Radiovisible hydrogel intervertebral disc nucleus

Abstract

A spinal implant for replacing the natural nucleus of the disc made from a polymer such as hydrogel having a radiopaque material located within the polymer. The material may be in the form of a powder dispersed throughout the polymer or may be in he form of a powder dispersed in layers or in other specific locations within the polymer. The radiopaque material is metal such as gold, tungsten, titanium, tantalum or platinum. The metal may also be in the form of a foil or wire located within the hydrogel such as polyurethane, thereby making the implant visible on x-rays. Other polymers besides hydrogel may be used with the radiopaque material being dispersed therein.

1 . A method for forming a radiopaque polymeric spinal nucleus implant, comprising: 
 obtaining a polymer in a liquid phase (e.g. solution, melt, or pre-polymer);    mixing radiopaque particles with said polymer liquid phase; and    placing a first layer of the polymer solution in a mold, cooling the mold to solidify the layer, placing a first layer of said mixed polymer solution and radiopaque particles on top of the cooled first layer of polyvinyl and thereafter cooling the layer containing the radiopaque metal to form a layered implant.    
   
   
       2 . The method as set forth in  claim 1 , wherein said radiopaque material is a metal.  
   
   
       3 . The method as set forth in  claim 2 , wherein the metal is selected from the group consisting of gold, tungsten, tantalum, platinum, titanium and a combination thereof.  
   
   
       4 . The method as set forth in  claim 3 , wherein the polymer is a hydrogel.  
   
   
       5 . The method as set forth in  claim 4 , wherein the solution is a polyvinyl alcohol solution.  
   
   
       6 . The method as set forth in  claim 5 , wherein a second layer of the polyvinyl alcohol solution is placed on top of said first layer of mixed polymer solution, the second layer pf polyvinyl alcohol solution cooled and a second layer of mixed polyvinyl alcohol and radiopaque particles is placed on the cooled second layer of polyvinyl alcohol solution and thereafter cooling the second mixed layer.  
   
   
       7 . The method as set forth in  claim 1 , wherein the polymer is a polyurethane.  
   
   
       8 . The method as set forth in  claim 1  further comprising placing a second layer of polymer solution in the mold on said first layer of mixed polymer and radiopaque particles, cooling said second polymer solution layer to solidify the same and placing a second layer of said mixed polymer and radiopaque particles solution on said second layer of polymer solution.  
   
   
       9 . The method as set forth in  claim 3  wherein the particle has a diameter of between 10 and 100 μm.  
   
   
       10 . The method as set forth in  claim 9 , wherein the particle has a minimum diameter of about 75 μm.  
   
   
       11 . The method as set forth in  claim 1 , wherein the polymer solution is selected from the group consisting of a hydrogel, a cross-linked protein and a polyurethane.  
   
   
       12 . A method for forming a radiopaque polymeric spinal nucleus implant, comprising: 
 obtaining a polymer in a liquid phase (e.g. solution, melt, or pre-polymer);    mixing radiopaque particles with said polymer liquid phase; and    placing a first layer of the polymer solution in a mold, freezing the mold to solidify the layer, placing a first layer of said mixed polymer solution and radiopaque particles on top of the solidified first layer of polyvinyl and thereafter freezing the layer containing the radiopaque metal to form a layered implant.