Patent ID: 7875081

Claim:
A knee joint prosthesis comprising: a femoral component having an anterior side, a posterior side, a pair of laterally spaced condylar portions, and an intercondylar portion joining the condylar portions and including a recess; a cam surface located adjacent the intercondylar recess on the anterior side of the femoral component, the cam surface having a saddle shape and being defined by an at least substantially concave first radius of curvature and a convex third radius of curvature that is perpendicular to the concave first radius of curvature; and a tibial component including a platform having an upper surface that includes first and second laterally spaced concavities, each adapted for receiving one condylar portion of the femoral component and a tibial post for reception in the intercondylar recess of the femoral component, the tibial post having a saddle shaped anterior cam surface that is complementary to the saddle shaped anterior cam surface of the femoral component and is defined by an at least substantially convex second radius of curvature and a concave fourth radius of curvature that is perpendicular to the convex second radius of curvature; wherein the convex second radius of curvature of the tibial component is less than the concave first radius of curvature of the femoral component; wherein the saddle shaped anterior cam surface of the tibial post mates with the saddle shaped cam surface of the femoral component in an articulating manner in approximately 10 degrees of hyperextension of the knee.