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AssigneesOrthopaedic Hospital, University of Southern California
InventorsHarry A. McKellop, Fu-Wen Shen
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A method for improving the wear resistance of an implant, made of polyethylene, by crosslinking its bearing surface layer, while leaving its non-bearing interior uncrosslinked. Such crosslinking may be achieved by electron-beam irradiation or by chemical crosslinking of the implant or the polyethylene from which the implant is made. The resulting implant or polyethylene may be further treated to remove the residual free radicals (generated by the electron beam crosslinking process); to remove residual chemicals (generated by the chemical crosslinking process); to remove its most oxidized layer; to stabilize its size and shape; to improve, by remelting, its oxidation resistance; and/or to reshape it into the final implant. Also presented are the resulting implant and polyethylene.
An implant comprising a polyethylene, said polyethylene's surface layer being crosslinked, said crosslinking gradually decreasing to nearly zero in the interior of the polyethylene, the crosslinking is achieved by electron beam radiation or chemical means.
A method for improving the wear resistance of a bearing surface of an implant, wherein said bearing surface comprises polyethylene, the method comprises the steps of crosslinking the polyethylene with a free radical generating chemical and remelting the crosslinked polyethylene, during a process for making the implant so that the remainder of the implant, when made, that is not part of the bearing surface remains uncrosslinked, and the remelting improves oxidation resistance of the crosslinked polyethylene.
An implant comprising a polyethylene having a bearing surface, said bearing surface being crosslinked and such crosslinking gradually decreasing to nearly zero in the interior of the polyethylene, the crosslinking is achieved by electron beam radiation or chemical means.
A surface-gradient crosslinked implant comprising a polyethylene bearing surface having a maximum gel content of from about 80 to about 100% within the bearing surface, the gel content gradually decreasing to about 50% of the bearing surface gel content from about 0.5 to about 2.6 mm from the bearing surface, and tapering to nearly zero from about 2 to about 3 mm from the surface;
An implant comprising a polyethylene having a bearing surface, said bearing surface being crosslinked and said crosslinking gradually decreases below the bearing surface, said crosslinking is achieved by electron beam radiation or chemical means.
Dependencies are inferred from the claim text.