Importance

Loading Importance Indicators...

Abstract

A knee prosthesis comprises (i) a femoral component having a medial condyle and a lateral condyle and (ii) a tibial component. The rolling surface of the medial condyle is part-spherical and the tibial component has a complementary part-spherical depression in its upper surface to receive the medial condyle. The bearing surface of the lateral condyle includes a posterior part which has a curvature in a substantially sagittal plane about a first point on a transverse axis that passes through the center of curvature of the rolling surface of the medial condyle and an anterior part which has a curvature in the same plane about a point that lies on a second transverse axis parallel to, and anterior to, the first transverse axis. The tibial component has an arcuate groove to receive the lateral condyle and to permit, in flexion of the knee after implantation, limited anterior/posterior movement of the lateral side of the tibia relative to the femur. In flexion of the knee the posterior part of the rolling surface of the lateral condyle is received in this arcuate groove but, as the knee straightens and approaches its straightened condition, the anterior part of this rolling surface bears on the anterior end of the groove and thereby forces the lateral side of the tibial component to move anteriorly relative to the lateral condyle by a camming action. In this way anterior/posterior movement of the lateral side of the tibia relative to the femur is hindered in the straightened condition of the knee.

Loading the Abstract Image...

First Claim