Crosslinking of polyethylene for low wear using radiation and thermal treatments

Abstract

The present invention discloses methods for enhancing the wear-resistance of polymers, the resulting polymers, and in vivo implants made from such polymers. One aspect of this invention presents a method whereby a polymer is irradiated, preferably with gamma radiation, then thermally treated, such as by remelting of annealing. The resulting polymeric composition preferably has its most oxidized surface layer removed. Another aspect of the invention presents a general method for optimizing the wear resistance and desirable physical and/or chemical properties of a polymer by crosslinking and thermally treating it. The resulting polymeric compositions is wear-resistant and may be fabricated into an in vivo implant.

1 . A preformed polymeric composition comprising a crosslinked thermally treated polymer.  
     
     
         2 - 30 . (canceled).  
     
     
         31 . An implantable bearing component made by the process comprising the steps of: 
 (a) crosslinking, by irradiation, a preformed polymer in its solid state;    (b) remelting the crosslinked polymer; and    (c) fashioning the implantable bearing component from the crosslinked and remelted polymer, wherein the polymer is selected from the group consisting of: ultra high molecular weight polyethylene (UHMWPE) and high molecular weight polyethylene (HMWPE).    
     
     
         32 . The implantable bearing component of  claim 31 , wherein the polymer is crosslinked by gamma radiation at a dose of from about 1 to about 100 Mrad.  
     
     
         33 . The implantable bearing component of  claim 32 , wherein the gamma radiation dose is from about 4 to about 15 Mrad.  
     
     
         34 . The implantable bearing component of  claim 33 , wherein the gamma radiation dose is from about 4.5 to about 10 Mrad.  
     
     
         35 . The implantable bearing component of  claim 33 , wherein the implantable bearing component is for use in a joint prosthesis.  
     
     
         36 . The implantable bearing component of  claim 35 , wherein the joint prosthesis is selected from the group consisting of: hip, knee, ankle, elbow, jaw, shoulder, finger and spine joint prostheses.  
     
     
         37 . The implantable bearing component of  claim 36 , wherein the joint prosthesis is selected from the group consisting of: hip and knee joint prostheses.  
     
     
         38 . The implantable bearing component of  claim 33 , wherein the implantable bearing component is selected from the group consisting of: an acetabular cup, an insert of an acetabular cup, and a liner of an acetabular cup.  
     
     
         39 . A joint prosthesis comprising: 
 a first member adapted to be secured to a first bone constituting a first portion of a joint;    an articulating surface on the first member;    a second member adapted to be secured to a second bone constituting a second portion of the joint; and    the implantable bearing component of  claim 33 , said implantable bearing component being adapted for disposition between the second member and the articulating surface, said implantable bearing component being adapted to receive said articulating surface for movement therein.    
     
     
         40 . The joint prosthesis of  claim 39 , wherein the joint prosthesis is selected from the group consisting of: hip, knee, ankle, elbow, jaw, shoulder, finger and spine joint prostheses.  
     
     
         41 . The joint prosthesis of  claim 40 , wherein the joint prosthesis is selected from the group consisting of: hip and knee joint prostheses.  
     
     
         42 . The joint prosthesis of  claim 39 , wherein the joint prosthesis is for use in a hip joint replacement wherein: 
 (a) the first bone is a femur;    (b) the second bone is a pelvic bone;    (c) the first member is a prosthetic stem;    (d) the second member is a prosthetic acetabular shell;    (e) the articulating surface is a prosthetic femoral head; and    (f) the implantable bearing component is selected from the group consisting of: an acetabular cup liner and an acetabular cup insert.    
     
     
         43 . The joint prosthesis of  claim 39 , wherein said articulating surface and said first member are separate units.  
     
     
         44 . A joint prosthesis comprising: 
 a first member adapted to be secured to a first bone constituting a first portion of the joint;    an articulating surface on the first member;    the implantable bearing component of  claim 33  adapted to be secured to a second bone constituting a second portion of the joint, said implantable bearing component being adapted to receive said articulating surface for movement therein.    
     
     
         45 . The joint prosthesis of  claim 44 , wherein the joint prosthesis is selected from the group consisting of: hip, knee, ankle, elbow, jaw, shoulder, finger and spine joint prostheses.  
     
     
         46 . The joint prosthesis of  claim 45 , wherein the joint prosthesis is selected from the group consisting of: hip and knee joint prostheses.  
     
     
         47 . The joint prosthesis of  claim 44 , wherein the joint prosthesis is for use in a hip joint replacement wherein: 
 (a) the first bone is a femur;    (b) the second bone is a pelvic bone;    (c) the first member is a prosthetic stem;    (d) the implantable bearing component is a prosthetic acetabular cup; and    (e) the articulating surface is a prosthetic femoral head.    
     
     
         48 . The joint prosthesis of  claim 44 , wherein said articulating surface and said first member are separate units.  
     
     
         49 . The joint prosthesis of  claim 42 , wherein said prosthetic femoral head and said prosthetic stem are separate units.  
     
     
         50 . The joint prosthesis of  claim 47 , wherein said prosthetic femoral head and said prosthetic stem are separate units.  
     
     
         51 . The implantable bearing component of  claim 31 , wherein the implantable bearing component is for use in a joint prosthesis.  
     
     
         52 . The implantable bearing component of  claim 51 , wherein the joint prosthesis is selected from the group consisting of: hip, knee, ankle, elbow, jaw, shoulder, finger and spine joint prostheses.  
     
     
         53 . The implantable bearing component of  claim 52 , wherein the joint prosthesis is selected from the group consisting of: hip and knee joint prostheses.  
     
     
         54 . The implantable bearing component of  claim 31 , wherein the implantable bearing component is selected from the group consisting of: an acetabular cup, an insert of an acetabular cup, and a liner of an acetabular cup.  
     
     
         55 . A joint prosthesis comprising: 
 a first member adapted to be secured to a first bone constituting a first portion of a joint;    an articulating surface on the first member;    a second member adapted to be secured to a second bone constituting a second portion of the joint; and    the implantable bearing component of  claim 31 , said implantable bearing component being adapted for disposition between the second member and the articulating surface, said implantable bearing component being adapted to receive said articulating surface for movement therein.    
     
     
         56 . The joint prosthesis of  claim 55 , wherein the joint prosthesis is selected from the group consisting of: hip, knee, ankle, elbow, jaw, shoulder, finger and spine joint prostheses.  
     
     
         57 . The joint prosthesis of  claim 56 , wherein the joint prosthesis is selected from the group consisting of: hip and knee joint prostheses.  
     
     
         58 . The joint prosthesis of  claim 55 , wherein the joint prosthesis is for use in a hip joint replacement wherein: 
 (a) the first bone is a femur;    (b) the second bone is a pelvic bone;    (c) the first member is a prosthetic stem;    (d) the second member is a prosthetic acetabular shell;    (e) the articulating surface is a prosthetic femoral head; and    (f) the implantable bearing component is selected from the group consisting of: an acetabular cup liner and an acetabular cup insert.    
     
     
         59 . The joint prosthesis of  claim 55 , wherein said articulating surface and said first member are separate units.  
     
     
         60 . A joint prosthesis comprising: 
 a first member adapted to be secured to a first bone constituting a first portion of the joint;    an articulating surface on the first member;    the implantable bearing component of  claim 31  adapted to be secured to a second bone constituting a second portion of the joint, said implantable bearing component being adapted to receive said articulating surface for movement therein.    
     
     
         61 . The joint prosthesis of  claim 60 , wherein the joint prosthesis is selected from the group consisting of: hip, knee, ankle, elbow, jaw, shoulder, finger and spine joint prostheses.  
     
     
         62 . The joint prosthesis of  claim 61 , wherein the joint prosthesis is selected from the group consisting of: hip and knee joint prostheses.  
     
     
         63 . The joint prosthesis of  claim 60 , wherein the joint prosthesis is for use in a hip joint replacement wherein: 
 (a) the first bone is a femur;    (b) the second bone is a pelvic bone;    (c) the first member is a prosthetic stem;    (d) the implantable bearing component is a prosthetic acetabular cup; and    (e) the articulating surface is a prosthetic femoral head.    
     
     
         64 . The joint prosthesis of  claim 60 , wherein said articulating surface and said first member are separate units  
     
     
         65 . The joint prosthesis of  claim 58 , wherein said prosthetic femoral head and said prosthetic stem are separate units.  
     
     
         66 . The joint prosthesis of  claim 63 , wherein said prosthetic femoral head and said prosthetic stem are separate units.  
     
     
         67 . The implantable bearing component of  claim 31 , wherein the polymer is crosslinked by radiation selected from the group consisting of: gamma radiation, electron beam radiation, and photon radiation.  
     
     
         68 . The implantable bearing component of  claim 31 , wherein the preformed polymer is in the form of a polyethylene bar or polyethylene block.