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 spinal disc prosthesis insertion apparatus, comprising:
 a shell including a hollow interior, an open upper end, and an open lower end opposing said open upper end; and   a compressed, solid compressible prosthesis element slidably disposed in said shell.   
     
     
         2 . The spinal disc prosthesis insertion apparatus of  claim 1  wherein said shell and said prosthesis element each have a circular cross-section. 
     
     
         3 . The spinal disc prosthesis apparatus of  claim 1  wherein said shell further comprises a finger tab disposed adjacent to said upper end of said shell. 
     
     
         4 . The spinal disc prosthesis apparatus of  claim 3  wherein said finger tab extends around the perimeter of said shell and radially extends outwardly therefrom. 
     
     
         5 . The spinal disc prosthesis apparatus of  claim 2  wherein a portion of the outside surface of said shell adjacent said lower end of said shell is tapered to impart a coring surface to said lower end of said shell. 
     
     
         6 . The spinal disc prosthesis apparatus of  claim 1  wherein two or more compressed, solid compressible prosthesis elements are slidably disposed in said shell. 
     
     
         7 . A spinal disc prosthesis consisting of a single compressible prosthesis element that can be compressed to a size that allows the element to be inserted through the back of a patient into an enlarged disc cavity formed within the interiors of adjacent spinal vertebrae of the patient. 
     
     
         8 . The disc prosthesis of  claim 7  wherein the prosthesis element is formed of a solid material comprising polyurethane, polyurethane coated with a material that makes the element inert with respect to the patient's body, polypropylene, polyethylene, polytetrafluoroethylene or polydimethylsiloxane. 
     
     
         9 . The disc prosthesis of  claim 7  wherein the prosthesis element deforms at pressures in the range from about 400 psi to about 600 psi. 
     
     
         10 . The disc prosthesis of  claim 9  wherein said prosthesis element is formed of a solid, rubbery compressible material that expands back to its original shape after it is compressed. 
     
     
         11 . A spinal disc prosthesis for insertion in adjacent spaces within the interiors of adjacent vertebrae to restore spine function, said spinal disc prosthesis comprising two solid compressible prosthesis elements, said prosthesis elements being formed of a material that allows the prosthesis elements to be compressed, upon the application of mechanical force alone, to a size small enough for the prosthesis elements to be inserted in adjacent spaces within the interiors of adjacent vertebrae and that causes the prosthesis elements, solely upon removal of the mechanical force, to expand to their original shape thereby causing the prosthesis elements to be trapped in said spaces within the interiors of adjacent vertebrae. 
     
     
         12 . The disc prosthesis of  claim 11  wherein the two solid compressible prosthesis elements are formed of a solid material comprising polyurethane, polypropylene, polyethylene, polytetrafluoroethylene or polydimethylsiloxane. 
     
     
         13 . The disc prosthesis of  claim 11  wherein the two solid compressible prosthesis elements are formed of polyurethane coated with a material that makes the cylinders inert with respect to the patient's body. 
     
     
         14 . The disc prosthesis of  claim 11  wherein the two solid compressible prosthesis elements deform at pressures in the range from about 5 psi to about 600 psi. 
     
     
         15 . The disc prosthesis of  claim 11  wherein the two solid compressible prosthesis elements are each formed of a solid material comprising polyurethane. 
     
     
         16 . The disc prosthesis of  claim 11  wherein the two solid compressible prosthesis elements are each formed of a cylindrical shape.