Surgical Approach: Fixation at C1-2 Kamal R.M. Woods, MD Department 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 Spinal Canal • • • 1/3 cord 1/3 dens 1/3 empty http://www.pt.ntu.edu.tw/hmchai/Kines04/KINspine/Spine.files/AAAjointSup.jpg

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 Type II Type IIa Type III Small oblique avulsion of upper 1/3 of odontoid Fracture at junction of dens and C2 Comminuted fracture at base of odontoid Fx through body of C2, incl one or both sup articular processes

Types of C2 Fractures http://www.nypemerge

ncy.org

Hangman Fractures http://www.nypemerge

ncy.org

Jefferson Fractures • • • Unilateral/bilateral Ant + Post arch of C1 Axial loading to head(ex: diving) http://uuhsc.utah.edu/rad/medstud/NeuroCaseStudies/Images/ Neuro%20Case%2015%20jefferson%20fracture.jpg

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 III Odontoid 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 Fractures Type I Type II Type III No AOD AOD Collar Surgery ???

MRI TL intact Brace/halo TL disrupted Comminuted Fails Simple fx Posterior Fusion Post fusion Ant vs post fus

Type II Odontoid Fxs: Non-surgical • • • 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, 1974 7 Apuzzo et al, 1978 26 Ekong et al, 1981 10 Hadley et al, 1985 12 Clark & White, 1985 8 Dunn & Seljeskog, 1986 9 Hanssen & Cabanela, 1987 77 Schweigel, 1987 33 Hadley et al, 1989 2 Ryan & Taylor, 1993 78 Seybold & Bayley, 1998 34 Greene et al, 1997 35 49 45 17 40 106 88 42 47 65 35 37 88 36 33 41 26 32 24 50 10 28 77 29 28 None specified Age >40 yr, displacement >4 mm Age ≥55 yr, displacement >4-6 mm Not age, displacement >6 mm Not age, displacement >5 mm Age >65 yr, posterior displacement Age >72 yr, posterior displacement Not age, not displacement Not age, displacement ≥6 mm Posterior displacement Not age, displacement unknown 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 Methods of C1-2 Wiring • • • Interspinous Facet/Transarticluar Interlaminar/Sublaminar (Halifax clamp)

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 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 Harm’s procedure Screws 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 • • • • Roy-Camille Variations in entry point, trajectory An technique lowest risk of nerve root injury screw

Posterior C1-2 Fusion • • with Pedicle Screws 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

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)* * Posterior fusion 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.

Anterior Odontoid Screw: Surgical • • • • • Prone Shoulder roll Halter traction Head extended vs neutral Approach 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 Expose identical to ant odontoid screw fix 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

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

References • 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.

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