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 disbursed throughout the polymer or may be in he form of a powder disbursed 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 disbursed therein.

1 . A spinal implant for replacing the natural nucleus of the disc made of a material comprising: 
 a radiopaque material located within the implant material.    
     
     
         2 . The spinal implant as set forth in  claim 1 , wherein the radiopaque material is a metal.  
     
     
         3 . The spinal implant as set forth in  claim 2 , wherein the radiopaque metal is a powder disbursed throughout the implant.  
     
     
         4 . The spinal implant as set forth in  claim 3 , wherein the metal powder is selected from the group consisting of gold, tungsten, tantalum, platinum, titanium and a combination thereof.  
     
     
         5 . The spinal implant as set forth in  claim 4 , wherein the powder has a diameter of between 10 and 100 μm.  
     
     
         6 . The spinal implant as set forth in  claim 5 , wherein the powder has a maximum diameter of about 75 μm.  
     
     
         7 . The spinal implant as set forth in  claim 2 , wherein the metal is in the form of a foil.  
     
     
         8 . The spinal implant as set forth in  claim 7 , wherein the metal foil is in the form of flakes scattered throughout the implant.  
     
     
         9 . The spinal implant as set forth in  claim 8 , wherein the flakes are 1-100 μm in size.  
     
     
         10 . The spinal implant as set forth in  claim 7 , wherein the metal foil is selected from the group consisting of gold foil, tungsten foil, tantalum foil, titanium foil and platinum foil.  
     
     
         11 . The spinal implant as set forth in  claim 2 , wherein the metal is at least one wire.  
     
     
         12 . The spinal implant as set forth in  claim 11 , wherein the metal wire has a diameter of 1-100 μm.  
     
     
         13 . The spinal implant as set forth in  claim 12 , wherein the metal is selected from the group consisting of gold, tungsten, tantalum, titanium and platinum.  
     
     
         14 . The spinal implant as set forth in  claim 1 , wherein the implant material is selected from the group consisting of a hydrogel, a cross-linked protein and a polyurethane.  
     
     
         15 . A spinal implant for replacement of the part of a natural disc nucleus comprising a hydrogel having a radiopaque material within the hydrogel.  
     
     
         16 . The spinal implant as set forth in  claim 15 , wherein the radiopaque material is a metal powder.  
     
     
         17 . The spinal implant as set forth in  claim 15 , wherein the metal powder is disbursed in layers throughout the polymer.  
     
     
         18 . The spinal implant as set forth in  claim 17 , wherein the metal powder is selected from the group consisting of gold, tungsten, tantalum, platinum, titanium and a combination thereof.  
     
     
         19 . 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 a radiopaque material with said polymer liquid phase;    placing said-mixed liquid phase in a mold or in a cavity bounded by the contours of a space created in an intervertebral disc; and    cooling said mixed solution to form a solid implant.    
     
     
         20 . The method as set forth in  claim 19 , wherein said radiopaque material is a metal.  
     
     
         21 . The method as set forth in  claim 20 , wherein the metal is selected from the group consisting of gold, tungsten, tantalum, platinum, titanium and a combination thereof.  
     
     
         22 . The method as set forth in  claim 21 , wherein the polymer is a hydrogel.  
     
     
         23 . The method as set forth in  claim 22 , wherein the solution is a polyvinyl alcohol solution.  
     
     
         24 . The method as set forth in  claim 23  further including placing a first layer of the polyvinyl alcohol solution in the mold, cooling the mold to solidify the layer, placing a first layer of said mixed polyvinyl alcohol solution and metal powder on top of the cooled first layer of polyvinyl and thereafter cooling the layer containing the radiopaque metal to form a layered implant.  
     
     
         25 . The method as set forth in  claim 24 , wherein a second layer of polyvinyl alcohol is placed on top of said first layer of powder solution the second layer cooled and a second layer of polyvinyl alcohol powder metal mix is placed on the cooled second layer.  
     
     
         26 . The method as set forth in  claim 15 , wherein the polymer is a polyurethane.