Trauma X-ray - Lower limb
Calcaneus

Key points

  • Severe calcaneus fractures often result in loss of Bohler's angle
  • Calcaneus fracture often result from falling from height but may be due to more trivial injury

Falling from height can lead to severe calcaneal fractures, which may be accompanied by axial loading fractures of the spine.

Calcaneal fractures due to a fall from height are often comminuted and intra-articular. The extent of injury is easily underestimated by X-ray appearances.

Low impact trauma or twisting injuries of the calcaneus can result in subtle X-ray changes.

Standard views

Lateral and axial.

Bohler's angle

Severe injury may result in flattening of the calcaneus. This results in a reduction of 'Bohler's angle'.

On a lateral view this angle is formed by the intersection of two lines. The first line is drawn from (1) - the upper edge of the calcaneal body posteriorly to (2) - the upper edge of the posterior articular facet of the calcaneus at the subtalar joint. From this point another line is drawn to (3) - the upper edge of the anterior process of the calcaneus.

Bohler's angle is normally between 28-40 degrees.

Normal calcaneus - Lateral

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Normal calcaneus - Lateral

  • Bohler's angle is normal (39° in this case)

Normal calcaneus - Axial

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Normal calcaneus - Axial

  • The cortex of the calcaneus is intact

Calcaneal fracture - Lateral view

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Calcaneal fracture - Lateral view

  • Flattening of Bohler's angle (18° in this case)
  • Depression of the articular surface of the posterior subtalar joint (red line) from its normal position (green line)
  • Fracture lines can be seen passing through the calcaneus

Calcaneal fracture - Axial view

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Calcaneal fracture - Axial view

  • Loss of smooth cortical edge (orange line)