Three column concept of spinal fractures

Last revised by Mostafa El-Feky on 25 Dec 2022

The three-column concept of thoracolumbar spinal fractures (of Denis) forms the basis of a number of widely used thoracolumbar spinal fracture classification systems.

While the three-column concept was initially developed for classification of thoracolumbar spinal fractures, it can also be applied to the lower cervical spine 3 as the general vertebral anatomy is similar to the thoracic and lumbar vertebrae. Due to its simplicity, it is widely used in routine clinical practice and can be used in reports with the expectation that the treating clinicians will be familiar with the idea of anterior, middle and posterior columns.

The specific classification system that Francis Denis described (see below) has been superseded by more modern classifications (AO classification of thoracolumbar injuries and the thoracolumbar injury classification and severity score), yet the 3-column concept remains central to them. 

Denis divided the vertebral column into 3 vertical parallel columns based on biomechanical studies related to stability following traumatic injury. Instability occurs when injuries affect 2 contiguous columns (i.e. anterior and middle column or middle and posterior column). Obviously a 3 column injury is also unstable.

The three columns are: 

Only of historical interest, it is worth noting that in the original 1976 article 1, Denis differentiated five types of fractures A-E:

  • type A
    • fracture of both endplates without kyphosis
    • mechanism of injury: pure axial load
    • predilection site: low lumbar region
  • type B
    • fracture of the superior endplate (CT may also demonstrate a sagittal split of the lower endplate)
    • most frequent burst fracture
    • mechanism of injury: axial load and flexion
    • predilection site: thoracolumbar junction
  • type C
    • fracture of the inferior endplate
    • rare
    • mechanism of injury: probably axial load and flexion.
    • no particular site pattern could be identified
  • type D
    • burst rotation fracture
    • burst fracture with comminution of the vertebral body, large central defect on CT, loss of posterior height, an increase of the interpedicular distance, vertical fracture of the lamina, bone retropulsed into the spinal canal
    • mechanism of injury: axial load and rotation
    • predilection site: mid lumbar region
  • type E
    • burst lateral flexion fracture
    • fractured posterior wall of the vertebral body with fragment extrusion towards the side of the flexion
    • mechanism of injury: axial load and lateral flexion

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Cases and figures

  • Figure 1: illustration
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  • Figure 2: illustration
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  • Case 1: burst fracture - Denis type B
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  • Case 2: three column thoracic spine fracture
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