Nucleus Prosthesis

Abstract

An nucleus prosthesis is disclosed having a plurality of linked segments configured to form, in a closed position, a disc shape. A method includes inserting a plurality of linked segments into an annulus fibrosus and closing the prosthesis so that a first segment inserted into the annulus fibrosus and a last segment inserted into the annulus fibrosus are substantially abutted. Another method includes inserting a plurality of linked segments into an intervertebral disc space and closing the prosthesis so that a first segment inserted into the intervertebral disc space and a last segment inserted into the intervertebral disc space are substantially abutted.

1 . A nucleus prosthesis comprising a plurality of segments, including a leading segment and a trailing segment, and a linkage coupling the segments, the prosthesis having:
 an open position in which the segments are disposed along the linkage in a serial line with the leading segment at an end of the serial line and the trailing segment at another end of the serial line; and   a closed position in which the segments are disposed to form a disc shape with the leading segment and the trailing segment substantially apposed.   
     
     
         2 . The prosthesis of  claim 1  in which one or more of the segments has an inner portion having a first elasticity and an outer portion having a second elasticity. 
     
     
         3 . The prosthesis of  claim 1  in which the linkage comprises a ligament. 
     
     
         4 . The prosthesis of  claim 3 , comprising a closure element on an end of the ligament. 
     
     
         5 . The prosthesis of  claim 4 , in which the closure element is configured to engage another end of the ligament, with such engagement configured to urge the prosthesis into a closed position. 
     
     
         6 . The prosthesis of  claim 3 , comprising a retainer disposed along the ligament and configured to hold the segments in the disc shape. 
     
     
         7 . The prosthesis of  claim 3  in which the ligament takes a secant path through the segments 
     
     
         8 . The prosthesis of  claim 1 , comprising a strip to which one or more of the segments are coupled. 
     
     
         9 . The prosthesis of  claim 8  in which one or more segments are coupled to the strip by a pin located in a channel of the strip. 
     
     
         10 . The prosthesis of  claim 8  in which a hinge between two of the segments is coupled to the strip by a pin located in a channel of the strip. 
     
     
         11 . The prosthesis of  claim 8  in which the strip is configured to fold around the segments. 
     
     
         12 . The prosthesis of  claim 11  in which the strip is configured to enclose the generally cylindrical shape. 
     
     
         13 . The prosthesis of  claim 1 , comprising an enclosure configured to hold the multi-segmented nucleus prosthesis. 
     
     
         14 . The device of  claim 13  in which the bag comprises a fabric sack. 
     
     
         15 . An nucleus prosthesis comprising:
 a plurality of segments configured for disposition in a disc shape; and   joints between the segments configured to enable vertical movement between individual segments when the segments are disposed in a disc shape.   
     
     
         16 . The prosthesis of  claim 15  in which the joints are formed by a male interlocking member on one of the segments and a female interlocking member on another one of the segments. 
     
     
         17 . The prosthesis of  claim 16  in which the male interlocking members comprise pins and the female interlocking members comprise channels. 
     
     
         18 . A method comprising:
 inserting a plurality of linked segments into an intervertebral disc space; and   coupling the segments together such that a face of a first segment inserted into the intervertebral disc space and a face of a last segment inserted into the intervertebral disc space are substantially apposed.   
     
     
         19 . The method of  claim 18 , comprising tightening a ligament disposed along the segments. 
     
     
         20 . The method of  claim 19 , comprising attaching a closure element located on one end of the ligament to another end of the ligament.