# US 2014/0194934 A1 · Antioxidant stabalized crosslinked ultra high molecular weight polyethylene for medical device applications > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0194934 A1 - Document ID: US20140194934A1 - Status: Published application - Kind: A1 - Application number: 14/157,695 - Filed: 2014-01-17 - Published: 2014-07-10 - Earliest claimed: 2007-04-10 - Assignees: Zimmer, Inc. - Applicants: Zimmer, Inc. - Inventors: Alicia Rufner; John Knight; Toni Rowe; Dirk Pletcher; Ray Gsell; Werner Schneider; Hallie E. Brinkerhuff - Web page: https://patentgrep.com/patent/US20140194934A1 ## CPC - C08J 3/247: {Heating methods} - A61B 17/8085: {with pliable or malleable elements or having a mesh-like structure, e.g. small strips (A61B17/8071, A61B17/8076 take precedence)} - A61L 27/16: obtained by reactions only involving carbon-to-carbon unsaturated bonds - A61L 27/505: {Stabilizers} - C08J 3/28: Treatment by wave energy or particle radiation - C08L 23/06: Polyethylene - C08J 2323/26: modified by chemical after-treatment - C08K 5/005: {Stabilisers against oxidation, heat, light, ozone} - C08K 5/1545: Six-membered rings - C08K 9/10: Encapsulated ingredients - C08L 2312/06: by radiation - Y10T 428/31: Surface property or characteristic of web, sheet or block - Y10T 428/315: Surface modified glass [e.g., tempered, strengthened, etc.] - C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29) - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - A61L: METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES (preservation of bodies or disinfecting characterised by the agents employed A01N; preserving, e.g. sterilising, food or foodstuffs A23; preparations for medical, dental or toiletry purposes A61K) - C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06) - C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract An antioxidant combined with UHMWPE prior to subjecting the UHMWPE to crosslinking irradiation. In one exemplary embodiment, the antioxidant is tocopherol. After the antioxidant is combined with the UHMWPE, the resulting blend may be formed into slabs, bar stock, and/or incorporated into a substrate, such as a metal, for example. The resulting product may then be subjected to crosslinking irradiation. In one exemplary embodiment, the UHMWPE blend is preheated prior to subjecting the same to crosslinking irradiation. Once irradiated, the UHMWPE blended product may be machined, packaged, and sterilized in accordance with conventional techniques. ## Claims ### Claim 1 (canceled) ### Claim 2 An orthopedic implant, comprising: a consolidated blend of UHMWPE and an antioxidant which has been irradiated to crosslink the blend, wherein the consolidated and irradiated blend has a pin-on-disk wear rate of about 0.02 mg/Mc to about 0.58 mg/Mc. ### Claim 3 (depends on 2) The orthopedic implant of claim 2, wherein the consolidated blend comprises a consolidated blend of UHMWPE power and a solvent-dissolved antioxidant. ### Claim 4 (depends on 2) The orthopedic implant of claim 2, wherein the consolidated and irradiated blend has been irradiated with a total dose of about 100 kGy to about 1000 kGy to crosslink the blend. ### Claim 5 (depends on 2) The orthopedic implant of claim 2, wherein the consolidated and irradiated blend has an elongation-at-break of about 246.2% to about 411.2%. ### Claim 6 (depends on 2) The orthopedic implant of claim 2, wherein the consolidated and irradiated blend has a crosslink density of more than about 0.18 moles/dm3. ### Claim 7 (depends on 2) The orthopedic implant of claim 2, wherein at least some of the antioxidant remains in the crosslinked blend after the crosslinking irradiation. ### Claim 8 (depends on 2) The orthopedic implant of claim 2, wherein the antioxidant is tocopherol or a salt or ester thereof. ### Claim 9 (depends on 8) The orthopedic implant of claim 8, wherein about 0.011 wt % to about 0.882 wt % of the consolidated and irradiated blend is tocopherol or a salt or ester thereof that has reacted with the polyethylene and remaining tocopherol or a salt or ester thereof. ### Claim 10 (depends on 8) The orthopedic implant of claim 8, wherein about 0.016 wt % to about 0.575 wt % of the consolidated and irradiated blend is tocopherol or a salt or ester thereof that has reacted with the polyethylene. ### Claim 11 (depends on 8) The orthopedic implant of claim 8, wherein about 0.001 wt % to about 0.592 wt % of the consolidated and irradiated blend is remaining tocopherol or a salt or ester thereof. ### Claim 12 (depends on 2) The orthopedic implant of claim 2, wherein the consolidated and irradiated blend has about no detectable oxidation after about 8 weeks of accelerated aging performed according to ASTM F2003. ### Claim 13 (depends on 2) The orthopedic implant of claim 2, wherein the consolidated and irradiated blend has about no detectable oxidation after about 24 weeks of accelerated aging performed according to ASTM F2003. ### Claim 14 (depends on 2) The orthopedic implant of claim 2, wherein the surface oxidation index of the blend is about zero after about 8 weeks of accelerated aging performed according to ASTM F2003. ### Claim 15 (depends on 2) The orthopedic implant of claim 2, wherein the surface oxidation index of the blend is less than about 0.02 after about 24 weeks of accelerated aging performed according to ASTM F2003. ### Claim 16 (depends on 2) The orthopedic implant of claim 2, wherein the bulk oxidation index of the blend is about zero after about 8 weeks of accelerated aging performed according to ASTM F2003. ### Claim 17 (depends on 2) The orthopedic implant of claim 2, wherein the consolidated and irradiated blend is molded into at least one of a substrate, a polymeric article, and an antioxidant stabilized polymeric article. ### Claim 18 (depends on 2) The orthopedic implant of claim 2, wherein after about 50 days of immersion in deionized water at about 70° C., about none of the antioxidant remaining in the consolidated and irradiated blend has leached into the water. ### Claim 19 (depends on 2) The orthopedic implant of claim 2, wherein after subjecting a 1-cm cube of the consolidated and irradiated blend to soaking in an about 100-mL deionized water bath at a temperature of at least about 70° C. for at least about 53 days leaches a sufficiently small quantity of the antioxidant such that an absorbance reading of the water in an about 10 mm quartz tube at about 297 nm shows no greater than about 0.01 units of increase from a reference water absorbance. ### Claim 20 (depends on 2) The orthopedic implant of claim 2, wherein the consolidated and irradiated blend is molded into at least one of a substrate, a polymeric article, and an antioxidant stabilized polymeric article. ### Claim 21 An orthopedic implant, comprising: a consolidated blend of UHMWPE and tocopherol or a salt or ester thereof which has been irradiated to crosslink the blend, wherein about 0.011 wt % to about 0.882 wt % of the consolidated and irradiated blend is tocopherol or a salt or ester thereof that has reacted with the polyethylene and remaining tocopherol or a salt or ester thereof, about 0.001 wt % to about 0.592 wt % of the consolidated and irradiated blend is remaining tocopherol or a salt or ester thereof, and the consolidated and irradiated blend has a pin-on-disk wear rate of about 0.02 mg/Mc to about 0.58 mg/Mc.