We have been performing vascularized iliac bone grafts using the superficial circumflex iliac artery (SCIA) for the treatment of femoral head osteonecrosis at Toho University since 1982. The purpose of this study was to research the mechanical stress in the femoral head and the stiffness of grafted iliac bone. We made three types of theoretical femoral head models. The first was of the normal femoral head. The second was of the necrotic femoral head. The third was of the necrotic femoral head with grafted iliac bone. All models were analyzed by three-dimension finite element analysis. The normal femoral head model showed regular mechanical stress, but the necrotic femoral head showed irregular mechanical stress, under analysis. The necrotic femoral head with grafted iliac bone showed high mechanical stress at the grafted iliac bone. As a result of this, the total mechanical strain in the femoral head was less than for the normal femoral head. This analysis seems to show that the iliac bone grafted, by our method, could bear mechanical load on the femoral head, and has sufficient stiffness.
