Methods for making oxidation resistant polymeric material

Abstract

The present invention relates to methods for making oxidation resistant medical devices that comprise polymeric materials, for example, ultra-high molecular weight polyethylene (UHMWPE). The invention also provides methods of making antioxidant-doped medical implants, for example, doping of medical devices containing cross-linked UHMWPE with vitamin E by diffusion, post-doping annealing, and materials used therein.

1 - 89 . (canceled)  
     
     
         90 . A method of making a medical implant comprising non-oxidizing cross-linked ultrahigh molecular weight polyethylene (UHMWPE) containing detectable residual free radicals, wherein the method comprises: 
 a) compression molding the UHMWPE to another piece, thereby forming an interface and an interlocked hybrid material;    b) doping the interlocked hybrid material with an antioxidant by diffusion in a supercritical fluid at 105° C. for 24 hours;    d) annealing the antioxidant-doped interlocked hybrid material in boiling water under atmospheric pressure for 100 hours at 100° C.;    e) irradiating the interlocked hybrid material by ionizing radiation at a dose of 100 kGy, thereby forming a medical implant having interlocked hybrid material comprising non-oxidizing cross-linked UHMWPE containing detectable residual free radicals, wherein the irradiation is carried out in a vacuum;    (f) packaging the medical implant having interlocked hybrid material comprising non-oxidizing cross-linked UHMWPE containing detectable residual free radicals; and    (g) sterilizing the packaged antioxidant-doped cross-linked medical implant by ionizing radiation or gas sterilization, thereby forming a sterile, oxidation-resistant, and cross-linked medical implant, wherein the implant comprises medical devices selected from the group consisting of acetabular liner, shoulder glenoid, patellar component, finger joint component, ankle joint component, elbow joint component, wrist joint component, toe joint component, bipolar hip replacements, tibial knee insert, tibial knee inserts with reinforcing metallic and polyethylene posts, intervertebral discs, sutures, tendons, heart valves, stents, and vascular grafts.