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
