Prosthetic hip failure. Metal prosthetic shaft of a hip joint, removed due to severe arthritis of the attached bone. At centre right is the rounded ball of the femur thigh-bone which forms a joint with the hip. The outer cartilage (at right) has peeled away due to necrosis of the femur head. Severe arthritis, such as this, will require a complete hip replacement operation in which the whole joint including ball and socket is man-made. Prosthetic hip joints are very successful in relieving the stiffness and pain of arthritis, while increasing hip and leg movement. A failed first prosthesis is not that uncommon.