Spinal Disc Prosthesis Apparatus and Placement Method

Abstract

A spinal disc prosthesis and method of placing a spinal disc prosthesis between adjacent vertebrae are provided. The inventive spinal disc prosthesis can comprise one or more solid, compressible prosthesis elements that are formed prior to the method of placing the prosthesis, or one or more solid prosthesis elements that are formed in situ. The inventive method of placing a spinal disc prosthesis between adjacent vertebrae of a patient is based on a posterior approach. The invention also includes a spinal disc prosthesis insertion apparatus and specially constructed surgical instruments for use in carrying out the method.

1 . A router for forming additional spaces within the interiors of adjacent spinal vertebrae that intersect an enlarged partially circular space formed from the back and to one side of a space between the adjacent vertebrae that was previously occupied by a degenerated disc, said router comprising:
 an enlarged cylindrical portion of a size sufficient to form said additional spaces and having a diameter equal to or slightly less than the diameter of said enlarged partially circular space, said enlarged cylindrical portion including a flat upper surface, a flat lower surface and a cylindrical body connecting said upper surface to said lower surface, said cylindrical body including a plurality of sharp cutting points on the outside surface thereof for forming said additional spaces; and   a cylindrical shaft extending outwardly from said upper surface of said enlarged cylindrical portion, said shaft having a diameter substantially less than the diameter of said enlarged cylindrical portion.   
     
     
         2 . The router of  claim 1  wherein the cylindrical shaft is of a size of about ⅛ of an inch in diameter, and said enlarged cylindrical portion is of a size of about 9/16 of an inch in diameter. 
     
     
         3 . A rasp comprising an elongated shaft and a file portion attached to said shaft and transversely extending therefrom. 
     
     
         4 . The rasp of  claim 3  wherein said file portion extends substantially perpendicularly from said elongated shaft. 
     
     
         5 . The rasp of  claim 3  wherein the surface of said file portion includes a plurality of filing ridges thereon. 
     
     
         6 . The rasp of  claim 3  wherein said elongated shaft and said file portion each have a cylindrical cross-section. 
     
     
         7 . A thumbscrew apparatus comprising an elongated tapered tube having a cap on the large end, having a thumbscrew threadedly connected through the cap and having a push rod attached to the thumbscrew within the tapered tube for compressing and pushing a solid compressible cylinder formed of a rubbery substance. 
     
     
         8 . The thumbscrew apparatus of  claim 7  wherein a solid compressible cylinder compressed in the tapered tube thereof is pushed out by the thumbscrew and push rod.