a medical implant made of polymeric material having an increased oxidation resistance is formed by a method including the steps of placing a resin powder in a sealed container . a substantial portion of the oxygen is removed from the sealed container by either a vacuum , an oxygen absorbent or by flushing with inert gas . the container is then repressurized with a gas such as nitrogen , argon , helium or neon so that long term storage may be possible . on use , the resin is transferred to a forming device which both melts and forms the resin in an oxygen reduced atmosphere to produce a polymeric raw material such as a rod or bar stock . the medical implant is then formed from this raw material annealed and sealed in an air - tight package in an oxygen reduced atmosphere . the implant is then radiation sterilized and thereafter annealed in the package for a predetermined time and temperature sufficient to form cross - links between any free radicals in neighboring polymeric chains .