Intervertebral Disc Nucleus Implants and Methods

Abstract

Nucleus pulposus implants that are resistant to migration in and/or expulsion from an intervertebral disc space are provided. In one form of the invention, an implant includes a load bearing elastic body surrounded in the disc space by an anchoring, preferably resorbable, outer shell. In certain forms of the invention, the elastic body is surrounded by a supporting member, such as a band or jacket, and the supporting member is surrounded by the outer shell. Kits for forming such implants are also provided. In another form of the invention, an implant is provided that has locking features and optional shape memory characteristics. In yet another aspect of the invention, nucleus pulposus implants are provided that have shape memory characteristics and are configured to allow short-term manual, or other deformation without permanent deformation, cracks, tears, breakage or other damage. Methods of forming and implanting the implants are also described, as are delivery devices and components thereof for delivering the implants.

1 . A method of determining the appropriate size of an implant to be implanted in an intervertebral disc space comprising:
 a) preparing the intervertebral disc space to receive an implant;   b) inserting an inflatable balloon into the prepared disc space;   c) filling the balloon with fluid; and   d) measuring the amount of fluid used to fill the balloon.   
     
     
         2 . The method as claimed in  claim 1 , wherein the intervertebral disc space is prepared by removing at least a portion of natural nucleus pulposus from the disc space. 
     
     
         3 . The method as claimed in  claim 1 , wherein the intervertebral disc space is prepared by forming a small incision in the annulus fibrosus, and removing at least a portion of natural nucleus pulposus from the disc space. 
     
     
         4 . The method as claimed in  claim 1 , wherein the implant comprises a load bearing elastic body surrounded by an outer shell. 
     
     
         5 . The method as claimed in  claim 1 , wherein the implant is comprised of a shape memory material formed from a hydrophilic material. 
     
     
         6 . The method as claimed in  claim 1 , wherein the implant fully replaces the natural nucleus pulposus. 
     
     
         7 . The method as claimed in  claim 1 , further comprising distracting the disc space to a desired level prior to inserting the inflatable balloon. 
     
     
         8 . The method as claimed in  claim 1 , wherein the fluid is saline. 
     
     
         9 . A method of implanting an implant in an intervertebral disc space comprising:
 a) preparing the intervertebral disc space to receive the implant;   b) measuring the size of the prepared disc space by inserting an inflatable balloon, filling the balloon with fluid, and measuring the amount of fluid required to fill the balloon, to thereby determine the appropriate size of the implant; and   c) placing an appropriately sized implant into the prepared disc space.   
     
     
         10 . The method as claimed in  claim 9 , wherein the intervertebral disc space is prepared by removing at least a portion of natural nucleus pulposus from the disc space. 
     
     
         11 . The method as claimed in  claim 9 , wherein the intervertebral disc space is prepared by forming a small incision in the annulus fibrosus, and removing at least a portion of natural nucleus pulposus from the disc space. 
     
     
         12 . The method as claimed in  claim 9 , wherein the implant fully replaces the natural nucleus pulposus. 
     
     
         13 . The method as claimed in  claim 9 , further comprising distracting the disc space to a desired level prior to measuring the size of the disc space. 
     
     
         14 . The method as claimed in  claim 9 , wherein the fluid is saline. 
     
     
         15 . A method of determining the appropriate size of an implant to be implanted in an intervertebral disc space comprising:
 a) preparing the intervertebral disc space to receive an implant;   b) distracting the disc space to a desired level;   c) inserting an inflatable balloon into the prepared disc space;   d) filling the balloon with fluid; and   e) measuring the amount of fluid used to fill the balloon.   
     
     
         16 . The method as claimed in  claim 15 , wherein the intervertebral disc space is prepared by removing at least a portion of natural nucleus pulposus from the disc space. 
     
     
         17 . The method as claimed in  claim 15 , wherein the intervertebral disc space is prepared by forming a small incision in the annulus fibrosus, and removing at least a portion of natural nucleus pulposus from the disc space. 
     
     
         18 . The method as claimed in  claim 15 , wherein the implant comprises a load bearing elastic body surrounded by an outer shell. 
     
     
         19 . The method as claimed in  claim 15 , wherein the implant fully replaces the natural nucleus pulposus. 
     
     
         20 . The method as claimed in  claim 15 , wherein the fluid is saline.