Osteochondrosis of the accessory ossification centre of the medial malleolus.

We report a case of a painful accessory ossification centre of the medial malleolus in an 11-year-old girl who was not involved in sports activities. The patient was treated conservatively, with complete clinical and radiographic healing of the medial malleolus 6 months after the first presentation. We ruled out the uncommon pathological conditions causing chronic pain in the medial malleolus during skeletal growth, such as traction apophysitis of the medial malleolus, osteochondrosis, osteochondritis or avascular necrosis of the distal tibial epiphysis. We speculate that this painful condition may be classified as an osteochondrosis of the accessory ossification centre of the medial malleolus.