Norwich Image Interpretation Course

Heidi Nunn (Advanced Practice Reporting Radiographer)

The Thoracolumbar Spine

Fracture prevalence Projections Stability Classification of trauma Pathology

(hover over images to zoom, click to enlarge)

Learning outcomes
  • Assess skeletal radiographs using a systematic approach
  • Describe spinal anatomy
  • Understand the concept of stability and the 3 column concept
  • Understand mechanisms of injury and the likely fractures/dislocations which may result
  • Search for subtle injuries and understand their clinical significance
  • Understand common eponyms
  • Recognise potential ligament injuries
  • Recognise common pathological conditions seen around the spine
Fracture prevalence
  • 60-70% of thoracolumbar spine fractures in adults occur at T12, L1 and L2, with 90% of all fractures being seen between T11 and L4.

  • It is therefore important that T11/T12 is included on all trauma lumbar spine radiographs.

  • 20% of thoracolumbar fractures are seen in association with other skeletal injuries:

    Compression fracture at thoracolumbar junction + fractures of the os calcis.
    Upper thoracic spine wedge fractures + sternum fractures.


Assess on both images:

  • Height of vertebral bodies should be equal.
  • Width of intervertebral disc spaces should be uniform.
  • Continuity of superior and inferior endplates: should remain unbroken.
  • Distance between spinous process should be equal.
  • Trace the posterior elements; the pedicles, laminae, and spinous processes.
Normal lumbar spine    Normal lumbar spine
Normal lumbar spine    Normal lumbar spine

Specifically on the AP image:

  • Soft tissue signs - Widening of the paraspinal line adjacent to the left side of the thoracic spine is indicative of a haematoma resulting from a fracture:
Paraspinal haematoma T4/5 dislocation
  • Pleural cap - Refers to a paraspinous haematoma, which dissects over lung apex.
  • Inter-pedicular distance. Should become gradually wider from L1 to L5.
  • Check for an "empty" vertebral body on the AP radiograph; the posterior elements should be superimposed.
  • Transverse processes should remain intact.

Specifically on the lateral image:

  • Malalignment. Trace the anterior, posterior and spinolaminar lines. If two of these lines are disrupted, the injury is considered unstable.
  • Posterior vertebral body cortex should be slightly concave.
Significance of Injury and the concept of stability
  • The spine may be split into three "columns" for the purpose of assessment of stability:
    1. Anterior column - Involves the anterior two thirds of the vertebral body/intervertebral disc, and the anterior longitudinal ligament.
    2. Middle column - Involves the posterior aspect of the vertebral body/intervertebral disc, and the posterior longitudinal ligament.
    3. Posterior column - Involves the posterior elements - the lamina, facet joints, spinous processes, and the associated ligaments.
  • An injury to the spine is considered unstable if two of the three columns are disrupted. Generally, if the middle column is disrupted, either the anterior or posterior columns are also involved, and the injury is unstable.
  • The middle column is the fulcrum from which the spine pivots into flexion and extension. It is generally thought that the middle column remains intact, and is therefore stable, in simple flexion and extension injuries. Axial compression, distraction and rotational injuries, or a combination of these with flexion or extension, usually disrupt the middle column.
Classification of acute trauma
  • Wedge Compression Fracture:

    Forward flexion causes wedge compression deformity of the anterior vertebral body, with the normal posterior concavity of the vertebral body remaining intact. Often occurs in association with fracture to the superior endplate:

Fracture superior endplate L1    Anterior wedge compression fracture L1
(* author's own Xrays!)
  • Burst Fracture:

    Initially may appear to be an anterior wedge compression fracture, however closer inspection of the lateral view will demonstrate retropulsion of a fragment of the posterior vertebral body into the spinal canal. This may be subtle and a loss of the normal concavity of the posterior vertebral cortex may be the only indication. AP may demonstrate widening of the inter-pedicle distance, often with a sagittal fracture of the inferior half of the vertebral body. High probability of neurological deficit.

Burst fracture
Abnormal interpedicular distance due to burst fracture    Convex posterior vertebral body cortex due to burst fracture
  • Chance Fracture:

    May occur with use of lap belt during a deceleration injury. Refers to compression fracture of the vertebral body with transverse/horizontal fractures of the posterior elements:

Chance fracture    Chance fracture
  • With an increase in distraction, the AP will demonstrate an "empty" vertebral body, as the posterior elements will not be superimposed on the vertebral body. There will be an increase in the inter-spinous distance and a break in continuity of the pedicles or spinous process. Lateral will show an increase in the inter-spinous distance with horizontal fractures of the spinous process/lamina/pedicles running into the vertebral endplates.

  • Fracture-dislocation:

    The anterior and posterior vertebral lines will demonstrate malalignment, with disruption of the facets posteriorly. Occurs in association with anterior wedging of the vertebral body below, with a characteristic triangular fragment arising from the antero-superior margin. Lateral dislocations are also seen. High probability of neurological deficit:

Fracture-dislocation L2/L3    Fracture-dislocation L2/L3
  • Transverse process fracture:
  • Fractures may occur to transverse processes. These are often subtle and may only be seen through careful windowing of the image. Overlying bowel gas often obscures image detail:

Fracture left L1 transverse process. Overlying bowel gas right L1 transverse process
  • Spondylosis:

    Refers to degenerative changes of the intervertebral disc spaces, which is demonstrated by disc space narrowing, endplate sclerosis and osteophyte formation. Facet joint OA is seen posteriorly. The associated osteophytes may impinge on the nerve root foramina.

Spondylosis thoracic spine    Spondylosis thoracic spine
Spondylosis lumbar spine    Spondylosis lumbar spine
  • Spondylolysis:

    A fracture that may be acute or chronic in origin, that extends from the inferior facet across the pars interarticularis, to the superior facet (the pars interarticularis is the area of the lamina that lies within the facets). This defect may be bilateral and may lead to a spondylolisthesis. Spondylolysis is evident on an oblique radiograph by identifying the "Scotty dog":

= Transverse process
= Pedicle
= Superior facet
Front leg
= Inferior facet
Collar through neck
= Fracture

Scotty dog    Fracture pars interarticularis    Fracture pars interarticularis
  • Spondylolisthesis:

    A forward displacement of one vertebra upon another. May be due to:

    Congenital weakness of the pars interarticularis
    Degenerative facet joint disease

    May not be symptomatic, however, if severe, may cause foraminal stenosis, causing nerve root impingement. Consequently it will be treated surgically. Grade I refers to a displacement of up to 25%, and a grade II refers to malalignment of 25-50%:

Spondylolisthesis L5/S1 with pars defect
  • Paget's disease:

    The lumbar spine is often affected. There are three key features:

    Bone is expanded
    The cortex is thickened
    The trabeculae is coarse

Paget's disease L2
  • Metastatic disease:

    Primary tumours may metastasize to the vertebral bodies. May either demonstrate a "moth-eaten", permeative appearance:

Diffuse metastases    Diffuse metastases
  • or, specifically to the lumbar spine, an "ivory vertebra":

Ivory vertebra L3    Ivory vertebra L3
  • or destruction of the pedicle:
Metastasis pedicle L3    Metastasis pedicle L3
  • Abdominal aortic aneurysm:

    Attendance to casualty with back pain may be due to an abdominal aortic aneurysm. This may be demonstrated on either AP or lateral lumbar spine radiographs, if the aorta is calcified:

Abdominal aortic aneurysm    Abdominal aortic aneurysm
  • Ankylosing spondylitis

    Refers to calcification of the anterior and posterior longitudinal ligaments and intervertebral discs resulting in fusion of the spine from the sacroiliac joints up through the thoracolumbar spine to the cervical spine. This "bamboo spine" may fracture:

Ankylosing spondylitis    Ankylosing spondylitis
Ankylosing spondylitis with fracture T8/T9    Ankylosing spondylitis with fracture T8/T9
Ankylosing spondylitis    Ankylosing spondylitis


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