Prosthesis

A prosthesis for implantation in a bone, the prosthesis comprising:

• a collar having a first surface and a second surface generally on an opposite side of the collar for engaging the bone and transferring forces to the bone,
• a neck extending outwardly from the first surface and adapted to receive a ball thereon, and
• a stem extending outwardly from the second surface of the collar for reception in the bone,
• the second surface of the collar being shaped to promote force transmitting engagement of the second surface with the bone over at least a substantial portion of the second surface, to limit engagement of the second surface with the bone at an area of stress concentration in the second surface, and to inhibit line contact between the second surface and the bone.

A femoral prosthesis for implantation in a femur, the prosthesis comprising:

• a collar having a first surface and a second surface generally on an opposite side of the collar for engaging the femur and transferring forces to the femur,
• a neck extending outwardly from the first surface and adapted to receive a ball thereon, and
• a stem extending outwardly from the second surface of the collar for reception in the femur,
• the second surface of the collar including a recess adjacent to the stem to promote force transmitting engagement of the second surface with the femur over at least a substantial portion of the second surface and to inhibit contact with the femur generally at a location where the stem intersects the collar to thereby inhibit bone resorption.

A femoral prosthesis for implantation in a femur having a femoral neck and a resected portion, the prosthesis comprising:

• a collar having a first surface, a second surface generally on an opposite side of the collar for engaging the femoral neck and a laterally outwardly facing surface extending generally perpendicular to the first surface and the second surface,
• a neck extending outwardly from the first surface and adapted to receive a ball thereon, and
• a stem extending outwardly from the second surface of the collar for reception in the femur, the stem defining a longitudinal axis of the prosthesis,
• the laterally outwardly facing surface being adapted to at least partially engage the resected portion upon implantation in the femur, being formed to promote bone ingrowth and having a partial cylindrical shape generally complementary to the resected portion to thereby inhibit movement about axes perpendicular to the longitudinal axis upon implantation in the femur.

A prosthesis for implantation in a bone, the prosthesis comprising:

• a collar having a first surface and a second surface generally on an opposite side of the collar for engaging the bone and transferring forces to the bone,
• a neck extending outwardly from the first surface and adapted to receive a ball thereon, and
• a stem extending outwardly from the second surface of the collar for reception in the bone,
• the second surface of the collar being shaped to inhibit contact with the bone generally at a location where the stem intersects the collar.

A prosthesis for implantation in a bone, the prosthesis comprising:

• a collar having a first surface and a second surface generally on an opposite side of the collar for engaging the bone and transferring forces to the bone,
• a neck extending outwardly from the first surface and adapted to receive a ball thereon, and
• a stem extending outwardly from the second surface of the collar for reception in the bone, the stem being configured for transosseous implantation in which the stem enters the femur generally at one side thereof, crosses a medullary canal and enters cortical bone on an opposite side of the femur,
• the second surface of the collar being shaped to promote force transmitting engagement of the second surface with the bone over at least a substantial portion of the second surface, to limit engagement of the second surface with the bone at an area of stress concentration in the second surface, and to inhibit line contact between the second surface and the bone.