The bone below the pelvis is the femur, which is the bone of the thigh area and the strongest long tube bone in the body. At the proximal end of the femur is the head of the femur, which together with the acetabulum in the pelvic area forms the hip joint. The part of the femoral head that extends backward is called the femoral neck, which is relatively weak and prone to fracture after trauma, and the fracture will easily lead to the destruction of blood flow in the femoral head area, causing necrosis of the femoral head. The part of the femoral neck that extends backward is called the intertrochanteric area. There is a femoral spur between the femur, which is the part of the femur that has the largest extension of strength, and also the part of the trunk and lower limbs where the strength is concentrated. Therefore, the elderly are prone to fracture of the intertrochanteric femur after trauma. The largest extension of the intertrochanteric femur is the femoral stem, and the distal femur has the femoral condyles, which together with the tibial plateau form the knee joint.