Patent ID: 8043375

Claim:
A cartilage implant comprising: an articular end for repair of articular cartilage defects having a circular perimeter, a convex upper face, and a concave lower face, the convex upper face having a spherical radius and the concave lower face having a spherical radius; and a stem extending from the concave lower face away from the convex upper face along a vertical axis, the stem having a plurality of circular perimeters along the vertical axis, and a maximum stem circular perimeter at the intersection of the stem and the concave lower face, the maximum stem circular perimeter less than the articular end circular perimeter, wherein: the stem has a cylindrical portion having a maximum circular perimeter extending at least one millimeter from the concave lower face away from the convex upper face along the vertical axis, and a conical portion extending from the cylindrical portion away from the convex upper face along the vertical axis, the conical portion having a plurality of stem circular perimeters decreasing in diameter from the maximum circular perimeter of the cylindrical portion to a lesser stem circular perimeter along the vertical axis of the stem; and wherein the stem has a plurality of circumferential grooves, wherein each circumferential groove extends continuously around at least one of the plurality of circular perimeters, wherein at least one circumferential groove is defined between two adjacent circular perimeters and has the shape of a partial torus extending radially inward of the adjacent circular perimeters, wherein the at least one circumferential groove blends into at least one of the two adjacent circular perimeters, wherein the stem blends into the concave lower face, and wherein the articular end and the stem each consist essentially of: a graphite core and a pyrocarbon coating, the pyrocarbon coating having an average thickness ranging from about 100 to about 1000 microns.