Process for medical implant of cross-linked ultrahigh molecular weight polyethylene having improved balance of wear properties and oxidation resistance

A process for preparing an orthopaedic implant prosthesis bearing having an improved balance of wear properties and oxidation resistance comprising the steps of:

• providing an ultrahigh molecular weight polyethylene preform from which the bearings are to be fabricated;
• heating the preform to a temperature of about 280° C. to about 355° C. for a period of time greater than about 0.5 hours;
• cooling the preform to a temperature below the melting temperature to obtain a solid preform;
• irradiating the solid preform with about 0.5 to about 10 Mrad of gamma radiation to cross-link the preform;
• and
• quenching the free radicals in the preform.

A process for preparing an orthopaedic implant prosthesis bearing having an improved balance of wear properties and oxidation resistance comprising the steps of:

• providing an ultrahigh molecular weight polyethylene preform from which the bearings are to be fabricated;
• heating the ultrahigh molecular weight polyethylene preform to a temperature of about 280° C. to about 355° C. for a period of about 0.5 hours or greater;
• irradiating the preform to cross-link the preform with gamma radiation at a dose of about 1.5 to about 6 Mrad;
• quenching the free radicals in the preform by annealing the preform at a temperature of about 150° C. to about 170° C. for up to about 60 hours;
• cooling the cross-linked preform;
• and
• forming a bearing from the cross-linked preform.

A process for preparing an orthopaedic implant prosthesis bearing having improved mechanical properties and increased wear resistance comprising the steps of:

• providing a polyethylene preform from which the bearings are to be fabricated;
• irradiating the preform;
• and
• heating the preform to a temperature greater than its melting temperature and less than its decomposition temperature for a time sufficient to increase its percent elongation to break properties.