Abstract: An orthopedic joint replacement has first and second joint components that can be placed in load-bearing articulation with one another. The first joint component has first and second convex spherical condylar segments defining first and second radii. The second joint component has a spherical first concave condylar segment with a radius equal to the radius of the first convex spherical condylar segment. The second joint component also has a non-spherical second concave condylar segment. The first convex spherical condylar segment of the first joint component is in congruent contact with the first spherical concave condylar segment of the second joint component. The second spherical convex condylar segment of the first joint component is in line contact with the non-spherical concave condylar segment of the second joint component.

Abstract: A hinged knee prosthesis includes a femoral component with a tibiofemoral articular surface that is distinct from the patellofemoral articulating surface. Fully congruent tibiofemoral articulation is provided for virtually all flexion angles. Additionally, the bearing is capable of at least limited axial rotation relative to the tibial component but is restrained against dislocation. Accordingly, dislocation is much less likely even n those situations where collateral ligaments are insufficient.