Patent ID: 8092530

Claim:
A cartilage implant comprising: an articular end for repair of articular cartilage defects having an oval 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, the concave lower face having a first surface comprising a second circular pitch radius and a second circular roll radius, and at least two second surfaces both external to the first surface and both tangent to the first surface, each second surface having a third circular pitch radius and a third circular roll 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 the 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; and a stem extending from the concave lower face away from the convex upper face, the stem having a plurality of oval shaped perimeters in planes perpendicular to the vertical axis, wherein: the stem has a first stem portion having a maximum oval shaped perimeter extending at least one millimeter from the concave lower face away from the convex upper face along the vertical axis, 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 oval shaped perimeters decreasing in diameter along at least one axis from the maximum oval shaped perimeter of the first portion to a lesser second stem oval shaped 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 oval shaped perimeters, wherein at least one circumferential groove is defined between two adjacent second stem oval shaped perimeters and has a shape of a partial, oval, non-planar torus extending radially inward of the adjacent second stem oval shaped perimeters, wherein the at least one circumferential groove blends into at least one of the two adjacent second stem oval shaped 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.