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AssigneeBiomet Manufacturing, LLC
InventorsDavid Schroeder, Jordan Freedman, James Gunter, Brian Salyer, H. Hawkins
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Solid-state deformation processing of crosslinked high molecular weight polymers such as UHMWPE, for example by extrusion below the melt transition, produces materials with a combination of high tensile strength and high oxidative stability. The materials are especially suitable for use as bearing components in artificial hip and other implants. Treated bulk materials are anisotropic, with enhanced strength oriented along the axial direction. The material is oxidatively stable even after four weeks of accelerated aging in a pressure vessel containing five atmospheres of oxygen (ASTM F2003). Because of its oxidative stability, the deformation processed material is a suitable candidate for air-permeable packaging and gas sterilization, which has thus far been reserved for remelted crosslinked UHMWPE.
A gamma-crosslinked UHMWPE in the form of a bulk material characterized by an axial direction, wherein the tensile strength in the axial direction is greater than 50 MPa.
A gamma-crosslinked UHMWPE having a concentration of free radicals greater than 0.06×1015 spins/g and less than 3×105 spins/g, and stable to oxidation for 4 weeks in 5 atm oxygen at 70° C., as measured by an increase in the oxidation index of 0.5 or less.
A method for solid state deformation processing of gamma-irradiated UHMWPE comprising deforming the UHMWPE by extruding it at a temperature below its melt transition.
A method of making a bearing component made of UHMWPE, suitable for use in a medical implant comprising
A method according to 32, wherein the sterilizing is non-irradiative.
A method according to 31, further comprising sterilizing the component after machining.
Dependencies are inferred from the claim text.