Patent ID: 8603182

Claim:
A bipolar hip prosthesis that in use receives a femoral head component, the bipolar hip prosthesis comprising: (a) a bipolar shell having an outer surface and an inner cavity that meet at a portal surface; (b) a polyethylene liner that fits within the inner cavity, the liner comprising an outer surface and an inner surface that meet at an interface surface, wherein the interface surface does not extend to the portal surface of the shell, wherein at least a portion of the polyethylene liner is cross-linked; and (c) a locking system located entirely within the inner cavity of the shell between the liner interface surface and the shell portal surface, the locking system adapted to secure a femoral head component within the shell and comprising an outer surface and a capture surface, wherein the capture surface comprises a bearing surface for the femoral head component and is adapted to provide clearance for a femoral neck or stem component in use, wherein the bearing surface is smaller in diameter than the femoral head component when in use, and wherein the locking system comprises a locking retainer and a non-split ring, the non-split ring comprising a polyethylene material that is not cross-linked or that is cross-linked to a lesser extent than the polyethylene liner, the non-split ring further comprising a groove and wherein the locking retainer fits into the groove of the non-split ring.