Oxidation-resistant and wear-resistant polyethylenes for human joint replacements and methods for making them

  • US 8,658,710 B2
  • Filed: 05/24/2007
  • Issued: 02/25/2014
  • Est. Priority Date: 04/27/2000
  • Status: Expired due to Term
First Claim
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1. A method for producing a wear-resistant and oxidation-resistant medical implant of a joint prosthesis, said method comprising the steps of:

  • (I) providing an oxidation-resistant medical implant of a joint prosthesis comprising a polyethylene component; and

    (II) irradiating the oxidation-resistant medical implant at a radiation dose of above 5 Mrad to about 25 Mrad so as to crosslink the implant thereby improving its wear resistance, without thermally treating the implant to extinguish free radicals in the irradiated and crosslinked implant during or subsequent to irradiating the oxidation-resistant implant;

    wherein the oxidation-resistant implant contains an antioxidant rendering it resistant to oxidation caused by free radicals generated by the irradiation of step (II); and

    the irradiated oxidation-resistant implant possesses the characteristics of;

    a degree of swelling of between about 1.7 to about 3.6;

    a molecular weight between crosslinks of between about 400 to about 3,500 g/mol; and

    a gel content of between about 95% to about 99%.

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