Bone graft without blood vessels 1. Classification according to bone graft material: a. According to the different sources of bone graft material, they are divided into: autologous bone graft, allogeneic bone graft and artificial bone graft; b. According to the different materials taken from bone tissue, they can be divided into cancellous bone graft or cortical bone graft; 2. The above bone graft material can be implanted into the femur through different paths around the femoral head. There are four main routes to the femoral head: a. via the greater trochanter; b. via the femoral neck; c. via the craniocervical junction; d. via the cartilage of the femoral articular surface. Except for the a. path which enters the femoral head through the greater trochanter and does not enter the joint, the other three b. c. d. paths require incision of the hip joint and enter the femoral head through the joint. Therefore, the latter three routes may affect the postoperative joint function and may even destroy the original blood flow of the femoral head.