Wear resistant surface-gradient crosslinked polyethylene
AssigneesOrthopaedic Hospital, University of Southern California
InventorsHarry Alden McKellop, Fu-Wen Shen
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Abstract
A method for improving the wear resistance of an implant 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. The resulting implant may be further treated to remove the residual free radicals (generated by the electron beam crosslinking process), to remove its most oxidized layer, and/or to stabilize its size. In the case of chemical crosslinking, the resulting implant may be further treated to remove residual chemicals from the crosslinked surface layer.
Claims13
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 at about 0.5 to about 2 mm from the bearing surface, and tapering to nearly zero by about 2 to about 3 mm from the bearing surface;
- the remainder of the implant remains uncrosslinked.
A method for improving the wear resistance of a bearing surface of an implant, wherein said bearing surface comprises polyethylene, the method comprises the step of subjecting the bearing surface of the implant which is fully formed to electron-beam radiation to crosslink the bearing surface, while the remainder of the implant that is not part of the bearing surface is not subjected to the electron-beam radiation and, therefore, remains uncrosslinked.
A method for improving wear resistance of a bearing surface of an implant, wherein said bearing surface comprises polyethylene, the method comprising the step of crosslinking the polyethylene with a free radical generating chemical, 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, the resultant implant is termed a surface crosslinked implant.
A method for improving the wear resistance of a bearing surface of an implant, wherein said bearing surface comprises polyethylene, the method comprises the step of subjecting the bearing surface of the implant which is partially formed to electron-beam radiation to crosslink the bearing surface, while the remainder of the partially formed implant that is not part of the bearing surface is not subjected to the electron-beam radiation and, therefore, remains uncrosslinked.
Dependencies are inferred from the claim text.