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US 6,184,265 B2Granted
Low temperature pressure stabilization of implant component
AssigneeDePuy Orthopaedics, Inc.
InventorsJohn V. Hamilton, Mary Beth Schmidt, Keith Greer
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AssigneeDePuy Orthopaedics, Inc.
InventorsJohn V. Hamilton, Mary Beth Schmidt, Keith Greer
Estimating the term…
Wear resistance and oxidation resistance of polymer material or a polymer component for bioimplantation are improved by packaging a polymer object in a sealed gas impermeable package substantially free of oxygen, irradiating the package with penetrating radiation to an extent sufficient to effect a desired substantial level of cross-linking within the polymer, and warming the packaged object while maintaining an elevated hydrostatic pressure to cause gases released during irradiation to recombine, stabilizing the material against subsequent oxidative change. The pressure stabilization terminates active sites, substantially eliminating free radicals. When applied to finished parts, the process simultaneously hardens and sterilizes the parts without degrading mechanical properties or dimensions. When applied to bulk material or unfinished parts, the part may be subsequent machined or otherwise finished, and sterilized by any conventional means. The procedure achieves high levels of cross linking without increasing susceptibility to aging or chemical degradation.
A method of preparing of a prosthetic wear surface component formed of a polymer material, such method comprising the steps of
A method of forming a prosthetic polymer wear surface component having enhanced oxidation resistance, such method comprising the steps of
A method of improving oxidative stability of an irradiated polymer implant component without increasing the degree of cross-linking induced by irradiation wherein the method is characterized by the steps of irradiating the component in a sealed container and, while still in the container, stabilizing the component by warming the component and subjecting the warm component to a hydrostatic pressure between about twenty and one hundred atmospheres or more, for a time effective to recombine evolved gases generated by the radiation with the polymer implant material.
An implantable prosthetic component formed of UHMWPE and being characterized by post-forming exposure to gamma radiation to introduce an effective level of cross-linking;
Dependencies are inferred from the claim text.