Abstract: An artificial knee joint for surgical implantation into a knee comprises at least one femoral member of hard plastic material and at least one tibial member having a highly polished metal upper surface. The femoral member is received in a groove cut in the condyle of the femur, and its rear end face, constituting the inferior surface of the femoral member, bears against the upper surface of the tibial member. The inferior surface is arcuate polycentered in the sagittal plane and arcuate in the coronal plane. The superior surface of the femoral member has three different planar portions angularly disposed to one another, for load bearing purposes in three different angles of flexion of the knee.