Patients who suffer from hip pain and immobility caused by osteoarthritis and rheumatoid arthritis have an option of hip joint replacement surgery or hip joint arthroplasty in which a diseased and/or damaged hip joint is replaced with a prosthetic hip joint. In a typical hip joint arthroplasty, a proximal portion of the femur is resected and a distal portion of the acetabulum is milled. A prosthetic hip cup is attached to the acetabulum and a hip stem is attached to the femur.
Typical prosthetic hip cups include a shell or cup that is secured to milled portion of the acetabulum by bone cement, fasteners and/or features on the cup surface and a bearing or liner which includes a convex outer periphery that is secured to a concave inner periphery of the cup. Typically the liner is secured to the cup by fixed barbs on the convex outer periphery of the liner that fit into a circumferential groove positioned in the concave inner periphery of the cup. The liner, typically made of polyethylene, is pressed into the cup, typically made of metal, with the aid of a rubber mallet. During installation the barbs are deformed to pass the lip of the cup and then enter the groove of the cup. The force necessary to deform the barbs limits their size which in turn limits the securing strength of the liner to the cup. Occasionally the liner may need to be removed from the cup in situa on a patient. To remove the liner from the cup, a tool is forced between the convex outer periphery of the liner and the concave inner periphery of the cup, to pry the liner from the cup. During this removal, the barbs are again deformed to pass the lip of the cup. The force necessary to deform the barbs and the difficulty of forcing the tool between the cup and the liner makes removal of the liner from the cup in situa difficult. Therefore, it would be advantageous to provide an improved hip prosthesis.
USPTO Backgrounds
USPTO Backgrounds