Cervical fractures

Assessment of cervical cord injuries

Physical Exam

  • Assess for associated injury
  • BP decreases in quadriplegia (Neurogenic shock), due to
    • Disruption of sympathetic outflow
    • Unopposed vagal tone
  • Do not fluid overload
  • Bradycardia / arrhythmias may be present
  • May need tracheostomy if either :
    • Vital capacity is less than 20% predicted
    • Vital capacity is less than 1000 cc

Plain X-Ray

  • Direct evidence of instability
    • Increased angulation between spinous processes > 11° than in adjacent segments
    • Anterior / posterior translation of the vertebral bodies > 3.5 mm
    • Segmental disc space widening on lateral X-Ray
    • Facet joint widening
    • Malalignment of spinous processes on AP view
    • Rotation of the facets on lateral view
    • Tilt of vertebral body on AP view
  • Findings suggestive of unstable injuries
    • Increased retropharyngeal space
      • Anterior to C3 : normal < 3 mm
      • C4 and below : normal varies 8-10 mm
    • Minimal compression fracture of anterior vertebral bodies
    • Avulsion fracture at or near insertion of spinal ligaments
    • Nondisplaced fracture lines

Tomography

  • Good visualisation of posterior elements
  • Helpful for diagnosis of dens fracture

CT

  • Assesses bony encroachment on canal
  • Best method for accurate bone definition

MRI

  • Evaluates neural elements
  • Disc disruption
  • Ligamentous integrity

Stress X-Rays

  • Flexion-extension lateral view
  • Contraindicated in altered state of consciousness

The 3-column cervical spine

  • Denis first described the 3 column spine for thoracolumbar fractures
  • This 3 column concept has been extended to the cervical spine by Allen
  • Each cervical motion segment can be divided into :
    • Anterior
      • Resists compression by vertebral body centrum, anterior disc
      • Resists tension by anterior annulus, anterior longitudinal ligament
    • Middle
      • Resist compression by posterior vertebral body and the 2 unco-vertebral joints
      • There is no significant disc material in the middle column
      • Resists tension by posterior annulus, posterior longitudinal ligament
    • Posterior
      • Resists compression by R+L facet joints and lateral masses
      • Resists tension by facet joint capsules, interspinous ligaments

Unstable Cervical Injuries

  • Atlanto-occipital joint translation > 1 mm
  • Apex of dens to basion > 5 mm
  • Anterior translation of vertebrae > 3.5 mm
  • Flexion at any one level of > 11
  • Facet joints subluxation of > 50%
  • Traumatic rupture of transverse (cruciate) ligament considered, if the atlanto-dens interval is
    • > 3 mm in an adult
    • > 5 mm in children
  • Jefferson fracture with lateral shift of the lateral masses of C1 on C2 of > 7 mm implies division of the transverse ligament allowing the two halves to separate
  • Retropharyngeal soft tissue should not be
    • > 3 mm at C3
    • > width of the vertebral bodies below the level of C4/C5
  • Unilateral facet dislocation classically leads to anterior subluxation of up to 25%, whereas bilateral dislocation results in anterior subluxation of at least 50%

Atlanto- Occipital Dislocation

  • Mechanism : hyperextension and distraction
  • The basion to posterior arch of C1 distance is < opisthion to anterior arch C1; if this is reversed, dislocation has occurred
  • Treatment
    • Often fatal
    • If patient has survived, avoid traction
    • Definitive treatment is fusion of occiput to C1

Transverse Ligament Rupture

  • Transverse ligament is the main restraint to anterior motion of C1
  • Normal distance between anterior ring of atlas and dens is < 3 mm
  • Injuries may be
    • Isolated
    • Associated with fractured atlas
    • Associated with atlanto-axial subluxation
  • Mechanism : flexion
  • Treatment
    • If there is bony avulsion, immobilise in SOMI until healed
    • Check flexion-extension views to assess transverse ligament competency
    • If there is midsubstance tear, perform primary atlanto-axial fusion

Atlanto-axial Rotatory Subluxation

  • Mechanism
    • Spontaneous
    • Traumatic
  • Presents with
    • Neck pain
    • Occipital neuralgia
    • Vertebrobasilar insufficiency symptoms
  • X-Ray
    • Odontoid view shows rotator malalignment
    • AP view shows C2 spine rotated off midline
  • CT 
    • Perform in R+L rotation
    • If C1 fails to reposition :
      • There is a fixed deformity
      • The dens separates from the anterior arch of C1 with increased rotation
  • Classification : based on Atlanto-dental interval
    • Type I : < 3 mm indicates intact transverse ligament
    • Type II : 3-5 mm
      • Failed transverse ligament
      • Intact alar ligaments
    • Type III : > 5 mm indicates both transverse ligament and alar ligament have failed
    • Type IV : Complete posterior dislocation of atlas
  • Treatment
    • All symptomatic subluxations should be reduced through light weight skeletal traction
    • If transverse ligament is insufficient, fuse C1 to C2 (types 2,3,4) after reduction

Atlas Fracture

  • Mechanism
    • Axial compression leads to forced widening of ring
    • Hyperextension causes posterior arch fracture
  • Classification
    • Stable fractures
      • Simple arch fracture
      • Nondisplaced lateral mass fracture
      • Fracture of TP
    • Unstable fractures
      • Combined overlap > 7 mm in odontoid view
      • Transverse ligament is insufficient
  • Treatment
    • Stable fracture : hard collar for 8 weeks
    • Unstable fracture : immobilise in SOMI / halo for 8 weeks

Odontoid Fracture

  • Classification: (Anderson & Alonzo)
    • Type I : Avulsion of the tip (avulsion fracture of alar ligament)
    • Type II : Waist fracture (junction of dens with body of axis)
      • 50% heal with immobilisation
      • Some series have reported 20 – 80% non-union rate
      • Increased risk of non union if
        • Initial displacement > 5 mm
        • Initial angulation >10 degrees
        • Posterior vs. anterior displacement
        • Age greater than 50 years 
        • Treatment with prolonged traction
        • No halo
    • Type III : Fracture into body of C2
  • Treatment
    • Type I : Stable
    • Type II : If high risk for non-union : SOMI for 8 weeks
    • Type III
      • High risk for non-union, if treated with hard collar alone
      • SOMI for 8 weeks 

Traumatic Spondylolisthesis of C2

  • Classification
    • Type I
      • No angulation
      • Up to 3 mm of anterior translation
      • Stable
    • Type II
      • Angulation > 10 degrees
      • Anterior translation > 3 mm
    • Type III
      • Very unstable
      • Severe angulation / displacement
      • Dislocation of one or both C2-C3 facets
  • Treatment
  • Type I : Hard collar for 8 weeks
  • Type II : SOMI for 8 weeks
  • Type III :
    • CR of dislocated facets may not be possible
    • May need ORIF with fusion

References