Patent ID: 8876901

Claim:
An articular cartilage implant comprising: an articular end for repair of articular cartilage defects, the articular end having a perimeter, a convex upper face, and a concave lower face, the convex upper face having a first circular pitch radius and a first circular roll radius, at least a portion of the concave lower face having a spherical radius, the convex upper face blending into a rim, wherein at least a first and second portion of the rim extends at least a first distance along a vertical axis and a third and fourth portion of the rim tapers inward along the vertical axis, the rim blending into the concave lower face; wherein the first circular pitch radius ranges from about 15 to about 30 millimeters, wherein the first circular roll radius ranges from about 20 to about 40 millimeters; and a stem extending from the concave lower face away from the convex upper face along the vertical axis, the stem having a plurality of stem perimeters along the vertical axis; wherein the stem has a first stem portion having a maximum stem perimeter extending at least one millimeter from the concave lower face away from the convex upper face along the vertical axis, the maximum stem perimeter being less than the articular end perimeter, and a second stem portion extending from the first stem portion away from the convex upper face along the vertical axis, the second stem portion having a plurality of second stem portion perimeters decreasing in stem perimeter from the maximum stem perimeter of the first stem portion to a lesser second stem portion stem 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 second stem portion perimeters, wherein at least one circumferential groove is defined between two adjacent second stem portion perimeters and has a shape of a partial, non-planar torus extending radially inward of the adjacent second stem portion perimeters, wherein the at least one circumferential groove blends into at least one of the two adjacent second stem portion 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.