Northwestern University Feinberg School of Medicine

Orthopedic Teaching

Ankle Case 3 Background

Malleolar Fractures


Malleolar fractures are commonly encountered in emergency medicine. They typically result from twisting injuries.

  • Two-thirds are isolated to the lateral malleolus (distal fibula)
  • One quarter are bimalleolar (involving the medial malleolus)
  • 7% are trimalleolar (lateral and medial malleolus plus posterior distal tibia)
  • 2% are open fractures



The primary issue when assessing these injuries is ankle stability. Fractures are less stable when:

  • fibula fractures are at or proximal to the tibia-fibula syndesmosis
  • medial and lateral ankle injury is present.