Anatomy

Denis proposed the concept of 3 column spine :

  • Anterior  column
    • ALL
    • Anterior vertebral body
    • Anterior annulus
  • Middle column
    • PLL
    • Posterior vertebral body
    • Posterior annulus
  • Posterior column
    • Osseous neural arch
    • Pedicles
    • Facet joints
    • Ligaments
      • Ligamentum flavum
      • Interspinous
      • Supraspinous

Pathogenesis

The columns can fail individually or in combination by 4 basic mechanisms of injury

  • Compression
    • Injures the anterior column, due to anterior or lateral flexion
    • Middle column remains intact
    • Posterior column is usually intact, but may fail in tension
  • Distraction
  • Rotation
  • Shear

Clinical Presentation

History

  • Nature of incident 
  • Change in LOC
  • Neurological symptoms

Examination

  • Check for head / pectoral girdle injury
    • Head control
    • Check for tenderness over head and back 
    • Any limitation of movement of the patient’s head to either side
  • Spine
    • Local haematoma
    • Vertebral tenderness
    • Step in spine
  • Limbs
    • Voluntary movement of all 4 limbs
    • Sensory exam
    • Muscle force
    • Reflexes
  • Priapism
  • Sensory / motor exam
    • Examine sequential nerve roots
    • Determine a root lesion / cord lesion
    • Spinal shock : total absence of spinal neural activity
      • Due to functional apraxia of neural circuits, rather than anatomical damage
      • Usually resolves in 24 hour
      • If spinal shock is present a complete lesion cannot be diagnosed with certainty
      • Its presence can be shown by bulbocavernosus reflex
      • Bulbocavernosus reflex :
        • Stimulation causes reflex contraction of the anal sphincter about the gloved finger
        • Stimulants are
          • Squeeze on the glans penis
          • Tap on the mons pubis
          • Tug on the catheter stimulating the trigone of the bladder
      • If the bulbocavernosus has not returned in 24 hours, its absence confirms complete lesion, as spinal shock resolves within 24 hours
    • Determine completeness / incompleteness of lesion
      • Inability of the patient to feel the finger in the rectum confirms a complete lesion
      • If sphincter doesn’t contract voluntarily about the finger complete motor paralysis is confirmed
  • Determine the sensory level
  • Examine distally for any evidence of sparing
  • Sacral sparing
    • Indicates preservation of the lateral columns
    • Recovery of lost muscle function is quite likely

Imaging and Diagnostic Studies

X-Ray

  • Compression fracture
    • Decreased height of anterior vertebral body
    • Posterior body height normal
    • Further subdivided into :
      • Stable
        • Anterior compression < 40% of posterior body height
        • Clinically stable, neurologic loss is rare
      • Unstable
        • Loss of vertebral height is > 50%
        • Angulation > 20 degrees
        • Multiple adjacent compression fractures
  • Burst fracture
    • Essential feature is disruption of the middle column
    • If posterior elements are involved, there is 50% chance of neurologic injury
    • Varying degrees of retropulsion into the neural canal
    • Spreading of posterior elements
  • Flexion-distraction (Seatbelt type) fracture
    • Neurologic deficit is rare
    • Widening of interspinous distance
    • Column involvement
      • Anterior : no damage or compression
      • Middle : distraction
      • Posterior : distraction
  • Fracture-dislocation
    • Associated with severe neurologic damage
    • All 3 columns fail under compression, tension, rotation or shear
    • Subluxation / dislocation may be seen

CT Scan

  • Better visualisation of bony particles and delineation of complex fracture patterns
  • Shows the degree of canal compromise

MRI

  • Useful for ruling out soft tissue (ligamentous) injuries
  • Clearly visualises neural components and potential damage / compression effect

Classification

  • Compression fracture : 4 types
    • Involvement of both endplates
    • Superior endplate only
    • Inferior endplate only
    • Buckling of anterior cortex with both endplates intact
  • Burst fracture : 5 types
    • Fracture of both end plates seen in low lumbar region
      • Does not lead to kyphosis
      • Due to pure axial load
    • Fracture of the superior endplate
      • Seen at the thoracolumbar region
      • Due to axial load and flexion
    • Fracture of inferior endplate
      • Rare
      • Due to axial load and flexion
    • Burst rotation due to axial load and rotation
    • Burst lateral flexion due to axial load and lateral flexion
  • Flexion-distraction (Seatbelt type) fracture : 3 types
    • Purely bony (Chance fracture)
    • Purely ligamentous
    • Mixed
  • Fracture-dislocation : 3 types
    • Flexion-rotation
      • Posterior and middle columns fail under tension and rotation
      • Anterior column fails under compression and rotation
    • Shear
      • May be PA shear, with the vertebra above shearing forward on the one below
      • May be AP shear, with vertebra above shearing back on the one below
    • Flexion distraction
      • Resembles the seatbelt type of injury
      • The entire annulus is torn, allowing the vertebra above to sublux / dislocate on the one below

Treatment

Compression fracture

  • If stable
    • Symptomatic relief
    • Hyperextension exercises
    • Avoid compression loads for 3 months
  • If unstable
    • Mobilise as above
    • Monitor for progression of deformity
    • If progresses, perform ORIF
  • A vertebral compression fracture wedged more than 40% of normal height usually needs a posterior stabilisation procedure, as these fractures may compress further, even after 3 months

Burst fracture

  • Non-operative
    • Reserved for patients with no neural involvement
    • Good long term results with no neurologic deterioration and little residual back pain
  • Operative
    • Indications :
      • Kyphosis > 40 degrees; associated with progression of deformity
      • Neural injury
      • Loss of vertebral height > 50%
      • Angulation > 20 degrees
      • Canal compromise > 40%
    • Posterior decompression and instrumentation : obtains adequate canal decompression in 75% alone
    • Anterior decompression : indicated when post-operative CT shows residual canal compromise > 25% plus incomplete spinal lesion

Flexion-distraction fracture

  • Posterior decompression and stabilisation

Fracture-dislocation

  • Realign the spinal column
  • Stabilise spine to allow early mobilisation
  • Early mobilisation
    • Reduces morbidity
    • Reduces mortality
    • Allows earlier return to the community

Timing of surgery

  • Emergency intervention indicated if there is :
    • Cauda equina syndrome
    • Progression of neurologic deficit
  • For all others, ORIF when medical and surgical conditions is optimal
  • No evidence that early decompression enhances results or that delay compromises results
  • External spinal support probably has no value and should not be used

Outcome

  • 25% have no residual symptoms
  • 55% have mild discomfort, but no disability
  • 20% have severe symptoms leading to disability