A good understanding of normal appearances and a systematic approach are required for assessment of the T-spine and the L-spine (see previous page).
Injury classification
The 'three column model' (see previous page) can be used to form a basic classification of thoracolumbar spinal injuries (see box). This page also discusses osteoporotic fractures, and fractures of the transverse and spinous processes.
Spinal injuries which are seen to disrupt structures of 2 or more columns are considered 'unstable'. If the middle column is seen to be injured it is usually taken that another column must be injured even if no anterior or posterior column fracture is visible.
If an injury is seen which disrupts 1 column then a second fracture is also present in approximately 15% of cases. If a 2 column injury is seen then likelihood of a second fracture increases to 40%.
RULE: If you see one fracture - check for another
1 Column - Anterior compression injury
Anterior compression injury is a common fracture pattern which results from traumatic hyper-flexion with compression. Although considered 'stable' the greater the loss of height anteriorly the greater the risk of middle column involvement. X-ray may underestimate the extent of injury and so if there has been high risk injury or other suspicion of instability then CT should be considered.
Loss of vertebral body height can be seen but the fracture is not visible on this view
2 column - 'Burst' fracture
'Burst' fractures result from high force vertical compression trauma. Posterior displacement of vertebral body fracture fragments into the spinal canal leads to a high risk of spinal cord or nerve root damage.
The T12 vertebral body has lost height and the adjacent rib is fractured
The interpedicular width should increase gradually from superior to inferior (white dotted lines)
At the level of the fracture there is sudden widening of the interpedicular width - Note: This sign is not always visible in burst fractures
The normal paravertebral soft tissues (asterisks) is widened by a paraspinal haematoma at the level of the fracture
3 column - Flexion-distraction fracture
Flexion-distraction injuries are associated with high force deceleration injuries and are most common at the thoracolumbar junction. Also known as 'Chance-type' fractures (after the radiologist who first described them) these injuries are unstable and carry a high risk of neurological deficit and abdominal organ injury.
The 'fracture' line may pass through the disc rather than the vertebral body, and so there may not be visible bone injury of the anterior column.
The interspinous distance is increased at the level of the fracture
In this case the pedicles and transverse processes have been split horizontally
Osteoporotic 'insufficiency' injuries
Thoracolumbar spine injuries are very common in patients with osteoporosis. Common fracture patterns include 'wedge' injuries and 'biconcave' fractures.
Note the low density (blackness) of the vertebral bodies
Compression injuries of both the superior and inferior endplates of the vertebral body have resulted in a biconcave appearance
The vertebral body has also lost height anteriorly - compare to level below (superimposed dotted line)
Other fractures
Spinal fractures may be isolated to the spinous or transverse processes.
Transverse process fractures are often not visible with X-ray - (only seen on CT), and are often associated with other fractures - so if seen are a prompt to recheck all X-ray images available and consider further imaging. Transverse process fractures are also associated with injury to the kidneys.
