Patent ID: 7815684

Claim:
A knee prosthesis comprising: a femoral component for securement to the femur; a tibial component for securement to the tibia; and a bearing component between the femoral and tibial components, the femoral component defining medial and lateral condyles having anterior and posterior portions and an open intercondylar area, the bearing component having respective condylar bearing surfaces shaped to match said condyles, and the femoral component defining at said intercondylar area one of a cam or follower and the bearing component defining the other of said cam or follower, the cam comprising a convex part-cylindrical surface and the follower comprising a matching concave part-cylindrical surface, wherein the medial and lateral condyles are engaged with the bearing surfaces via a first congruent contact area both when the knee is extended and over a first range of flexion throughout which the cam and follower are disengaged, a centre of a radius of curvature of each part-cylindrical surface of the cam and follower being coincident and also axially collinear with a centre of a radius of curvature of the posterior portions of the condyles of the femoral component, when the cam and follower part-cylindrical surfaces are engaged via a second-congruent contact area over a second range of flexion throughout which the cam and follower are engaged, and wherein the second congruent contact area extends out into the respective condylar bearing surfaces.