Patent ID: 8852286

Claim:
An implant comprising: an articular end having an upper surface, a side surface, and a lower surface; the upper surface and lower surface each intersect the side surface, the upper surface has a first surface curvature, a central surface curvature, and a second surface curvature, wherein the central surface curvature is formed along a partial torus and has a saddle point; and a stem, which extends from the lower surface in a direction away from the upper surface of the articular end and has a central axis, wherein the location of the saddle point is offset along a horizontal direction from the location of the central axis by a distance ranging from between about 1 to about 5 millimeters, the stem having at least one groove about a perimeter of the stem, the groove defined by a partial torus having a groove tubular radius ranging from about 0.25 millimeters to about 2 millimeters, the groove blending into the stem with a groove blend having an edge radius ranging from about 0.1 millimeters to about 1 millimeter, the groove extends continuously about the perimeter of the stem.