Abnormal Bone Fragments near Malleolus

Round-shaped bone fragments of either malleolus were examined on 293 radiographs of the ankle joints for 3 years. We found 15 fragments in the lateral malleolus and 8 fragments in the medial ones. These fragments were differentiated according to the shape of fragment, clinical course, stress roentgenography and operative findings. The fragments in the lateral malleolus were classified into (1) fresh, (2) old avulsion fractures of the fibular ligament of the ankle and (3) Os subfibulare. The fragment in the medial malleolus were classified into (1) pseudarthrosis of the medial malleolus, (2) Os subtibiale and (3) extra center of ossification for the medial malleolus.