Abstract From 1980 to 1985, 21 cases of free transplantation of fibula were performed. There were 6 children in this series, and 4 children were followed up for 9 to 12 years (average 10 years). The Xray showed that distal epiphysis of tibia had a normal width at the medial side and gradully tapered toward the lateral side in a "wedgeshaped" apperance. The articular space of the tibiotalar joint inclined to the fibularside. The hight of the talus was higher laterally, leading to eversion deformity of the ankle joint. The medial and lateral malleoli were smaller than normal, and thus the ankle joint mortise became shallow. The trabeculae of the tibia were irregularly arranged. The lateral cortex of the tibia was thicker than that of the medial one. In one case, the bone density of the lateral side of the "wedgeshaped" epiphysis had increased as high as that ofthe cortex with disappearance of trabeculae. The biomechanics of fibular boneand the mechanism of development of disturbance of ankle joint in childhood were analyzed. Close attention should be paid to this disturbance.