t ing p oster ior con st r u ct s, t h e an ter ior ap p roach h as becom e in creasingly popu lar, as it en ables th e surgeon to decom press the spinal canal directly, an d en tails low m orbidit y an d ease of pat ien t p osit ion ing.22 Clin ical st u d ies are gen erally sm all ser ies, bu t t h ey h ave sh ow n accept able clin ical resu lt s in m ost cases of cer vical d islo cat ion t reated by an terior fu sion w ith locked plates. A ret rosp ect ive st u dy of 14 pat ien ts w h o su st ain ed acu te cer vical sp in e fract u res or d islocat ion s w it h associated p oster ior ligam en tou s d isr u pt ion (DFS2 or DFS3) t h at w ere treated w ith anterior decom pression, struct ural bon e graft , an d an terior n on locked plat ing w as con d u cted by Gar vey et al.23 At an average of 30 m on t h s’ follow -u p , t h ey saw n o loss of xat ion , an d solid ar t h rod esis as evalu ated by X-ray in all patients. Another retrospective study of 22 pat ien t s t reated w ith an terior st r u ct u ral graft an d locked u n icor t ical plat ing for bilateral facet fract u re dislocat ion s fou n d on e in st ru m en tat ion -related failure, but all pat ien ts ult im ately h ad solid fusion on the n al follow -up exam in at ion .24 Brod ke et al25 perform ed a p rosp ect ive ran dom ized st u dy of 52 p at ien t s w it h u n st able cer vical inju r ies, w it h associated sp in al cord inju r y, t h at w ere able to be closed redu ced p reop erat ively. All pat ien ts requ ired surgical st abilizat ion , w ith inju r y p at tern s th at w ere am en able to eith er an an ter ior or p oster ior st abilizat ion procedu re. Th e p osterior stabilizat ion group dem on st rated a 100% fusion rate, com p ared w it h a 90% fu sion in t h e an ter ior st abilizat ion grou p , w it h t h e d i eren ce n ot being st at ist ically sign i can t . Th e au t h ors con clu ded th at th ere w ere n o sign i can t differen ces in fusion rates, align m en t , n eurologic recover y, or long-term com p lain t s of pain in pat ien ts t reated w ith eith er an terior or posterior fu sion an d in st ru m en t at ion . An oth er retrospect ive review of 50 p at ien ts t reated w ith

eith er an terior p lat ing an d fu sion (38 p at ien t s) or circum ferential fusion (12 patients) found no sign i can t di eren ces in fu sion rates, com plicat ion rates, an d n eu rologic recover y bet w een th e t reat m en t grou ps.26 Joh n son et al27 review ed th e radiograp h s of 87 p at ien t s w ith u n ilateral or bilateral facet d islocat ion s an d fract u res t reated w ith an terior st ruct ural graft an d plat ing to evaluate factors th at p red isp ose to loss of align m en t . Th ey fou n d t h at loss of p ostop erat ive align m en t occu rred in 13%of th e facet dislocat ion s an d fract ures t reated w ith an terior cer vical diskectom y, fu sion , an d p lat ing. Radiograph ic failu re w as st rongly correlated w ith th e presen ce of en dp late fract ure an d less st rongly w ith facet fract ure on injur y radiograph s. Pseudarth rosis w as correlated w ith th e presen ce of en d-plate fract ure. Th ey did n ot n d an in creased failure rate w hen com paring unilateral to bilateral facet dislocat ion s. Th e auth ors con cluded th at th e presen ce of an en d-plate fract ure or facet fract ure in association w ith a unilateral or bilateral facet fracture dislocation or sublu xation should alert th e su rgeon to a high risk of radiograph ic failu re w ith an terior plat ing alon e, an d th at a prim ar y posterior fusion or a com bin ed an terior/ p osterior approach sh ou ld be con sidered .

Factors Contributing to Treatment Decision Despite the biom echanical and clinical data presen ted above, n o con sen su s exists regarding th e p referred su rgical ap proach to facet dislocat ion s. A su r vey an alysis of 25 m em bers of th e Sp in e Trau m a St u dy Grou p illu st rates th e variat ion s in su rgical t reat m en t for cer vical facet dislocations.28 Mem bers evaluated 10 facet dislocat ion cases an d w ere asked to in d icate th eir preferred su rgical app roach . Poor agreem en t w as obser ved am ong surgeon s in th e ch oice of su rgical app roach (kap p a < 0.1). Th ere w as a trend tow ard an an terior or com bined approach w h en a disk hern iat ion w as presen t . Th e auth ors believe th at th e p oor agreem en t on th e treatm ent of these injuries likely re ects a com bin at ion of factors in cluding surgeon t rain ing and experience. They also suggest that the treat-

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Chapter 11 m en t decision s are likely to be a ected by th e n eurologic st at us of th e pat ien t , in terpretat ion of a disk h ern iat ion , an d th e classi cat ion of th e inju r y as a un ilateral or bilateral inju r y. With few object ive criteria on w h ich to base a t reat m en t decision an d alm ost n o t reat m en t guidelin es, th ere are m ult iple factors to con sider w h en ch oosing a t reat m en t app roach . Factors in clu de su rgeon exp erien ce an d com for t w ith open reduct ion tech n iques, in terpretat ion of MRI n dings, an d associated en d-plate an d facet fract ures. Th e h abit u s of a pat ien t as w ell as th e injur y level also m ay a ect t reatm en t d ecision s, as p rop er in t raop erat ive im ages an d p ostop erat ive w ou n d in fect ion s are con cern s in th ese sit u at ion s.

Fig. 11.4 Suggested treatm ent algorithm.

Treatment Algorithm Th e su rgical m an agem en t of cer vical facet d islocat ion s is h igh ly variable, w ith few gu idelin es to h elp su rgeon s m ake a clin ical decision . Given t h at on ly level IV dat a are available to guide treatm ent, only suggestions can be m ade. By follow in g t h e p r in cip le of “safet y of t h e sp in al cord rst ,” Nassr et al28 an d th e Spin e Trau m a St u dy Grou p proposed an algorith m th at w e h ave sligh tly m odi ed to ser ve as a guide in m an aging th ese injuries (Fig. 11.4). Th is t reat m en t algorith m is based on th e result of at tem pted closed reduct ion , presen ce or absen ce of a t rau m at ic disk h ern iat ion , an d th e injury t ype (unilateral versus bilateral). Th e

Cervical Dislocations (AO Type-C Injuries) rst bran ch poin t w h en u sing th is algorith m is w h eth er or n ot su ccessful closed reduct ion h as been ach ieved before t aking th e pat ien t to th e operat ing room . Cases in w h ich closed reduct ion is n ot at tem pted, du e to th e p at ien t being obt un ded or to con cern s about disk h ern iat ion , are t reated sim ilarly to th ose of un successful closed redu ct ion at tem pt s. Th e oth er p rem ise in using th e suggested algorith m is th at an MRI

125

is obtain ed in all pat ien ts before th ey u n dergo su rger y. Associated disk h ern iat ion seen on MRI dict ates th e p referred m an agem en t after at tem pted closed red uct ion . In cases of suspected disk h ern iat ion , th e u se of an an terior or an terior an d posterior procedu re to decom p ress th e n eu ral elem en t s regard less of t h e p at ien t ’s n eu rologic st at u s is recom m en d ed (Fig. 11.5). If an an ter ior

a

b

c

d

Fig. 11.5a–d (a) Midline MRI demonstrating bilateral facet dislocation with associated disk herniation in a young man with concomitant head injury. (b,c) Parasagit tal MRI cuts demonstrating

bilateral dislocated facets. (d) Postoperative lateral radiograph after anterior diskectomy with open reduction and anterior-posterior fusion.

126

Chapter 11 p rocedure is ch osen as th e in it ial approach in th e presen ce of an u n red u ced dislocat ion th at is du e to disk h ern iat ion , th en an open an terior reduction m ay be attem pted. If an anterior open redu ct ion is su ccessfu l, it can be follow ed by an an terior fusion an d in st rum en tat ion . If an attem pted an terior open redu ct ion is u n su ccessfu l, th en a su bsequ en t posterior op en redu ct ion an d stabilizat ion is required. Th e presen ce of bilateral facet dislocation often signi es a higher en ergy injur y, an d som e au th ors favor th e addit ion of p osterior xat ion du e to th e loss of redu ct ion occasion ally seen w ith an terior-on ly procedu res.28 In cases of un successful closed reduct ion for bilateral facet dislocat ion w ith n o disk h ern iat ion , a st an d -alon e p osterior p roced u re is a reason able opt ion . In th is sit u at ion , m any su rgeon s w ould rein force an an terior procedure w ith addit ion al posterior xat ion , so a stan dalon e posterior procedure en t ails less surger y for th e pat ien t . Th is scen ario in th e set t ing of com p lete spin al cord inju r y h ad th e h igh est tenden cy for a posterior approach in th e Spin e Trau m a St u dy Grou p su r vey.28 In ou r op in ion , if redu ct ion is to be don e p osteriorly, th ere sh ou ld be n o qu est ion as to w h eth er th ere is any “at r isk” d isk m ater ial th at cou ld p oten t ially lead to cord com pression an d n eu rologic deterioration . Open posterior reduct ion is done w ith th e pat ien t in th e pron e posit ion , m aking it di cult to obtain con t rolled dist ract ion an d, th erefore, m ore likely to d rag disk m aterial in to th e can al. An terior open redu ct ion h as been sh ow n to be an e ect ive surgical option for pat ien t s w h o fail closed reduction.22 Follow ing com plete diskectom y, gradu al dist ract ion w ith Gard n erWells ton gs or Casp er ret ractor p in s is at tem pted . If fur th er dist ract ion is n eeded, a lam in ar sp reader in th e a ected disk space is used to disengage t h e facets. Redu ct ion is su ccessfully ach ieved in th e m ajorit y of dislocat ion s w ith cep h alad rotat ion to t ran slate th e an teriorly dislocated ceph alad ver tebral body p oster iorly u n d er u oroscop ic gu idan ce. An ter ior op en redu ct ion an d st abilizat ion m on itored by spin al cord evoked poten t ials h as been sh ow n to be an e ect ive an d safe m eth od for

t reat m en t in p at ien t s w ith ou t or w ith a m ild spinal cord injury.29 Unilateral dislocations m ay requ ire op en rotat ion al m an ipu lat ion sim ilar to closed reduct ion tech n iqu es to successfully at tain redu ct ion . Failu re to ach ieve an terior open redu ct ion h as been repor ted in u p to 25% of at tem pted cases.22 A su rgical tech n iqu e successfu lly used in th e t reat m en t of pat ien ts w ith fract ure dislocat ion s t h at are ir red u cible t h rough an an terior open approach w as described by Allred an d Sledge.30 After diskectom y an d en d-p late prep arat ion , a t ricor t ical bon e graft w as h arvested from th e iliac crest , placed in th e in terspace, an d h eld w ith a but t ress plate screw ed in t w o p laces in to th e sup erior ver tebral body. Th e an terior w ou n d th en w as closed, an d t h e posterior elem en t s w ere exposed an d th e facet s reduced by exing th e n eck an d posteriorly t ran slat ing th e su p erior segm en t . Flu oroscopy w as used during th e reduct ion to en sure th at th e graft w as pu lled in to th e in terspace, th at th e screw s in th e bu t t ress p late did n ot p u ll ou t of th e su perior ver tebral body, an d th at th e redu ced graft did n ot im p inge on th e spin al cord. Posterior fu sion w as p erform ed an d th e p osterior w ou n d closed. Th is tech n iqu e elim in ates th e n eed for a th ird p rocedu re to com p lete an terior stabilization after posterior reduction and fu sion for a failed an terior redu ct ion .

Vertebral Artery Injury Ver tebral ar ter y injur y (VAI) m ay presen t as a spect ru m of injur y from rem ain ing clin ically silen t to posterior circu lat ion st roke, qu ad riplegia, an d death . Bet w een 70%an d 78%of VAIs occu r in associat ion w ith a cer vical spin e in jur y, an d VAI h as been rep or ted to be presen t in 19 to 39% of cer vical spin e fract u res.31 Th e relat ively h igh reported in ciden ce of VAI an d th e w id e ar ray of p ossible clin ical sequ elae m ake early id en t i cat ion of t h ese h igh -r isk p at ien t s essen t ial. A VAI can occu r as an in t im al tear, a d issect ion , a p seu d oan eu r ysm , an occlu sion , or a t ran sect ion . In t im al tears en tail th e torn in t im a occasion ally sw inging in to an d occlu ding th e vessel lu m en . Ar terial dissect ion en t ails th e

Cervical Dislocations (AO Type-C Injuries) possibilit y th at blood m igh t collect in th e ar terial w all an d create a false lu m en th at can ob st r u ct th e ar terial lu m en , resu lt ing in th rom bu s form at ion . A pseu doan eur ysm m ay form outside of th e ar terial w alls, an d, if large en ough , can im p inge an d obst r u ct th e ar ter y. Tran sect ion is th e m ost severe form of VAI an d can lead to death . Pat ien t s w h o are at h igh risk for a VAI sh ou ld be screen ed at in it ial presen tat ion , in cluding pat ien ts w ith basilar sku ll fract u res, occip itocer vical dissociat ion s, fract u re displacem en t into the transverse foram en of m ore than 1 m m , an kylosing spon dylit is/di use idiopath ic skeletal hyperostosis, and cervical facet subluxation/ dislocat ion s.32 Angiography w as t radit ion ally con sidered th e “gold st an dard” for diagn osis of VAI. Recen t st udies h ave d em on st rated th e less invasive m u lt idetector com pu ted tom ograp hy angiogram (MDCTA) to be an e ect ive screen ing tool w ith detect ion rates sim ilar to th ose of angiography,33 m aking it th e prim ar y m eth od for diagn osis at m any t rau m a cen ters. Treat m en t of sym ptom at ic VAI in cludes an t icoagu lat ion , blood pressure con t rol, th rom bolyt ic th erapy, an d en dovascu lar or su rgical p roced u res. Th ere is n o con sen su s in t h e literat u re, h ow ever, regard in g t h e ben e t of an t icoagu lat ion versu s an t ip latelet t h erapy for asym ptom at ic cer vical ar ter ial d issect ion .32,34 Low -d ose system ic h ep ar in th erapy w ith a par t ial th rom bop last in t im e goal of 40 to 50 secon ds w as recom m en ded by Bi et al.35 Th is is follow ed by oral an t icoagu lat ion th erapy for 3 to 6 m on th s or un t il angiography results h ave ret u rn ed to n orm al. Pat ien t s u n able to receive h eparin are t reated w ith an t iplatelet th erapy in it s p lace. Many cen ters em p loy oral an t iplatelet th erapy for 3 m on th s in pat ien ts w ith VAI requ iring su rgical m an agem en t of th eir spin al injuries to decrease th e risk of stroke an d m it igate th e risk of postsurgical bleeding com p licat ion s.

■ Chapter Summary Cer vical facet dislocat ion s are par t of a broad spect ru m of injuries an d en com pass a variet y of inju r y p at ter n s. Th ese p at ien t s m u st be t reated u rgen t ly an d carefu lly, w it h st abilizat ion an d p rotect ion of th e cer vical sp in e. Con ven t ion al an d advan ced im aging tech n iqu es provide excellent visualizat ion of th e injur y an d associated n eurologic com pression . Select ion of th e appropriate t reat m en t is based on th e goals of providing m ech an ical stabilit y to th e spin al colum n an d n eu rologic decom pression . Su rgical in ter ven t ion can be don e by an an ter ior, p oster ior, or com bin ed ap p roach . Th is d ecision is m ade based on several factors, in cluding th e t ype of injur y, th e n eurologic stat u s, an d th e p at ien t’s m edical com orbid it ies an d con com itan t inju ries.

Pearls Careful history and physical exam ination, along with advanced imaging m odalities, including CT and MRI, should be used to identify the t ype and extent of injury. Closed reduction of cervical facet dislocation can be at tempted in the awake, alert, and cooperative patient. These injuries can be treated successfully surgically by an anterior, posterior, or combined approach, and should be based on the success of closed reduction in the presence of disk herniation. Pitfalls An MRI should be obtained prior to any surgical intervention. When an associated herniated disk is present, an anterior diskectomy and open reduction is favored over open posterior reduction. Vertebral artery injury is associated with cervical facet dislocations, so these patient s should be screened and treated appropriately when detected.

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Chapter 11 Refe re nces Five Must-Read Refe rences 1. Allen BL Jr, Ferguson RL, Leh m an n TR, O’Brien RP. A m echan ist ic classi cat ion of closed, in direct fract ures an d dislocat ion s of the low er cer vical spin e. Spin e 1982;7:1–27 PubMed 2. Vaccaro AR, Hulbert RJ, Patel AA, et al; Spin e Traum a St u dy Grou p. Th e su baxial cer vical sp in e inju r y classi cat ion system : a n ovel approach to recogn ize th e im por t an ce of m orph ology, n eurology, an d in tegrit y of th e disco-ligam en tous com plex. Spin e 2007;32: 2365–2374 Pu bMed 3. Jacobs B. Cer vical fract u res an d dislocat ion s (C3-7). Clin Orth op Relat Res 1975;109:18–32 PubMed 4. Boh lm an HH. Acute fract ures an d dislocat ion s of the cer vical spin e. An an alysis of th ree h un dred h ospit alized p at ien t s an d review of th e literat u re. J Bon e Join t Su rg Am 1979;61:1119–1142 PubMed 5. Harris JH, Ed eiken -Mon roe B. Th e Rad iology of Acu te Cer vical Spin e Trau m a. Balt im ore: William s & Wilkin s; 1987 6. Brow n CV, An tevil JL, Sise MJ, Sack DI. Spiral com p u ted tom ograp hy for t h e d iagn osis of cer vical, t h oracic, an d lu m bar sp in e fract u res: it s t im e h as com e. J Trau m a 2005;58:890–895, discussion 895– 896 PubMed 7. Sh an m ugan ath an K, Mir vis SE, Levin e AM. Rot at ion al injur y of cer vical facet s: CT an alysis of fract ure patter n s w it h im p licat ion s for m an agem en t an d n eu rologic ou tcom e. AJR Am J Roen tgen ol 1994;163: 1165–1169 Pu bMed 8. Vaccaro AR, Madigan L, Sch w eit zer ME, Flan ders AE, Hilibran d AS, Alber t TJ. Magn et ic reson an ce im aging an alysis of soft t issue disru pt ion after exion -dist ract ion injuries of th e subaxial cer vical spin e. Spine 2001;26:1866–1872 PubMed 9. Vaccaro AR, Nach w alter RS. Is m agn et ic reson an ce im aging in dicated before reduct ion of a un ilateral cer vical facet dislocat ion ? Spin e 2002;27:117–118 PubMed 10. Holdsw orth F. Fract ures, dislocat ion s, an d fract uredislocat ion s of th e sp in e. J Bon e Join t Su rg Am 1970; 52:1534–1551 PubMed 11. Ivan cic PC, Pearson AM, Tom inaga Y, Sim pson AK, Yue JJ, Panjabi MM. Mechanism of cer vical spinal cord injur y during bilateral facet dislocat ion. Spin e 2007; 32:2467–2473 Pu bMed 12. Darsaut TE, Ash forth R, Bh argava R, et al. A pilot st udy of m agn et ic reson an ce im aging-guided closed reduct ion of cer vical spin e fract ures. Spin e 2006;31: 2085–2090 PubMed 13. Eism on t FJ, Aren a MJ, Green BA. Ext r u sion of an in ter vertebral disc associated w ith t rau m at ic subluxat ion or dislocat ion of cer vical facet s. Case report . J Bon e Join t Surg Am 1991;73:1555–1560 PubMed 14. Grau er JN, Vaccaro AR, Lee JY, et al. Th e t im ing an d in uen ce of MRI on th e m an agem en t of pat ien t s

w ith cer vical facet dislocat ion s rem ain s highly variable: a su r vey of m em bers of th e Sp in e Trau m a St u dy Group. J Spin al Disord Tech 2009;22:96–99 Pu bMed 15. Wing P, Dalsey W, Alvarez E. Early acute m an agem en t in ad u lt s w it h sp in al cord inju r y: a clin ical pract ice gu idelin e for h ealth care p rofession als. Con sor t ium for spin al cord m edicine guidelin e. 2008;31: 408–479 16. Grah am AW, Sw an k ML, Kin ard RE, Low er y GL, Dials BE. Posterior cer vical ar th rodesis an d st abilizat ion w ith a lateral m ass plate. Clin ical an d com puted tom ograph ic evalu at ion of lateral m ass screw placem en t an d associated com plicat ion s. Spin e 1996;21: 323–328, discu ssion 329 PubMed 17. Kw on BK, Fish er CG, Boyd MC, et al. A prospect ive ran dom ized con t rolled t rial of an terior com pared w ith posterior st abilizat ion for un ilateral facet inju ries of the cer vical spine. J Neurosurg Spin e 2007;7: 1–12 PubMed 18. Coe JD, Warden KE, Sut terlin CE III, McAfee PC. Biom ech an ical evaluat ion of cer vical spin al st abilizat ion m eth ods in a h um an cadaveric m odel. Spin e 1989; 14:1122–1131 Pu bMed 19. Duggal N, Ch am berlain RH, Park SC, Son nt ag VK, Dickm an CA, Craw ford NR. Un ilateral cer vical facet dislocat ion : biom ech an ics of xat ion . Spin e 2005;30: E164–E168 Pu bMed 20. Pa xin os O, Gh an ayem AJ, Zin dr ick MR, et al. An ter ior cer vical d iscectom y an d fu sion w it h a locked p late an d w edged graft e ect ively st abilizes exion d ist ract ion st age-3 inju r y in t h e low er cer vical sp in e: a biom ech an ical st udy. Spin e 2009;34:E9–E15 PubMed 21. Hen riqu es T, Olerud C, Bergm an A, Jón sson H Jr. Dist ract ive exion injuries of th e subaxial cer vical spin e t reated w ith an terior plate alon e. J Spinal Disord Tech 2004;17:1–7 PubMed 22. Reindl R, Ouellet J, Har vey EJ, Berr y G, Arlet V. An terior reduct ion for cer vical spin e dislocat ion . Spin e 2006;31:648–652 Pu bMed 23. Gar vey TA, Eism on t FJ, Robert i LJ. An terior decom pression , st ruct ural bone graft ing, an d Caspar plate st abilizat ion for un st able cer vical sp in e fract u res an d/or dislocat ion s. Spin e 1992;17(10, Suppl):S431– S435 PubMed 24. Razack N, Green BA, Levi AD. Th e m an agem en t of t raum at ic cer vical bilateral facet fract ure-dislocat ion s w ith un icort ical an terior plates. J Spinal Disord 2000;13:374–381 PubMed 25. Brodke DS, An derson PA, New ell DW, Grady MS, Ch apm an JR. Com parison of an terior and posterior ap p roach es in cer vical sp in al cord inju ries. J Sp in al Disord Tech 2003;16:229–235 PubMed 26. Song KJ, Lee KB, Kim SR. Availabilit y of an terior cervical p lat ing according to th e severit y of inju r y in

Cervical Dislocations (AO Type-C Injuries) dist ract ive exion inju r y in low er cer vical sp in e. J Korean Or th op Assoc 2005;40:195–202 27. Joh n son MG, Fish er CG, Boyd M, Pit zen T, Oxlan d TR, Dvorak MF. Th e rad iograp h ic failu re of single segm en t an terior cer vical plate xat ion in t rau m at ic cer vical exion dist ract ion inju ries. Spin e 2004;29: 2815–2820 Pu bMed 28. Nassr A, Lee JY, Dvorak MF, et al. Variat ion s in surgical t reat m en t of cer vical facet dislocat ion s. Spin e 2008;33:E188–E193 Pu bMed 29. Du W, Wang C, Tan J, Sh en B, Ni S, Zh eng Y. Man agem ent of subaxial cer vical facet dislocat ion th rough an terior ap p roach m on itored by sp in al cord evoked poten t ial. Sp in e 2014;39:48–52 Pu bMed 30. Allred CD, Sledge JBC. Irreducible dislocat ion s of th e cer vical spin e w ith a prolapsed disc: prelim in ar y result s from a t reat m en t tech n ique. Spin e 2001;26: 1927–1930, discu ssion 1931 Pu bMed 31. Bi W L, Ray CE Jr, Moore EE, et al. Treat m en t-related ou tcom es from blun t cerebrovascular injuries: im -

por t an ce of rout in e follow -up ar teriography. Ann Surg 2002;235:699–706, discussion 706–707 PubMed 32. Lebl DR, Bon o CM, Velm ah os G, Metkar U, Nguyen J, Harris MB. Ver tebral ar ter y injur y associated w ith blun t cer vical spin e t rau m a: a m ult ivariate regression analysis. Spin e 2013;38:1352–1361 PubMed 33. Paulus EM, Fabian TC, Savage SA, et al. Blun t cerebrovascular inju r y screen ing w ith 64-ch an n el m u lt idetector com puted tom ography: m ore slices n ally cut it . J Traum a Acute Care Surg 2014;76:279–283, discu ssion 284–285 PubMed 34. Ken nedy F, Lanfranconi S, Hicks C, et al; CADISS Investigators. Antiplatelets vs ant icoagulation for dissection: CADISS non ran dom ized arm and m eta-an alysis. Neurology 2012;79:686–689 Pu bMed 35. Bi W L, Moore EE, Elliot t JP, et al. Th e devast at ing potent ial of blunt vertebral arterial injuries. Ann Surg 2000;231:672–681 Pu bMed

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12 Cervicothoracic Junction Injuries Ripul Rajen Panchal

■ Introduction Injuries to th e cer vicoth oracic jun ct ion (CTJ) are rare. Alth ough th e repor ted in ciden ce of CTJ inju r y ranges from 2 to 9% of all cer vical spin al t raum as,1–3 th e t r u e in ciden ce is di cult to determ in e due to failures to diagn ose a CTJ injur y on in it ial evaluat ion . In pat ien t s w h o are diagn osed, the prevalen ce of n eu rologic im p air m en t is h igh (59–83%).1,2,4 Th e m ost com m on cau ses of CTJ inju ries are m otor veh icle acciden ts an d falls from a h eigh t th at result in fract u re-dislocat ion (Fig. 12.1).1,5 Physician s sh ou ld m ain t ain a h igh level of susp icion on in it ial assessm en t in p at ien t s w h o are involved in h igh - e n e rgy t rau m a . Early id en t i cat ion of CTJ inju r y is key t o d et e r m in in g t h e ap p ro p r iate m an age m e n t an d e n ablin g an opt im al progn osis.1,3

■ Clinical Anatomy Th e CTJ is a u n iqu e region of th e spin al colu m n , con sist ing of th e C7 an d T1 ver tebrae an d t h e in ter ver tebral d isk (Fig. 12.2). How ever, d u e to th e an atom ic an d biom ech an ical variabilit y of th is region , issues con cern ing th e CTJ often in clu de th e C7 th orough T3 vertebrae.6 Th e CTJ is a transition zone, from a exible lordotic cervical spin e to a rigid kyp h ot ic th oracic sp in e. Th is ch ange in sp in al cu r vat u re an d st i n ess

ren ders th e CTJ a region of h igh st ress th at is p redisposed to in stabilit y w h en subjected to t raum a. Th e CTJ is also a t ran sit ion zon e in ter m s of bony m or p h ology.7 Th e lateral m ass of t h e cer vical sp in e ten d s to d ecrease in size an d t ran sit ion s in to th e w ide pedicles of th e u p p er t h oracic sp in e; t h ese ch anges create a ch allen ge in ter m s of in st r u m en t at ion an d st abilizat ion . Biom ech an ically, th e CTJ is an area subject to sign i can t extern al forces creat ing a large lever arm w ith xed a th oracic spin e an d a hyperm obile cer vical spin e, in com parison w ith th e th oracic sp in e. Esp ecially in th ose pat ien t s w h o h ave u n dergon e previous ver tebral fusion procedu res, th is region is su scept ible to failu re post-in st ru m en tat ion , even w ith m in or t rau m a (Fig. 12.3a,b).

■ Diagnosis History and Physical Examination Despite th e low in ciden ce of CTJ inju ries, th e occu rren ce of n eurologic im pairm en t associated w ith CTJ inju r y is h igh an d th e im p airm en t is u su ally severe. Nich ols an d colleagu es 1 iden t i ed 37 pat ien t s w ith CTJ inju r y in th eir ret rospect ive review of 397 pat ien t s w ith cervical sp in al inju ries. Th ey reported th at 22 of th e 37 p at ien t s (59%) h ad n eu rologic im pair-

Cervicothoracic Junction Injuries

Fig. 12.1 Midline sagit tal computed tomography (CT) reconstruction demonstrating traumatic fracture-dislocation of the cervicothoracic junction (CTJ) at C7-T1.

m en t , an d 12 of t h e 22 im paired p at ien t s (55%) w ere tet raplegic or paraplegic. Ch en an d Eism on t 7 reported th at 15 of 18 pat ien t s (83%) h ad n eu rologic d e cit s an d 10 of t h e 15 im p aired p at ien t s (67%) h ad com p lete sp in al cord inju r y. Th e h igh occu r ren ce of sign i can t im p air m en t is t h e resu lt of t h e large sp in al cord–to-can al rat io; t h e sp in al cord is th u s su scept ible to severe com p rom ise w ith dislocat ion -t yp e inju r ies. Ad d it ion ally, t h e blood su p p ly to t h e sp in al cord in t h is region is lim ited.4 Th e m ost com m on p resen t in g com p lain t of p at ien t s w it h CTJ inju r y is p ain .8 Du e to th e m ech an ism s involved in CTJ inju r ies, m ost p at ien t s presen t w ith a global injur y of th is region , an d isolated rad iculopathy is u n com m on .9 Clin ician s sh ou ld dorsally p alp ate th e CTJ area for poin t ten dern ess or step -o s.7 On exam , pat ien ts are likely to exh ibit sign s of m yelopathy: upper m otor neuron signs, weakness, p at h ological re exes (Babin ski’s sign ), an d bow el or bladder dysfu n ct ion . How ever, in th e set t ing of con com it an t inju r y involving oth er region s of th e cen t ral n er vou s system (CNS), or

Fig. 12.2 Schematic of the cervicothoracic junction. (Illustration by Avani R. Panchal.)

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a

b

c

Fig. 12.3a–d Lateral radiograph (a) and lateral CT reconstruction (b) illustrating kyphotic deformit y resulting from CTJ instrumentation failure with T3 fracture (arrow). Intraoperative image (c) and lateral

d

postoperative radiograph (d) showing dorsal-only approach to correct the CTJ deformit y, with T1 pedicle subtraction osteotomy due to restricted access ventrally.

Cervicothoracic Junction Injuries u n der t h e in uen ce of d rugs or m edicat ion s, th ese feat ures m ay be di cu lt to iden t ify. In Nich ols et al’s 1 series, n in e pat ien t s (24%) h ad n o p ain or n eu rologic de cit s an d seven of th em (19%) h ad an altered level of con sciousn ess from a t raum at ic brain inju r y or su bst an ce abu se. Th erefore, w h en evalu at ing a t rau m at ized pat ien t , it is crucial to carr y out adequate im aging st udies.

Diagnostic Studies Th e CTJ is a di cu lt region to visu alize on th e su p in e lateral radiograp h s th at are u su ally don e in th e em ergen cy room . A sw im m er’s view m ay p rovide adequ ate visu alizat ion of th e CTJ align m en t on plain lm s, bu t su ch view s m ay be di cu lt to obtain in obese p at ien t s or in th ose w ith a sh or t n eck or large sh ou lders. In Evan s 2 series, n early t w o th irds of th e pat ien t s w ere m isdiagn osed on adm ission , an d on e p at ien t w as diagn osed on ly w h en h e becam e p araplegic after m obilizat ion . Kan eriya an d cow orkers 10 fou n d t h at t h e rou t in e th ree-view lm s failed to dem on st rate CTJ in 50 of 196 t rau m a p at ien t s (26%). Th e risk of n on con t igu ou s inju r y in pat ien t s w ith CTJ in ju r y is est im ated to be u p to 15%. W h en inju r y in th e CTJ region is su spected, com puted tom ograp hy (CT) or m agn et ic reson an ce im agin g (MRI) sh ou ld be con sid ered , esp ecially w h en th e pat ien t h as exp erien ced h igh -en ergy t raum a an d th e clin ical exam in at ion or radiograph s are lim ited by a con com itan t inju r y, substan ce abuse, or pat ien t h abit u s. High -resolut ion , m u lt idetector CT h as becom e th e im aging m odalit y of ch oice at large level I t raum a cen ters du e to it s speed, sen sit ivit y, an d accu racy in diagn osing fract u res, an d it m ay be par t icularly u sefu l in detect ing CTJ inju r y. Recon st r u cted CT im agin g ten d s to illu st rate th e su btle p osterior bony inju ries th at are overlooked on radiograph s.7 MRI facilitates determ in ing th e p resen ce of soft t issu e injur y, in clu ding disk h ern iat ion , ligam en tou s injur y, an d n eu ral inju r y. Th e u t ilit y of MRI prior to closed redu ct ion in an aw ake an d aler t pat ien t is u n cer tain .11 CT angiography or m agn et ic reson an ce angiography m ay h elp determ in e local vascular disr u pt ion .

■ Management Th e inju ries to th e CTJ region in clu de ligam en tou s inju r y, disk ru pt ure, fract u res (body, arch , an d facets), an d dislocat ion s. Vaccaro et al12 describe th e Su baxial Cer vical Sp in e Inju r y Classi cat ion (SLIC) scale, w h ich assesses th e m orph ology, th e diskoligam en tous com p lex, an d th e n eurologic st at u s. A w eigh ted score from th e th ree categories determ in es th e severit y of inju r y an d h elp s gu id e m an agem en t (≤ 3 = n on op erat ive, 4 = “gray zon e,” an d ≥ 5 = su rgical). Th e AO (Arbeit sgem ein sch aft fü r Osteosyn th esefragen ) classi cat ion system for su baxial spin e fract u res is based on th e th oracic an d lum bar classi cat ion origin ally described by Magerl’s grou p.13,14 It also categorizes th e inju ries in to th ree t ypes based on injur y m orph ology: t ype A, com pression in jur y; t ype B, dist ract ion injuries; and t ype C, torsion inju ries. How ever, th ere is n o classi cat ion system speci c to CTJ injur y. Fig. 12.4 p rovides an algorith m th at m ay assist w ith th e m an agem en t of p at ien ts w ith CTJ inju r y. Stable inju ries are m an aged w ith bracing, but th ey sh ou ld be follow ed for delayed in st abilit y, esp ecially in th ose pat ien ts w ith purely ligam en tous injur y. CTJ injuries w ith su blu xat ion or dislocat ion requ ire im m ediate redu ct ion for n eu ral decom p ression .

Nonsurgical An extern al orth osis or h alo im m obilizat ion sh ou ld be con sidered for inju ries involving sp in ous process fract ures, lateral m ass fract ures, com pression fract ures w ith out deform it y, an d su blu xat ion s th at are deem ed stable inju ries. An or th osis w ith ch est exten sion or h alo vest m ay p rovid e adequ ate st abilizat ion . How ever, kyp h osis greater th an 11 degrees or su blu xat ion greater th an 3.5 m m on radiograp h s (especially u p righ t lm s) sh ou ld raise a con cern regarding in stabilit y.15 CTJ injur y involving dislocat ion m u st u n dergo early closed redu ct ion an d stabilizat ion . Skull t ract ion w ith Gardn erWells tongs or h alo ring m ay requ ire a w eigh t u p to 140 p ou n d s.4,16 Prom pt su rgical red u ct ion sh ou ld be p er for m ed if closed red u ct ion fails.

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Chapter 12 n at ion of bot h (Table 12.1). Th e locat ion of th e n eural com pression dictates th e approach for decom pression .7 Desp ite advan ces in tech n iqu es an d in st r u m en t at ion tech n ologies, th ere is n o on e best ap proach . Th e app roach of ch oice dep en ds on th e su rgeon’s u n derst an din g of th e clin ical an d rad iograp h ic p resen t at ion of th e p at ient (spin al level of inju r y, direct ion of n eu ral com p ression , exp osu re requ ired, an d body h abit u s), an d th e su rgeon’s fam iliarit y w ith th e poten t ial tech n iques an d in st ru m en tat ion system s.6 If in dicated, in traoperat ive t ract ion sh ou ld be em ployed, st ar ting w ith 10 p oun ds an d in creasing by 5 poun ds p er spin al level as approach ing m ore dist ally from th e h ead . In t raop erat ive n eu rophysiological m on itoring of th e spin al cord an d n er ve root in tegrit y m ust be ut ilized. Fig. 12.4 Basic algorithm for management of CTJ injuries.

Surgical Approaches Th e goals of su rgical m an agem en t of CTJ inju ries are n eu ral decom pression , realign m en t of spin e, an d stabilizat ion of th e CTJ. Th e surgical approach es can be ven t ral, dorsal, or a com bi-

Ventral Approaches Ven t ral approach es provide rest ricted exposu re of th e CTJ. Th e CTJ is su rrou n d ed by osseous (m an ubrium , stern oclavicular join t , an d m edial clavicle) an d n on osseou s (vascu lar an d n onvascular) st r uct u res (Fig. 12.2). Th e vascu lar st ru ct u res in clu de th e great vessels (left su bclavian vein , left brach ioceph alic vein s, left

Table 12.1 Surgical Approaches to CTJ Injury Low Cervical Approach description

Illustration Indication(s)

Transverse or longitudinal (medial to sternocleidomastoid m uscle) Fig. 12.5 Access to C7-T1

Advantages

Familiar approach, enables anterior colum n reconstruction

Disadvantages

Injury to vital structures

Low Cervical w ith Extension

Posterior

Posterior w ith Extension

Transmanubrial; transsternal

Midline

Costotransversectomy; lateral extracavitary approach

Fig. 12.6 Access below C7-T1

Fig. 12.7 Posterior decom pression and stabilization Fam iliar approach

Fig. 12.8 Anterior and posterior stabilization Avoid vital structures; enables anterior column reconstruction High morbidit y (pulmonary)

Direct visualization of thecal sac, enables anterior colum n reconstruction Injury to vital structures; high m orbidit y

Unable to reconstruct anterior spinal column

Cervicothoracic Junction Injuries

Fig. 12.5 Low cervical transverse or longitudinal (medial to sternocleidom astoid muscle) approach to CTJ injury. (Illustration by Avani R. Panchal)

Fig. 12.6 Low cervical approach with transmanubrialtranssternal extension to a CTJ injury. (Illustration by Avani R. Panchal)

Fig. 12.7 Posterior midline approach to a CTJ injury. (Illustration by Avani R. Panchal)

Fig. 12.8 Posterior approach with extension for a costotransversectomy (short arrow), with a lateral extracavitary approach (long arrow) to a CTJ injury. (Illustration by Avani R. Panchal)

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Chapter 12 com m on carot id ar ter y, su bclavian ar ter ies, an d th e aor t ic arch ). Th e n onvascu lar st r u ct u res in clu de th e t rach ea, esop h agu s, recu rren t lar yngeal n er ves (RLNs), an d th oracic du ct . Addit ion ally, th e CTJ t ran sition from lordot ic cervical sp in e to kyp h ot ic th oracic spin e places th e p roxim al t h oracic ver tebrae deep, an d w ith lim ited ven t ral access. Many sp in e su rgeon s are fam iliar w ith th e st an dard Sm it h -Robin son an terom ed ial ap p roach or th e low an terior cer vical approach . An ap p roach from t h e left sid e is favored du e to th e m ore predictable path of th e RLN, but th e th oracic du ct is at risk of inju r y w ith th is approach . Th is tech n iqu e provides access to C7-T1 in m ost cases. Pat ien ts w ith sh or t n ecks, proxim al th oracic kyph osis, or h igh sh ou lders m ay requ ire an exten sion of t h is ap p roach . Du r in g p reop erat ive p lan n in g, t h e su rgeon sh ou ld draw an in ter ver tebral disk lin e on a sagit tal im age, parallel to th e low est in ter vertebral disk space of in terest (Fig. 12.9); if th e ven t ral osseou s st ru ct u res (m an u briu m , rst rib, or stern oclavicu lar join t) fall cep h alad to th e lin e, th e su rgeon sh ou ld p repare for a likely low an terior cer vical ap p roach w ith an exten sion (t ran sm an u brial or t ran sstern al) or con sider p osterior ap proach es.17 Low cer vical ap p roach es w it h exten sion u su ally p rovid e exp osu re d ow n to T3.18 Th e in cision is exten ded dow n th e m idlin e over th e m anubrium and if n ecessar y furth er dow n over th e stern u m in a variable h ockey-st ick fash ion . For t ran sm an u brial exten sion , th e osteotom y sh ou ld be lateralized to th e left side, involving th e m an u briu m an d left m edial aspect of th e clavicle. Th e m an u briu m an d stern oclavicu lar join t can be disarticulated as one, w ith the sternocleidom astoid m uscle still at tached. Th e local n on osseous st r uct ures sh ou ld be iden ti ed an d dissected w ith cau t ion . Th e RLN ten ds to be located bet w een th e t rach ea an d th e esoph agu s. Fu r th er exten sion of th e osteotom y to in clu de th e stern u m p rovides exp osu re below th e CTJ region . Th e m orbidit y rates for low cer vical exten sion ap proach es are h igh , an d so th is ap proach sh ou ld be reser ved for selected p at ien t s; an ap p roach su rgeon sh ou ld be con su lted w h en p ossible. Preop erat ive im aging m u st be th or-

Fig. 12.9 Midline sagit tal CT reconstruction displaying intervertebral disk line, indicating the need for a ventral extension approach to access this region.

ough ly st u d ied to id en t ify relevan t an atom y to p reven t com p licat ion s. Addit ion ally, an terior st abilizat ion alon e m ay n ot be en ough to sat isfy th e biom ech an ical requirem en ts of th e CTJ, an d sh ould be supplem en ted w ith posterior st abilizat ion ; th ere is a on e-th ird failu re rate for th e stan d-alon e an terior approach es.19

Dorsal Approaches A dorsal approach is th e m ain stay approach for all spin e su rgeon s. Dorsal tech n iques perm it u n lim ited sp in al level of d ecom p ression , red u ct ion , an d st abilizat ion , w h ereas ven t ral ap proach es, even w ith exten sion , provide a rest ricted exp osu re to t h e ven t ral spin e. Posterior decom pression via lam in ectom ies sh ou ld be accom pan ied by in st rum en ted stabilizat ion to preven t kyph ot ic deform it y at th e CTJ.6 Th e exten sion s of th is approach are th e posterior lateral ap proach es: t ran sp edicular, costot ran s-

Cervicothoracic Junction Injuries versectom y, an d lateral ext racavit ar y. Th e t ran spedicular approach en ables lateral decom p ression (Fig. 12.3c,d). Th e costot ran sversectom y involves rem oval of th e t ran sverse process, 2 to 3 cm of th e p roxim al rib, an d th e p ed icle; t h is rem oval p rovid es access to t h e an terolateral spin al cord. Th e lateral ext racavitar y approach (w h ich requires m uch longer rib resect ion ) en ables ip silateral ven t ral decom pression an d recon st r u ct ion of th e an terior colu m n . W h en don e bilaterally, th e lateral ext racavitar y ap proach provides circu m feren t ial access to th e th ecal sac, but th is bilateral ap proach is tech n ically ch allenging. Resn ick an d Ben zel20 repor ted a h igh in ciden ce of adverse even ts (55%), w ith pulm on ar y even ts as th e m ost com m on . Th e dorsal ap proach is th e ap proach of ch oice for m ost spin e su rgeon s for su rgical m an agem en t of CTJ inju ries, becau se it perm its decom pression, realign m ent, and spin e st abilizat ion via a single in cision .

■ Chapter Summary Th e CTJ region is a u n iqu e t ran sit ion zon e in w h ich inju r y is in frequ en t , bu t w h en it d oes occu r it is often associated w ith severe im p airm en t . CTJ inju ries are ch allenging to diagn ose, requ iring CT an d MRI. Early diagn osis an d d islocat ion redu ct ion m ay im prove th e clin ical outcom e; h ow ever, in cases w ith com plete spin al cord inju r y, th e progn osis is p oor. Non op erat ive m an agem en t sh ou ld be con sidered for st able CTJ inju ries; an or th osis sh ou ld be con sid ered w it h close follow -u p to id en t ify d elayed in st abilit y. Un st able inju r ies sh ou ld be t reated su rgically, w ith ven t ral, dorsal, or com -

bin at ion app roach es for n eu ral decom pression , realign m en t of spin e, an d stabilizat ion of th e CTJ. Desp ite advan ces in tech n iqu es an d in st rum entation, prevention of com plications still depen ds on th e su rgeon’s u n derstan ding of t h e pert in en t an atom y based on preop erat ive im aging, an d on th e su rgeon’s experien ce w ith th e ch osen approach . CTJ injuries sh ould be app roach ed w ith cau t ion du e to th e com p lexit y of th is region an d th e poten t ial h igh p erils of det rim en tal com plicat ion s.

Pearls Physicians should m aintain a high level of suspicion for CTJ injury when assessing patients involved in high-energy trauma, until such injury is excluded with adequate im aging. Early closed reduction and decompression of the spinal cord may improve prognosis. A surgical approach (ventral, dorsal, or com bination of both) should be considered based on the clinical and radiographic presentation, and on the surgeon’s experience with appropriate approaches. Pitfalls Do not set tle for poor visualization of the CTJ region on imaging. Do not operate on neurologically intact patients without neurophysiological m onitoring. Avoid dorsal decompression of the CTJ without stabilization. Purely ligam entous injuries are unstable and require stabilization.

Acknow ledgement I t h an k Avan i R. Pan ch al for t h e ch apter illu st rat ion s.

Refere nces Five Must-Read Refe rences 1. Nich ols CG, You ng DH, Sch iller W R. Evalu at ion of cervicoth oracic ju nct ion injur y. Ann Em erg Med 1987; 16:640–642 PubMed 2. Evan s DK. Dislocat ion s at th e cer vicoth oracic jun ct ion . J Bon e Join t Surg Br 1983;65:124–127 PubMed 3. Am in A, Saifuddin A. Fract ures an d dislocat ion s of th e cer vicoth oracic ju n ct ion . J Sp in al Disord Tech 2005;18:499–505 Pu bMed

4. An HS, Vaccaro A, Cotler JM, Lin S. Spin al disorders at th e cer vicoth oracic ju n ct ion . Spin e 1994;19:2557– 2564 PubMed 5. Len oir T, Ho m an n E, Th even in -Lem oin e C, Lavelle G, Rillardon L, Gu igu i P. Neu rological an d fu n ct ion al outcom e after un st able cer vicoth oracic jun ct ion in jur y t reated by posterior reduct ion an d syn th esis. Spin e J 2006;6:507–513 Pu bMed

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Chapter 12 6. Wang VY, Ch ou D. Th e cer vicoth oracic jun ct ion . Neurosurg Clin N Am 2007;18:365–371 Pu bMed 7. Ch en J, Eism on t FJ. Cer vicoth oracic t rau m a: d iagn osis and t reat m en t . Sem in Spin e Surg 2005;17:84–90 8. Sapkas G, Papadakis S, Katon is P, Roidis N, Kon t akis G. Operat ive t reat m en t of u n st able injuries of th e cer vicoth oracic ju n ct ion . Eu r Sp in e J 1999;8:279– 283 PubMed 9. Rao R. Neck pain , cer vical radiculopathy, an d cer vical m yelopathy: path ophysiology, n at ural h istor y, an d clin ical evalu at ion . J Bon e Join t Surg Am 2002;84-A: 1872–1881 PubMed 10. Kan eriya PP, Sch w eit zer ME, Sp et tell C, Coh en MJ, Karasick D. Th e cost-e ect iven ess of obliqu e radiograp hy in t h e exclu sion of C7-T1 inju r y in t rau m a p at ien t s. AJR Am J Roen tgen ol 1998;171:959–962 PubMed 11. Gelb DE, Hadley MN, Aarabi B, et al. In it ial closed reduct ion of cer vical spin al fract ure-dislocat ion inju ries. Neurosurger y 2013;72(Suppl 2):73–83 Pu bMed 12. Vaccaro AR, Hulbert RJ, Patel AA, et al; Spin e Traum a St udy Group. Th e su baxial cer vical sp in e inju r y classi cat ion system : a n ovel approach to recogn ize th e im por t an ce of m orph ology, n eurology, an d in tegrit y of t h e d isco-ligam en tou s com p lex. Sp in e 2007;32: 2365–2374 PubMed 13. Ger t zbein SD. Scoliosis Research Societ y. Mult icen ter spine fract ure st udy. Spine 1992;17:528–540 PubMed

14. Magerl F, Aebi M, Gert zbein SD, Harm s J, Nazarian S. A com prehen sive classi cat ion of th oracic an d lum bar inju ries. Eu r Sp in e J 1994;3:184–201 Pu bMed 15. W h ite AA, Panjabi MM. Clin ical Biom echan ics of th e Spin e, 2nd ed. Ph iladelph ia: Lippin cot t; 1990 16. Cotler JM, Herbison GJ, Nasut i JF, Dit u n no JF Jr, An H, Wol BE. Closed reduct ion of t raum at ic cer vical spin e dislocat ion u sing t ract ion w eigh t s u p to 140 poun ds. Spin e 1993;18:386–390 PubMed 17. Karikari IO, Pow ers CJ, Isaacs RE. Sim ple m ethod for determ ining the need for sternotom y/m anubriotom y w ith th e an terior approach to th e cer vicoth oracic junction. Neurosurgery 2009;65(6, Suppl):E165–E166, discu ssion E166 Pu bMed 18. Kaya RA, Tü rkm e n oğlu ON, Koç ON, et al. A p e rsp e ct ive for t h e sele ct ion of su r gical ap p roach es in p at ien t s w ith u p per th oracic an d cer vicoth oracic ju nct ion in st abilit ies. Surg Neurol 2006;65:454–463, discu ssion 463 Pu bMed 19. Boockvar JA, Ph ilips MF, Telfeian AE, O’Rou rke DM, Marcot te PJ. Resu lt s an d risk factors for an terior cervicoth oracic jun ct ion su rger y. J Neurosurg 2001;94 (1, Suppl):12–17 Pu bMed 20. Resn ick DK, Ben zel EC. Lateral ext racavit ar y ap proach for th oracic an d th oracolum bar spin e t raum a: operative com plications. Neurosurgery 1998;43:796– 802, discu ssion 802–803 PubMed

13 Cervical Trauma in Combination w ith Ankylosing Spondylitis or Di use Idiopathic Skeletal Hyperostosis Jorrit-Jan Verlaan and F. Cumhur Oner

■ Introduction During assessm en t of a t raum a pat ien t in th e em ergen cy d ep ar t m en t , th e cer vical sp in e is protected u n t il fract u res or ligam en tou s d isrupt ion s h ave been iden t i ed or r uled out beyon d a reason able dou bt .1 After com plet ion of th e p rim ar y su r vey an d t reat m en t of th e im m ediate life-threatening injuries, attention m ay focus on th e cer vical spin e. Follow ing th e in tegrat ion of t h e p r in cip al in for m at ion , in clu d ing traum a m echanism , ndings on the physical exam ination, and im aging studies, the presence or absen ce of clin ically sign i can t cer vical in ju ries can t yp ically be ascer t ain ed w ith a h igh level of con den ce an d reliabilit y. Un der som e circum stances, however, the inform ation needed to determ in e th e degree of cer vical inju r y can be m islead ing, resu lt in g in a late or even an in correct diagn osis an d, su bsequ en tly, a su b opt im al ou tcom e. Speci cally, for pat ien ts w ith an kylosis of th e sp in al colu m n su sp ected of a cer vical inju r y, th e t raum a m ech an ism an d result s obt ain ed from p hysical an d radiograph ical exam in at ion m ay be m arkedly di eren t com pared w ith a gen eral t rau m a popu lat ion .2,3 Sp in al an kylosis is cau sed m ain ly by t w o d ist in ct path ological p rocesses: an kylosing spon dylit is (AS) an d d i u se id iop at h ic skelet al hyperostosis (DISH). Th e presen ce of both AS

an d DISH is in creasingly being recogn ized as an im por t an t m od i er for th e diagn ost ic w orku p , t reat m en t , reh abilitat ion , an d, ult im ately, clin ical ou tcom e of t rau m a p at ien ts.4 Th is ch apter d iscu sses h ow AS an d DISH m ay in u en ce decision m aking du ring variou s crit ical p h ases, from th e in it ial (p reh ospit al) assessm en t to d isch arge an d follow -u p of pat ien ts w ith cer vical inju r y.

■ Etiology and Epidemiology

of Ankylosing Spinal Disorders An kylosing spon dylit is an d di use idiopath ic skeletal hyperostosis are t w o w ell-de n ed but poorly u n derstood disorders of th e spin al colum n.5,6 Their com m on ch aracteristic is progressive ankylosis (fusion of segm ents), although th e u n derlying m ech an ism is di eren t in each con dit ion . AS is a system ic in am m ator y disorder from th e group of seron egat ive spon dyloar t h rop at h ies, a ect ing t h e sp in al colu m n an d , to a lesser exten t , periph eral join t s an d n on skeletal st r uct ures. Th e key path ological feat ure of AS is th e gradual dest ruct ion of articular cart ilage in the sacroiliac an d facet joints and obliteration of the intervertebral disk space,

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Chapter 13 leading to fusion of th e sp in al colu m n an d p elvic ring.5 Th e cascad e of even t s leading u p to ar t icu lar dest r u ct ion is largely u n kn ow n , alth ough som e st udies poin t to a gen et ic basis of th e disease. Typical sym ptom s associated w ith AS are p ain , st i n ess, an d fat igu e p r im ar ily located in th e sp in e. AS is m ost often foun d in m ales, w ith th e rst sym ptom s occu rring in th e second or (less frequen tly) th ird decade of life, an d it h as an overall prevalen ce of 0.1 to 1.4%.5 As progression an d expression of AS can be qu ite variable, a long laten cy period m ay be obser ved bet w een th e st ar t of th e d isease an d on set of th e rst sym ptom s. Diagn ost ic w orku p for suspected AS requ ires an terop osterior/lateral radiograph s of th e com plete spin al colum n an d pelvis, alth ough early abn orm alit ies m ay be found on ly on com puted tom ography (CT) or m agn et ic reson an ce im aging (MRI). Th e presen ce of clin ical sym ptom s, dem ograph ic criteria, and radiograph ic sign s of sacroiliit is (in th e early stages of AS) or an kylosis of th e sacroiliac join t s an d sp in al colu m n (in m ore advan ced st ages) usually con rm s th e diagn osis of AS. Treat m en t of AS is m ostly sym ptom at ic, alth ough som e drugs (n on steroidal an t i-in am m atory drugs, im m unosuppressants, and t um or n ecrosis factor-α blockers) h ave been sh ow n to d ecelerate progression of th e disease.7 Th e h allm ark of DISH, on th e oth er h an d, is p rogressive ossi cat ion of sp in al an d ext rasp in al ligam en t s w h ile th e art icular surfaces are spared.8 DISH is m ost likely a system ic con dit ion based on a low -grad e in am m ator y p rocess w ith possible lin ks to t ype 2 diabetes m ellit u s, ath erosclerosis, an d cardiovascu lar disease.6,9 Th e prevalen ce of DISH is h igh ly variable (ranging bet w een 2.9% an d 30%) an d dep en ds on geograp h ic locat ion (p ossibly im plying a gen et ic p redisp osit ion ), select ion bias, an d th e im aging m odalit y used.10 In dividu als a ected by DISH are u su ally n ot aw are of it s presence because DISH is m ostly w ithout sym p tom s.6 Com plain t s som ew h at sp eci c for DISH in clu de back p ain , sp in al st i n ess, an d dysph agia, th e lat ter being presen t w h en large ossi cat ion s h ave developed in th e an terior part of th e cer vical spin e.11 To est ablish t h e diagn osis of DISH, t h e criteria from Resn ick an d Niw ayam a’s group 8 are

m ost often u sed . Th ey requ ire th e presen ce of ow ing ossi cat ion s over at least four con t igu ou s ver tebral bod ies w it h ou t gross evid en ce of sp on dylosis, d isk d egen erat ion , or AS. CT is con sidered th e gold st an dard im aging m odalit y to diagn ose DISH. As bon e form at ion in DISH is, by de n it ion , ubiquitou s at th e m om en t of diagn osis, t reat m en t is m ain ly directed at relieving sym ptom s w ith th e prescript ion of an algesics for spin al pain an d dietar y m easu res in cases w ith dysp h agia.12 Rarely is resect ion of cer vical ossi cat ion s n ecessar y to en sure adequate in take of n ut rit ion .11 As DISH is related to th e m et abolic syn drom e, an in crease in th e n u m ber of cases is exp ected in t h e com in g d ecades.

■ Biomechanical E ects of

Spinal Ankylosis As th e h ealthy cer vical sp in e is a exible st r u ct u re able to d isp erse t rau m at ic en ergy over m u lt ip le levels, th e am ou n t of force n eed ed for a fract ure or ligam en t r upt ure to occur is sub st an t ial. In advan ced st ages of AS an d DISH, th is exibilit y is lost .3 On lateral rad iograp h s or sagit t al recon st r u ct ion s of CT scan s, t h e ch anges directly a ecting th e biom ech an ical ch aracterist ics of th e cer vical spin e in pat ien t s w it h AS an d DISH can be easily ap p reciated . In AS, facet join t s an d th e in ter ver tebral disk sp ace are obliterated an d th e cer vical sp in e can th erefore be regarded, from a biom ech an ical p erspect ive, as a long bon e.3 In DISH, ossi cat ion s develop m ain ly an teriorly from th e cer vical vertebral bodies in th e an terior longit udin al ligam en t , alt h ough ossi cat ion s of t h e p oster ior longit u din al ligam en t , avu m ligam en t , an d in ter/su p rasp in al ligam en t s m ay also be obser ved.13 Th e facet join t s an d in ter ver tebral disk sp aces in DISH are (by de n it ion ) in it ially u n a ected , bu t d ep en d in g on t h e n u m ber of bridgin g ossi cat ion s, t h e cer vical sp in e becom es p rogressively an kylosed . In advan ced AS an d DISH, som e secon dar y e ect s of an kylosis em erge, in clu ding osteop orosis of th e ver tebral bodies as a result of st ress sh ielding (alth ough bon e deposits in DISH m ay cause false n orm al

Cervical Trauma in Combination readings in bon e m in eral den sitom et r y test s) an d d isu se at rop hy of su r rou n d ing soft t issu es.14,15 Long-st an ding AS or DISH m ay u lt im ately lead to a st i , brit tle n eck, w ith local osteoporosis an d a dysfu n ct ion ing soft t issu e envelope. Moreover, fusion of m ult iple cer vical levels creates long lever arm s an d, as a resu lt , m in or force is required to create dam age-in d ucing torque.16 As h as been d em on st rated by several au th ors, m ost inju ries in p at ien t s w ith an kylosis of th e spin al colu m n w ere cau sed by low -en ergy im pact s, for in st an ce, a fall from a sit t ing or st an ding p osit ion or a low -sp eed collision bet w een m otor veh icles.3 Du ring im p act , local en ergy p eaks cau se th e cer vical sp in e to fract ure, largely com parable to a long bon e (for

Fig. 13.1 Midsagit tal reconstruction computed tomography (CT) scan of a 61-year-old man with ankylosing spondylitis after being hit by a car as pedestrian, showing clear hyperextension fracture with severe angulation and translation (C-t ype). The patient’s neurologic status was classi ed as American Spinal Injury Association (ASIA) grade A at admission.

exam ple, a fem u r) w ith com p lete discon t in u it y bet w een th e fract ure segm en ts.17 As su rroun d ing soft t issues are m ostly dysfun ct ion al (by at rophy or du e to in clu sion in th e p ath ological p rocess), an kylosed sp in e fract u res easily dislocate p rim arily an d secon darily an d are th us in h eren tly u n stable (Figs. 13.1 and 13.2). Tw o t ypes of fract ures are frequen tly obser ved in th e an kylosed spin e: hyperexten sion fract ures t ype B3 according to th e recen tly publish ed AO (Arbeitsgem einsch aft fü r Osteosynthesefragen) Spin e classi cat ion system , an d t ran slat ion / sh ear fract ures (t ype C).17 Th ese fract u res can be located in th e m iddle or at th e ext rem es of m u lt ip le fu sed segm en t s. According to th e AO Sp in e classi cat ion , th ese h igh ly u n st able fract u re t yp es are p referably treated w ith su rgical st abilizat ion , as adequ ate redu ct ion an d im m obilizat ion m ay be di cu lt to ach ieve n on operat ively. Prim ar y or secon dar y n eurologic inju r y is com m on due to m alalign m en t of th e spin al can al follow ing t raum a or pat ien t m an ipulat ion , resp ect ively.3

Fig. 13.2 Midsagit tal reconstruction CT scan of a 60-year-old man with di use idiopathic skeletal hyperostosis after missing the three lowest treads of a ight of stairs, resulting in a hyperextension fracture (B3 t ype) of C5. At adm ission the patient was neurologically intact.

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Chapter 13

■ Prehospital Assessment

and Transportation of Patients w ith Cervical Ankylosed Spine Fractures According to m any m odern t rau m a su pport protocols, establish ing an d m ain t ain ing a free air w ay and im m obilization of the cervical spine are th e ver y rst step s a rst respon d er sh ou ld perform w h en m an aging a t rau m a p at ien t .1 To im m obilize th e cer vical sp in e, a rigid collar an d accom p anying h ead blocks/st rap s are ap p lied an d t h e pat ien t is st rap ped t igh tly on a long sp in e board to p rotect th e com p lete sp in al colu m n d u r in g t ran sp or t at ion . Alt h ough t h is p ract ice is gen erally accepted an d m ay h ave p reven ted n um erou s cases of secon dar y w orsen ing in t h e p resen ce of u n st able sp in e fract u res, it can be h ar m fu l for p at ien t s w it h p reexist ing deform it ies or an kylosis of th e cervical spin e.3 Many pat ien ts w ith AS develop kyp h osis in th e cer vicoth oracic ju n ct ion an d th oracic spine du ring th e course of th eir disease. Alt h ough less p ron ou n ced th an in AS, pat ien t s w ith DISH m ay also d evelop xed sp in al deform it ies th at can n ot be addressed by act ive or passive post ural reduct ion . For th ese pat ien t s, at tem pt s to xate th e sp in e on a st raigh t board m ay lead to discom for t or, in cases of acute fract u res, to fu r th er fract u re dislocat ion an d, as a consequen ce, iat rogen ic spin al cord injur y. Som e st u dies h ave rep or ted th e occu rren ce of spinal fract u res an d iat rogen ic paraplegia in pat ien ts w ith AS as a resu lt of p at ien t posit ion ing du ring elect ive su rger y, an d it is n ot un th in kable th at im m obilizat ion on a spin e board m ay also cause this t ype of injury.18 Transpor t at ion of t rau m a p at ien ts w ith (a su spicion of) sp in al an kylosis on a sp in e board is suggested to be feasible an d safe p rovid ed p reexist ing deform it ies are respected as m u ch as possible and patients are supported and xated in a com fortable position using adjuncts including vacuum m at tresses, pillow s, or sandbags.3 Trau m a pat ien ts w ith cer vical an kylosis w ho are u n able to m ain t ain a paten t air w ay presen t a con siderable ch allenge to em ergen cy physician s.19 Many factors com p ou n ding a difcu lt en d ot rach eal in t u bat ion are p resen t in

pat ien ts w ith spin al an kylosis, in clu ding sh or t n eck, lim ited cer vical range of m ot ion or deform it y, lim ited open ing of th e m ou th , obesit y, anterior cer vical osteophytes, and possible cervical spin e fract u re. Physician s n ot pro cien t in doing d i cu lt en dot rach eal in t u bat ion m ay better revert to bag-valve-m ask ventilation until m ore experien ced p erson n el an d equ ip m en t (to at tem pt in t ubat ion w ith ber opt ic devices, for exam ple) are available. Neu rologic de cits, var ying from t ran sien t t ingles in th e ext rem it ies to com p lete tet rap legia, m ay frequ en t ly accom pany an kylosed spin e fract ures. According to a recen t st udy, 57% of pat ien t s w ith AS an d 30% of pat ien ts w ith DISH h ad n eurologic de cits at adm ission du e to th eir spin al fract u re.3 Du ring in it ial (p reh osp ital) assessm en t , a gross m otor/sen sor y exam in at ion sh ould be perform ed to est ablish (de cit s in ) fu n ct ion , as th is clin ical in form at ion is of great im por t an ce for guidan ce of th e diagn ost ic w orku p an d to determ in e surgical urgen cy.

■ Treatment Principles in

Cervical Ankylosed Spine Fractures Con sidering th at th e cer vical spin e in AS an d DISH beh aves sim ilarly to a long bon e, w ith respect to biom ech an ical ch aracterist ics, it m ay n ot be un reason able to apply som e prin ciples of long bon e fract ure m an agem en t to th e in jured an kylosed cer vical spin e.20 It is w ell establish ed th at for long bon e fract ures to h eal, th e in tegrit y of su rrou n ding soft t issu es (w h ich provide at t ach m en ts to bon e, su pply n u t rien ts, and form a barrier against m icroorganism s) is of great im portance. Furtherm ore, for a fractured long bon e to h eal in an acceptable p osit ion , som e sor t of st abilit y to th e fract ure fragm en t s sh ou ld be o ered. In long bon es, stabilizat ion can be relat ive (w h en u sing plaster cast s or in t ram edu llar y n ails) or absolu te (w ith com pression plates), dep en ding on th e t ype of bon e h ealing, direct or in direct , th at is an t icipated.20 In th e presen ce of m ult iple fract ure fragm en ts, fract ure fu sion is usu ally th rough in direct bon e h ealing w ith developm en t of a fract ure h em a-

Cervical Trauma in Combination tom a an d subsequ en t form at ion of callus. Regard less of t h e t yp e of st abilizat ion o ered , xat ion sh ou ld be over a long t rajector y to p reven t im plan t failu re du e to screw p u llou t (or fract ure dislocat ion in in adequ ate plaster cast s in cases of n on op erat ive t reat m en t ), as lever ar m s are, by d e n it ion , large in long bon es. Th e t reat m en t of an kylosed cer vical spin e fract ures is suggested to be sim ilar to in direct long bon e h ealing an d requ ires relat ive st abilit y by m ean s of xat ion poin t s over a long t rajector y in “bridging p late” fash ion .20 As a r u le of th u m b, fract u res sh ou ld be in st r um en ted over at least th ree segm en t s cran ially an d th ree segm en ts caudally to th e fract ure to avoid im plan t failure. Th e ideal in st ru m en tat ion for an kylosed fract ures of th e cer vical spine provides su cient bone purchase on both sides of the fracture w hile avoiding stress risers at biom ech an ically vu ln erable locat ion s su ch as th e cer vicoth oracic jun ct ion . Th erefore, th e auth ors often in clude th e u pper th oracic spin e in th e cau dal par t of th e con st ru ct ion an d sh ift th e st ress-riser–in du cing ext rem e of th e con st r uct ion aw ay from th e ju n ct ion w h ile ben et in g from t h e su p er ior bon e p u rch ase of t h oracic p ed icle screw s com p ared w it h (C7) cer vical screw s (Fig. 13.3). Th e con sequen t loss of m ot ion at th e cer vicoth oracic ju n ct ion is of n o con cern in pat ien ts w ith AS an d of m in or consequ en ce in p at ien t s w ith DISH du e to preexisten t an kylosis. Depen ding on bon e qu alit y, fou r to six lateral m ass screw s are t yp ically used for th e cran ial part of th e fract u re to pro-

a

b

Fig. 13.3a–d Im ages of the cervical spine of a 62-year-old man with ankylosing spondylitis after a fall from a standing position. (a) Lateral radiograph obtained at adm ission with kyphotic deformit y showing at C5-C6. (b) Midsagit tal reconstruction CT

vide su cien t pu rch ase. Screw s m ay be used in C1 according to th e Harm s tech n iqu e an d in C2 (pedicle screw s). In th e suba xial spin e, w e p refer to u se lateral m ass screw s, as t h ey are relat ively safe, easy, an d qu ick to u se, even in th e face of abn orm al an atom y as frequ en tly obser ved in AS an d DISH, w ith out th e n eed for excessive soft t issue dissect ion or m an ipu lat ion of th e u n st able cer vical spin e. Reduct ion of an kylosed cer vical fract ures m ay often be required, especially in th e presen ce of n eurologic de cit s. Inju r y of th e spin al cord in an kylosed fract ures is t ypically th e resu lt of rot at ion or t ran slat ion of th e cran ial part of th e spin al segm en t relat ive to th e cau dal part , leading to m alalign m en t in stead of n arrow ing of th e spin al can al as a result of bon e fragm ent protrusion in, for exam ple, burst-t ype fract u res.21 As careful reduct ion results in realign m en t of th e oth er w ise in tact spin al can al, a com plete decom pression can be ach ieved in the m ajorit y of neurologically intact cases w ith ou t th e n eed for lam in ectom y. For pat ien ts w ith n eurologic de cit s or in cases w ith severe dislocation or locked fract ure fragm en ts requiring su bstan t ial un locking reduct ion m an eu vers, a lam in ectom y m ay be p erform ed at th e fract u re level to p rovide decom pression of t h e spin al cord an d visual in spect ion during fract u re redu ct ion .22 In agreem en t w ith th e prin ciples of in direct fract u re h ealing of long bon es, an kylosed cer vical spin e fract u res sh ould be align ed an d st abilized w ith out com pression or dist ract ion .21 As spin al fract u res in pat ien t s in

c

d

scan with translation of C5 relative to C6 and fusion of all visible segm ents except for C1. (c) Postoperative lateral radiograph showing long trajectory bridging from C3-T1. (d) Lateral radiograph at 1-year follow-up demonstrating fusion of C5-C6.

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Chapter 13 AS an d DISH h ave a ten den cy to fu se fairly rap idly on ce st abilized, th e u se of autografts or syn th et ic bon e fu sion en h an cers is n orm ally n ot n eeded .

■ Complications Related

to the Management of Cervical Ankylosed Spine Fractures Several pit falls can be iden t i ed in th e t reatm en t of an kylosed cer vical fract u res. First , th e fract u re n eed s to be recogn ized .23 Un fort u n ately, a p at ien t ’s d elay in p resen t in g for m ed ical at ten t ion an d a p hysician’s delay in d iagn osing th e con dit ion both occu r frequen tly. Pat ien t s w ith AS (an d som et im es w ith DISH) h ave becom e u sed to experien cing ep isodes of sp in al p ain an d do n ot alw ays becom e alarm ed after a t rivial fall or acciden t , an d as a resu lt th ey seek m edical h elp on ly after an in crease in sym ptom s. Physician s are n ot alw ays fam iliar w ith the radiographic abnorm alities associated w ith AS an d DISH, an d m ay n ot recogn ize fract ures on rout in e st udies. Furth erm ore, an kylosed cer vical spin e fract u res w ith a B3 t yp e hyp erexten sion con gu rat ion often h inge on a p osteriorly located fu lcr u m an d m ay close d ow n w h en pat ien t s are lying su p in e an d h aving th eir h ead su pp or ted by cu sh ion s.23 As a gen eral ru le, a physician n eeds to proactively r u le ou t a fract u re in p at ien t s w it h any sign s of spin al an kylosis com plain ing of n eck pain or sp in al pain after su ering a t rau m at ic even t , h ow ever sm all. In som e cases t h e fract u re is visible on ly on MRI, an d t h is m odalit y sh ou ld be u sed liberally, as t h e con sequ en ces of d isch arging a p at ien t w it h a m issed an kylosed sp in e fract ure m ay be disast rou s.24 A secon d com m on pitfall is secon dar y deteriorat ion of n eu rologic fu n ct ion after h osp it al adm ission due to spin al cord injur y caused by loss of spin al align m en t .3 Ever y m an ip u lat ion or t ran sfer of th e pat ien t sh ould be perform ed w ith m axim um at ten t ion to m ain t ain ing align m en t of th e com p lete sp in al colu m n . Th e correct m an euver to t ran sfer a pat ien t or to ch ange

a patient’s position is by using the log-roll tech n ique. Th is tech n ique requires at least th ree (but preferably m ore) w ell-in st ru cted in dividu als for safe execu t ion . Alth ough h alo-vest xat ion of fract u res of th e an kylosed spin e is n ot recom m en ded as de n it ive t reat m en t , it m ay be h elpful in providing su cien t stabilizat ion to decrease th e risk of secon dar y n eurologic de cit du ring m an ipu lat ion or t ran sfer of th e patient. Furtherm ore, halo-vest xation m ay be valuable w h ile posit ion ing th e pat ien t on th e operat ing t able an d to m ain tain gross align m en t du ring su rger y. A t h ird p it fall can be en cou n tered d u r in g th e n al step s of su rgical xat ion of t h e an kylosed cer vical sp in e. Preexisten t deform it ies sh ou ld be ackn ow ledged an d respected w h en xat ing th e cer vical spin e in it s n al p osit ion , as (over)correct ion of th e, u sually kyph ot ic, deform it y m ay n ot be tolerated an d cou ld lead to iat rogen ic spin al cord injur y due to st retch ing or vascu lar com p rom ise.24 Th erefore, th e surgeon sh ou ld t r y to recon st ru ct th e m ost p robable pret rau m a align m en t of th e cer vical sp in e based on all radiograph ic st u dies (preferably also from an earlier date) an d t r y to ap p roxim ate th is previou s state w h en con n ect ing rods to th e im plan ted screw s.

■ Chapter Summary An kylosis of th e cer vical spin e is a relat ively frequen t n ding caused by AS an d DISH. As cer vical segm en t s becom e progressively fused, th e exibilit y of t h e n eck decreases con siderably, an d th e biom ech an ical ch aracterist ics of th e cer vical sp in e in creasingly resem ble t h at of long bon es. As a resu lt of st ress sh ielding, th e bon e m in eral den sit y in th e an kylosed spin al colum n is t ypically low er th an in a con t rol pop u lat ion . Th e com bin at ion of cer vical an kylosis an d p oor bon e st rength resu lts in a st i an d brit tle n eck suscept ible to fract ure after even m in im al t raum a. During t ran spor t an d diagnost ic w orkup, un til de n itive t reatm ent can be star ted, great care sh ould be t aken to preven t fu r th er fract u re dislocat ion an d iat rogen ic sp in al cord injur y. Fract u res of th e an kylosed

Cervical Trauma in Combination cervical spine can be di cult to diagnose due to preexist ing abn orm alit ies con fou n d ing in terpretat ion of radiograp h ic st u dies, in con clu sive resu lt s du e to in su cien t/in ap p rop riate im aging tech n iqu es, pat ien t delay in p resen t ing an d physician delay in diagn osing, an d u n derest im at ion of th e t raum at ic im pact . In pat ien t s w ith sign s of an kylosis of th e spin al colu m n an d w ith n eck or back pain follow ing (m in or) t rau m a, p hysician s sh ou ld h ave an ext rem ely h igh in d ex of su sp icion for a sp in al fract u re. Treat m en t of fract u res of th e an kylosed cer vical spin e h as som e sim ilarit ies w ith long bon e fract u re t reat m en t prin ciples. Su rgical xat ion is u su ally th e t reat m en t of ch oice, as in d irect fract u re st abilizat ion (w ith h alo -vest xat ion or collar) is often in su cien t an d m ay lead to fract u re d islocat ion , secon dar y n eurologic de cits, or form at ion of pseu dar th rosis. In gen eral, long bridging-t yp e con st r uct s sh ou ld be u sed to provide adequ ate st abilizat ion at t h e fract u re site w h ile th e in st r u m en t at ion sh ou ld p referably n ot en d at vuln erable locat ion s such as th e cer vicoth oracic ju n ct ion . Th e ou tcom e of th e m an agem en t of pat ien t s w ith an kylosed cer vical sp in e fract ures depen ds m ain ly on th eir n eurologic

st at u s at adm ission an d p reven t ion of secon dar y n eu rologic injur y. Pearls Maintain a high index of suspicion for cervical ankylosed spine fractures in every traum a patient with signs of spinal ankylosis and tenderness of the neck. Protecting the cervical spine is of extrem e im port ance in patient s with cervical ankylosed spine fractures until de nitive treatment has been established. Treatm ent principles for cervical ankylosed spine fractures follow long bone fracture management to a large extent. Early m obilization and ambulation are key factors for good clinical outcom e following cervical ankylosed spine fracture. Pitfalls Failure to recognize a cervical ankylosed spine fracture may have disastrous consequences. Preexisting deform ities should be respected when im mobilizing patients with (known) ankylosing disorders of the spine prior to transfer. Secondary neurologic de cits have great negative impact on ultim ate clinical outcom e and m ay often be avoidable.

Refere nces Five Must-Read Refe rences 1. Navarro S, Mon t m any S, Rebasa P, Colilles C, Pallisera A. Im pact of ATLS t rain ing on p reven t able an d p oten t ially preven t able death s. World J Surg 2014;38: 2273–2278 Pu bMed 2. Caron T, Bran sford R, Nguyen Q, Agel J, Ch apm an J, Bellabarba C. Sp in e fract u res in p at ien t s w it h an kylosing sp in al d isorders. Sp in e 2010;35:E458–E464 Pu bMed 3. Wester veld LA, van Bem m el JC, Dh er t W J, On er FC, Verlaan JJ. Clin ical outcom e after t raum at ic spin al fract ures in pat ien t s w ith an kylosing spin al disorders com p ared w ith con t rol pat ien t s. Sp in e J 2014; 14:729–740 PubMed 4. Wester veld LA, Verlaan JJ, On er FC. Sp in al fract u res in pat ien t s w ith an kylosing sp in al disorders: a system at ic review of th e literat ure on t reat m en t , n eurological st at us an d com plicat ion s. Eur Spin e J 2009;18: 145–156 PubMed 5. Brau n J, Siep er J. An kylosing sp on dylit is. Lan cet 2007;369:1379–1390 Pu bMed

6. Mad er R, Verlaan JJ, Bu skila D. Di u se id iop at h ic skelet al hyp erostosis: clin ical feat u res an d p at h ogen ic m ech an ism s. Nat Rev Rh eum atol 2013;9:741– 750 PubMed 7. van d en Berg R, St an islaw ska-Bier n at E, van der Heijde DM. Com parison of recom m en dat ion s for the use of an t i-t um ou r n ecrosis factor th erapy in an kylosing sp on dylit is in 23 cou n t ries w orldw ide. Rh eu m atology (Oxford) 2011;50:2270–2277 PubMed 8. Resn ick D, Sh apiro RF, Wiesn er KB, Niw ayam a G, Ut singer PD, Sh au l SR. Di u se id iop at h ic skelet al hyp erostosis (DISH) [an kylosing hyp erostosis of Forest ier an d Rotes- Qu erol]. Sem in Ar t h r it is Rh eu m 1978;7:153–187 PubMed 9. Sen olt L, Hulejova H, Kr yst ufkova O, et al. Low circulat ing Dickkopf-1 an d it s lin k w ith severit y of spinal involvem en t in di use idiopath ic skelet al hyperostosis. An n Rh eum Dis 2012;71:71–74 PubMed 10. Wester veld LA, van U ord HM, Verlaan JJ, On er FC. Th e prevalen ce of di use idiopath ic skelet al hyper-

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Chapter 13 ostosis in an out pat ien t populat ion in Th e Netherlan ds. J Rh eu m atol 2008;35:1635–1638 Pu bMed 11. Verlaan JJ, Bosw ijk PF, de Ru JA, Dh ert W J, On er FC. Di u se id iopath ic skelet al hyp erostosis of th e cer vical sp in e: an u n d erest im ated cau se of dysp h agia an d air w ay obst ruct ion . Spin e J 2011;11:1058–1067 PubMed 12. Sarzi-Put t in i P, At zen i F. New develop m en t s in ou r un d erst an ding of DISH (di u se idiop ath ic skelet al hyp erostosis). Cu rr Op in Rh eu m atol 2004;16:287– 292 PubMed 13. Verlaan JJ, On er FC, Maat GJ. Di use idiopath ic skeletal hyp erostosis in an cien t clergym en . Eu r Sp in e J 2007;16:1129–1135 PubMed 14. Wester veld LA, Verlaan JJ, Lam MG, et al. Th e in uen ce of di u se idiopath ic skelet al hyp erostosis on bon e m in eral d en sit y m easu rem en t s of th e sp in e. Rheum atology (Oxford) 2009;48:1133–1136 PubMed 15. Diederich s G, Engelken F, Marsh all LM, et al; Osteoporot ic Fract u res in Men Research Grou p . Di u se idiop at h ic skelet al hyp erostosis (DISH): relat ion to vertebral fract ures an d bon e den sit y. Osteoporos In t 2011;22:1789–1797 Pu bMed 16. Verlaan JJ, Wester veld LA, van Keu len JW, et al. Quan t it at ive an alysis of the an terolateral ossi cat ion m ass in d i u se idiop ath ic skelet al hyperostosis of th e th oracic spin e. Eur Spin e J 2011;20:1474–1479 Pu bMed 17. Vaccaro AR, On er C, Kepler CK, et al; AOSpin e Spin al Cord Inju r y & Trau m a Kn ow ledge For u m . AOSpin e th oracolu m bar spin e injur y classi cat ion system : fract ure descript ion , n eu rological st at us, an d key m odi ers. Spin e 2013;38:2028–2037 PubMed

18. Dan ish SF, Wilden JA, Sch uster J. Iat rogen ic paraplegia in 2 m orbidly obese pat ien t s w ith an kylosing spon dylit is un dergoing tot al h ip ar th roplast y. J Neurosurg Spine 2008;8:80–83 PubMed 19. Th om pson C, Moga R, Crosby ET. Failed videolar yn goscop e in t u bat ion in a p at ien t w it h d i u se id io p at h ic skelet al hyp erostosis an d sp in al cord inju r y. Can J An aesth 2010;57:679–682 Pu bMed 20. William s TH, Sch en k W. Bridging-m in im ally invasive locking plate osteosyn th esis (Bridging-MILPO): tech n ique descript ion w ith prospect ive series of 20 t ibial fract u res. Inju r y 2008;39:1198–1203 PubMed 21. Sapkas G, Kateros K, Papadakis SA, et al. Su rgical outcom e after spin al fract u res in pat ien t s w ith an kylosing spondylit is. BMC Muscu loskelet Disord 2009;10: 96–24 PubMed 22. Aoki Y, Yam agat a M, Ikeda Y, et al. Failu re of con servat ive t reat m en t for th oracic spin e fract u re in an kylosing spon dylit is: delayed n eurological de cit du e to spin al epid u ral h em atom a. Mod Rh eu m atol 2013; 23:1008–1012 Pu bMed 23. Gilard V, Curey S, Derrey S, Perez A, Prou st F. Cer vical spin e fract ures in pat ient s w ith an kylosing spon dylit is: Im port an ce of early m an agem en t . Neuroch irurgie 2014;60:239–243 Pu bMed 24. Elgafy H, Bransford RJ, Chapm an JR. Epidural h em atom a associated w ith occult fract u re in ankylosing sp on dylit is pat ien t: a case rep or t an d review of th e literat u re. J Sp in al Disord Tech 2011;24:469–473 PubMed

14 Rheumatoid Arthritis and Osteoporosis David T. Anderson

■ Introduction Rh eum atoid ar th rit is (RA) is a ch ron ic, in am m ator y au toim m u n e disorder ch aracterized by sym m et ric erosive syn ovit is of th e p erip h eral join ts. It a ects 1 to 2%of th e w orld populat ion an d often en t ails early involvem en t of th e cervical sp in e, a ect ing anyw h ere from 17 to 86% of pat ien ts.1 It can lead to p rogressive dest ru ct ion of th e syn ovial join ts, ligam en ts, an d bon e in th e cer vical sp in e, p ar t icu larly in th e atlan toaxial segm en t . Th is progressive dest ru ct ion can furth er lead to in stabilit y th at gen erally follows three characteristic patterns, w hich m ay occu r togeth er or alon e: atlan toaxial im p act ion (AAI), at lan toaxial su blu xat ion (AAS), an d su b a xial su blu xat ion (SAS). Each form of in stabilit y can in t urn lead to sp in al cord com pression and neurologic sym ptom s.2–8 With the increased u se of disease-m odifying ant irh eu m at ic dr ugs (DMARDs), th e n eed for surgical decom p ression an d st abilizat ion for cer vical sp in e p ath ology du e to RA h as fallen .9,10 Neverth eless, th e spin e surgeon caring for pat ien t s w ith RA in th e set t ing of cer vical spin e t rau m a m u st be aware of the speci c challenges this patient pop ulat ion presen t s. Preexist ing in stabilit y, n eu ral com p ression , deform it y, com prom ised bon e qualit y, an d im p aired h ealing capabilit ies can all com plicate th e t reat m en t of cer vical spin e t rau m a in p at ien t s w ith RA. Sp in e t rau m a cen ters sh ou ld be en couraged to develop soun d

t reat m en t p rotocols to e ect ively t reat th ese u n iqu e pat ien t s. Osteop orosis is a p rogressive bon e disease ch aracterized by loss of bon e m ass an d den sit y, deteriorat ion of th e m icroarch itect u re of bon e, an d fragilit y fract ures. It is a w idespread disease th at a ects m illion s of elderly pat ien ts, both m en an d w om en , regardless of eth n icit y. It leads to an in creased risk of fract ures of th e h ip, spin e, an d w rist , m ost n ot ably. With th e aging pop u lat ion , it is esp ecially bu rden som e on h ealt h care system s. Osteop orosis is a relat ively silen t , asym ptom at ic d isease u n t il a fract u re occu rs, causing sign i can t m orbidit y, m ort alit y, an d cost . It is est im ated th at 50% of w om en after age 50 an d 20% of m en after age 50 w ill sust ain an osteoporot ic fract ure.11 Vertebral com pression fract ures are m ore com m on an d occu r earlier in th e disease, bu t h ip fract u re risk in creases exp on en t ially w ith age. Ver tebral com p ression fract u res can lead to ch ron ic back p ain , p rogressive k yp h osis, d im in ish ed qu alit y of life, an d in creased u t ilizat ion of m ed ical resou rces.12 Osteop orosis gen erally resu lt s in th oracic an d lum bar com pression fract ures. How ever, decreased bon e m in eral den sit y in th e eld erly can also lead to ch aracterist ic fract u re p at tern s of t h e cer vical sp in e in t h e set t in g of even low -en ergy t rau m a. Od on toid fract u res h ave recen t ly received m u ch at ten t ion d u e to th e con t roversy th at exist s over opt im al t reat m en t .

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Chapter 14 Addit ion ally, cer vical ver tebral body com pression fract u res an d fract u re dislocat ion s at th e cer vicoth oracic ju n ct ion w arran t at ten t ion becau se of th e deform it y th ey m ay create an d th e ch allenges th at th is region of th e sp in e p resen t . When treating these fractures, the surgeon m ust be acutely aw are of th e in h eren t di cult ies in both n on surgical as w ell as surgical m an agem en t . Bot h are associated w it h r isks of com p licat ion s, m orbidit y, an d death in th e elderly pop u lat ion .

■ Rheumatoid Arthritis Pathophysiology and Biomechanics Rh eu m atoid pat ien ts experien ce a cell-m ediated im m u n e resp on se again st soft t issue early, car t ilage later, an d bon e last . A com plex in terplay of rh eu m atoid factor (an im m un oglobu lin M [IgM] an t ibody), m on on u clear cells, in terleu kin -1 (IL-1), an d t u m or n ecrosis factor-α (TNF- α ) result s in a cascade of even t s, in clu ding an t ibody-an t igen react ion s, m icrovascu lar proliferat ion , an d even t u ally hyp erp lasia of th e syn oviu m . Th is can lead to p an n u s form at ion , erosive join t an d soft t issu e dest r u ct ion , an d even t u al su blu xat ion an d in stabilit y.2,4,7 Th e cer vical sp in e h as several sep arate syn ovial-lin ed join t s. Th e occip itoat lan t al an d atlan toaxial art icu lat ion s do n ot h ave in ter vertebral disks, an d th erefore th eir en t ire st abilit y relies on th ese syn ovial join ts an d th e com p lex ligam entous structures (transverse cruciate and alar ligam en ts) providing su ppor t . For th is reason , th e occipitoatlan t al an d atlan toaxial join ts are m ost com m on ly a ected. Th ree t yp ical p at tern s of in st abilit y can develop. First , AAI is th e resu lt of rost ral m igrat ion of th e odon toid p rocess d u e to dest ru ct ion of ar t iculat ion of th e occipital con dyles, th e C1 lateral m ass, an d th e C1- C2 lateral m asses. Th is pat tern is also called basilar invagin at ion an d cran ial set tling. Th is pat tern can result in com pression of th e brain stem , an d it m ay carr y a poor progn osis. Usu ally diagn osed on lateral upright radiographs, several di erent proposed

m easu rem en t s (McRae’s lin e, McGregor’s lin e, the Ran aw at m ethod, an d others) h ave been developed over the years to m ake the diagnosis. Th e secon d p at tern , AAS, is th e m ost com m on form of in st abilit y in RA an d is th e resu lt of dest ru ct ion of th e t ran sverse ligam en t com plex or erosion of th e odon toid p rocess, w h ich in turn leads to abnorm al anterior-posterior m ot ion of th e atlan toa xial ar t icu lat ion in exion an d exten sion . Th is is exacerbated in exion an d is m an ifested on lateral radiograph s as an in crease in th e an terior atlan to-den s in ter val (AADI) greater t h an 5 m m an d a d ecrease in t h e p oster ior at lan to -d en s in ter val (PADI) to less t h an 14 m m .3 Rep et it ive com p ression of th e u p p er cer vical sp in al cord in exion can resu lt in n eu rologic sym ptom s or inju r y. Th e th ird pat tern , SAS, en t ails in stabilit y th at is th e resu lt of syn ovial dest r uct ion of th e facet join t s, capsules, an d w eaken ing of th e posterior ligam en tou s com p lex. From C3 to C7, th ere is progressive sublu xat ion of on e ver tebral body on an oth er th at can result in th e h allm ark “st aircase” on u p righ t lateral rad iograp h s (Fig. 14.1). This entit y can be distinguished from degen erat ive spon dylolisth esis by th e lack of

Fig. 14.1 Rheumatoid arthritis. Involvement of the cervical spine t ypically results in progressive anterior subluxation of one vertebral body on the next, creating a “staircase” spine on standing lateral radiograph. Note the involvement of the C2–C3 and C3–C4 segments, not t ypically seen in the degenerative cervical spine.

Rheumatoid Arthritis and Osteoporosis osteophyte form at ion an d by th e frequen t in volvem en t of th e C2–C3 an d C3–C4 segm en ts. Neu ral com p ression an d su bsequ en t sym p tom s can resu lt . Again , exion an d exten sion view s w ill d eter m in e t h e exten t of su blu xat ion . Sp ace available for t h e cord (SAC) of less th an 14 m m sh ou ld aler t t h e su rgeon to p ossible cord com pression .

Imaging Th e ch allen ge in t reat in g RA p at ien t s w h o presen t w ith t rau m a is to delin eate preexist ing deform it y from n ew t rau m at ic ch anges. RA p at ien t s m ay ver y w ell p resen t w ith m ild sym p tom s. At baselin e, rh eum atoid involvem en t of the cer vical spine is often asym ptom atic or m ay on ly in clu de n eck pain .1,2 It is im por t an t to u n d erst an d th at 40 to 80% of RA p at ien t s w ill h ave n eck pain , an d 43 to 86%w ill already h ave su blu xat ion on rad iograp h s; h ow ever, on ly 7 to 34% w ill h ave any n eu rologic de cit s.2,3,8 A ver y com plete histor y and physical exam should u n cover any n ew sym ptom s, n eu rologic sym p tom s, an d de cit s. Uprigh t radiograph s sh ould be obt ain ed w h en ever p ossible. Most t rau m a cen ters n ow u se com p u ted tom ograp hy (CT) as a screen ing tool for h ead an d n eck t raum a, w h ich can dem on st rate any obviou s n ew fracture. Magnetic resonan ce im aging (MRI) should be obt ain ed for any p at ien t p resen t in g w ith n eu rologic ch anges on p hysical exam in at ion . It also sh ou ld be con sidered in th e set t ing of basilar invagin at ion on rad iograp h s. MRI h elps d i eren t iate n ew t rau m at ic inju r y from p reexist ing deform it y, in stabilit y, or degen erat ion . More im por t an tly, MRI disp lays an abn orm al spin al cord sign al, w h ich m ay guide treatm ent. Traum a protocols h ave been est ablish ed in m ost cen ters an d sh ould be closely follow ed. The Advanced Traum a Life Support (ATLS) guidelin es aid th e team in determ in ing th e presence of any life-th reaten ing inju ries, in addressing th ose injuries, an d in un covering any dist ract in g inju r ies, regard less of an RA d iagn osis. How ever, a th orough h istor y sh ou ld be t aken , in cluding qu est ion s abou t a p rior diagn osis of RA. If th e pat ien t repor t s a prior diagn osis, this sh ould im m ediately aler t th e t reat ing team to p ay close at ten t ion to m ore su btle sym ptom s

an d sign s on p hysical exam . All p at ien t s are assessed for dist ract ing inju res an d n eu rologic st at u s. CT of t h e cer vical sp in e is st an dard screen ing protocol in m ost em ergen cy depar tm en ts. If any n eurologic de cit s are fou n d, an MRI sh ould be obt ain ed. If th e pat ien t is n eurologically in t act an d can st an d, up righ t radiograph s an d exion -exten sion view s sh ould be obt ain ed at th e d iscret ion of th e spin e t rau m a team based on th e n dings on CT. It can be ver y h elpfu l to obt ain any prior radiograp h s, CT, or MRI if th e p at ien t h as been seen an d evalu ated by a sp in e specialist prior to th e t raum a. Th ese prior n dings can h elp dist inguish n ew t raum a from exist ing deform it y. During the clinical evaluation, patients should be assessed for p ain an d ten dern ess to p alp at ion . Neck p ain an d occip it al h eadach es are t h e m ost com m on sym ptom s in RA pat ien ts.1 Neu rologic exam sh ou ld u n cover any de cit s, m yelopathic signs, w eakness, gait disturbances, n e m otor skill de cit s, or p aresth esias in th e h an ds. It is param oun t to obt ain a good h istor y an d determ in e any preexist ing sym ptom s.

Treatment Treat m en t of cer vical sp in e fract u res sh ou ld adh ere to th e st an dard of care for th e speci c fract ure pat tern iden t i ed. Non operat ive t reatm ent for relatively stable fracture patterns m ay be in dicated. Im m obilizat ion in a h ard cer vical or th osis or h alo vest is a reason able opt ion , but h alo vest ut ilizat ion in th e elderly seem s to be falling ou t of favor due to th e h igh rate of associated com plicat ion s.13 Unstable fracture patterns, injuries w ith cont in ued sp in al cord com p ression , an d in com plete n eu rologic inju ries m ay requ ire su rgical st abilizat ion even t u ally w ith decom p ression . Sp in e su rgeon s sh ou ld adh ere to th e Su baxial Cervical Spine Injur y Classi cation (SLIC) guidelin es.14 If surgical t reat m en t of a RA pat ien t w ith com orbid cer vical spin e t raum a is in dicated, the treat ing surgeon sh ould strongly consider th e u se of an terior an d p osterior xat ion du e th e poor bon e qu alit y often en cou n tered in RA pat ien t s. On e approach or th e oth er, used alon e, m ay be at h igh risk of failure. Again , th is pat ien t p opu lat ion can p resen t ch allenges an d

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Chapter 14 obst acles in t h e for m of osteop orot ic bon e, p reexist ing deform it y or sten osis, m edical com orbidities, functional lim itations, and relative act ivit y of th e disease itself. Th e risks an d ben e t s of su rger y m u st be th orough ly evalu ated an d discu ssed w ith th e pat ien t an d fam ily. Th e u lt im ate goal of su rgical in ter ven t ion is to decom press any cord com pression , st abilize any in st abilit y, an d restore align m en t . Presu rgical h alo t ract ion can be ut ilized to aid in th is goal. Th e pat ien t m ay require several days of t ract ion before su rger y is at tem pted. With th e m u lt it u de of bon e graft ing opt ion s an d in st rum en t at ion available, ever y at tem pt sh ou ld be m ad e to ach ieve a solid ar t h rod esis. Met icu lou s fu sion bed p reparat ion , carefu l p lacem en t of rigid in st rum en tat ion , an d st rong con siderat ion of t h e u se of au tograft s w ill aid in th e fu sion . In addit ion , th e t reat ing su rgeon sh ou ld con sider longer p ostop erat ive im m obilizat ion th an for a t ypical p at ien t w ith ou t RA. Th e th ree speci c pat tern s of in stabilit y in th e RA p at ien t w ith t rau m a sh ou ld be t reated accordingly. In th e RA p at ien t w ith SAS, a SAC of less t h an 14 m m , an d dyn am ic in st abilit y on exion -exten sion radiograph s, an an terior/ posterior procedu re sh ou ld be con sidered. If th e in st abilit y is n ot redu cible, th e an terior ap proach sh ou ld be don e rst to restore sagit t al align m en t , follow ed by posterior in st rum en ted fu sion . In th e RA p at ien t w ith AAS, a SAC of less th an 14 m m , cord com p ression , an d dyn am ic in st abilit y, con siderat ion sh ou ld be given to a posterior C1–2 ar th rodesis. If th e in st abilit y is xed, lam in ectom y m ay be requ ired . In th e RA pat ien t w ith AAI an d cord com p ression , su rger y m ay be in dicated . Tract ion follow ed by an occipit al-cer vical fu sion is a reason able ch oice. If th e deform it y is xed, a C1 lam in ectom y m ay be requ ired.

■ Osteoporosis Pathophysiology Osteop orosis is a system ic disease th at even t u ally redu ces th e m ech an ical st rength of bon e. Essen t ial in p reven t in g osteop orosis is t h e ach ievem en t of n orm al peak bon e m ass, w h ich

occurs in th e th ird decade of life. Proper n u t rit ion , app ropriate calciu m an d vitam in D in take, regular m en st r ual cycles, an d a regular exercise p rogram all con t ribu te to overall bon e h ealt h . After m en op au se, w om en u n d ergo accelerated bon e loss w it h ou t t h e p rotect ive e ect s of est rogen . After th e age of 50, w om en an d m en gradually lose bon e m ass.11 Th e Nat ion al Osteop orosis Fou n dat ion h as iden t i ed an d publish ed pat ien t ch aracterist ics th at m ay predict poor bon e qu alit y. Th ey in clu de a h istor y of previous fragilit y fract ure or a fract ure in a rst-degree relat ive, Caucasian eth n icit y, sm oking, low body m ass in dex, fem ale gen der, dem en t ia, p oor h ealth , an d fragilit y.15 Bon e qu alit y can be assessed w it h p lain rad iograp h s an d CT, bu t is bet ter evalu ated w it h a du al-en ergy radiograph absorpt iom et r y (DEXA). A T-score of 1 to 2.5 st an dard deviat ion s below th e valu e for h ealthy 25-year-old con t rols is con sidered osteopen ia. Osteop orosis is d e n ed as greater th an 2.5 st an dard d eviat ion s below t h e con t rol. DEXA scan s can closely follow bone qualit y during m edical treatm en t of osteoporosis, an d can p rovide in form at ion th at m ay aid in th e elect ive t reat m en t of sp in e p ath ology. It is n ot rout in ely obt ain ed in th e set t ing of t raum a, h ow ever. Osteop orosis a ect s th e can cellou s por t ion of bon e earlier an d, on ly in th e later st ages, affects cor t ical bon e. Th e w eigh t-bearing ver tebral bodies of th e an terior colum n of th e spin e con sist largely of can cellou s bon e covered by a th in cor t ical sh ell. Conversely, th e posterior elem en ts of th e spin al colu m n con t ain larger quantities of cortical bone an d are m echanically st ronger. Osteop orosis a ect s th e m icroarch itect ure of th e can cellous bon e, an d th erefore fract u res are m ore pron e in th ese areas u n der h igh er st ress w ith less m ech an ical st rength .16

Fracture Patterns Osteop orot ic com p ression fract u res t yp ically occu r in th e m idth oracic region (T5–T8) an d th e t h oracolu m bar ju n ct ion (T10-L2). Th e m idth oracic ver tebrae are t h e region of th e m ost kyp h osis an d h ave in creased load on th e an ter ior colu m n an d w eaker can cellou s bon e in exion. The thoracolum bar junction represen ts

Rheumatoid Arthritis and Osteoporosis a st raigh t sect ion of th e spin e w h ere th ere is a t ran sit ion from a relat ively st i th oracic sp in e (due to th e added stabilit y of th e rib cage) to a m obile lum bar spin e. Th is m akes th e region su scept ible to com p lex forces, m ost n ot ably in clu ding axial com pression , leading to failure of th e an terior colum n an d com pression an d bu rst-t yp e fract ures. Align m en t an d th e e ect s of ar th rosis also p lay a role in t h e osteop orot ic com p ression fract u re p at tern s in t h e agin g sp in e. Areas of lordosis t ypically are protected due to the com pressive forces being t ran sm it ted th rough th e m ore cor t ical bon e-r ich p oster ior elem en t s; com p ression fract u res of th e cer vical sp in e an d lu m bar sp in e are th erefore seen less often . Addit ion ally, degen erat ive ch anges an d ar th rosis can lead to sclerosis of th e su bch on dral bon e an d h ave an overall protect ive e ect . Often th e older pat ien t exh ibits both osteoporosis an d degen erat ive ch anges con com itan tly. In regard to th e cer vical spin e, t h ere are t w o fract u re p at tern s t h at t yp ically d evelop as a resu lt of t h e overall clin ical p ict u re of w eak osteop orot ic bon e, st i ar th rit ic segm en t s, an d possible u pp er th oracic kyp h osis. Fract u res at th e atlan toa xial com p lex an d fract u res of th e cer vicoth oracic jun ct ion requ ire special at ten t ion . Fract u res at th e C1- C2 ar t icu lat ion in th e osteoporot ic spin e are often th e result of relat ively low -en ergy falls. Th e elderly sp in e can often assu m e a hyperkyph ot ic th oracic region , w h ich is accom pan ied by a com pen sator y hyperlordot ic u p per cer vical segm en t . Ad dit ion ally, th e u n iqu e an atom y of th e C2 ver tebral body pu ts th e odon toid at risk in th ese falls. Th ere is also a h igh p rop or t ion of can cellou s bon e in t h e C2 body an d a h or izon t ally orien ted join t at C1- C2. Th is allow s con sid erable m ot ion at th e C1- C2 ar t iculat ion but put s st ress on th e od on toid process, especially in acciden tal falls. Th ere h as long been sign i can t con t roversy over th e m an agem en t of odon toid fract u res in th e elderly. Fract u res at t h e cer vicot h oracic ju n ct ion can also be seen in t h e osteoporot ic spin e w ith low -en ergy t rau m a. In t h e set t ing of hyp erkyp h osis of t h e u p p er t h oracic sp in e, t h e cervicoth oracic ju n ct ion can be pu t in a posit ion th at p redisp oses it to m ore com pressive forces,

as w ell as sh ear forces, in t raum a. Alth ough t radit ion ally di cu lt to im age, th e cer vicoth oracic ju n ct ion is n ow easily evalu ated w ith th e readily available and quick CT scan in the em ergen cy depar t m en t . Again , th e t ran sit ion from relat ively st i th oracic segm en ts to th e m ore m obile cer vical sp in e can p u t th e ver tebral bodies of C7 an d T1 at risk for fract u res in th e elderly p opu lat ion .

Treatment and Surgical Strategies Man agem en t of cer vical sp in e t rau m a sh ou ld adh ere st rictly to th e ATLS guidelin es, w ith identi cation of any life-threatening conditions and distracting injuries, a thorough history, and a n eurologic exam . Evaluat ion of th e elderly pat ien t w ith h igh - or low -en ergy t rau m a often in clu des a CT scan of th e cer vical spin e. Th e t reat ing su rgeon m u st be aw are of th e in h eren t ch anges in bony arch itect u re an d align m en t th at p u t s p ar t icu lar areas of th e cer vical spin e at risk in th is p at ien t popu lat ion . In th e osteoporot ic an d st i spin e, clin ician s sh ou ld m ain tain a h igh in dex of su spicion for injuries at th e atlan toaxial ju n ct ion an d th e cer vicoth oracic jun ct ion . Th e w orkup sh ould in clude an MRI if th ere is any n eu rologic d e cit . In m ost t rau m a cen ters, an MRI w ill be obt ain ed if a fract u re is id en t i ed as w ell. Plain rad iograp h s in t h e w eigh t-bearing posit ion , if possible, can also aid in th e t reat m en t ch oice. As m en t ion ed previou sly, th e t reat m en t of geriat ric t ype II odon toid fract ures h as been th e su bject of in ten se debate for years. More recen tly, th e AO (Arbeitsgem ein sch aft fü r Osteosyn th esefragen ) Spin e Nor th Am erica organization has closely studied non operative versus operat ive t reat m en t in a m u lt icen ter st udy w ith a large n um ber of pat ien t s.17–19 Odon toid fract u re m an agem en t , regardless of t reat m en t ch oice, is in h eren tly di cu lt an d can result in m u lt iple com plicat ion s, sign i can t m orbidit y, an d even m or t alit y. Typ e I an d t ype III odon toid fract u res are t yp ically t reated n on operat ively w ith h ard collar im m obilizat ion . Type II fract u res (Fig. 14.2) p resen t a ch allenge du e their higher rate of nonunion.17–20 Nonoperative t reat m en t opt ion s in clude h ard cer vical orth osis or h alo vest im m obilizat ion . Again , th e h alo

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Fig. 14.2 Type II geriatric odontoid fracture in the set ting of osteoporosis. A relatively minor trauma in an elderly patient resulted in this fracture pat tern. Note the sti , spondylotic, and osteoporotic cervical spine.

vest im m obilization has fallen out of favor in the elderly p op u lat ion du e to th e h igh rate of com plicat ion s an d gen eral p at ien t in toleran ce.13,20 How ever, it is a reason able opt ion in a you nger pat ien t w ith ou t risk factors for n on u n ion . A h ard cer vical or t h osis is t h e m ost com m on opt ion for n on op erat ive t reat m en t . It m ay n ot resu lt in a bony u n ion of th e fract u re, bu t a brou s u n ion m ay provide su cien t stabilit y. In th e AO Spin e st u dy, 36%of p at ien ts u n der w en t con ser vat ive care. Of th ose, 81% w ere t reated in a h ard collar, 9% in a soft collar, an d 10% in h alo vest im m obilizat ion .17 Op erat ive t reat m en t can be con sidered in th e p at ien t w ith risk factors for n on u n ion w h o is ot h er w ise a su it able su rgical can didate. Addit ion ally, displaced fract u res an d n on un ion s w it h in st abilit y are in d icat ion s for su rgical in ter ven t ion . Pract ices seem to var y w id ely across t rau m a cen ters. Surgical approach es in clude an an terior odon toid screw or p osterior

C1–C2 ar th rodesis (Fig. 14.3). Tran soral resect ion of th e odon toid an d posterior stabilizat ion is reser ved for rare cases. In th e AO Sp in e st u dy, 64% of pat ien ts u n der w en t operat ive xat ion of a t yp e II od on toid fract u re. Of t h ose, 79% underwent posterior C1–C2 fusion w ith screw xat ion , 12% u n d er w en t an ter ior od on toid screw xat ion , an d th e rem ain der u n der w en t posterior fu sion w ith variou s w iring or screw xation techniques. In this study, operative treatm en t w as associated w ith a h igh er u n ion rate, relat ively equ ivalen t com plicat ion rate, an d an overall bet ter ou tcom e. In it ial n on operat ive t reat m en t , m ale gen der, older age, an d n eu rologic im pairm en t w ere associated w ith failu re of treatm ent. Follow -up studies con rm ed that, regardless of t reat m en t , th e 1-year m ort alit y rate w as relat ively h igh at 18%.19 Addit ion ally, 22%of th ose p at ien t s in it ially t reated n on op eratively developed sym ptom atic nonunions, and over 60% of th ose p at ien t s requ ired d elayed

Rheumatoid Arthritis and Osteoporosis qu ire op erat ive xat ion to regain ad equ ate align m en t an d st abilit y. Com p ression fract u res t yp ically occu r at t h e low er levels of t h e cer vical sp in e an d m ay be accom p an ied by a hyp erkyph ot ic upper th oracic spin e, m aking access an teriorly di cu lt . Flexion -exten sion lm s sh ou ld p rovide t h e t reat ing su rgeon w ith en ough in form at ion to decide if an an terior ap proach is feasible. St rong con siderat ion sh ou ld be given to a com bin ed an terior-posterior ap proach to obtain a rigid con st ru ct an d a solid ar th rodesis.

■ Chapter Summary

Fig. 14.3 Type II geriatric odontoid fracture. A suitable candidate for surgical intervention, this patient was treated with posterior C1-C2 fusion. Anatomic limitations required the use of translam inar screws at C2.

su rgical xat ion .18 Th ese st u dies rep resen t th e m ost robu st literat u re w e h ave at t h is p oin t regarding th e t reat m en t of geriat ric odon toid fract ures. Again , th ey h igh ligh t th e in h eren t di cu lt y in t reat ing th ese fract u res th at are often par t ially th e result of osteoporot ic bon e. As th e population ages, the spine surgeon t reating th ese inju ries m u st closely w eigh th e risks an d ben e ts of t reat m en t opt ion s an d provide this inform ation to the pat ient and fam ily w hen join tly m aking decision s regarding t reat m en t . Fractures at the cer vicothoracic junction also presen t ch allenges in th e osteoporot ic sp in e. Failu re of th e an terior colu m n in th is region can lead to an in crease in kyp h osis of th e u pp er th oracic region an d possibly ch in -on -ch est deform it ies. Addit ionally, fract u res in th is region are often m ech an ically un stable an d m ay re-

Rh eum atoid ar th rit is is a ch ron ic, proliferat ive autoim m un e disease w ith early involvem en t of th e cer vical spin e. Alth ough su rger y for cer vical spin e deform it ies h as becom e less frequen t w ith th e use of DMARDs, th e spin e surgeon t reat ing cer vical t rau m a m u st be aw are of th e challenges inherent in this di cult patient pop u lat ion . Cer vical t rau m a protocols sh ould be closely follow ed , regard less of a p reexist in g d iagn osis of RA. How ever, th e sp in e su rgeon m u st be acu tely aw are of th e m u lt ip le p roblem s often en cou n tered w h en t reat ing cer vical sp in e t rau m a in t h ese p at ien t s. Again , t h e d ifcu lt y lies in d ist in gu ish in g p reexist in g d efor m it y from n ew t rau m a. Carefu l h istor y regarding n ew sym ptom s is ver y im por t an t . W h en surger y is in dicated, st rong con sideration should be given to com bined an terior and posterior xat ion to aid in fu sion . Ever y attem pt sh ould be m ade to ach ieve n ear-n orm al an atom ic align m en t as w ell an d preven t developm en t of any n eu rologic declin e. Lastly, th e su rgeon n eeds to be aw are of th e ch allenges in th e p ostoperat ive recover y of t h ese pat ien t s in regain ing fun ct ion . Osteoporosis is a progressive bon e disease ch aracterized by loss of bon e m ass an d den sit y, deteriorat ion of th e m icroarch itect ure of bon e, an d fragilit y fract ures. Com pression fract ures of th e m idth oracic an d th oracolum bar region s are th e m ost com m on form of spin e fract ures en cou n tered , bu t sp ecial at ten t ion m u st be paid to th e osteoporot ic spin e in th e set t ing of

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Chapter 14 cer vical sp in e t rau m a. Preexist in g d efor m it y of th e u p p er th oracic region an d u p per cer vical region accom pan ied by a relat ively st i sp in e create ch aracterist ic fract ures of th ese t w o region s. Proper w orkup an d iden t i cat ion of poten t ial ch allenges w ill aid th e t reat ing surgeon in dealing w ith th ese fract u res. Regardless of treatm en t choice, th ese fract ures generally rep resen t a poor progn osis for th e pat ien t . W h en operat ive t reat m en t is in dicated, special con siderat ion m u st be given to xat ion in w eak bon e. Carefu l tech n ique, prolonged im m obilizat ion , close follow -u p , an d good reh abilitat ion are im por t an t in ach ieving a solid ar th rodesis an d overall recover y.

Pearls Strict adherence to sound surgical techniques can help avoid surgical complications. However, when treating RA patients, the surgeon m ust be ready to deal with complications in this challenging patient population. The risk of pseudarthrosis can be mitigated with meticulous preparation of fusion bed, careful placement of rigid instrumentation, and the use of autograft with allograft extenders. Prolonged collar imm obilization or the possible use of the halo vest in select patients can help in achieving a solid arthrodesis. The recovery and rehabilitation of RA patients after cervical spine surgery is often prolonged. A strong rehabilitation and physical therapy team is paramount. Patient s m ay have functional lim it ation due to lim b deform ities, in addition to any preexisting myelopathic sym ptom s. Early involvem ent of the physical medicine and rehabilitation team is helpful. The treating surgeon m ust be acutely aware of the inherent di culties in treating fractures of the cervical spine that present in osteoporotic patients. Preexisting deform it y, including hyperkyphotic thoracic segm ent s, com pensatory hyperlordotic cervical segm ents, and sti spines, all can make treatm ent di cult. Patient s with osteoporosis often present with other com orbidities that m ust be t aken into account when discussing treatm ent options. A careful assessment of overall health and risk strati cation is important.

Early involvement of the m edical team and the physical medicine and rehabilitation team is helpful in transitioning the patient from initial injury, through treatment, and ultimately to a rehabilitation program . Identi cation of speci c needs and proper assistive devices can facilitate functional recovery and avoid m edical problems. When treating t ype II odontoid fractures with operative xation, meticulous preparation of fusion surfaces is param ount in achieving a successful union. Careful at tention must be paid to preoperative im aging to determine the feasibilit y of various screw trajectories. Longer and thicker screws a ord bet ter purchase and therefore more rigid xation. C2 pedicle screws should be favored over the shorter C2 pars screw, but m ay not be feasible based on the vertebral artery pathway. Strong consideration should be given to anterior/ posterior approaches when dealing with the cervicothoracic junction due to the higher stresses in this region. Longer constructs m ay be necessary to achieve mechanical stabilit y. Pitfalls The RA patient m ay have several m edical com orbidities that can have a negative im pact in the set ting of undergoing cervical decompression and stabilization. It is important to have the m edical team closely involved in the treatm ent plan. Active RA disease and the DMARDs used to treat it can be di cult to manage. The skin of RA patients can cause wound healing problems. Regardless of treatm ent choice, management of osteoporotic fractures entails considerable risk of complications. Construct failure and screw pullout may be avoided with prolonged imm obilization in a collar for C1-C2 fractures. Consideration should be given to a custom molded cervicothoracic brace in the set ting of operative xation in this region. If loss of xation is identi ed at the cervicothoracic junction, revision surgery with re-instrumentation and extension of the construct m ay be required.

Rheumatoid Arthritis and Osteoporosis Refere nces Five Must-Read Refe rences 1. Raw lin s BA, Girardi FP, Boachie-Adjei O. Rh eum atoid ar th rit is of th e cer vical sp in e. Rh eu m Dis Clin Nor th Am 1998;24:55–65 Pu bMed 2. Kim DH, Hilibran d AS. Rh eum atoid arth rit is in th e cer vical spin e. J Am Acad Or th op Su rg 2005;13:463– 474 Pu bMed 3. Boden SD, Dodge LD, Boh lm an HH, Rech t in e GR. Rh eu m atoid ar th rit is of th e cer vical sp in e. A longter m an alysis w it h p red ictors of p aralysis an d recover y. J Bon e Join t Su rg Am 1993;75:1282–1297 PubMed 4. Pellicci PM, Ranaw at CS, Tsairis P, Br yan W J. A p rosp ect ive st u dy of t h e p rogression of rh eu m atoid ar t h rit is of t h e cer vical sp in e. J Bon e Join t Su rg Am 1981;63:342–350 PubMed 5. Ran aw at CS, O’Lear y P, Pellicci P, Tsairis P, March isello P, Dorr L. Cer vical sp in e fu sion in rh eu m atoid ar th rit is. J Bon e Join t Su rg Am 1979;61:1003–1010 PubMed 6. Nurick S. Path ogen esis of spin al cord disorders. Brain 1972;95:87–100 PubMed 7. Zeidm an SM, Ducker TB. Rh eu m atoid ar th rit is. Neu roan atom y, com pression , an d grading of de cit s. Spin e 1994;19:2259–2266 PubMed 8. You se JA, Forsyth e SL, Glover N, Pat terson AJ. Rh eu m atoid ar th rit is. In : Vaccaro AR, Anderson P, eds. Cer vical Spin e Trau m a. Ph iladelp h ia: Roth m an In st it ute; 2010 9. Kauppi MJ, Neva MH, Laih o K, et al; FIN-RACo Trial Group. Rh eu m atoid atlan toaxial sublu xat ion can be preven ted by in ten sive u se of t radit ion al disease m odifying an t irh eum at ic drugs. J Rheum atol 2009; 36:273–278 PubMed 10. Mallor y GW, Halasz SR, Clarke MJ. Advan ces in th e t reat m en t of cer vical rh eum atoid: Less surger y an d less m orbid it y. World J Or t h od 2014;5:292–303 PubMed

11. Lan e JM, Russell L, Kh an SN. Osteop orosis. Clin Orth op Relat Res 2000;372:139–150 PubMed 12. Cu m h u r On er F. Osteop orosis. In : Vaccaro AR, An derson P, eds. Cer vical Spin e Trau m a. Ph iladelphia: Roth m an In st it u te; 2010 13. Majercik S, Tash jian RZ, Bi W L, Harrington DT, CioWG. Halo vest im m obilizat ion in th e elderly: a death sen ten ce? J Trau m a 2005;59:350–356, discu ssion 356–358 PubMed 14. Joaqu im AF, Patel AA, Vaccaro AR. Cer vical inju ries scored according to th e Subaxial Injur y Classi cat ion system : an an alysis of th e literat ure. J Cran iover tebr Ju n ct ion Spin e 2014;5:65–70 PubMed 15. Hein em an n DF. Osteoporosis. An over view of th e National Osteoporosis Foundation clin ical practice guide. Geriat rics 2000;55:31–36, qu iz 39 Pu bMed 16. W h ite AA, Panjabi MM. Clin ical Biom ech an ics of th e Spin e. Ph iladelphia: Lippin cot t; 1978:31 17. Ch ap m an J, Sm ith JS, Kopjar B, et al. Th e AOSp in e Nor th Am erica Geriat ric Odon toid Fract ure Mor t alit y St udy: a ret rospect ive review of m ort alit y ou tcom es for operat ive versus n on operat ive t reat m en t of 322 pat ien t s w ith long-term follow -up. Spin e 2013;38:1098–1104 PubMed 18. Sm ith JS, Kep ler CK, Kopjar B, et al. E ect of t ype II odontoid fract ure n on un ion on ou tcom e am ong elderly p at ien t s t reated w ith ou t su rger y: based on th e AOSpin e Nor th Am erica geriat ric odon toid fract u re st udy. Spin e 2013;38:2240–2246 PubMed 19. Feh lings MG, Aru n R, Vaccaro AR, Arn old PM, Ch ap m an JR, Kopjar B. Predictors of t reat m en t outcom es in geriatric patients w ith odon toid fractures: AOSpin e Nor th Am erica m ult i-cen t re prospect ive GOF st udy. Spin e 2013;38:881–886 Pu bMed 20. Lew is E, Liew S, Dow rick A. Risk factors for n on u nion in th e n on -operat ive m an agem en t of t ype II dens fract u res. ANZ J Surg 2011;81:604–607 PubMed

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15 Pediatric Cervical Spine Ahmet Alanay and Caglar Yilgor

■ Introduction Th is ch apter discu sses cer vical sp in al inju r y in ch ildren , w h ich is som ew h at di eren t from th at in adu lt p at ien t s, du e to di eren ces in an th rop om et rics, biom ech an ics, clin ical p resen tat ion , an d m an agem en t prin ciples. Alth ough an in frequ en t en t it y, becau se of th e h igh rates of associated m orbidit y an d m ort alit y, th e diagn osis sh ould be qu ickly an d accu rately m ade. The epidem iology, developm ental anatom y, and n or m al var ian t s by age t h at com p licate t h e in ter p ret at ion of n d in gs in th ese p at ien t s are exp lain ed in t h is ch apter. Mech an ism s an d p at tern s of injur y, clin ical an d radiological cervical spin e clearan ce, t reat m en t st rategies, an d p ossible com plicat ion s are described.

■ Epidemiology Cer vical sp in e inju r y in ch ild ren is rare, rep resen t in g a sm all p ercen t age of all p ediat ric t rau m as. How ever, th ose w h o su st ain inju r y h ave a h igh m orbidit y an d m or t alit y in com p ar ison w ith ad u lt p at ien t s. More th an 60% of sp in al inju r ies in ch ild ren are in t h e cer vical sp in e. Sp in al cord inju r y w ith t ran sien t or p er m an en t n eu rologic inju r y is com m on . Abou t h alf of th ese inju ries do n ot dem on st rate radiograph ic evidence of bony involvem ent . Chil-

dren you nger th an 8 years of age are less likely to su st ain fract u res an d are at greater r isk for cord inju r ies. On e th ird to on e h alf of all ch ildren w ith cer vical injuries dem on st rate n eurologic de cit s; 75% of th ese are in com plete an d th e rest are com plete. Th e m or talit y rate ranges from 16 to 18%. How ever, due to th eir greater h eal ing poten t ial, su r viving ch ildren h ave su perior outcom es w h en com pared w ith adults, w ith u p to 90% part ial an d 60% com plete recover y.1 Sixt y percen t of inju ries occu r in boys, w ith a bim odal dist ribut ion th at peaks at age 2 to 4 years an d 12 to 15 years. Th e m ost com m on ly id en t i ed inju r y t yp e am ong all ages is isolated ligam en tou s inju r y. Even in ch ild ren older th an 10 years of age, 20% of inju r ies are p u rely ligam en tou s. Th e sp in al colu m n sh ow s sign i can t di eren ces bet w een in fan ts (0 to 2 years), young ch ildren (>2 to 8 years), an d older ch ildren (>8 years) related to th e p rop or t ion alit y of th e h ead to th e spin e, bon e com posit ion , ver tebral body sh ape, developm en t of n eck m uscu lat ure, in clin at ion of facet join t s, an d ligam en tou s la xit y. Fur th erm ore, th e presen ce of syn ch on droses con fers in creased su scept ibilit y to sh ear forces. The younger the child, the m ore likely the injury involves the upper cervical spine. Lower cer vical injuries are associated w ith a higher percentage of spinal cord traum a, w hereas upper cer vical injuries h ave h igh er rates of m or t alit y,

Pediatric Cervical Spine w ith atlan to occipital dislocat ion h aving th e h igh est . Motor veh icle acciden t s, w ith th eir im pact on veh icle occupan t s, pedest rian s, an d bicycle riders, are th e m ost com m on source of inju r y. Falls an d sp or t s inju ries accou n t for u p to 30% of inju ries in you nger ch ildren an d older ch ildren, respect ively. Nonacciden tal traum a is also fou n d in sm aller n u m bers th at often p resen t w ith associated inju ries to th e h ead, th orax, abdom en , an d m u scu loskelet al system . Con dit ion s su ch as Dow n syn drom e, m u co polysacch aridosis or spon dyloep iphyseal dys p lasia, an d con gen it al an om alies in clu d ing dysrap h ism an d os od on toid eu m can p red is pose ch ildren to cer vical spin e an d cord inju r y.

■ Mechanism of Injury Cer vical sp in e inju ries are cau sed by exion , extension, lateral exion, com pression, distraction , an d rot at ion , an d by th e sim u lt an eou s or sequ en t ial e ect s of th ese factors. For exam p le, the n onacciden tal traum a due to vigorous sh aking would occur secondary to exion-extension an d rotat ion t yp e m om en ts. Hyper exion injuries in clude exion teardrop fract u re, w edge (com p ression ) fract u res, uni- and bilateral facet subluxation/dislocations, an terior sublu xat ion , an d spin ou s process fractures. Spinous process fractures, unilateral facet fract u res, an d som e an terior su blu xat ion s are considered stable, w hereas the rest are unstable. Th e m ech an ism of inju r y in hyp erexten sion is often a blow to th e face or foreh ead. Hyp erexten sion injuries in clude avulsion of th e an terior arch of C1, isolated fract ure of th e posterior arch of C1, hyp erexten sion teardrop fract u re, hyp erexten sion d islocat ion , lam in a fract u re, an d t raum at ic spon dylolysis of C2 (Hangm an ’s fract u re).2 Th e hyp erexten sion teard rop is a result of avulsion of th e an terior longit udin al ligam en t . Alt h ough it is m ore frequ en t at C2 in ad u lt s, in ch ild ren it is m ore com m on in t h e su baxial spin e an d is often associated w ith spin al cord inju r y an d p revertebral soft t issu e sw elling.

Axial com p ression forces can resu lt in th e Je erson fract u re of th e atlas or th e bu rst fract u re in th e low er cer vical sp in e. Th is m ech a n ism is especially dangerous if it occu rs w ith t h e n eck sligh t ly exed becau se it br in gs t h e sp in al align m en t in to a st raigh t lin e w h ere t h e n orm al force dist ribu t ion is dist u rbed an d th e n eck m u scu lat u re can n ot assist w ith sh ock absorpt ion . Rotat ion inju ries occu r u su ally in com bin a t ion w ith exion or exten sion forces an d are often associated w ith vertebral ar ter y injur y. Lateral exion injuries are relatively uncom m on, an d in clu de lateral ver tebral body com pression fract u re, u n cin ate an d t ran sverse p rocess fract u re, an d occipit al con dyle fract u re.2 Oth er t yp es of inju r ies su ch as atlan to- occip ital dissociat ion , atlan toa xial inju r ies, an d odon toid fract u res do n ot resu lt from a single m ech an ism an d are du e to a com bin at ion of forces. Inappropriate or inadequate rest raint w ithin m otor veh icles m ay in crease th e rates an d se verit y of injur y. Placing sm all ch ildren in adu lt th ree p oin t seat belt s resu lt in an im balan ce bet w een th eir propor t ion ately larger h ead an d rest rain t of th e torso, cau sing injur y du e to hyper exion of th e n eck.

Associated Injuries Approxim ately h alf of th e pat ien ts h ave oth er associated traum atic injuries. Injur y to the head is th e m ost com m on associated inju r y seen in u p to 40% p at ien t s, an d is associated w it h a low er Glasgow Com a Scale score an d h igh er m or t alit y, an d w it h sp in al cord inju r y. Ot h er com m on ly associated inju r ies in clu d e solid organ an d abdom in al w all injuries, an d skelet al inju ries su ch as p elvic an d ext rem it y fract u res. Th oracic an d vascu lar t rau m a m ay be less frequ en tly p resen t . Alth ough m u lt ilevel sp in al inju ries m ay be id en t i ed in u p to 40% of th e p at ien ts, m u lt ilevel cer vical sp in al injur y is un com m on , w ith on ly 1% of m ore th an on e level of dislocat ion , an d 3% of fract ures involving m ore th an on e cer vical ver tebra.3 Injuries to th e spin al cord at C3- C5 m ay resu lt in p h ren ic n er ve failu re w ith su bsequ en t

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Chapter 15 apnea or hypoventilation. Spinal shock can also a ect t h e card iovascu lar system , lead in g to hyp oten sion or bradycard ia. Hen ce, at ten t ion sh ou ld be p aid to breath ing an d circu lat ion in a ch ild w ith su spected cer vical injur y.

■ Developmental Anatomy

and Embryology Most ver tebrae origin ate from fou r p rim ar y ossi cat ion cen ters: on e in each h em i-arch an d t w o w ith in th e cen t r um . Longit u din al an d cir cum feren t ial grow th occurs in th e ch on droepiphyseal portions. Longitudinal grow th is th e resu lt of en ch on dral ossi cat ion , w h ereas circu m feren t ial grow t h is d u e to p er ich on d ral an d p er iosteal ap p osit ion . Th rough a sep arate p oster ior grow t h p late at t h e sp in ou s p rocess synchon drosis, posterior elem ents also dem on st rate longit udin al grow th . Ossi cat ion of th e an terior arch of th e atlas begin s bet w een th e th ird m on th an d rst year of life. Ossi cat ion of th e posterior arch is com pleted by th e age of 3 years. Th e syn ch on droses bet w een th e body an d th e posterior elem en t s fuse by 7 years of age.4 Th e a xis h as t w o ad d it ion al ossi cat ion cen ters t h at fu se in t h e m id lin e to for m t h e od on toid p rocess. Th e body an d t h e od on toid fu se bet w een ages 3 an d 6 years, yet t h e fu sion lin e m igh t rem ain visible th rough ou t th e life.4 Th ere is a secon dar y ossi cat ion cen ter at th e ap ex of t h e od on toid t h at ap p ears an d fu ses bet w een t h e ages of 6 an d 12 years. Failu re of fu sion resu lt s in p ersisten t ossicu lu m term in ale, w h ich sh ou ld be d i eren t iated from os od on toid eu m . An ot h er secon dar y ossi cat ion cen ter at t h e in fer ior ep ip hyseal r in g ap p ears at p u ber t y an d fu ses w ith t h e body by age 25 years.4 Th e develop m en t of th e su baxial cer vical spine is sim ilar from C3 to C7. Th e cen t ral par t ossi es rst , an d th e arch es fu se in th e m idlin e bet w een th e ages of 3 an d 6 years. Secon dar y ossi cat ion cen ters are located at th e an terior t ran sverse p rocesses, sp in ou s p rocess apices, an d superior an d in ferior epip hyseal rings.4

■ Normal Anatomic,

Biomechanical, and Radiological Variations It is im por t an t to un derstan d th e ch anging an atom y of th e pediat ric cer vical spin e to in terpret inju r y pat tern s an d dist inguish inju r y from a large n u m ber of n orm al varian t s. Alt h ough it var ies w it h age, in gen eral, t h e follow in g an atom ic d i eren ces in ch ild ren are frequen tly seen : • Th e facet join t s are m ore sh allow an d h orizon tal. • Th e in tersp in ou s ligam en ts, join t capsu les, and cartilaginous end plates are m ore stretch able w ith out tearing. • Th e u n cin ate process, w h ich rest ricts rota t ion al an d lateral m ovem en ts, is absen t in ch ildren you nger th an 10 years of age. • Ver tebral bodies are w edge sh aped an d sp i n ou s processes are n ot fu lly develop ed. Biom ech an ical variat ion s arise from th e fact th at t h e im m at u re sp in e is m ore elast ic. Th e skelet al elem en t s are far m ore st retch able th an th e n eu ral elem en t s; th u s, post t rau m at ic m y elop athy, even w ith ou t any eviden t injur y to th e ver tebral colu m n , is m u ch m ore com m on in ch ildren th an adu lt s. Th is also exh ibit s th e u n d erlying cau se for th e ph en om en on called spin al cord inju r y w ith ou t radiograp h ic abn or m alit y (SCIWORA). Th is en t it y is discussed in detail later in th is ch apter. Oth er biom ech an i cal variat ion s in ch ildren are th e follow ing: • Su baxial hyp erm obilit y is p resen t , du e to th e aforem en t ion ed an atom ic t rait s, an d is m ore prom in en t in ch ildren un der 8 years of age. • Th e in h eren t hyperm obilit y of th e pediat ric spin e resu lt s in a h igh er fulcrum of m ot ion at C2- C3. Th is fu lcr u m sh ifts cau dally tow ard C5- C6 by th e age of 10, su bsequ en tly result ing in m ore adu lt -like inju r y pat tern s in older ch ildren an d adolescen t s.5 • Th e at lan to occip it al join t is less st able in ch ild ren d u e to p hysiological ligam en tou s laxit y, th e p resen ce of syn ch on droses, m ore

Pediatric Cervical Spine plan ar C1 lateral m asses an d sm aller occip i tal con dyles th at in crease th e join t’s suscep t ibilit y to t ran slat ion al inju r y. On both plain radiograp h s an d com pu ted tom ography (CT), syn ch on droses m ay be m istaken for fract u re lin es. Secon dar y ossi cat ion cen ters, bi d sp in ou s p rocesses, an d u n fu sed r ing ap op hyses can m im ic t rau m at ic inju r y. Conversely, fract u res th rough syn ch on droses m ay be m isin terpreted as w ith in th e realm of n orm al. Th erefore, fam iliarit y w ith th e average ages of app earan ce an d fu sion , an d w ith th e t yp es of grow t h p lates an d secon dar y ossi cat ion cen ters is essen t ial. Grow t h p lates are in gen eral sym m et rical an d h ave sm ooth an d sclerot ic borders. Common normal radiological variations are as follow s: Pseudosubluxation or pseudolisthesis is com monly observed in the upper cervical vertebrae before the age of 8 years, with anterior displacement of C2 on C3, and to a less com mon degree of C3 on C4. It may be present in up to 20% of normal children. Pseudosubluxation is di erentiated from a true instabilit y with the use of posterior cervical (Swischuk’s) line.6 A line is drawn to connect anterior cortical borders of the spinous processes of C1 to C3 on a true lateral radiogram . If the anterior cortical border of the spinous process of C2 is > 2 mm away from this line, a true anteriorly displaced C2 is suggested. The loss/absence of cervical lordosis can be seen in children up to 16 years of age. Wedging of immature vertebral bodies up to 3 mm may be present below C2 until ~ 8 years of age. This is due to the ovoid appearance with vertebral interspaces equivalent to the height of the vertebral bodies and should not be confused with compression fractures. With increasing age, the vertebral bodies adopt a more rectangular shape. However mild C3 wedging can persist until the age of 12 years.7 The atlanto-dens interval (ADI) is the distance bet ween the anterior aspect of the dens and the posterior aspect of the anterior ring of the atlas. ADI may be increased in children, and values up to 4.5 or 5 mm are accepted to be within the normal range. In adults, a noteworthy prevertebral space would often suggest edema or hemorrhage resulting from cervical injury. A widened retropharyngeal

space up to 6 mm m ay be observed as a thickened prevertebral shadow on plain radiographs in children. This is related to expiration, especially if the child is crying. When in doubt, repeat radiography perform ed in m ild extension and inspiration may be used to distinguish bet ween norm al variations and abnormal ndings. Synchondroses of C2 may be misinterpreted for fractures. The apical odontoid synchondrosis may appear as separations in children bet ween 6 and 12 years of age. The dens–C2 body synchondrosis may be mistaken for a t ype II dens fracture. In contrast, the most common injury involving the odontoid process in children younger than 6 years of age is a fracture through this particular synchondrosis, which m ay be missed. Dorsal tilting of the dens is norm al, whereas ventral tilting is not. Pseudo-Je erson fracture m ay be seen in openmouth odontoid views of children up to 7 years of age, and is particularly comm on in children younger than 4 years of age. This phenom enon describes the appearance of spread of the atlas on the axis where the lateral masses can displace as much as 6 mm from the dens, which is due to the discrepancy in the growth rate of the atlas compared with the axis.

■ Cervical Spine Clearance Prehospital Considerations Im m ediate in-the- eld cervical im m obilization of pat ien t s w ith m ult isystem t raum a, a blu n t inju r y above th e clavicle, or a suspiciou s m ech an ism of injur y, or of p at ien t s presen t ing w ith a n eu rologic de cit or an altered level of con sciou sn ess, is likely essen t ial to p reven t rep etit ive spin al cord or spin al colum n injur y. All p at ien t s sh ould be t reated as th ough th ey h ave an un stable spin e un t il proven oth er w ise. Th erefore, im m obilizat ion of th e cer vical spin e before clin ical or radiograph ic clearan ce is th e stan dard of care. Becau se of t h e p rop or t ion ately large h ead in you n ger ch ild ren , im m obilizat ion sh ou ld be don e w ith eith er a backboard w ith a recess for th e occiput or a st an dard backboard w ith pads placed u n der th e torso to elim in ate backboard-in duced exion an d par t ial air w ay ob-

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Chapter 15 st r u ct ion . A rigid cer vical collar an d san dbags u sed in com bin at ion w ith th e st raps of th e backboard is m ost e ect ive in lim it ing cer vical spine m otion. Yet it sh ould be kept in m in d that im m obilizat ion can be p roblem at ic in a frigh ten ed or com bat ive ch ild. Plu s, cer vical collars m ay lead to supraphysiological dist ract ion . Th us, alth ough th ree poin t im m obilizat ion re m ain s th e aim , m an ual in lin e im m obilizat ion as tolerated m ay be m ore app rop riate in su ch circu m st an ces. If cer vical sp in e inju r y is su sp ected, direct t ran sport to a p ediat ric t rau m a cen ter sh ou ld be con sidered . How ever, if t h e closest cen ter requ ires t ravelin g lon g d ist an ces, local h osp it als m ay p rovid e im p or t an t in ter ven t ion s to stabilize th e p at ien t p rior to t ran sp or t .

Assessment of the Risk of the Patient and Diagnostic Recommendations Clearan ce of t h e p ed iat r ic cer vical sp in e can be d on e u sin g clin ical, radiograp h ic, an d ad van ced im aging data. It is depen den t on an accu rate assessm en t of t h e d egree of r isk to th e in d ivid u al ch ild . To date, t h ere are n o vali dated p red ict ion rules th at are derived from ch ildren . In stead, th e adu lt dat a are gen erally ext rap olated . Clin ical clearance requires a syn thesis of histor y, presen tat ion , an d p hysical exam in at ion . In t h e set t ing w h ere t h e ch ild is aler t an d as ym ptom at ic, an d can be con sid ered low r isk u sing several criteria, th e cer vical spin e can be cleared . Bu t in t h e ch ild w h o can n ot be con sid ered low risk, th e con sen su s on th e m eth od of clearan ce is less clear. Th e rst goal of clearan ce is to st rat ify t h e ch ild in to on e of t h e follow ing categor ies: (1) low risk, (2) con sciou s bu t n ot low risk, an d (3) u n con scious or obt u n ded . Th e Nat ion al Em ergen cy X Radiography Ut ilizat ion St u dy (NEXUS) 8 iden t i ed ve criteria to determ in e if th e risk is low : (1) n o m idlin e cer vical ten d er n ess on d irect p alp at ion , (2) n or m al aler t n ess, (3) n o evid en ce of in toxicat ion , (4) n o n eu rologic abn or m alit y, an d (5) n o p ain fu l or d ist ract ing inju r ies. Use of

th ese criteria w as est im ated to redu ce th e n eed for p ediat ric sp in al im aging by u p to 20%. How ever, th e NEXUS st u dy in clu des few ch ildren u n der th e age of 9 an d n o ch ildren u n d er th e age of 2 years w ith spin al cord inju r y. Th erefore, care m u st be t aken in t h e ext rap olat ion of resu lt s to th ese subgroups.8 Som e auth ors advocate adding a sixth criteria: th e abilit y to appropriately com m unicate verbally.9 Pain -free range of m ot ion an d th e m ech an ism of injur y m ay also be con sidered w h en deciding on th e n eed for im aging.10 In a m ore recen t st u dy, cer vical spin e im ag ing w as n ot recom m en ded in ch ildren over th e age of 3 years w h o are aler t; h ave n o n eu rologic d e cit , m idlin e cer vical ten d er n ess, or p ain fu l d ist ract in g inju r y; d o n ot h ave u n explain ed hyp oten sion ; an d are n ot in toxicated .11 In an oth er st udy of ch ildren in th is age group, im aging w as n ot recom m en ded in ch ildren w h o h ave a Glasgow Com a Scale score > 13; do n ot h ave a n eurologic de cit , m idlin e cer vical ten dern ess, or pain ful dist ract ing injur y; are n ot in toxicated; do n ot h ave un explain ed hy poten sion ; an d did n ot su stain an inju r y in a m otor veh icle acciden t , a fall from a h eigh t > 3 m (10 feet), or a nonaccidental traum a as a kn ow n or su spected m ech an ism of injur y.11 Alth ough preh osp it al im m obilizat ion is cu rren t ly recom m en ded, t rain ed preh osp ital providers m ay also safely im p lem en t th ese low -risk criteria to preven t un n ecessar y in ter ven t ion s. Con sciou s ch ild ren w h o do n ot m eet t h e low -r isk cr iter ia requ ire im m obilizat ion an d fu r t h er invest igat ion . Lee et al12 p rop osed a 10-criteria tool for im m obilizat ion an d radiograp h ic evaluat ion th at in clu des sim ilar p oin t s to th ose discu ssed above. Th ere is n o clear con sen su s on th e m eth od of clearan ce for un con sciou s or obt un ded ch ild ren . Nat ion al In st it u te for Healt h an d Care Excellen ce (NICE) recom m en ds com pu ted tom ography (CT) scan n ing of h ead an d cer vical sp in e w ith in 1 h ou r of p resen t at ion .13 Th e u se of m agn et ic reson an ce im aging (MRI) in th is su bgrou p of p at ien t s facilit ates earlier clearan ce an d a sh or ter in ten sive care unit (ICU) an d overall h osp ital stay. For ch ildren w h o are likely to rem ain un con scious beyon d 48 h ours, or for w hom clearance is unlikely to be obtained

Pediatric Cervical Spine w ithin 72 hours, MRI is recom m ended.14 In this report, MRI altered the diagnosis in 34% from that obtained from plain radiograph s or CT, an d 23% of th e ch ildren w ith n orm al radiograph s h ad abn orm al n dings on MRI. How ever, it is ver y un likely th at a pat ien t w h o is n orm al or h as a stable injur y pat tern th at dem onst rates abn orm al MRI n dings w ill even t ually develop in stabilit y.

Use of Plain Radiographs in Clearing the Pediatric Cervical Spine An teroposterior an d lateral view s, oblique radiograp h s, exion an d exten sion lm s, open m outh odontoid im ages, and radiographs taken u n der sligh t t ract ion are opt ion s th at m ay be u sed for cer vical sp in e clearan ce. Am on g t h ese view s, t h e lateral im age, in w h ich t h e exter n al au d itor y can als an d t h e low er cer vical facet s are su p er im p osed , h as t h e h igh est sen sit ivit y for cer vical sp in e inju r y. Oblique radiograph s an d odon toid view add lit tle diagn ost ic valu e to conven t ion al radio grap h s in th e pediat ric p op u lat ion , part icu larly in you nger ch ildren or ch ildren w h o are less cooperat ive. An odon toid view m ay n ot be n ec essar y for cer vical spin e clearan ce for ch ildren younger th an 8 years of age. Form erly, exion an d exten sion radiograph s w ere u sed for evalu at ion of th e n eu rologically in tact p at ien t s w ith n orm al in it ial radiograph s bu t a p ersisten ce of sp in al ten d ern ess. Th is dyn am ic evaluat ion of cer vical stabilit y sh ould best be perform ed w ith an act ive range of m ot ion , w h ich is u su ally lim ited du e to m u scle spasm an d pain . Also, th ese ch ildren sh ould n ot be subjected to passive exion an d exten sion th at p oses a risk for fu r th er inju r y. Because exion and extension lm s have not been sh ow n to be clearly ben e cial, an d becau se MRI is n ow m ore w idely available, th ese lm s h ave fallen out of favor. MRI can detect all th e ch anges th at w ould be foun d on dyn am ic lm s, w h ereas exion an d exten sion lm s m igh t m iss several ligam entous injuries th at are iden ti ed on MRI. Th e curren t t ren d is to u se dynam ic im ages 2 to 3 w eeks later in the follow -up

evalu at ion of a p reviou sly d etected ligam en tou s inju r y t h at is associated w it h p ossible in stabilit y. A radiograph u n der sligh t t ract ion can fu rth er illu st rate th e disru pt ion of th e diskoligam en tous st ru ct ures. Th e use of such lm s h as also fallen out of favor for sim ilar reason s. Skelet al developm en t m akes th e in terpretat ion of roen tgen ogram s age dep en den t . Carefu l evalu at ion of th e in terspin ous distan ces, disk sp aces, an d n eu roforam in a is n ecessar y at each level. Th e u se of Sw isch u k’s lin e an d th e ADI w as described above. An oth er m easu re, th e Pow ers rat io, is th e d ist an ce from th e t ip of th e basion to th e posterior arch of th e at las, divided by th e dist an ce from th e op isth ion to t h e p osterior aspect of th e an terior arch of th e atlas. A rat io > 0.9 suggests atlan to occip ital dislocat ion . Tw o oth er m easu res, th e Wacken h eim clivus lin e an d th e rule of th irds, m ay also be used to determ in e atlantoaxial instabilit y (AAI). Th e Wacken h eim lin e is draw n along th e posterior cor t ical m argin of th e clivus, w h ich sh ould in tersect th e odon toid or be t angen t ial to it . It suggest s AAI if it does n ot in tersect . Th e ru le of th irds st ates th at th e den s an d t h e sp in al cord sh ou ld each ll on e th ird of th e can al space, an d th e n al th ird sh ou ld be free. Norm al values for oth er m easurem en ts th at m igh t be useful for determ in ing ligam en tou s inju r y are as follow s: • Basion -den s in ter val (BDI) < 10.5 m m in CT (u n reliable in age 5 m m an terior displacem en t w ith bilateral an terior facet dislocat ion s. • Type IV is a p osterior disp lacem en t of th e axis on th e atlas an d is rare. In it ial m an agem en t con sists of 1 to 4 w eeks of cer vical t ract ion follow ed by 4 to 6 w eeks of im m obilizat ion . Delays in th e diagn osis an d t reat m en t lead to C1- C2 ad h eren ce, an d are related w ith in creased rates of irredu cibilit y, a greater ch an ce of recu rren ce, h igh er rates of C1- C2 m ot ion loss, an d greater n eed for su rgical stabilizat ion . Fig. 15.1 dem on st rates th e m an agem en t of a 16-year-old p at ien t w it h AARS w h o w as t reated w ith h alo t ract ion an d im m obilizat ion .

Odontoid Fracture C2 h as th e m ost n u m erous syn ch on droses, an d h as by far th e h igh est in ciden ce of syn ch on drosis injur y. Fract ures of th e odon toid are relat ively com m on an d t yp ically occu r t h rough th e syn ch on drosis at th e base of th e odon toid. Sm all ch ildren secu red in for w ard-facing car seats h ave sustain ed th is injur y pat tern . Patien ts are u sually n eurologically in tact . In gen eral, th is ep iphyseal inju r y m ay h ave an in t act periosteal sleeve, in creasing th e likelih ood of su ccessfu l redu ct ion an d h ealing w ith im m obilizat ion in exten sion .

Low er Cervical Spine Injury Alth ough relat ively un com m on , fract ure, fract u re/d islocat ion , d islocat ion , an d p u rely ligam entous injur y m ay be seen, usually in children over 9 years of age. In n eu rologically in t act pat ien t s, th e in it ial m an agem en t sh ou ld be don e w ith em ergen t m an u al redu ct ion follow ed by extern al im m obilizat ion . Im m ediate MRI sh ou ld follow to determ in e th e presen ce of an epidural h em atom a or h ern iated disk. Som e of th ese p at ien t s m ay requ ire su rger y du e to irredu cibilit y or on an em ergen t basis to t reat com p ressive path ology w ith in th e spin al can al.

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a

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Fig. 15.1a–f A 16-year-old patient with atlantoaxial rotatory subluxation. (a) Coronal, (b) axial 15-mm maximum intensit y projection, and (c) threedimensional (3D) reconstruction images. (d) Coronal,

(e) axial 15-mm maximum intensit y projection, and (f) 3D reconstruction images of the same patient after halo traction and immobilization, showing complete reduction.

Pediatric Cervical Spine

SCIWORA Pang an d Wilberger 18 rst de n ed th is en t it y in 1982 as n eurologic sign s or sym ptom s w ith n o radiograp h ic abn orm alit y. Advan ces in im aging led to a ch ange in de n it ion , w h ereby p lain lm s an d CT n dings are n orm al, bu t MRI displays p ath ological n dings su ch as cord ed em a, p arasp in al m u scle edem a or h em or rh age, ep id u ral or su bd u ral h em atom as, cord hem orrhage, ligam entous disruption, disk edem a or h ern iat ion , an d com p lete cord t ran sect ion . Th e basis for th e existen ce of SCIWORA is th at t h e sp in al colu m n can st retch u p several cen t im eters before r u pt u re an d can d isp lay a t ran sien t d isp lacem en t w it h su bsequ en t realign m en t , w h ereas the spin al cord th at is teth ered su periorly an d inferiorly is dam aged after several m illim eters of t ract ion . Alth ough delayed on set of several days h as been rep or ted, closer an alysis often sh ow s t ran sien t n eu rologic sym ptom s at or n ear th e t im e of in it ial t rau m a or su btle n eu rologic de cits th at w ere m issed in th e in it ial physical exam in at ion . Th ere are som e clin ical an d radiograp h ic n dings th at m ay be h elpfu l in determ in ing progn osis. Severit y an d com p leten ess of inju r y gen erally correlates w ith th e outcom e. Ch il dren w ith com p lete lesion s rarely im prove. Ch ildren w ith severe, in com p lete lesion s im prove, but are un likely to regain fu ll fu n ct ion . In com parison , ch ildren w ith m ild to m od erate de cit s im p rove, an d som e ach ieve fu ll recover y. Age an d th e locat ion of inju r y m ay also h elp to determ in e th e progn osis. SCIWORA is m ore likely to occur at u pper levels an d be m ore severe in ch ildren younger th an 8 years of age, an d at low er levels an d be less severe in older ch ildren . MRI can be a bet ter predictor of ou tcom e th an n eu rologic stat us alon e. Th e absen ce of spin al cord sign al ch anges on T2w eigh ted im ages indicates an excellen t progn o sis. Minor hem orrhage and edem a only predicts a favorable outcom e. Major h em orrh age an d com plete spin al cord disru pt ion suggest severe an d possibly p erm an en t inju r y. Typ ically, SCIWORA is m an aged w it h 12 w eeks of exter n al im m obilizat ion follow ed by 12 w eeks of act ivit y m od i cat ion to allow lig-

am en tou s inju r ies to h eal, an d to p reven t recurren ce.

Sports Injuries Sp or t s related inju ries are th e secon d m ost com m on cau se of cer vical sp in e inju r y in ch ildren older th an 10 years of age an d in adolescen t s. Soft t issu e injuries resu lt ing from direct t rau m a in clu de sp rain s an d st rain s. Com m on n dings are m idlin e ten dern ess, m u scle spasm , an d loss of range of m ot ion w it h in t act n eu rology. Man agem en t con sists of cer vical im m obilizat ion an d m edical th erapy w ith gradu al ret urn to sport s act ivit ies. Th e injur y th at causes st inging or burn ing th at sp reads from t h e sh ou lders to th e h an d after injuries in con tact or collision spor ts are called “bu rn ers” or “st ingers.” Th e t ran sien t w eakn ess resu lt ing from brach ial plexus t ract ion t ypically involves on ly on e arm an d last s u p to 30 m in u tes. Most of th ese injuries do n ot requ ire t reat m en t an d resolve w it h in a few m in utes or several days. Recurren t burn ers an d st ingers m ay requ ire w orking w ith a t rain er or th erapist . If th e injur y result s in spin al cord con cussion , also kn ow n as cer vical cord n eu rap raxia, th e sen sor y an d m otor sym ptom s m ay involve both arm s, both legs, or all four ext rem it ies. Pat ien ts are m an aged w ith 2 w eeks of cer vical im m obilizat ion in a h ard cer vical collar follow ed by dyn am ic lm s.

Neonatal Injuries In fan ts w ith bir th -related cer vical spin e an d spin al cord injuries presen t w ith accidit y an d absen ce of spon tan eous m ot ion ; th ese injuries are associated w ith ceph alic presen t at ion an d th e u se of forceps. Th e u p per cer vical sp in e is m ost suscept ible to inju r y. Extern al cu stom m ade im m obilizat ion sp an n ing from t h e occipu t to th e th orax m ay be u sed.

C2 Fracture Bilateral fract u res of t h e p ars in terar t icu lar is of C2 leading to t raum at ic spon dylolisth esis are rare in children. Di erentiating this injur y from

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Chapter 15 syn ch on droses in you ng ch ildren can be di cu lt an d m ay require advan ced im aging.

Os Odontoideum A w ell-cor t icated odon toid process th at lacks con t in u it y w ith th e C2 body is called os odon toideum . It m ay be associated w ith atlan toaxial in st abilit y an d m yelop athy. In gen eral, th e be lief is th at th e risks of un t reated os odon toideu m ou t w eigh th e risks of C1- C2 fu sion .

■ Treatment Strategies Alth ough som e pat ien ts w ill require h ospitalizat ion or an ICU st ay, m ost p ediat ric cer vical spin e inju ries can be t reated con ser vat ively. Surger y is gen erally in dicated for un st able in juries, irreducible fractures or dislocations, progressive n eu rologic de cit s, or deform it ies du e to epidural h em atom a, disk prot rusion , or cord com pression . With th e advan ce of xat ion system s an d tech n iqu es recen tly, m ore an d m ore su rgeon s prefer to elect ively t reat pat ien ts su rgically if h alo im m obilizat ion is to be used for a long t im e, given th e h azards of prolonged im m obilizat ion in ch ildren . Due to the paucity of data on the use of m ethylpredn isolon e speci c to pediat ric p at ien t s, cou pled w ith th e con t roversy su rrou n ding it s adm in ist rat ion , steroids are n ot con sidered a st an dard procedure an d are u sed at th e discre t ion of th e t reat ing physician . Halo im m obilizat ion m ay safely be u sed in ch ildren as you ng as 7 m on th s old. Du e to th e th in calvaria before th e age of 5, st able xat ion requ ires m ore pin s w ith less torqu e to decrease th e risk of sku ll p en et rat ion . Weigh t sh ou ld be adm in istered caut iously w ith close n eurologic m on itoring, becau se of th e in creased risk of overdist ract ion due to ligam en tous la xit y an d underdeveloped m usculature. Minor com plica tions, such as pin site infections are com m on. Cer vical in st ru m en tat ion in ch ildren h as satisfactor y results w ith low com plicat ion rates. Th e car t ilagin ous n at ure an d sm all size of th e an atom y dem an d great accu racy in th e place m en t of screw s. Man ipulat ion during in t ubat ion m u st be don e rigorou sly in th e ch ild w ith

u n st able cer vical spin e to preven t addit ion al sp in al cord injur y. Th e pat ien t sh ou ld be t urn ed w ith a cer vical collar, an d a radiograph sh ould be obtain ed prior to prepping to con rm th at n o ch ange in posit ion occurred during t ran sfer. Th e iliac crest , ribs, or calvarial grafts m ay be u sed to ach ieve fu sion . Com m ercially available bon e graft s, d em in eralized bon e m at r ix, or bon e subst it utes m ay st ill m ain tain th e rates of fu sion w h ile redu cing h ar vest related m orbidit y. Wou n d closure is im p or t an t , an d soft t issu es sh ou ld adequ ately cover bu lky im p lan ts to allow for proper h ealing. Occipitocer vical fusion can be achieved w ith th readed con tou red rods an d w iring. Plate-rod con st ructs cou pled w ith C1- C2 t ran sar t icular screw s or C2 p edicle screw s m ay also be u sed . Atlan toaxial fu sion m ay be ach ieved by p osterior w iring u sing several graft t ypes or using rod screw constructs. Subaxial stabilization m ay be at t ain ed via an an terior or posterior ap p roach . Pedicle or lateral m ass screw s can be u sed for posterior in st ru m en ted fusion . Sh or t stat ure an d low -pro le an terior plates are ap p rop riate for an terior fusion .

■ Outcomes and Late

Complications Alth ough outcom es are gen erally favorable due to the greater h ealing poten tial of children, m ost ch ild ren h avin g cer vical sp in al cord inju r y before t h eir grow t h sp u r t w ill d evelop sp in al d eform it ies. Su ch deform it ies are paralyt ic or n eu rom uscular in n at u re, an d sh ould be ad dressed accordingly. Post t rau m at ic syringom yelia can develop du e to residu al kyp h osis or can al sten osis after rem odeling. Su ch p at ien t s m ay presen t w ith an upw ard creeping n euro logic level and increased spasticit y. The results of sh u n t su rgeries are n ot alw ays ver y sat isfying.

■ Chapter Summary Cer vical sp in e inju r y in ch ild ren is rare, rep re sen t ing a sm all p ercen t age of all p ed iat r ic t rau m a p at ien t s. Th e m ost com m on ly iden t i

Pediatric Cervical Spine ed inju r y t yp e am ong all ages is isolated ligam en tou s inju r y. How ever, th ose w h o su stain inju r y h ave a h igh m orbidit y an d m or t alit y in com p arison to adu lt s. Motor veh icle acciden t s are th e m ost com m on cau se of injur y. Sp in al cord inju r y w ith t ran sien t or p erm an en t n eu rologic inju r y is com m on ; h ow ever, ch ildren h ave bet ter ou tcom es du e to th eir greater h eal ing p oten t ial. Ap p roxim ately h alf of t h e p atien ts h ave oth er associated t raum at ic injuries. It is im por tan t to un derstan d th e ch anging an atom y of t h e p ediat ric cer vical sp in e to interpret injur y pat tern s an d dist inguish injur y from a large n u m ber of n or m al var ian t s. Im m ed iate in -t h e- eld cer vical im m obilizat ion is essen t ial to preven t repet it ive spin al cord or spin al colu m n inju r y. Clearan ce of th e pediat ric cer vical spin e can be don e u sing clin ical, radio graph ic, an d advan ced im aging dat a. An tero posterior an d lateral plain rad iograp h s sh ou ld be th e rst-lin e screen ing tool w h en ever clin ical clearan ce can n ot be ach ieved. CT sh ould be used ju diciou sly to m an age th e ch ild w ith th e low est p ossible radiat ion exp osu re. MRI is rec om m en ded for all p at ien t s w ith an abn orm al neurologic exam ination and for patients requiring sp ecial invest igat ion of th eir soft t issu es an d sp in al cord. Most p ed iat r ic cer vical sp in e inju r ies can be t reated con ser vat ively. Su rger y is gen erally indicated for unstable injuries, irreducible fractures or dislocat ion s, p rogressive n eu rologic de cits, or deform ities. Halo im m obilization m ay safely be used in ch ildren . Cer vical in st rum en tat ion in ch ildren h as sat isfactor y results w ith low com p licat ion rates. Alth ough ou tcom es are

gen erally favorable due to greater h ealing poten t ial of ch ildren , som e ch ildren h aving cer vical spin al inju r y before th eir grow th spu r t w ill develop sp in al deform it ies.

Pearls Cervical spinal injuries represent a small percentage of all pediatric traum as, but they entail high morbidit y and mortalit y. Associated spinal, head, and other injuries are seen in approximately half of the patients. The changing anatomy of the pediatric cervical spine should be understood to facilitate interpreting injury pat terns and distinguish injury from a large number of norm al variants. Although im mediate in-the- eld cervical imm obilization is currently recom mended, trained prehospital providers may also safely implem ent the low-risk criteria. When a halo is to be applied, more pins with less torque should be used to decrease the risk of penetration of the thin calvaria. Cervical instrum entation in children has satisfactory results with low complication rates. Pitfalls Odontoid view radiographs m ay be inconclusive for children under the age of 8 years. A widened retropharyngeal space m ay not indicate edema or hem orrhage, especially if the child is crying. Normal initial radiographs do not exclude spinal injury. The spinal column can stretch up several centimeters and display a transient displacem ent with subsequent realignm ent, whereas the spinal cord is dam aged after several m illim eters of traction.

Refere nces Five Must-Read Refe rences 1. Easter JS, Barkin R, Rosen CL, Ban K. Cer vical sp in e injuries in ch ildren , par t I: m ech anism of injur y, clinical presen t at ion , an d im aging. J Em erg Med 2011; 41:142–150 PubMed 2. Jun ew ick JJ. Cer vical spin e injuries in pediat rics: are ch ildren sm all adu lt s or n ot? Pediat r Radiol 2010; 40:493–498 Pu bMed 3. Leon ard JR, Ja e DM, Ku p p erm an n N, Olsen CS, Leonard JC; Pediat ric Em ergen cy Care Applied Research

Net w ork (PECARN) Cer vical Spin e St udy Group. Cervical spine injur y pat tern s in ch ildren . Pediat rics 2014;133:e1179–e1188 Pu bMed 4. Fesm ire FM, Luten RC. Th e pediat ric cer vical spin e: develop m en tal an atom y an d clin ical aspect s. J Em erg Med 1989;7:133–142 Pu bMed 5. d’Am ato C. Ped iat ric sp in al t rau m a: inju ries in ver y young ch ildren . Clin Orth op Relat Res 2005;432:34– 40 Pu bMed

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Chapter 15 6. Sw ischuk LE. Anterior displacem ent of C2 in children: physiologic or pathologic. Radiology 1977;122:759– 763 PubMed 7. Euban ks JD, Gilm ore A, Bess S, Cooperm an DR. Clear ing th e pediat ric cer vical spin e follow ing injur y. J Am Acad Or th op Surg 2006;14:552–564 Pu bMed 8. Viccellio P, Sim on H, Pressm an BD, Sh ah MN, Mow er W R, Ho m an JR; NEXUS Group. A prospect ive m ult i center st udy of cer vical spin e injur y in ch ildren . Pediat rics 2001;108:E20 Pu bMed 9. Gore PA, Ch ang S, Th eodore N. Cer vical spin e inju ries in ch ildren : at ten t ion to radiograph ic di eren ces an d st abilit y com pared to th ose in th e adu lt pat ien t . Sem in Pediat r Neurol 2009;16:42–58 Pu bMed 10. Ch ung S, Mikrogian akis A, Wales PW, et al. Traum a associat ion of Can ada Ped iat r ic Su bcom m it tee Nat ion al Ped iat r ic Cer vical Sp in e Evalu at ion Pat h w ay: con sen sus guidelin es. J Traum a 2011;70:873–884 PubMed 11. Rozzelle CJ, Aarabi B, Dh all SS, et al. Man agem en t of pediat ric cer vical spin e an d spin al cord injuries. Neu rosu rger y 2013;72(Suppl 2):205–226 PubMed 12. Lee SL, Sen a M, Green h olz SK, Fledderm an M. A m u l t idisciplinar y approach to th e developm en t of a cer-

vical spin e clearan ce protocol: process, rat ion ale, an d init ial result s. J Ped iat r Su rg 2003;38:358–362, discussion 358–362 Pu bMed 13. Nat ion al In st it ute for Health an d Care Excellen ce. Head injur y gu idan ce (CG176). h t t p://w w w.n ice.org .u k/gu idan ce/CG176. Accessed Novem ber 27, 2014 14. Flyn n JM, Closkey RF, Mah bou bi S, Dorm an s JP. Role of m agn et ic reson an ce im aging in th e assessm en t of pediat ric cer vical spin e injuries. J Ped iat r Or th op 2002;22:573–577 PubMed 15. Ram rat t an NN, On er FC, Boszczyk BM, Castelein RM, Hein i PF. Cer vical spin e injur y in th e young ch ild. Eur Spin e J 2012;21:2205–2211 PubMed 16. Su n PP, Po en barger GJ, Du rh am S, Zim m erm an RA. Spect rum of occipitoatlan toaxial injur y in young ch ild ren . J Neu rosu rg 2000;93(1, Su p p l):28–39 PubMed 17. Ph illip s WA, Hen singer RN. Th e m an agem en t of rot ator y atlan to axial sublu xat ion in ch ildren . J Bon e Join t Su rg Am 1989;71:664–668 PubMed 18. Pang D, Wilberger JE Jr. Spin al cord injur y w ith out radiograph ic abn orm alit ies in ch ildren . J Neurosu rg 1982;57:114–129 PubMed

16 The New AOSpine Subaxial Cervical Spine Injury Classi cation System Gregory D. Schroeder, Paul W. Millhouse, Alexander R. Vaccaro, F. Cumhur Oner, and Luiz Roberto Vialle

Th ere are t w o m ain goals of an inju r y classi cat ion system . Th e rst is to facilit ate accu rate com m u n icat ion bet w een h ealth care p rofession als, in clu ding t reat ing p hysician s, t rain ees, an d research ers. Th e secon d is to guide th e t reat m en t of th e inju r y. Th e u t ilit y of classi cat ion system s in or th op edic t rau m a var y sign i can tly, w ith som e w ell-design ed classi cat ion s, su ch as th e Sch at zker classi cat ion for t ibial plateau fract ures,1,2 being used for over 40 years, w h ereas classi cat ion system s of oth er inju ries are con st an t ly replaced. In 1951, Böh ler 3 p u b lish ed th e rst m ajor classi cat ion of inju ries to t h e spin al colu m n , bu t as th e kn ow ledge of sp in al an atom y, biom ech an ics, an d physiology im proved , t h ese early sp in al inju r y classi cat ion s proved to be in adequ ate. Th is h as led to m any iterat ion s of subaxial cer vical spine in ju r y classi cat ion s. In 1970, Holdsw or th 4 p u blish ed a m ech an ist ic classi cat ion for the en t ire spin e based on h is obser vat ion of over 2,000 pat ien t s w ith spin al injuries. Th is w as the rst m ajor classi cat ion to de n e st able an d u n st able inju ries, and to recognize the biom echanical im portance of t h e p oster ior ligam en tou s com p lex. In an e or t to im p rove u p on th is classi cat ion , th e Allen an d Fergu son an d th eir grou p 5 later created a m ore detailed m ech an ism -based classicat ion , w h ich divided fract u res in to six m ajor t ypes: com p ressive exion , vert ical com p ression , distractive exion, com pressive extension , dist ract ive exten sion , an d lateral exion . De-

sp ite th e app aren t sim p licit y of th is classi cat ion , it h as poor reliabilit y an d lim ited clin ical relevance.6 Further m odi cations w ere m ade to th is system by Harris et al,7 w h o ch anged th e m ech an ism s to in clu d e exion , exion an d rotat ion , hyperexten sion an d rotat ion , ver t ical com p ression , exten sion , an d lateral exion ; h ow ever, t h ese ch an ges com p licated t h e system w ith ou t im proving th e clin ical relevan ce. Un derstan ding th e lim it at ion s of th e previous classi cat ion s an d using a sim ilar m eth odology as w as used in th e developm en t of th e Th oracolum bar Spin e Injur y Classi cat ion System (TLICS), Vaccaro et al8 developed th e Subaxial Injur y Classi cat ion (SLIC) an d Severit y Scale in 2007. Th is classi cat ion sim pli ed th e m orph ological categor y in to th ree basic t ypes: com p ression , dist ract ion , an d rot at ion /t ran slat ion . Addit ion ally, it w as the rst classi cat ion of subaxial cer vical spin e injuries to form ally con sider th e in tegrit y of th e diskoligam en tou s com p lex an d th e n eu rologic st at u s of th e pat ien t . Fin ally, th e SLIC system assign ed a p oin t valu e to th e m orph ology of th e inju r y, th e in tegrit y of th e diskoligam en tous com plex, an d th e n eu rologic st at u s of t h e pat ien t . An inju r y score w as determ ined based on the sum m ation of th e value for each variable, an d th is score could be used to propose appropriate treatm ent algorith m s. In spite of in it ial repor ts of acceptable reliabilit y,8 a m ore recen t in d ep en d en t validat ion st u dy rep or ted p oor in terobser ver reliabilit y for fract ure m orph ology (k = 0.29),

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Chapter 16

Fig. 16.1 Subt ype A0. Minor bony injury that does not a ect stabilit y, such as a spinous/transverse process fracture; additionally, this subt ype can be used for neurologic injuries without a fracture, such

as a central cord injury. (From Vaccaro AR, Koerner JD, Radcli KE, et al. AOSpine subaxial cervical spine injury classi cation system. Eur Spine J 2015 Feb 26 [Epub ahead of print]. Reproduced with permission.)

an d on ly m oderate reliabilit y for th e in tegrit y of th e diskoligam en tous com plex (k = 0.46).9 Fu r t h erm ore, becau se t h e classi cat ion w as design ed by a select grou p of su rgeon s w ith lim ited global inp u t , it h as been cr it icized for fostering th e view s of it s creators an d recom m ending treatm ents that m ay not be consistent w ith th e local t reat m en t pract ices. Lastly, m agn et ic reson an ce im aging (MRI) is often n eeded to assess th e in tegrit y of th e diskoligam en tous com p lex, an d t h is is n ot read ily available in m any par ts of th e w orld. Because of the aforem entioned concerns w ith previous subaxial cer vical spin e inju r y classi -

cat ion s, in 2015 AOSpin e pu blish ed th e n ew AOSpin e Su baxial Cer vical Spin e Injur y Classicat ion System . Th e n ew classi cat ion separates fract ures in to th ree m ajor m orp h ological t ypes 10 : • Type A: Com pression injur y (Figs. 16.1, 16.2, 16.3, 16.4, 16.5) • Type B: Inju r y to th e an terior or posterior ten sion ban d (Figs. 16.6, 16.7, 16.8) • Type C: Tran slat ion al injur y (Fig. 16.9) Ad d it ion ally, t yp e A an d B fract u res are fu rt h er su bcategorized (Table 16.1) sim ilar to th e AOSpine Thoracolum bar Classi cation system .11

Fig. 16.2 Subt ype A1. Compression fractures involving a single end plate without involvement of the posterior wall of the vertebral body. (From Vaccaro AR, Koerner JD, Radcli KE, et al. AOSpine subaxial cervical spine injury classi cation system. Eur Spine J 2015 Feb 26 [Epub ahead of print]. Reproduced with perm ission.)

Fig. 16.3 Subt ype A2. Coronal split fracture that involves both end plates but not the posterior wall. (From Vaccaro AR, Koerner JD, Radcli KE, et al. AOSpine subaxial cervical spine injury classi cation system. Eur Spine J 2015 Feb 26 [Epub ahead of print]. Reproduced with permission.)

The New AOSpine Subaxial Cervical Spine Injury Classification System

Fig. 16.4 Subt ype A3. Incomplete burst fracture involving one end plate and the posterior wall. (From Vaccaro AR, Koerner JD, Radcli KE, et al.

AOSpine subaxial cervical spine injury classi cation system. Eur Spine J 2015 Feb 26 [Epub ahead of print]. Reproduced with permission.)

Fig. 16.5 Subt ype A4. Complete burst fracture involving both end plates and the posterior wall. (From Vaccaro AR, Koerner JD, Radcli KE, et al.

AOSpine subaxial cervical spine injury classi cation system. Eur Spine J 2015 Feb 26 [Epub ahead of print]. Reproduced with permission.)

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Chapter 16 Fig. 16.6 Subt ype B1. Transosseous disruption of the tension band. (From Vaccaro AR, Koerner JD, Radcli KE, et al. AOSpine subaxial cervical spine injury classi cation system . Eur Spine J 2015 Feb 26 [Epub ahead of print]. Reproduced with perm ission.)

Fig. 16.7 Subt ype B2. Any injury that disrupts the posterior ligam entous tension band. (From Vaccaro AR, Koerner JD, Radcli KE, et al. AOSpine subaxial cervical spine injury classi cation system. Eur Spine J 2015 Feb 26 [Epub ahead of print]. Reproduced with permission.)

Fig. 16.8 ubt ype B3. Any injury that disrupts the anterior ligam entous tension band. (From Vaccaro AR, Koerner JD, Radcli KE, et al. AOSpine subaxial

cervical spine injury classi cation system. Eur Spine J 2015 Feb 26 [Epub ahead of print]. Reproduced with perm ission.)

The New AOSpine Subaxial Cervical Spine Injury Classification System Fig. 16.9 Type C. Translational injury. (From Vaccaro AR, Koerner JD, Radcli KE, et al. AOSpine subaxial cervical spine injury classi cation system. Eur Spine J 2015 Feb 26 [Epub ahead of print]. Reproduced with permission.)

Table 16.1 Subtypes of Fracture Types A and B for the New AOSpine Subaxial Cervical Spine Injury Classi cation System Type

De nition

A A0

Compression Injury Minor bony injury that does not a ect stabilit y such as a spinous/transverse process fracture; additionally, this can be used for neurologic injuries without a fracture such as a central cord injury in the set ting of a spondylotic spine Wedge fracture that involves a single (usually superior) end plate and does not disrupt the posterior wall Coronal split fracture that involves both end plates both not the posterior wall Incomplete burst fracture involving one end plate and the posterior wall Complete burst fracture involving both end plates and the posterior wall Tension band injury Transosseous disruption of the tension band Any injury that disrupts the posterior ligam entous tension band Any injury that disrupts the anterior ligamentous tension band

A1 A2 A3 A4 B B1 B2 B3

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Chapter 16 Next , inju ries to th e facet join t s are classi ed separately (Table 16.2; Figs. 16.10, 16.11, 16.12, 16.13), an d t h e n eu rologic st at u s of th e p at ien t is evaluated (Table 16.3). Lastly, p at ien tspeci c m odi ers, if appropriate, are assign ed (Table 16.4).

An in it ial reliabilit y an alysis of th e classi cat ion yield ed p rom isin g resu lt s, w it h good in terobser ver reliabilit y repor ted for m orph ological su bt yp es (k = 0.64).10 A w orldw ide reliabilit y st udy is ongoing. Addit ion ally, m u lt iple in tern at ion al st ud ies are being p erform ed on

Table 16.2 Grading of the Facet Injury for the New AOSpine Subaxial Cervical Spine Injury Classi cation System Injury

De nition

F1 F2 F3 F4 BL

A nondisplaced fracture that is less than < 1 cm in height and involves < 40% of the lateral mass Any displaced fracture or a fracture > 1 cm in height or involving > 40% of the lateral mass Floating lateral mass Any fracture that results in a subluxed, perched, or dislocated facet Bilateral facet involvement

Fig. 16.10 Subt ype F1. A nondisplaced fracture that is less than < 1 cm in height and involves < 40% of the lateral mass. (From Vaccaro AR, Koerner JD,

Radcli KE, et al. AOSpine subaxial cervical spine injury classi cation system. Eur Spine J 2015 Feb 26 [Epub ahead of print]. Reproduced with permission.)

Fig. 16.11 Subt ype F2. Any displaced fracture or a fracture > 1 cm in height or involving > 40% of the lateral mass. (From Vaccaro AR, Koerner JD, Radcli KE, et al. AOSpine subaxial cervical spine injury classi cation system. Eur Spine J 2015 Feb 26 [Epub ahead of print]. Reproduced with permission.)

The New AOSpine Subaxial Cervical Spine Injury Classification System

Fig. 16.12 Subt ype F3. Floating lateral mass. (From Vaccaro AR, Koerner JD, Radcli KE, et al. AOSpine subaxial cervical spine injury classi cation system.

Eur Spine J 2015 Feb 26 [Epub ahead of print]. Reproduced with perm ission.)

Fig. 16.13 Subt ype F4. Any fracture that results in a subluxed, perched, or dislocated facet. (From Vaccaro AR, Koerner JD, Radcli KE, et al. AOSpine subaxial cervical spine injury classi cation system . Eur Spine J 2015 Feb 26 [Epub ahead of print]. Reproduced with perm ission.)

Table 16.3 Grading for the Neurologic Status of the Patient for the New AOSpine Subaxial Cervical Spine Injury Classi cation System Status

De nition

N0 N1

Neurologically intact Neurologic symptoms that have completely resolved Persistent radiculopathy/nerve root injury Incomplete spinal cord injury Complete spinal cord injury Unable to obtain a neurologic exam Ongoing compression of the spinal cord

N2 N3 N4 Nx +

Table 16.4 Patient-Speci c Modi ers for the New AOSpine Subaxial Cervical Spine Injury Classi cation System Modi er

De nition

M1

Unclear integrit y of the posterior ligam entous complex Signi cant disk herniation present The patient has a of a sti ening/ metabolic bone disease such as di use idiopathic skeletal hyperostosis or ankylosing spondylitis Vertebral artery injury

M2 M3

M4

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Chapter 16 th e e ect of in dividu al variables on th e t reatm en t algorith m s, an d even t u ally an AOSp in e Su baxial Cer vical Inju r y Score w ill be p u b lish ed as a t reat m en t algorith m to accom p any the new classi cation. In an e ort to prevent the errors of th e p reviou s classi cat ion system s, th e develop m en t of th e su rgical algorith m is

being don e in a stepw ise fash ion using a m odied Delph i m eth od. In th is w ay, global inpu t w ill be used to determ in e th e t reat m en t algorith m , an d a u n iversally accepted t reat m en t algorith m for subaxial cer vical spin e injuries w ill be est ablish ed.

Refe re nces Five Must-Read Refe rences 1. Schat zker J, McBroom R, Bruce D. Th e t ibial plateau fract ure. Th e Toron to experien ce 1968–1975. Clin Or th op Relat Res 1979;138:94–104 2. Schat zker J. Com pression in th e su rgical t reat m en t of fract ures of th e t ibia. Clin Or th op Relat Res 1974; 105:220–239 3. Boh ler L. Die Tech nik der Kn och en bru ch beh an dlung. Wien : Mau d rich ; 1951 4. Holdsw orth F. Fract ures, dislocat ion s, an d fract ure-dislocat ion s of th e spine. J Bon e Join t Surg Am 1970;52:1534–1551 5. Allen BL Jr, Ferguson RL, Leh m an n TR, O’Brien RP. A m echan ist ic classi cat ion of closed, in direct fract ures an d dislocat ion s of the low er cer vical spin e. Spin e (Ph ila Pa 1976) 1982;7:1–27 6. Ston e AT, Bran sford RJ, Lee MJ, et al. Reliabilit y of classi cat ion system s for subaxial cer vical inju ries. Evid Based Spine Care J 2010;1:19–26

7. Harris JH Jr, Edeiken -Mon roe B, Kopan iky DR. A pract ical classi cat ion of acu te cer vical spin e inju ries. Or th op Clin Nor th Am 1986;17:15–30 8. Vaccaro AR, Hu lber t RJ, Patel AA, et al. Th e su baxial cer vical spin e injur y classi cat ion system : a n ovel approach to recognize the im portance of m orphology, neurology, and in tegrit y of th e disco-ligam en tous com plex. Spin e (Ph ila Pa 1976) 2007;32:2365–2374 9. van Mid den dorp JJ, Au dige L, Bar tels RH, et al. Th e Su baxial Cer vical Spin e Injur y Classi cat ion System : an exter n al agreem en t validat ion st u dy. Sp in e J 2013;13:1055–1063 10. Vaccaro AR, Koern er JD, Radcli KE, et al. AOSpine su baxial cer vical spin e inju r y classi cat ion system . Eur Spin e J. 2015 Feb 26 [Epub ah ead of prin t] 11. Vaccaro AR, On er C, Kepler CK, et al. AOSpin e th oracolum bar spin e injur y classi cat ion system : fract ure descript ion , n eu rological st at u s, an d key m odi ers. Spin e (Ph ila Pa 1976). 2013;38:2028–2037

Index

Note: Page referen ces follow ed by f or t in dicate pages or tables, resp ect ively. A Accessor y n er ve, 51 Agen cy for Health care Research an d Qu alit y (AHRQ), 94–95 Air w ay obst ruct ion , closed redu ct ion -related, 40 Alar ligam en t s, an atom y an d fu n ct ion of, 18, 19, 50 An kylosing spon dylit is biom ech an ics of, 140–141 cer vical spin e t raum a associated w ith , 102, 103, 139–146 preh ospit al assessm en t an d t ran sp or tat ion in , 142 t reat m en t for, 142–144, 143f de n it ion of, 102 diagn osis of, 140 epidem iology of, 140 evalu at ion of, 96 im aging of, 102, 140, 144–145 path ophysiology of, 139–140 An kylosis, sp in al, 139. See also An kylosing spon dylit is; Di u se idiopath ic skelet al hyp erostosis (DISH) osteoporosis associated w ith , 140–141 An sa cer vicalis, 14 An terior approach an atom ic con siderat ion s in , 1 to com p ression fract u res, 89–90 to facet join t dislocat ion s, 121, 122–123, 125–126 to lateral m ass fract u res, 111 bet w een n eu rovascu lar an d visceral com par tm en t s, 14, 14f An terior cer vical diskectom y an d fu sion of facet join t dislocat ion s, 121, 123 of facet join t fract ures, 107f of exion -dist ract ion inju ries, 100, 100f

An terior xat ion of exion -dist ract ion inju ries, 101–102 in rh eu m atoid ar th rit is p at ien t s, 149 An terior fu sion , in ch ildren , 166 An terior longit u din al ligam en t an atom y an d fu n ct ion of, 3, 4f, 18–19 inju ries to exten sion -dist ract ion inju r y-related, 100 lateral m ass fract ure-related, 109 tears, 22 AO Sp in e Subaxial Cer vical Sp in e Inju r y Classi cat ion System , 83–84, 84t, 115, 118, 119t, 169–176 com pression inju ries (t ype-A), 115, 118, 170, 170f, 171f su bt yp es of, 170f, 171f, 173t d ist ract ion /ten sion ban d inju ries (t ype B), 115, 118, 119t, 170, 172f subt yp es of, 170, 172f, 173t facet join t inju ries, 119t , 174, 174f, 174t, 175f n eurologic st at u s evalu at ion , 174, 175t reliabilit y an alysis of, 175, 177 t ran slat ion al inju ries (t ype C), 115, 118, 119t, 170, 173f subt ypes of, 173f Ascen ding cer vical arter y, an atom y of, 6 Aspen rigid cer vical orth osis, 41, 42, 42f Atlan to-axial com plex, osteop orot ic fract u res of, 151 Atlan to-axial fu sion , p osterior, of atlas fract u res, 65, 68–70, 68f, 69t Harm s tech n iqu e, 68, 69t, 70 Magerl/Gallie tech n iqu e, 68, 69, 69t, 70 Atlan to-axial join t s an atom y an d fu n ct ion of, 9, 18 dislocat ion of, 23

178

Index Atlan to-axial join t s (cont inued ) inju ries to, in ch ildren , 163 sublu xat ion of, 23 rh eu m atoid arth rit is-related, 147, 148, 150 rot ator y, in ch ild ren , 163, 164f Atlan to-axial ju n ct ion , in stabilit y of, 19 Atlan to-den s in ter val (ADI) an terior, in rh eum atoid ar th rit is, 148 in ch ildren , 159 de n it ion of, 159 in spin al in stabilit y, 19 Atlan to-occipital dissociat ion (AOD) an atom ic feat u res an d biom ech an ics of, 50–51 classi cat ion of, 53 delayed d iagn osis of, 59 diagn osis of, 51–56 epidem iology of, 49–50 progn osis an d ou tcom e of, 58 t reat m en t for, 56–58, 59 Atlan to-occipital join t s an atom y an d fu n ct ion of, 8–9, 15 in ch ildren , 158–159, 161 dislocat ion s of, 156–157, 162–163 Atlan to-occipital m em bran e, an atom y an d fu n ct ion of, 50 Atlas (C1), 77, 77f an atom y an d fu n ct ion of, 4f, 7f, 8, 15, 17–18 an om alies of, 77 develop m en t of, 76–77, 158 ossi cat ion cen ters of, 158 Atlas body, fract ures of, 79–80, 81 Atlas fract u res avulsion -t yp e, 22 burst , 61, 62 st able, 63 u n stable, 63, 68 classi cat ion of, 61, 62, 62f, 63f clin ical presen t at ion of, 61–62 Dickm an t ype, 63f, 65 Geh w eiler t ype, 62, 62f, 63–65 im aging of, 63, 63f, 70 Je erson , 61 in ch ild ren , 57 h alo vest im m obilizat ion of, 43 pseudo-Je erson , 159 non operat ive t reat m en t for, 45 op erat ive m anagem en t of, 65–70, 66f w ith isolated osteosyn th esis, 65–68, 71 th erapy algorith m for, 63–65, 64f w ith t ran sverse atlan t al ligam en t bony avu lsion , 61, 62, 63f, 64, 66f, 71 un stable, 62, 63 con ser vat ive m an agem en t of, 65 Axis (C2) an atom y an d fu n ct ion of, 2f, 8, 15, 18 in ch ild ren , 76–77 an om alies of, 77 develop m en t of, 76–77, 158 ossi cat ion cen ters of, 77, 77f, 158

Axis fract u res, 22–23 h angm an’s fract u res, 22–23, 77–79 C1- C2 p edicle xat ion of, 78 n on op erat ive t reat m en t for, 43, 44, 78 B Babin ski’s sign , 131 Basion -axial in ter val (BAI), 161 Basion -den s in ter val (BDI), 161 Biom ech an ics, of th e cer vical spin e, 17–24 in ch ild ren , 158–159 com pressive forces, 19 fu n ct ion al an atom y an d st abilit y, 17–19, 19t of inju red cer vical sp in e, 20–23 exten sion injuries, 22–23 exion inju ries, 20–22 inst abilit y, 19–20 Blu n t cer vical t rau m a evalu at ion of, 25–38 grad ing of, 32 Blu n t h ead t rau m a, 51 Braces for cer vicoth oracic ju n ct ion inju ries, 133 for com p ression fract u res, 89 Min er va-t ype, 41–42, 43–44 Brain inju r y, atlan to-occip it al d issociat ion -related, 51 “Burn ers”, 165 C C-sp in e clearan ce protocol, 30–32, 31f, 33f, 35 for ch ildren , 159–162, 167 C2. See Axis Cardiac arrest , cran iocer vical in st abilit y-related, 51 Cer vical collars, 40–42, 41f, 42f for atlan to-occip it al dissociat ion , 57 for cer vical sp rain s, 44 com plicat ions of, 42 for com p ression fract u res, 87 for cran iocer vical ju n ct ion inju ries, 56–57 for h angm an’s fract u res, 78 t ypes of, 41–42 u se in ch ildren , 160 Cer vical cord n eu rap raxia, 165 Cer vical im m obilizat ion in ch ild ren , 159–160 discon t in u at ion of, 25, 30–32, 35 Cer vical sp in e an atom y an d fu n ct ion of, 1–16 ad ult/ch ild com p arison of, 158–159 join t s an d ligam en t s, 3–4, 4f, 8–10, 15 m uscles, 4–6, 7f, 11f, 12 occip it al an d u pp er sp in e, 6–12 subaxial spin e, 12–15 suboccipit al region , 10–12, 10t, 11f u pper cer vical spin e, 17–18 vascu lar su p ply, 6 top ograp h ical relat ion sh ip s of, 13–15

Index Cer vical spin e injuries. See also speci c t ypes of inju ries evalu at ion of, 25–38, 95–97 C-spin e clearan ce p rotocol in , 30–32, 31f, 33f, 35 clin ical evalu at ion , 25–26 m agn et ic reson an ce im aging in , 34 plain radiography versus CT scan s in , 32–34 radiological assessm en t in , 26–30, 27f–30f n on operat ive m an agem en t of, 39–48 w ith cer vical orth oses, 40–42, 41f, 42f gen eral prin ciples of, 44–46 w ith h alo vest im m obilizat ion , 42–44 init ial assessm en t in , 39 w ith skelet al t ract ion , 39–40 Cer vical Spin e Inju r y Severit y Score (CSISS), 84, 105 Cer vical th oracic orth oses, 89 Cer vicoth oracic jun ct ion an atom y an d fu n ct ion of, 130, 131f, 134, 136 inju ries to, 130–138 closed reduct ion of, 133 diagn osis of, 130–133 fract ure-dislocat ion s, 130, 131f im aging of, 133, 137, 151 non surgical t reat m en t for, 133 osteoporot ic fract u res, 148, 151, 153 surgical approach es to, 134–137, 134t, 135f, 136f t reat m en t algorith m for, 133, 134f Ch ildren C2 an atom y in , 76–77 cer vical spin e inju ries in , 156–168 an atom ic con siderat ion s in , 158–159, 167 C2 fract ures, 76–77, 81 cer vical spin e clearan ce p rotocol for, 159–162, 167 epidem iology of, 156–157 im aging of, 76–77, 160–162 m ech an ism of inju r y in , 157–158 outcom es an d late com p licat ion s of, 166–167 speci c inju ries, 162–166 t reat m en t for, 166 Clay-sh oveler’s fract ures, 20 Closed redu ct ion, of cer vical spin e, 39–40. See also under speci c injuries Collet-Sicard syn drom e, 61–62 Com atose pat ien ts/un con sciou s p at ien t s C-spin e clearan ce protocol for, 32 cer vical spin e inju r y im aging in , 26, 28, 34, 35, 39 prior to closed reduct ion , 40 Com pression fract ures AO t ype-A, 83–93, 94, 170, 170f, 171f burst-t ype, 85–88, 86f–87f classi cat ion of, 83–84, 84t, 115, 118, 119t epidem iology of, 85 im aging of, 85–86, 86f–87f im pact ion -t ype, 84t, 85, 91 init ial m an agem en t of, 87–88 non surgical t reat m en t for, 88, 89, 91–92 split-t ype, 84t, 85, 91

subt yp es of, 170f, 171f, 173t surgical t reat m en t for, 88, 89–92 exion -com pression (teardrop ), 21, 157 osteop orot ic odon toid p rocess fract ures, 151–153, 153f pat tern s of, 150–151 t reat m en t for, 151–153 sim ple w edge, 21 Com p u ted tom ograp hy (CT), of cer vical spin e inju ries, 26, 29f, 34, 39 of atlan to-occipit al dissociat ion , 52–53 in ch ild ren , 160, 161–162 com parison w ith p lain radiograp h s, 32–34 Con dylar gap , 161 Con dyle-C1 in ter val (CCI), 52–53, 53f Cor t icosteroid s, as spin al cord injur y t reat m en t , 97 Costot ran sversectom y, 134t, 135f, 137 Cran ial n er ve p alsy cran iocer vical t rau m a-related, 51 occip it al con dyle fract u re-related, 59 Cran iocer vical dislocat ion . See Atlan to-occip ital dissociat ion Cran iocer vical dissociat ion . See Atlan to-occip it al d issociat ion Cran iocer vical ju n ct ion , an atom y an d fu n ct ion of, 50–51 Cran iover tebral join t s, an atom y an d fu n ct ion of, 8, 15, 16 Cran iover tebral ju n ct ion , inju ries to, 49 D Decom pression , of t rau m at ic cer vical spin e fract u res, 39–40 Decubit u s ulcers, cer vical or th oses-related, 42 Deep cer vical arter y, an atom y of, 6 Den s. See Od on toid p rocess Di u se idiop ath ic skelet al hyp erostosis (DISH), 22, 139–146 biom ech an ics of, 140–141 w ith C6-C7 exten sion -dist ract ion inju ries, 98f cer vical spin e fract u res associated w ith , 102, 103, 139–146 d iagn osis of, 140 epidem iology of, 140 im aging of, 140, 144–145 p reh ospital assessm en t an d t ran sport at ion for, 142 t reat m en t for, 142–144 d e n it ion of, 102 evalu at ion of, 96 im aging of, 102 DISH. See Di u se id iop ath ic skeletal hyperostosis (DISH) Disk disrupt ion , in exion -dist ract ion inju ries, 98–99 Disk h ern iat ion closed redu ct ion -related, 99 facet join t dislocat ion -related , 120–121, 123–124, 125–126, 125f, 127

179

180

Index Disk sp ace injuries, 22 Dist ract ion injuries (AO t ype-B), 94–104 an kylosing spon dylit is an d, 94 classi cat ion of, 95, 96f, 96t, 115, 118, 119t, 170, 172f, 173f closed redu ct ion of, 103 di u se skelet al hyperostosis an d, 94 exten sion -dist ract ion , 94 exten sion -dist ract ion injuries, 95 exion -dist ract ion , 94 hyp erexten sion inju ries, 95 im aging of, 97, 97f, 98f m an agem en t of, 97 m orph ology of, 95 subt ypes of, 170, 172f, 173f DLC, in com pression injuries, 88, 89, 91 Dorsal ap proach es, to cer vicoth oracic ju n ct ion inju ries, 132f, 136–137 Dorsal m uscles, an atom y an d fu n ct ion of, 4, 7f, 15 Du al-en ergy X-ray absorpt iom et r y (DEXA), 150 Du blin m eth od, of atlan to-occipital dissociat ion diagn osis, 52 Dysp h agia, 42, 51, 59 E Epidu ral space, 9, 10 Erector m uscle, an atom y an d fu n ct ion of, 5 Exten sion injuries, 22–23 Exten sion in st abilit y, 19 Exten sion -dist ract ion injuries (EDIs), 94, 95, 100–102, 101f closed redu ct ion of, 101 n on surgical t reat m en t for, 101 surgical app roach es to, 101–102 F Facet join t s an atom y an d fun ct ion of, 2f, 8, 12, 15, 18 dislocat ion s of, 21, 22, 115–129 bilateral, 97f, 117f, 120, 123, 125f, 126 classi cat ion of, 115–118, 118t, 119t closed redu ct ion of, 120–121, 124–125, 124f, 127 exion -dist ract ion , 97f, 99, 120 im aging of, 118–119, 120–121, 127 in it ial m an agem en t of, 120–121 pathom ech an ics of, 119–120 sublu xat ion s, 120 surgical m an agem en t of, 121–127, 122t, 124f u n ilateral, 115, 116f, 120, 123 fract ure-dislocat ion s of, 108, 108f, 120 fract ures of, 21, 22 level of inju r y of, 108 m ech an ism of inju r y of, 106, 113 n on operat ive t reat m en t for, 44 soft t issue involvem en t in , 109, 113 spin al cord inju r y associated w ith , 110 t reat m en t for, 111–113, 112–113 inju r y classi cat ion of, 174, 174f, 174t, 175f Fascia, cer vical, 13–14, 14f

Flexion injuries biom ech an ics of, 20–22 subaxial, 97 Flexion in st abilit y, 19 Flexion -dist ract ion injuries, 21, 94, 98–100 closed redu ct ion of, 99 of th e facet join ts, 97f, 99, 120 im aging of, 97f, 98f n on su rgical t reat m en t for, 99, 100, 101 surgical app roach es to, 99–100 Flexion -rot at ion inju ries, 21 Flexion -t ran slat ion inju ries, 21 Fract u res. See also speci c t ypes of fract ures closed redu ct ion of, 39–40 gu n sh ot w oun d-related, 44–45 G Gardn er-Wells tongs, 39, 45, 87, 133 Glossop h ar yngeal n er ve, 51 Grades of Recom m en dat ion , Assessm en t an d Evalu at ion (GRADE) Working Grou p , 94–95 Greater occipit al n er ve, an atom y an d fu n ct ion of, 10–11, 11f Gu n sh ot w ou n ds, 44–45 H Halo vest , 42–44 for atlas fract u res, 65 for cer vicoth oracic ju n ct ion inju ries, 133 com plicat ion s of, 44, 65, 89, 151–152 for com p ression fract u res, 88, 89 for cran iocer vical jun ct ion inju ries, 56–57 for d en s (odon toid process) fract u res, 44 for exion -d ist ract ion injuries, 99, 100, 101 for h angm an’s fract u res, 78 for occip it al con dyle fract u res, 59 u se in ch ildren , 163, 166, 167 u se in eld erly pat ien t s, 151–152 u se in rh eu m atoid arth rit is p at ien t s, 149 Hangm an’s fract u res, 22–23, 77–79 C1-C2 pedicle xat ion of, 78 n on op erat ive t reat m en t for, 43, 44 Harris basion -axis in ter val, 52 Hyp erexten sion inju ries as n eu rologic inju r y cau se, 101 spin al an kylosis-related, 141, 141f, 144 of th e up p er spin e, 22 Hyp er exion inju ries, in ch ildren , 157 Hyp oglossal n er ve lesion s, 51 Hyp oglossal n er ve p alsy, 57 Hyp oglossal n er ve, an atom y an d fun ct ion of, 51 I Iliocost alis m u scle, an atom y an d fu n ct ion of, 5, 5t Im aging, of cer vical spin e injuries, 25–38. See also Com p u ted tom ograp hy (CT): Magn et ic reson an ce im aging (MRI); X-rays in ch ild ren , 160–162 in com atose/u n con sciou s pat ien ts, 26, 28, 34, 35, 39, 160–162

Index In st abilit y, de n it ion of, 19–20 In st rum en t at ion , cer vical, u se in ch ildren , 166 In tersp in alis m uscle, an atom y an d fu n ct ion of, 5t, 6 In tersp in ou s ligam en t , an atom y an d fu n ct ion of, 3, 4f In tert ran sversarii m uscle, an atom y an d fu n ct ion of, 5t, 6 In ter vertebral disks. See also Disk disru pt ion ; Disk h ern iat ion ; Disk sp ace inju ries an atom y an d fu n ct ion of, 12, 15 J Je erson fract ures. See Atlas fract u res, Je erson Journal of Bone and Joint Surgery, Am erican Volum e, 94 K Kyph osis cer vicoth oracic ju n ct ion inju r y-related, 132f, 133, 136 osteoporosis-related, 150, 151 post t rau m at ic, in ch ildren , 166 L Lateral exion inju ries, in ch ildren , 157 Lateral m ass fract ure-sep arat ion , 22 Lateral m ass fract ures, 105–114 an atom ic con siderat ion s in , 105–106 classi cat ion of, 106–108, 107t com m in uted-t ype, 107, 111 de n it ion of, 105 oat ing m ass-t ype, 105, 107, 111, 112f level of inju r y of, 108 m ech an ism of inju r y of, 106 n eurovascular inju ries associated w ith , 109–110 path oan atom y of, 108–109 soft t issue involvem en t in , 109, 113 split-t ype, 107, 111 t reat m en t for, 111–112 Lateral m ass screw s, bicor t ical an d u n icort ical, 79, 81 Lat issim us dorsi m uscle, an atom y and fu n ct ion of, 5 Lee’s X-lin e m eth od, 52 Levator scapulae m u scle, an atom y an d fun ct ion of, 5, 13 Ligam en t injuries to cer vicoth oracic ju n ct ion , 137 in children , 161 as in stabilit y cause, 20 posterior, 20 Ligam en ta ava, an atom y an d fun ct ion of, 3–4, 4f Ligam en ts an atom y an d fu n ct ion of, 18 of cran iocer vical ju n ct ion , 50 Longissim us m u scle, an atom y an d fu n ct ion of, 5, 5t Longu s capit is m u scle, an atom y an d fu n ct ion of, 13 Longu s colli m uscle, an atom y an d fu n ct ion of, 13 Lordosis, cer vical, 17 absen ce of, in ch ildren , 159

Low er cer vical inju ries. See also Su baxial spin e in ch ild ren , 163 M Magn et ic reson an ce im aging (MRI), of cer vical sp in e inju ries, 28, 30, 30f, 39 of atlan to-occipit al dissociat ion , 53 in ch ild ren , 160, 162, 165 for diskoligam en tous com p lex in tegrit y assessm en t , 170 for in st abilit y determ in at ion , 20, 23 prior to closed redu ct ion , 40 Methylp redn ison e, u se in ch ildren , 166 Miam i-J rigid cer vical collars, 41, 42f, 43 Midth oracic region , osteoporot ic fract u res of, 150, 153–154 Min er va brace, 41–42, 43–44 Mu lt i du s m uscle, an atom y an d fu n ct ion of, 5t, 6 Mu scles, of th e back, 4–6, 7f, 11f, 12. See also speci c m uscles deep , 4, 5–6, 5t ext rin sic, 4–5 int rin sic, 4–5, 5t Myelop athy, t raum at ic, 28, 30f in ch ild ren , 158 N Neck, t ran sverse sect ion s of, 13–15, 14f Neon ates, cer vical spin e inju ries in , 165 Neu rologic exam in at ion , 96 in rh eu m atoid ar th rit is p at ien t s, 149 Neu rologic im p airm en t cer vicoth oracic ju n ct ion inju r y-related, 130–131, 133 in ch ild ren , 156, 167 spin al an kylosis-related, 142, 144, 145 Neu rologic st at u s, grading of, 174, 175t Nu ch al ligam en t , an atom y an d fun ct ion of, 3, 4f, 14f, 15, 50 O Obliqu u s capit is m u scles, an atom y an d fu n ct ion of, 10, 10t, 11f Occip it al ar ter y, an atom y of, 12 Occip it al bon e, an atom y of, 4f, 6–8, 7f Occipit al con dyles an atom y an d fu n ct ion of, 8, 50–51 fract ures of, 39, 44–45 an atom ic feat u res an d biom ech an ics of, 50–51 avu lsion fract u res, 50, 54, 54f, 55f–56f classi cat ion of, 53–56, 54f–56f com pression fract u res, 54f epid em iology of, 50 inciden ce of, 50 progn osis an d ou tcom e of, 58 t reat m en t for, 56–58 Occip itoatlan t al join t s an atom y an d fu n ct ion of, 50 in rh eu m atoid ar th rit is, 148

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Index Occipitocer vical dissociat ion . See Atlan to-occipit al dissociat ion (AOD) Occipitocer vical fusion , 57–58, 59 of atlas fract ures, 64 in ch ildren , 166 Occipitocer vical join t , an atom y an d fu nct ion of, 18 Occipitocer vical ju n ct ion dislocat ion of, 22 inst abilit y of, 19 Odon toid process (den s) an atom y an d fu n ct ion of, 2f, 8, 9, 10 ossi cat ion cen ters of, 158 Odon toid process (den s) fract ures, 73–77 an terior screw xat ion of, 73–74, 75, 76 in ch ildren , 157, 163 classi cat ion of, 73, 74f closed reduct ion of, 40 in elderly p at ien t s, 73, 74–76 non surgical t reat m en t for, 40, 43, 45 osteoporot ic, 151–153, 152f surgical versus n on su rgical t reat m en t for, 74–76 Orth oses, cer vical, 40–42, 41f, 42f com plicat ion s of, 42, 89 for osteoporot ic fract u res, 152 t ypes of, 41–42 use in rh eum atoid arth rit is pat ien ts, 149 Os odon toideum , 166 Ossi cat ion , di use idiopath ic skelet al hyperostosisrelated, 140 Osteop orosis as com pression fract u re cause, 147 odon toid process fract ures, 147–148, 151–153, 153f pat tern s of, 150–151 t reat m en t for, 151–153 path ophysiology of, 150 spin al an kylosis-related, 140–141 Osteosyn th esis, of th e atlas, 65–68, 67t P Pars in terart icularis fract u res. See also Hangm an’s fract ures; Spon dylolysis in ch ildren , 165–166 Ph iladelph ia cer vical collars, 41, 42, 43 Ph ren ic n er ve injuries, 157, 158 PMT® Cer vMax™ Cer vical Orth osis Collar, 41 Posterior approach an atom ic con siderat ion s in , 1 to com p ression fract u res, 91 to facet join t dislocat ion s, 121–123, 126 to exion -dist ract ion inju ries, 99–100, 101f to lateral m ass fract u res, 111 Posterior xat ion of exion -dist ract ion inju ries, 101–102 in rh eu m atoid arth rit is pat ien t s, 149 Posterior fusion , in ch ildren , 166 Posterior ligam en tou s com p lex, disrupt ion of, 97, 98f

Posterior longit u din al ligam en t an atom y an d fu n ct ion of, 3, 4f, 18–19 inju ries to facet join t fract u re-related, 109 exion -dist ract ion inju ries-related, 98–99 t ran sect ion , 20 Pow ers rat io, 52 in ch ild ren , 161, 163 Preden t al space, in ch ildren , 161 Prevertebral m u scles, an atom y an d fu n ct ion of, 4 Prevertebral sp ace, in ch ildren , 159 Pseu doar th roses, in ch ildren , 159 Pseu dosu blu xat ion , in ch ildren , 159 R Radiculop athy, facet join t fract u re-related , 110 Rect u s m u scles, an atom y an d fu n ct ion of, 10, 10t, 11f, 12, 13 Recu rren t lar yngeal n er ve, an atom y an d fu n ct ion of, 15 Ret rop h ar yngeal sp ace, in ch ildren , 159, 161 Ret rot rach eal sp ace, in ch ildren , 161 Rh eu m atoid arth rit is, 147, 148–150, 153 cer vical spin e t rau m a in evalu at ion of, 149 im aging of, 149 t reat m en t for, 149–150, 153, 154 path op hysiology an d biom ech an ics of, 148–149, 148f spin al in stabilit y in , 147 Rh om boid m uscles, an atom y an d fu nct ion of, 5 Rot at ion inju ries, 94 in ch ild ren , 157 Rot at ion , of cer vical spin e, 19, 19t Rot atores m u scle, an atom y an d fun ct ion of, 5t, 6 “Ru le of Sp en ce,” 63 S Sacroiliit is, 140 Scalen u s m u scles, an atom y an d fu n ct ion of, 13 SCIWORA (spin al cord injur y w ith out radiograp h ic abn orm alit y), 158, 162, 165 Seatbelt inju ries, in ch ildren , 157 Sem ispin alis capit is m u scle, an atom y an d fu n ct ion of, 10, 11f Sku ll base, fract ures of, 54, 54f Sm ith -Robin son an terom edial app roach , 136 Space available for th e cord (SAC), 19 in rh eu m atoid ar th rit is, 149, 150 Spin al cord con cu ssion , 165 Spin al cord inju r y atlan to-occipit al dissociat ion -related, 51 bu rst fract u re-related , 85 cer vicoth oracic ju n ct ion inju r y-related, 131 in ch ild ren , 157–158, 167 facet join t fract u re-related, 110 w ith ou t radiograp h ic abn orm alit y (SCIWORA), 158, 162, 165

Index Spin al cord, anatom y an d fun ct ion of, 9–10 Spin al sh ock, 96–97, 158 Spin ous processes an atom y an d fu n ct ion of, 2f, 3, 8, 14f avulsion of, 20 Splen ius capit is m uscle, an atom y an d fu n ct ion of, 5, 5t, 6 Splen ius cer vicis m uscle, an atom y an d fu n ct ion of, 5, 5t, 6 Spon dylolisth esis degen erat ive, di eren t iated from su baxial sublu xat ion , 148–149 t rau m at ic cer vical. See Hangm an’s fract u res Spon dylolysis lateral m ass injur y as, 107, 108, 111 u n ilateral, 109 Sport s-related injuries, 165 Sprain s, cer vical, 44 St abilit y, de n it ion of, 19 Sten osis, congen ital cer vical, 22 “St ingers,” 165 Subaxial cer vical spin e an atom y an d fu n ct ion of, 12–15, 18–19 develop m en t of, 158 dislocat ion s of, 39 fract ures of, 39 non operat ive t reat m en t for, 44 in st abilit y of, 19–20 Subaxial Cer vical Sp in e Inju r y Classi cat ion (SLIC) an d Severit y Scale, 84, 88, 95, 96t, 115, 118t, 133 lim itat ion s of, 169–170 Subaxial st abilizat ion , in ch ildren , 166 Suboccipit al m u scles, an atom y an d fun ct ion of, 6, 10, 10t Suboccipit al n er ve, an atom y an d fun ct ion of, 11–12, 11f Suboccipit al region , an atom y an d fun ct ion of, 10–12, 10t, 11f Suboccipit al t riangle, an atom y an d fun ct ion of, 10, 11f Sun’s in terspin ous rat io, 52 Sup raspin ous ligam en t , an atom y an d fu n ct ion of, 3, 4f Sw isch u k’s lin e, 59, 161 Sym path et ic t ru n k, 14, 15 Syn ch on droses, 156 di eren t iated from C2 fract u res, 165–166 m isin terpreted as fract ures, 159 T Teardrop fract u res, 21 in ch ildren , 157 Tectorial m em bran e, an atom y an d fu n ct ion of, 9, 50 Ten sion ban d inju ries (AO-t yp e B), 170, 172f su bt ypes of, 170, 172f, 173t Th ird occipit al n er ve, an atom y an d fu n ct ion of, 11, 11f

Th oracolum bar jun ct ion , osteoporot ic fract u res of, 150–151, 153–154 Th oracolum bar spin e inju ries, classi cat ion of, 83–84, 169 Tor t icollis, cran iocer vical t rau m a-related, 51 Tract ion , 39–40 for cer vicoth oracic ju n ct ion inju ries, 133 for com p ression fract u res, 87, 88 for facet join t d islocat ion s, 120 for h angm an’s fract u res, 78–79 Tran sart icu lar screw osteosyn th esis, of C0- C1, 57 Tran slat ion al inju ries (AO t yp e-C), 170, 173f classi cat ion of, 115, 118, 119t subt ypes of, 173f Tran sverse atlan t al ligam en t , bony avu lsion of, 61, 62, 63f, 64, 66f, 71 Tran sverse ligam en t , an atom y an d fu n ct ion of, 9 Tran sverse process, an atom y an d fu n ct ion of, 2f, 3, 8 Tran sversosp in alis m u scles, an atom y an d fu n ct ion of, 5–6, 5t , 5t Trapeziu s m uscle, an atom y an d fu n ct ion of, 5, 6, 7f Trau m at ic brain inju r y, occip it al con dyle fract u reassociated, 50 U Un cin ate p rocess an atom y an d fu n ct ion of, 18 fract ures of, 21 Un con sciou s pat ien ts. See Com atose/u n con sciou s pat ien ts Un covertebral join t s, an atom y an d fu n ct ion of, 12 Upp er cer vical spin e, fract u res of, 39 n on op erat ive t reat m en t for, 44–45 V Vagal n er ve, 51 Ven ou s p lexu ses an atom y an d fu n ct ion of, 6, 10 suboccipit al, 12 Ven t ral app roach es, to cer vicoth oracic ju n ct ion inju ries, 134, 136, 136f Vertebrae, cer vical. See also Atlas (C1); Axis (C2) an atom y an d fu n ct ion of, 1–3, 2f ossi cat ion cen ters in , 158 Vertebral arch , cer vical, an atom y an d fu n ct ion of, 1, 2f Vertebral arter y inju ries atlas fract ure-related, 63, 67, 97 axis fract u re-related, 97 in ch ildren , 157 diagn osis of, 127 facet join t dislocat ion -related, 127–128 facet join t fract ure-related, 110–111 exion -dist ract ion inju ries-related, 99 lateral m ass fract u re-related, 109–110 risk factors for, 127 t reat m en t for, 127

183

184

Index Vertebral arter y, an atom y of, 6, 8, 10, 11–12, 11f, 14f, 15 Vertebral bod ies, cer vical an atom y an d fu n ct ion of, 1, 2f fract ures of, 98f osteoporot ic com pression fract u res of, 148 w edging of, in ch ildren , 159 Vertebral foram en , an atom y an d fu nct ion of, 1, 2f, 3 Vertebral n otch , an atom y an d fu n ct ion of, 2f, 3 Vist a cer vical collars, 41

W W h iplash inju ries, t reat m ent for, 44 W h oley basion -den s in ter val, 52, 52f X X-rays, of cer vical sp in e inju ries, 26, 27f, 28f of atlan to-occipit al dissociat ion , 52, 53 com parison w ith com p u ted tom ography, 32–34 of cran iocer vical ju n ct ion inju ries, 59 of ped iat ric cer vical sp in e t raum a, 161–162