Free vascularized fibular grafting is a good biological reconstruction option for young and active patients with femoral head avascular necrosis (osteonecrosis) at pre-collapse stage. Free vascularized fibular grafting plays a significant role in preventing or minimizing development of femoral head collapse by decreasing the interosseous pressure and removal of the necrotic bone. It is believed that free vascularized fibular grafting provides support for chondral surface with a viable cortical bone, and improves the revascularization of the femoral head. In patients with osteonecrosis of the femoral head, vascularized fibula graft slows the course of the disease and delays or eliminates the need for hip prostheses.