Introduction to Trauma X-ray
Fracture displacement

Key points

  • Describe fracture displacement in terms of the abnormal position of the distal fragment in relation to the proximal bone

Displacement of fractures is defined in terms of the abnormal position of the distal fracture fragment in relation to the proximal bone. Types of fracture displacement include - angulation, rotation, change of bone length, and loss of alignment.

The severity and nature of displacement are key factors when considering fracture management.

Loss of alignment - 'displacement'

The term 'displacement' is often used as a specific term to describe loss of bone alignment along its long axis. Loss of alignment, or displacement, is usually accompanied by some degree of angulation, rotation or change in bone length.

Shortening

Proximal migration of the distal fracture component results in shortening of the overall bone length. An oblique fracture is more readily shortened than a transverse fracture, which would need to be fully 'off-ended' before it can shorten.

Displacement and shortening

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Displacement and shortening

  • The fracture on the left is displaced without shortening
  • The fracture on the right is both displaced and shortened
  • The roll-over image shows the normal bone position

Angulation

To describe fracture angulation the direction of the distal bone and degree of angulation in relation to the proximal bone should be stated.

Medial angulation can be termed 'varus', and lateral angulation can be termed 'valgus'.

Rotation

Rotation of a long bone fracture may be internal or external.

Angulation and rotation

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Angulation and rotation

  • The fracture on the left has resulted in angulation of the distal component
  • The fracture on the right has resulted in rotation of the distal component
  • The roll-over image shows the normal bone position

Distraction and impaction

A fracture resulting in increased overall bone length, is due to distraction (widening) of the bone components.

If there is shortening of bone without loss of alignment, the fracture is impacted. The bone substance of each component is driven into the other.

Distraction and impaction

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Distraction and impaction

  • The left roll over image shows fracture widening or 'distraction'
  • The right roll over image shows a line of increased density due to fracture impaction
  • The roll-over image shows the normal bone position

Displacement combinations

Most displaced fractures result in more than one type of displacement.

Displacement combination example - Humerus

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Displacement combination

  • Oblique fracture of the humerus mid-shaft
  • Lateral displacement
  • Shortening
  • Valgus angulation
  • Internal rotation