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
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
Fx through body of C2, incl
one or both sup articular
processes
Type III
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
No AOD
AOD
Type II
Type III
???
MRI
TL intact
Collar
Surgery
TL disrupted
Brace/halo
Posterior
Fusion
Fails
Comminuted
Simple fx
Post fusion
Ant vs post fus
Type II Odontoid Fxs:
Non-surgical
• Collar vs Management
Brace vs Halo
• 75% upper cervical motion restriction w/ halo
• 45% restriction w/ conventional braces (ex:
Minerva)
• Disadvantages of halo: precludes working, pinsite 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
33
Age >40 yr, displacement >4 mm
Ekong et al, 198110
17
41
Age ≥55 yr, displacement >4-6
mm
Hadley et al, 198512
40
26
Not age, displacement >6 mm
Clark & White, 19858
106
32
Not age, displacement >5 mm
Dunn & Seljeskog, 19869
88
24
Age >65 yr, posterior
displacement
Hanssen & Cabanela, 198777
42
50
Age >72 yr, posterior
displacement
Schweigel, 198733
47
10
Not age, not displacement
Hadley et al, 19892
65
28
Not age, displacement ≥6 mm
Ryan & Taylor, 199378
35
77
Posterior displacement
Seybold & Bayley, 199834
37
29
Not age, displacement unknown
Greene et al, 199735
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
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
• Unilateral/Bilateral
Fixation
• 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
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
Screws
• Roy-Camille
• Variations in
entry point,
trajectory
• An technique
lowest risk of
nerve root
injury
• screw
</=15mm
Posterior C1-2 Fusion
• 3 column
fixation (A)
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
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
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
• 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]
Case Presentation
Case Presentation
Case Presentation
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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 (2775%)
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
•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 22:6771, 1988.
•Hadley MN, Dickman CA, Browner CM, et al: Acute axis fractures: A review of 229 cases. J Neurosurg 71:642647, 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