Hip replacement. Close-up of an artificial hip socket in place during hip replacement surgery. Hip replacements are usually performed in elderly patients whose joints have eroded and are stiff and painful due to osteoarthritis. The old hip is replaced by cutting away the top of the femur (thigh bone). The pelvic bone is then hollowed out to insert the artificial socket, which is attached using special cement. An artificial ball is then attached to the head of the femur, and this is inserted into the socket to complete the procedure.