Ankle Fracture

The ankle mortise is a ring, and rings fail in more than one place

The talus sits within a mortise formed by the distal tibia (medial malleolus and plafond) and fibula (lateral malleolus), held together by the syndesmosis and the medial and lateral ligament complexes, together forming a closed ring around the talus. A ring structure can rarely be broken in only one place without failing elsewhere too, either through a second fracture, such as the medial or posterior malleolus, or a ligament rupture, such as the deltoid ligament or syndesmosis. This is why an isolated, undisplaced single-malleolar fracture with an intact ring is usually stable, while a fracture combined with disruption elsewhere in the ring is not.