Patent ID: 7641692

Claim:
A surgical implant suitable for use in a joint between the surfaces of two bones, comprising: two rigid opposing shells, each having an outer surface adapted to engage the surfaces of the bones of a joint in such a way that movement of the shell relative to the bone surface is resisted by friction between the outer surface and the surface of the bone; an inner surface that is smoother than the outer surface; and an edge between the outer surface and the inner surface; a deformable, resilient central body disposed between and slidable with respect to the inner surfaces of the shells, the central body comprising an outer surface, at least a portion of which has a shape that complements and articulates with the shape of the inner surfaces of both rigid opposing shells to allow the inner surfaces of the rigid opposing shells and the outer surface of the central body to move easily with respect to each other within a constrained range of motion, but to resist such movement outside the constrained range of motion, wherein an upper portion and a lower portion of the outer surface of the central body are harder than an interior region of the central body disposed between the upper and lower portions; a flexible sheath extending between edges of the opposing shells, having an inner surface that, together with the inner surfaces of the rigid shells, defines a cavity containing the central body; and a liquid lubricant, which occupies at least a portion of the cavity between the central body and the opposing shells.