The ankle joint is formed by the tibia, fibula, and talus. The tibia and fibula grow at different rates, but despite rather complex growth patterns, after the age of ten years, the ankle joint normally remains horizontal. There is thus a very delicate balance and any growth disturbance may affect the normal horizontal status of the joint. Removing a segment of fibula with resultant non-union will produce a valgus deformity if done in a young child. If non-union of the fibula occurs in the young child, a bone-grafting procedure should be done to restore a stable fibula. Such a graft maintains length and may even stimulate growth of the fibula. If a bone graft to restore the continuity of the bone does not seem feasible, then grafting the upper end of the lower fragment of the fibula to the distal tibial metaphysis will stabilize the distal end of the fibula so that no further valgus will occur. However, existing valgus deformity will not be corrected by this procedure. The horizontal status of the ankle joint can be restored by stapling the medial side of the distal tibial epiphysis if sufficient growth potential remains. If growth is almost completed, osteotomy of the tibia and fibula is the best solution and should be done by the procedure illustrated in Figure 6-B to minimize deformity.

The degree of valgus depends largely on how many years of growth are left. If the fibula is resected after the age of twelve (and probably even after the age of ten) there appears to be no danger of an excessive valgus deformity developing.