Trauma X-ray - Axial skeleton Thoracolumbar spine - Normal anatomy
Key points
Use a systematic approach
Correlate radiological findings with the clinical features
If 'instability' is suspected then further imaging with CT should be considered
If you see one fracture - check for another
Thoracolumbar spine - Systematic approach
Coverage - Adequate?
Alignment - Anterior/Posterior/Lateral
Bones - Cortical outline/Vertebral body height
Spacing - Discs/Spinous processes/Pedicles
Soft tissues - Paravertebral
Edge of image
In the context of trauma similar principles apply to imaging both the Thoracic spine (T-spine) and the Lumbar spine (L-spine). The plain X-ray anatomy and appearances of injuries to both these areas are discussed together.
Incorrect management of patients with spinal injury may cause or worsen neurological deficit. Therefore, patients with suspected spinal injury should be managed by experienced clinicians in accordance with local and national clinical guidelines. Imaging should not delay resuscitation.
Further imaging with CT or MRI (not discussed) is often appropriate in the context of a high risk injury, neurological deficit, limited clinical examination, or where there are unclear X-ray findings.
Good views of the T-spine and L-spine are difficult to achieve in the context of trauma. Clinical assessment is also often limited by distracting injuries or reduced consciousness. The clinico-radiological assessment of suspected T-spine or L-spine injuries therefore depends on careful consideration of both the clinical and radiological findings.
Thoracic spine - Standard views
AP and Lateral - Assess both views systematically (see box).
Images of the thoracic and lumbar spine are often large and the bones should be scrutinised in detail (see images below).
Note: The upper T-spine may not be visible on the lateral view - if injury is suspected here then a swimmer's view may be helpful - (see Cervical spine - Normal).
Thoracic spine systematic approach - Lateral and AP
Coverage - The whole spine is visible on both views
Alignment - Follow the corners of the vertebral bodies from one level to the next
Bones - The vertebral bodies should gradually increase in size from top to bottom
Spacing - Disc spaces gradually increase from superior to inferior - Note: Due to magnification and spine curvature the vertebral bodies and discs at the edges of the image can appear larger than those in the centre of the image
Soft tissues - Check the paravertebral line (see AP image below)
Edge of image - Check the other structures visible
Alignment - Vertebral body alignment is assessed by carefully matching the anterior and posterior corners of the vertebral bodies with the adjacent vertebra
Bones - Gradual increase in vertebral body height from superior to inferior
Spacing - Disc spaces gradually increase in height from superior to inferior
Alignment - The vertebral bodies and spinous processes (SP) are aligned
Bones - The vertebral bodies and pedicles are intact
Other visible bony structures include the transverse processes (TP), ribs, and the costovertebral and costotransverse joints
Spacing - Each disc space is of equal height when comparing left with right. The pedicles gradually become wider apart from superior to inferior
Soft tissue - Note the normal paravertebral soft tissue which forms a straight line on the left - distinct from the aorta
Lumbar spine - Standard views
AP and Lateral
The whole L-spine should be viewed in both views.
Divergence of the X-ray beam may limit assessment of the low lumbar spine levels - a further 'coned lumbosacral view' centred at the level of the lumbosacral junction may be helpful.
Alignment - The vertebral bodies and spinous processes are aligned
Bones - The vertebral bodies and pedicles are intact
Spacing - Gradually increasing disc height from superior to inferior. The pedicles gradually become wider apart from superior to inferior - Note: The lower discs are angled away from the viewer and so are less easily assessed on this view
Check carefully for pedicle integrity and transverse process fractures
Three column model
The clinico-radiological assessment of thoracolumbar spine stability is usually performed by spinal surgeons with the help of radiologists.
A simple model commonly used for assessment of spinal stability is the 'three column' model. This states that if any 2 columns are injured then the injury is 'unstable'. This theory is an over simplification if applied to plain X-rays alone. It is important to be aware that some injuries are not visible on X-ray and that 2 and 3 column injuries may be underestimated as 1 or 2 column injuries respectively.
If spinal instability is suspected on the basis of clinical or radiological grounds then further imaging with CT should be considered.
