Orthopaedic device for implantation in the body of an animal and method for making the same

Abstract

A method of preparing a orthopaedic implant which includes removing low-molecular-weight compounds from a mass of polymeric material from which the implant is made.

1 . A method of preparing a crosslinked UHMWPE bearing for use in an orthopaedic implant, the method comprising: 
 removing low-molecular-weight compounds from a mass of crosslinked UHMWPE; and    forming the mass of crosslinked UHMWPE into a bearing configured for use in an orthopaedic implant.    
     
     
         2 . The method of  claim 1 , wherein: 
 the removing of low-molecular-weight compounds is performed prior to forming the bearing.    
     
     
         3 . The method of  claim 1 , wherein: 
 the removing of low-molecular-weight compounds is performed subsequent to forming the bearing.    
     
     
         4 . The method of  claim 1 , wherein: 
 the forming includes forming the mass of crosslinked UHMWPE into a bearing having a concave bearing surface for engaging a convex articulating surface.    
     
     
         5 . The method of  claim 1 , wherein: 
 the forming includes forming the mass of crosslinked UHMWPE into a bearing having a convex articulating surface for engaging a concave bearing surface.    
     
     
         6 . The method of  claim 1 , wherein: 
 the removing includes heating the mass of crosslinked UHMWPE while subjecting the mass of crosslinked UHMWPE to a pressure less than 1 atmosphere.    
     
     
         7 . The method of  claim 1 , wherein: 
 the removing includes extracting the low-molecular-weight compounds from the mass of crosslinked UHMWPE with a fluid.    
     
     
         8 . The method of  claim 7 , wherein: 
 extracting the low-molecular-weight compounds from the mass of crosslinked UHMWPE includes contacting the mass of crosslinked UHMWPE with a liquid.    
     
     
         9 . The method of  claim 7 , wherein: 
 extracting the low-molecular-weight compounds from the mass of crosslinked UHMWPE includes contacting the mass of crosslinked UHMWPE with a supercritical fluid.    
     
     
         10 . The method of  claim 1 , wherein: 
 the removing low-molecular-weight compounds includes removing compounds that have a molecular weight of about 5000 or less.    
     
     
         11 . The method of  claim 1 , wherein: 
 the removing low-molecular-weight compounds includes removing compounds that have a molecular weight of about 300 or less.    
     
     
         12 . The method of  claim 1 , wherein: 
 the removing low-molecular-weight compounds includes removing compounds that have a carbon number of 20 or less.    
     
     
         13 . A method of preparing a crosslinked UHMWPE bearing for use in an orthopaedic implant, the method comprising: 
 removing an amount of polyethylene molecules having a molecular weight of 5000 or less from a mass of crosslinked UHMWPE so that the mass of crosslinked UHMWPE contains 0.1% or less of polyethylene molecules having a molecular weight of 5000 or less; and    forming the mass of crosslinked UHMWPE into a bearing configured for use in an orthopaedic implant.    
     
     
         14 . The method of  claim 13 , wherein: 
 the removing of low-molecular-weight compounds is performed prior to forming the bearing.    
     
     
         15 . The method of  claim 13 , wherein: 
 the removing of low-molecular-weight compounds is performed subsequent to forming the bearing.