Cervical Spine Mechanisms of Injury - Sally Tennant 28/8/2001

C1/C2 & C5-C7 especially vulnerable

Neurologicald amage in 40%

10% of traumatic cord injuries have no obvious XR evidence of vertebral injury

Allen et al

6 common patterns of injury:

Compression flexion

Vertical compression

Distractive flexion

Compression extension

Distraction extension

Lateral flexion

Instability

White & Panjabi

“Loss of ability of spine under physiological loads to maintain relationships between vertebrae in such a way that spinal cord/nerve roots are not damaged or irritated and deformity or pain does not develop”

White& Panjabi- cadaver studies

Supporting structures of lower C spine – anterior & posterior

Motion segment=2 adjacent vertebrae and intervening soft tissues

If a motion segment has all anterior elements and 1 posterior element intact OR all posterior and 1 anterior element intact, it will be stable under physiological loads.

Checklist- >5=clinical instability

Radiological instability

Horizontal translation of 1 vertebra relative to another of >3.5mm on lateral flexion/extension view

Angulation of >11 degrees of 1 vertebra relative to another

Atlas fractures

Jefferson 1920 – Burst fractures

53% have other cervical spine fractures especially of axis and dens

Usually seen on lateral view, but when anterior to lateral mass of C1 may not be seen on lateral

Through the mouth view should show displacement of lateral masses in burst fracture

3 main types:

• 1) undefined Posterior arch fracture

• 2) Lateral mass

• 3) undefined Burst fracture – 4 fractures, 2 in posterior arch, 2 in anterior arch ( Jefferson )

Caused by axial loading eg weight on head, head hitting roof of car in RTA, fall from height onto heels

Management– Immobilisation in rigid cervical orthosis or halo vest for most.

Isolated posterior arch fractures – stable-cervical collar for 8-12/52

Minimally displaced fractures lateral mass and Jefferson fractures –collar to prevent displacement,

Displacement of lateral mass of atlas >7mm from articular surfaces of axis-halo traction for 3-6/52 before halo vest.

Ruptured transverse ligament

Usually fall with blow to back of head, sudden flexion injuries

Midsubstance rupture, or avulsion

Produces anterior subluxation of C1 ring

Usually seen on flexion films, reduces in extension

Diagnosis made on C1/C2 instability on flexion/extension films

Anterior widening of atlanto-dens interval of >5mm on flexion view strongly suggestive

Needs surgical stabilisation

Initially skull tractrion, then posterior stabilisation with Gallie type of fusion.

Rotary subluxation C1 on C2

Different from that in children

Usually RTAs

Produces torticollis and decreased ROM

Open mouth odontoid views – “wink” sign – overriding of C1C2 joint on 1 side and normal on other

Reduce closed using halo ring

Halo vest.

If closed reduction fails or late presentation, open reduction, then fusion

Dens fractures

Anderson & D’Alonzo – 3 types

Type1 – uncommon, no instability even if don’t unite

Oblique fracture through upper odontoid

Type2 – Most common

Fracture at junction of odontoid process and C2 body

36% non-union rate for displaced and undisplaced

Best treated with surgery, especially if displaced

Determine whether displacement anterior or posterior-If posterior displacement,associated fractures of C1 ring more likely-if unrecognised, reduction may be lost. Also posteriorly displaced type 2 fractures more unstable when treated with Gallie type of fusion, therefore need bone block technique.

Type3 – large cancellous base and heal in 90% without surgery

Fracture through upper body C2

Undisplaced– halo vest or cervical collar.

Halo vest for all displaced-less rigid immobilisation produces higher non-union rates

Factors important in union:

Age

Displacement ->5mm,increased non union rate

Adequacy of reduction

Type of immobilisation