Knee prosthesis with increased balance and reduced bearing stress

Claim 1

In a knee prosthesis for replacing the natural knee, the knee prosthesis having a femoral component and a tibial component, the tibial component including a bearing member and the femoral component including at least one condylar element for confronting and engaging the bearing member to accomplish articulation of the knee prosthesis throughout a range of flexion, including a primary range of flexion between a hyperextended position and a flexed position, the femoral component and the tibial component ordinarily being aligned axially along a mechanical axis passing through the femoral head of the corresponding hip joint and the engagement between the condylar element of the femoral component and the bearing member of the tibial component ordinarily taking place at a contact area along articular surface areas of the condylar element and the bearing member, the improvement comprising: complementary medial-lateral surface profile contours extending along the articular surface areas, the medial-lateral surface profile contours having a single medial-lateral articular radius defining an arcuate profile common to the medial-lateral surface profile contours; and anterior-posterior surface profile contours along the condylar element and the bearing member, the anterior-posterior surface profile contour along the condylar element having an essentially constant anterior-posterior articular radius throughout the articular surface area of the condylar element which contacts the bearing member during articulation throughout the primary range of flexion, such that the contact area along the articular surface areas of the condylar element and the bearing member is maintained at a maximum throughout at least the primary range of flexion for minimizing stresses in the bearing member during articulation within the primary range of flexion.