Disc Nucleus Replacement and Method of Use

Abstract

An artificial disc nucleus replacement includes two mating halves which are inserted into the patient from opposite lateral sides of the patient's back, and joined together with screws.

What is claimed is: 
     
         1 . A disc nucleus replacement comprising:
 a first portion having a top, a bottom, a generally semi-circular lateral outer surface extending between the top and the bottom, a flat outer lateral surface extending between the top and the bottom, and at least one bore extending through the first portion from the semi-circular lateral outer surface to the flat outer surface;   a second portion having a top, a bottom, a generally semi-circular lateral outer surface extending between the top and the bottom, a flat outer lateral surface extending between the top and the bottom, and at least one bore extending through the second portion from the flat outer surface towards the semi-circular lateral outer surface;   sliding dovetail joint formed in the first and second portions; and   wherein the at least one bore of the first portion, the at least one bore of the second portion, the semi-circular lateral outer surface of the first portion, and the semi-circular lateral outer surface of the second portion are mutually configured and arranged so that when the first and second portions are oriented with the flat surfaces abutting and the semi-circular lateral outer surfaces forming a generally circular form, the at least one bore of the first portion aligns with the at least one bore of the second portion to permit a single screw to be positioned therein.   
     
     
         2 . The disc nucleus replacement according to  claim 1 , wherein the dovetail joint comprises:
 a tail extending laterally from the flat outer lateral surface of one of the first and second portions; and   a socket formed in the flat outer lateral surface of the other of the first and second portions.   
     
     
         3 . The disc nucleus replacement according to  claim 2 , wherein said at least one bore extends through said tail. 
     
     
         4 . A method of implanting a disc nucleus replacement into a disc of a patient, the disc nucleus replacement having two mating portions, the nucleus of the patient's disc having previously been removed, the method comprising:
 forming two lateral incisions in the disc;   pushing one portion of the disc nucleus replacement through one of the lateral incisions and into place in the center of the patient's disc; and   pushing a second mating portion of the disc nucleus replacement through the same or the other lateral incision and adjacent to and into alignment with the first portion of the disc nucleus replacement.   
     
     
         5 . The method according to  claim 4 , wherein the two-piece disc nucleus replacement includes a dovetail joint, and wherein inserting the second portion comprises aligning the two portions of the dovetail joint so that inserting the second portion into place also comprises mating together the two portions of the disc nucleus replacement. 
     
     
         6 . The method according to  claim 4 , further comprising:
 positioning at least one screw in aligned bores of the disc nucleus replacement; and   securing the two portions together with said at least one screw.