Knee joint prosthesis

Claim 1

A knee joint prosthesis comprising a tibial component; a tibial component insert; and a femoral component; said tibial component comprising an anchoring stem portion, one end of said stem portion adapted to the received in a longitudinal bore in a patient's tibia, the other end of said stem portion being integral with a table, the top surface of which is generally normal to the stem portion and having lateral edge flanges. said tibial component insert comprising a plate shaped to be received on the tibial component table in locking engagement with the table edge flanges and the upper surface thereof having a centrally positioned spheroidal depression surrounded by a plane surface; said femoral component comprising a stem, one end of said stem adapted to be received in a longitudinal bore in a patient's femur, the other end of said stem being integral with a depending generally spheroidal surface having generally the same radius as the radius of the spheroidal depression in said insert, said spheroidal surface having lateral shoulders each of which has a flat surface which engages the plane surface of the insert when the stems of the tibial and femoral components are in longitudinal alignment and a generally cylindrical surface having a radius of curvature about the axis of pivotal motion of the spheroidal surface with the spheroidal depression to permit rearward swing motion of the tibial component relative to the femoral component and relative axial rotation of said components.