Surgical Approach: Fixation at C1-2

Kamal R.M. Woods, MDDepartment of Neurological Surgery

Loma Linda University Medical Center

Surgical Management of

Odontoid Fractures•Kamal R.M. Woods, MD

•Department of Neurological Surgery

•Loma Linda University Medical Center

Outline

•Anatomy of upper cervical spine

•Types of odontoid fractures

•Mechanism of injury

•Non-surgical management

•Surgical approaches

•Case Presentation

•Summary

Ligaments at C1-2

http://www.pt.ntu.edu.tw/hmchai/Kines04/KINspine/Spine.files/AAAjointSup.jpg

•1/3 cord

•1/3 dens

•1/3 empty

Spinal Canal

Vertebral Artery•Arises from subclavian artery

•Enters foramen transversarium at C6

•Turns laterally at C2

•Exits foramina transversarium at C1

•Travels posteriorly at C1 (vertebral groove)

•Ascends superiorly along clivus http://www.nass.co.uk

Types of Odontoid Fractures

•Anderson and D’Alonzo classification (1974): FRACTURE FEATURE

Type I Small oblique avulsion of upper 1/3 of odontoid

Type II Fracture at junction of dens and C2

Type IIa Comminuted fracture at base of odontoid

Type III Fx through body of C2, incl one or both sup articular processes

Types of C2 Fractures

http://www.nypemergency.org

Hangman Fractures

http://www.nypemergency.org

Jefferson Fractures

http://uuhsc.utah.edu/rad/medstud/NeuroCaseStudies/Images/Neuro%20Case%2015%20jefferson%20fracture.jpg

•Unilateral/bilateral

•Ant + Post arch of C1

•Axial loading to head(ex: diving)

Mechanisms of Injury for Odontoid

Fractures•Flexion vs extension loading

•Flex loading anterior displacement of dens (more common; ex: MVC)

•Ext loading posterior displacement of dens (ex: fall on forehead)

Type I Odontoid Fractures•Upper 1/3 of dens

•Avulsion of alar ligament

•< 1% of odontoid fractures

•Usually stable b/c transverse ligament intact

•Associated with AOD- unstable

Type 1 Odontoid Fracture

Type II Odontoid Fractures

•Neck of dens

•Most common odontoid fracture

•Subtype IIa (comminuted) highly unstable

•Treatment controversial: external vs internal fixation

Type II Odontoid Fracture

Type II Odontoid Fracture

Type IIIOdontoid Fractures•Involve body and possibly superior

facet of C2

•Usually stable

•Unstable if transverse ligament disrupted

•Green: n=75; 69 conservative, 1 non-union

Type III Odontoid Fracture

Algorithm for Treatment of Odontoid Fractures

Odontoid Odontoid FracturesFractures

Type IType I Type IIType II Type IIIType III

AODAOD ?????? MRIMRI

TL intactTL intactTL disruptedTL disrupted

ComminuteComminutedd

Posterior Posterior FusionFusion

No AODNo AOD

SurgerSurgeryy

CollarCollar

Post fusionPost fusion

Simple fxSimple fx

Ant vs post Ant vs post fusfus

Brace/haloBrace/halo

FailsFails

Type II Odontoid Fxs: Non-surgical Management•Collar vs Brace vs Halo

•75% upper cervical motion restriction w/ halo

•45% restriction w/ conventional braces (ex: Minerva)

•Disadvantages of halo: precludes working, pin-site infection, skin break-down, skull perforation

•After several months of immobilization, significant number of patients still need surgery

•27-75% non-union rate with external fixation

Non-union of Type II Odontoid Fractures Treated Conservatively

AUTHOR AND YEAR NO. OF PATIENTS NONUNION RATE (%) SIGNIFICANT FACTORS

Anderson & D'Alonzo, 19747 49 36 None specified

Apuzzo et al, 197826 45 33Age >40 yr, displacement >4

mm

Ekong et al, 198110 17 41Age ≥55 yr, displacement

>4-6 mm

Hadley et al, 198512 40 26Not age, displacement >6

mm

Clark & White, 19858 106 32Not age, displacement >5

mm

Dunn & Seljeskog, 19869 88 24Age >65 yr, posterior

displacement

Hanssen & Cabanela, 198777 42 50Age >72 yr, posterior

displacement

Schweigel, 198733 47 10 Not age, not displacement

Hadley et al, 19892 65 28Not age, displacement ≥6

mm

Ryan & Taylor, 19937878 35 77 Posterior displacement

Seybold & Bayley, 19983434 37 29Not age, displacement

unknown

Greene et al, 19973535 88 28 Displacement ≥6 mm

Type II Odontoid Fxs: Indications for

Surgery•Fracture cannot be maintain by

external orthosis (serial xrays)

•Rupture of transverse ligament

•5mm or more displacement of dens

•Comminuted fracture of dens (type IIa)

•(Older patients)

Surgical Approaches to C1-2

fusion•Posterior bone and wire fusion

•Posterior transarticular screw fixation

•Anterior transfacetal screw fixation

•Posterior fusion with lateral mass screws/rods

•Posterior fusion with pedicle screws/rods

•Posterior fusion with translaminar screws/rods

•Anterior odontoid screw fixation

Anterior vs Posterior Approach

•50% cervical rotatory excursion at C1-2

•Posterior fusion eliminates atlantoaxial rotation, usually noticeable by patient

•Odontoid screw fixation: provides immediate stabilization, promotes bone healing, preserves C1-2 rotation

• Initial anterior approach morbid due to extensive neck dissection

Posterior C1-2 Approaches

• Initial exposure same for all posterior fusions

•Midline incision

•Avascular plane

•Bipolar dissection/blunt dissection (cobb and gauze)

•May extend superiorly to ext occipital protuberance

•Lateral dissection limited by vertebral arteries

Posterior C1-2 Bone and Wire Fusion

•Traditional approach to C1-2 fusion

•Traynelis (1997): 64% fusion, 2% morbidity/mortality

•Occiput-C2 (vs C1-2) if gross O-A instabilty or poor integrity of post C1 arch

Posterior Bone and Wire Fusion

•Interspinous

•Facet/Transarticluar

•Interlaminar/Sublaminar (Halifax clamp)

Methods of C1-2 Wiring

Interspinous Wiring

Facet/Transarticular Wiring

Interlaminar Wiring

Bone Graft

•Autograft vs allograft

•Tricortical iliac crest graft wedge (gold standard)

Posterior Fusion with C1-2 Transarticular

Screw Fixation•Unilateral/Bilateral

•3.5mm screw through the C2 pedicle, across the C1-2 facet, and into each lateral mass of C1

•C1 and 2 become rigidly coupled

•Articular surfaces of C1 and 2 are prepared to acheive fusion across the facet joint

•Interspinous wiring? Halo immobilization?

Posterior C1-2 Fusion with Lateral Mass

Screws•Harm’s procedure

•Useful when posterior elements absent or disrupted

•Superior rotational stability at facets vs wiring (biomechanical)

• Immediate rigidity -better fusion -no halo

Posterior C1-2 Fusion with Lateral Mass

Screws•Roy-Camille

•Variations in entry point, trajectory

•An technique lowest risk of nerve root injury

•screw </=15mm

Posterior C1-2 Fusion with Pedicle

Screws•3 column fixation (A)

•Superior to lateral mass screws (biomechanical)

•Preop CT: bones, verts, nn.

•Enter lateral to center of facet, close to post margin of superior articular surface

•Point of entry decorticated with high speed drill

•Angles vary (B, C)

Posterior C1-2 Fusion with Translaminar

Screws•First presented in 2003 at Cervical Spine Research Society

•Technique published in 2004

•Minimize injury to vertebral artery as seen with transarticular and pedicle screws

•Crossing, bilateral translaminar screws

Anterior Odontoid Screw Fixation

•Most type II, some type III

•Does not require intact posterior elements

•Acute fractures (6 months or less), not os odontoideum*

• Intact transverse ligament (absolute)*

•No oblique and anterior slope (relative)*

•No severe osteopenia (relative)*

Apfelbaum RI: Anterior Screw Fixation of Odontoid Fractures (Aesculap Scientific Info 24). Tuttlingen, Germany, Aesculap AG, 1992. 51a. Apfelbaum RI, Lonser RR, Veres R, et al: Direct anterior screw fixation for recent and remote odontoid fractures. J Neurosurg 93(2Supp):227-236.

* Posterior fusion

Anterior Odontoid Screw: Surgical

Approach•Prone

•Shoulder roll

•Halter traction

•Head extended vs neutral

•Radiolucent mouth prop

Anterior Odontoid Screw: Surgical

Approach•Low cervical incision (C5-6)

•Standard approach to C-spine

•Modified Caspar retractor

•Prevertebral space opened to C2

•Angled retractor to create tunnel to C2

Anterior Odontoid Screw: Surgical

Approach•K-wire placed on A-I lip of

C2

•8mm hand-operated hollow drill over K-wire

•Trough in body of C3

•Incise C2-3 annulus

•C2 body not disrupted

•Extend neck if retrolisthesis of dens present

Ant Odontoid Screw: Surgical

Approach•Drill guide system over K-wire

•Spike on outer tube impacted into C3

•K-wire removed and replaced with drill

•Drill to apex of odontoid

•Pilot hole through apical cortex of odontoid

Ant Odontoid Screw: Surgical

Approach•Pilot hole is tapped

•Lag screw inserted through the guide tube

• Image saved for comparison

•Final screw placed

•Stabilization confirmed by flex/ext of neck

•Procedure repeat if second screw needed, but no lag screw required

Anterior Odontoid Screw Fixation

Anterior C1-2 Transfacetal Screw

Fix•Expose identical to ant odontoid screw fix

•Facet joints are decorticated with angled curette

•Screws placed into the C2 vertebral body in the groove between the body and superior C2 facet

•Angle of drilling adjusted in a superiolateral direction to allow for passage through lateral mass of C2, across C1-2 joint space and into C1 lateral mass

•Maintains some C1-2 motion vs [posterior] transarticular screw???

Case Presentation

Case Presentation

Case Presentation

Summary• Odontoid fracture cause by flexion/extension loading

• Type 1 usually treated with collar unless AOD

• Type III treated with brace/halo unless disrupted transverse ligament or fails conservative treatment

• Treatment of type II controversial but surgical intervention usually recommended due to high rate of non-union (27-75%)

• Direct anterior odontoid screw preserves cervical rotation and offers immediate stabilization but needs intact TL; if type III fx then must be simple

• Posterior bone and wiring fusion is gold standard

• Posterior instrumentation (transarticular, lateral mass, pedicle, translaminar screws) offer immediate rigidity and superior stabilization/?fusion

References•Anderson LD, D'Alonzo RT: Fractures of the odontoid process of the axis. J Bone Joint Surg Am 56:1663-1674, 1974.

•Apuzzo ML, Heiden JS, Weiss MH, et al: Acute fractures of the odontoid process: An analysis of 45 cases. J Neurosurg 48:85-91, 1978.

•Clark CR, White AA III: Fractures of the dens: A multicenter study. J Bone Joint Surg Am 67:1340-1348, 1985.

•Dunn ME, Seljeskog EL: Experience in the management of odontoid process injuries: An analysis of 128 cases. Neurosurgery 18:306-310, 1986.

•Ekong CE, Schwartz ML, Tator CH, et al: Odontoid fracture: Management with early mobilization using the halo device. Neurosurgery 9:631-637, 1981.

•Greene KA, Dickman CA, Marciano FF, et al: Acute axis fractures: Analysis of management and outcome in 340 consecutive cases. Spine 22:1843-1852, 1997.

•Hadley MN, Browner C, Sonntag VKH: Axis fractures: A comprehensive review of management and treatment in 107 cases. Neurosurgery 17:281-290, 1985.

•Hadley MN, Browner CM, Liu SS, et al: New subtype of acute odontoid fractures (type IIA). Neurosurgery 22:67-71, 1988.

•Hadley MN, Dickman CA, Browner CM, et al: Acute axis fractures: A review of 229 cases. J Neurosurg 71:642-647, 1989.

•Hanssen AD, Cabanela ME: Fractures of the dens in adult patients. J Trauma 27:928-934, 1987.Winn, Richard. Youmans Neurological Surgery. 5th edition.

•Ryan MD, Taylor TK: Odontoid fractures: A rational approach to treatment. J Bone Joint Surg Br 64:416-421, 1982.

•Seybold EA, Bayley JC: Functional outcome of surgically and conservatively managed dens fractures. Spine 23:1837-1846, 1998.

References•http://www.medscape.com

•Netter, Frank. Atlas of Human Anatomy.

•Schmidek and Sweet. Operative Neurosurgical Techniques. 3rd edition.

•Schweigel JF: Management of the fractured odontoid with halo-thoracic bracing. Spine 12:838-839, 1987.

•http://www.wheelessonline.com/ortho/dens_fracture