Patent ID: 6730128
Filing Date: 2004-05-04
Classification: A61F

Abstract:
A knee joint prosthesis, comprising:a femoral component having an anterior side and a posterior side, the femoral component including a pair of laterally spaced condylar portions, each of which has a surface which is smoothly convexly curved antero-posteriorly to match generally the lateral profile of an anatomical femoral condyle and smoothly convexly curved laterally throughout its antero-posterior extent, and an intercondylar recess joining the condylar portions; a cam follower surface located adjacent the recess on the posterior side of the femoral component between the condylar portions, the cam follower surface dimensioned to extend greater in the posterior direction in a lower cam follower surface region when compared to an upper cam follower surface region; a tibial component having an anterior side and a posterior side, the tibial component including a platform having on its upper surface first and second laterally spaced concavities, each is adapted to receive, in complementary relationship, one of the condylar portions of the femoral component, a tibial post extending up from the platform, the tibial post positioned between the concavities, for reception in the intercondylar recess of the femoral component and having a concavely curved cam surface at a lower end thereof; a tibial auxiliary load bearing surface positioned posterior to the cam surface between the first and second concavities, the tibial auxiliary load bearing surface being adjacent the cam surface; the tibial auxiliary load bearing surface having a profile complementary to the profile of the cam follower surface; wherein, upon assembly of the knee joint prosthesis, the laterally spaced condylar portions of the femoral component are positioned on the first and second concavities of the tibial component in an arrangement that allows for rotation of the femoral component relative to the tibial component; wherein, during rotation of the femoral component in normal mechanical operation of the knee joint prosthesis, the cam follower surface engages the cam surface and the cam follower surface does not transmit a joint stabilizing load to the tibial auxiliary load bearing surface; and wherein, when the femoral component rotates at an angle representing a high degree of flexion in normal mechanical operation of the knee joint prosthesis, a gap is present between the cam follower surface and the tibial auxiliary load bearing surface.