Occult malunion of ankle fractures--a cause of disability in the athlete.

Occult malunion of the ankle is a condition in which the talus appears to be situated in its normal position on standard radiographs. The lateral malleolus, however, is incompletely reduced. This causes a subluxation of the distal tibiofibular joint and some degree of talar instability. The malunion of the lateral malleolus is best visualized on lateral radiographs or tomograms. This condition can be corrected by osteotomizing the lateral malleolus and restoring the integrity of the distal tibiofibular joint by pulling the lateral malleolus distally and internally rotating it.