Anterior calcaneal process fractures

Last revised by Assoc Prof Craig Hacking on 24 Aug 2021

Anterior calcaneal process fractures are often missed fractures of the calcaneus (up to 88% are not reported on radiographic examination of the ankle) 1 leading to non-union of bone fragments, unrecognised associated ligamentous injuries, and persistent ankle or foot pain.

Anterior process fractures are a relatively rare occurrence, accounting for only 3% of calcaneal fractures 2.

They are generally not isolated but occur in association with the following:

Plain radiography remains the primary imaging modality for assessing calcaneal trauma because the fractures of the anterior process of the calcaneus occur in precise locations with characteristic radiographic features 3.

Symptoms include nonspecific lateral ankle pain.

Two mechanisms for anterior calcaneal process fractures have been described 4:

  • the commonly recognized mechanism is an injury by flexion, inversion, and distraction of the bifurcate ligament leading to an avulsion fracture of variable size from the anterior calcaneal process
  • infrequently, impaction by eversion and dorsiflexion of the midfoot (known as the nutcracker mechanism) is observed

According to Degan et al. 5, this injury can be classified into three types:

  • type I: nondisplaced avulsion fractures with no calcaneocuboid joint involvement
  • type II: displaced fractures but still no calcaneocuboid joint involvement
  • type III: displaced fractures with calcaneocuboid joint involvement

There are no specific guidelines for the management of these injuries due to the rarity of its presentation. Typically, type I and type II fractures can be managed with plaster cast immobilization with surgery intended for symptomatic patients only; conversely, type III fractures are managed with open reduction - internal fixation (ORIF) as they have a higher rate of malunion/non-union 5.

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Cases and figures

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