Patent ID: 7160330

Claim:
In a knee prosthesis for implantation to replace a natural knee joint and emulate movements of the natural knee joint during articulation, the natural knee joint having a lateral compartment and a medial compartment, the knee prosthesis having a femoral component including at least one condylar element with a condylar surface having a transverse axis of rotation, and a tibial component including at least one articular surface for engagement with the condylar surface of the femoral component in one of the lateral and medial compartments for articulation of the knee prosthesis through flexion about the transverse axis of rotation: an improvement wherein the condylar surface and the articular surface are configured for enabling engagement between the condylar surface and the articular surface along a generally arcuate track during articulation about the transverse axis of rotation for flexion within at least a prescribed range of flexion extending up to a predetermined degree of flexion while enabling relative rotational movement between the femoral component and the tibial component to take place about a longitudinal axis of rotation, the generally arcuate track having a center of curvature placed in a generally coronal plane, and the longitudinal axis of rotation being located essentially in a generally sagittal plane intersecting the coronal plane at an intersection, and being spaced a predetermined distance from the intersection such that upon flexion within the prescribed range of flexion the transverse axis of rotation will be maintained essentially in a generally medial-lateral longitudinal plane located in close proximity with the coronal plane, with the longitudinal plane spaced from the longitudinal axis of rotation essentially by the predetermined distance and movable about the longitudinal axis of rotation in response to relative rotational displacement between the femoral component and the tibial component, to intersect the coronal plane at angles corresponding to the relative rotational displacement during if flexion within the prescribed range of flexion.