Radiation and melt treated ultra high molecular weight polyethylene prosthetic devices

Abstract

A medical prosthesis for use within the body which is formed of radiation treated ultra high molecular weight polyethylene having substantially no detectable free radicals, is described. Preferred prostheses exhibit reduced production of particles from the prosthesis during wear of the prosthesis, and are substantially oxidation resistant. Methods of manufacture of such devices and material used therein are also provided.

1 - 123 . (canceled) 
   
   
       124 . An apparatus made by a process comprising the steps of:
 (a) irradiating a polymer in its solid state, whereby said irradiating step comprises passing the polymer through a radiation source a first time;   (b) irradiating the polymer in its solid state, whereby said irradiating step comprises passing the polymer through a radiation source a second time; and   (c) heating the polymer,   
     wherein the polymer comprises ultrahigh molecular weight polyethylene. 
   
   
       125 . The apparatus of  claim 124 , further comprising irradiating the polymer in its solid state, whereby said irradiating step comprises passing the polymer through a radiation source a third time. 
   
   
       126 . The apparatus of  claim 124 , wherein the heating step occurs after each pass of the polymer through the radiation source. 
   
   
       127 . The apparatus of  claim 124 , further comprising the step of fashioning an implantable bearing component from the polymer. 
   
   
       128 . The apparatus of  claim 124 , wherein the polymer has a first degree of oxidation prior to the irradiating and heating steps, and a second degree of oxidation after the irradiating and heating steps, and wherein the first degree of oxidation and the second degree of oxidation are substantially the same. 
   
   
       129 . The apparatus of  claim 127 , wherein the irradiating and heating steps precede the fashioning step. 
   
   
       130 . A method of producing a polymer comprising the steps of:
 (a) irradiating a polymer in its solid state, whereby said irradiating step comprises passing the polymer through a radiation source a first time;   (b) irradiating the polymer in its solid state, whereby said irradiating step comprises passing the polymer through a radiation source a second time;   (c) heating the polymer,   
     wherein the polymer comprises ultrahigh molecular weight polyethylene. 
   
   
       131 . The method of  claim 130 , further comprising irradiating the polymer in its solid state, whereby said irradiating step comprises passing the polymer through a radiation source a third time. 
   
   
       132 . The apparatus of  claim 130 , wherein the heating step occurs after each pass of the polymer through the radiation source. 
   
   
       133 . The apparatus of  claim 130 , further comprising the step of fashioning an implantable bearing component from the polymer. 
   
   
       134 . The method of  claim 130 , wherein the polymer has a first degree of oxidation prior to the irradiating and heating steps, and a second degree of oxidation after the irradiating and heating steps, and wherein the first degree of oxidation and the second degree of oxidation are substantially the same. 
   
   
       135 . The method of  claim 133 , wherein the irradiating and heating steps precede the fashioning step.