Absence of the medial malleolus. A case report with a 20-year follow-up study.

This may be the second case report of the absence of the medial malleolus in the orthopedic literature. A six-year-old girl had an open fracture with a loss of the medial malleolus. During the 20-year follow-up study, she had no instability of the ankle, as in the first report, but after time she developed degenerative arthritis in the tibiotalar articulation.