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^o
• 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