sentences:  The femur cap of the hip resurfacing devices does not require the femur bone be cut off; instead the top of the femoral head is shaped to closely fit the underside of the cap.Both hip resurfacing and hip replacement require that a cup is placed in the acetabulum of the hip socket.The main advantage of the hip resurfacing surgery is that when a revision is required, there is still an intact femur bone left for a THR stem.