Supplementation or replacement of a nucleus pulposus of an intervertebral disc

Abstract

A degenerated nucleus pulposus located in a central core region of an intervertebral disc within the annulus fibrosus is supplemented or replaced by a method wherein an amount of a biocompatible material is introduced into the central core region by a process including the steps of 1) forming a channel through a vertebral body adjacent to said intervertebral disc, extending from an exterior surface of the vertebral body to the central core region of the annulus fibrosus; 2) introducing an amount of a biocompatible material through the channel into the central core region of the annulus fibrosus; 3) pressurizing the biocompatible material through the channel to a postsurgical pressure sufficient to alleviate symptoms caused by the degenerated nucleus pulposus; and 4) sealing the channel while maintaining the sufficient postsurgical pressure. After sealing the channel, a vertebroplasty may optionally be performed in the vertebra.

1 . A method for replacing or supplementing a nucleus pulposus in an intervertebral disc, said intervertebral disc having an annulus fibrosus with a central core containing said nucleus pulposus, said method comprising: 
 forming a channel through a vertebral body adjacent to said intervertebral disc, said channel extending from an exterior surface of said vertebral body to said central core of said annulus fibrosus;    introducing an amount of a biocompatible material through said channel into said central core of said annulus fibrosus;    exerting pressure on said biocompatible material through said channel; and    sealing said channel while maintaining said pressure.    
   
   
       2 . The method of  claim 1 , wherein said pressure is sufficient to at least approximately restore natural function of said intervertebral disc.  
   
   
       3 . The method of  claim 1 , wherein said pressure is sufficient to at least approximately restore natural intervertebral spacing.  
   
   
       4 . The method of  claim 1 , wherein said biocompatible material is pressurized to a pressure approximating natural pressure of the nucleus pulposus.  
   
   
       5 . The method of  claim 1 , wherein said biocompatible material has a compressional modulus not greater than about 4 Mpa.  
   
   
       6 . The method of  claim 1 , wherein said biocompatible material is a hydrogel.  
   
   
       7 . The method of  claim 6 , wherein said hydrogel is comprised of a material selected from the group consisting of poly(vinyl alcohol) and an associating hydrogel that is a blend of poly(vinyl alcohol) and poly(vinylpyrrollidone).  
   
   
       8 . The method of  claim 1 , wherein said biocompatible material is selected from the group consisting of a polyurethane and a silicone.  
   
   
       9 . The method of  claim 1 , wherein said channel is sealed with a plug of a biocompatible sealing material.  
   
   
       10 . The method of  claim 9 , wherein said biocompatible sealing material is selected from the group consisting of a bone cement, an autograft, an allograft, and a xenograft.  
   
   
       11 . The method of  claim 10 , wherein said bone cement is selected from the group consisting of poly(methylmethacrylate), calcium phosphate, calcium sulfate, calcium carbonate, and hydroxyapatite  
   
   
       12 . The method of  claim 1 , wherein said channel is sealed with a plug of biocompatible sealing material and a mechanical plug.  
   
   
       13 . The method of  claim 12 , wherein said mechanical plug is selected from the group consisting of a bone screw and a barbed plug.  
   
   
       14 . The method of  claim 1 , wherein said implant is pressurized by inserting a bone screw or a barbed plug into said channel.  
   
   
       15 . The method of  claim 1 , additionally comprising a step of performing a vertebroplasty in said vertebral body after sealing said channel.  
   
   
       16 . A restorative implant for an intervertebral disc comprising: 
 a quantity of a biocompatible material implanted in a central core of a human intervertebral disc replacing or supplementing a nucleus pulposus, said quantity of biocompatible material being accessible through a channel formed in an adjacent vertebra; and    a plug positioned in said channel and exerting pressure on said quantity of implanted low modulus material.    
   
   
       17 . The implant of  claim 16 , wherein said postsurgical pressure is sufficient to at least approximately restore natural function of said intervertebral disc.  
   
   
       18 . The implant of  claim 16 , wherein said postsurgical pressure is sufficient to at least approximately restore natural intervertebral spacing.  
   
   
       19 . The implant of  claim 16 , wherein said biocompatible material is pressurized to a pressure approximating natural pressure of the nucleus pulposus.  
   
   
       20 . The implant of  claim 16 , wherein said biocompatible material has a compressional modulus not greater than about 4 Mpa.  
   
   
       21 . The implant of  claim 16 , wherein said biocompatible material has a Poisson ratio in a range of from about 0.30 to 0.50.  
   
   
       22 . The implant of  claim 26 , wherein said biocompatible material is a hydrogel.  
   
   
       23 . The implant of  claim 22 , wherein said hydrogel is a comprised of a material selected from the group consisting of poly(vinyl alcohol) and an associating hydrogel that is a blend of poly(vinyl alcohol) and poly(vinylpyrrollidone).  
   
   
       24 . The implant of  claim 16 , wherein said biocompatible material is selected from the group consisting of a polyurethane and a silicone.  
   
   
       25 . The implant of  claim 16  additionally comprising a predetermined quantity of a generally incompressible material positioned in said channel between said implanted material and said plug.  
   
   
       26 . The implant of  claim 25  wherein said generally incompressible material is selected from the group consisting of bone cement, an autograft, an allograft, and a xenograft.  
   
   
       27 . The implant of  claim 16  wherein said plug is selected from the group consisting of a bone screw and a barbed plug.  
   
   
       28 . A restorative implant for an intervertebral disc implanted by the method of  claim 1.