A 31-Year-Old with Pain After Twisting His Ankle

Differential Diagnosis

• Calcaneus accessorius
• Fracture, anterior process of the calcaneus
• Fracture, dorsal navicular
• Fracture, tuberosity of the calcaneus

Diagnosis

This patient was diagnosed with an avulsion fracture of the anterior process of the calcaneus (and also likely of the dorsal navicular).

Learnings and What to Look for

• An irregular crescentic bony fragment projects lateral to the foot on the AP view, corresponding to an avulsion of the anterior process of the calcaneus on the lateral view
• These fractures are missed 88% of the time and can lead to nonunion, unrecognized associated ligamentous injuries, and persistent ankle or foot pain
• Degan classification:
  • 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

Pearls for Urgent Care Management

• Types 1 and 2 are treated with plaster casting
• Type 3 is managed with open reduction internal fixation due to higher tendency for nonunion

Acknowledgment: Images and case presented by Experity Teleradiology (www.experityhealth.com/teleradiology).