Prosthetic intervertebral discs having substantially rigid end plates and fibers between those end plates

Abstract

Prosthetic intervertebral discs and methods for using the same are described. The subject prosthetic discs include upper and lower endplates separated by a compressible core member. The prosthetic discs described herein include one-piece, two-piece, three-piece, and four-piece structures. The subject prosthetic discs exhibit stiffness in the vertical direction, torsional stiffness, bending stiffness in the saggital plane, and bending stiffness in the front plane, where the degree of these features can be controlled independently by adjusting the components of the discs. The interface mechanism between the endplates and the core members of several embodiments of the described prosthetic discs enables a very easy surgical operation for implantation.

1 . A prosthetic intervertebral disc comprising: 
 a first substantially rigid, physiologically acceptable end plate,    a second substantially rigid, physiologically acceptable end plate,    a compressible core member positioned between said first and second end plates, said core member comprising at least one fiber extending between and engaged with said first and second end plates.    
     
     
         2 . The prosthetic intervertebral disc of  claim 1  wherein said at least one fiber extends through said first end plate and through said second end plate.  
     
     
         3 . The prosthetic intervertebral disc of  claim 2  wherein said at least one fiber extending through said first end plate and through said second end plate is a single fiber.  
     
     
         4 . The prosthetic intervertebral disc of  claim 1  wherein said at least one fiber is oblique to said first end plate and said second end plate.  
     
     
         5 . The prosthetic intervertebral disc of  claim 1  wherein the core member and the at least one fiber extending between and engaged with said first and second end plates are configured to permit relative rotation of said first end plate relative to said second end.  
     
     
         6 . The prosthetic intervertebral disc of  claim 1  wherein the first end plate comprises a material is selected from the group consisting of titanium, titanium alloys, stainless steel, cobalt/chromium, ultrahigh molecular weight polyethylene (UHMW-PE), polyetheretherketone (PEEK), ceramics, and graphite.  
     
     
         7 . The prosthetic intervertebral disc of  claim 1  wherein the second end plate comprises a material is selected from the group consisting of titanium, titanium alloys, stainless steel, cobalt/chromium, ultrahigh molecular weight polyethylene (UHMW-PE), polyetheretherketone (PEEK), ceramics, and graphite.  
     
     
         8 . The prosthetic intervertebral disc of  claim 1  further comprising a plurality of fibers, wherein each of said plurality of fibers extends through said first end plate and through said second end plate.  
     
     
         9 . The prosthetic intervertebral disc of  claim 8  wherein said plurality of fibers define two or more layers of fibers of said core member.  
     
     
         10 . The prosthetic intervertebral disc of  claim 9  wherein two or more different fibers define the two or more layers of fibers of said core member.  
     
     
         11 . The prosthetic intervertebral disc of  claim 8  wherein each of said plurality of fibers defines a layer of fibers of said core member.  
     
     
         12 . The prosthetic intervertebral disc of  claim 8  wherein the fibers of a first layer and the fibers of a second layer exhibit the same tension.  
     
     
         13 . The prosthetic intervertebral disc of  claim 8  wherein the fibers of a first layer and the fibers of a second layer exhibit different tensions.  
     
     
         14 . The prosthetic intervertebral disc of  claim 8  wherein said fibers of a first layer extend at a first angle and said fibers of a second layer extend at a second angle, wherein said first angle is different than said second angle.  
     
     
         15 . The prosthetic intervertebral disc of  claim 1  wherein at least one of said at least one fibers comprises a member selected from the group consisting of elastomers, metals, and polymers and said at least one of said at least one fibers is further is selected from multifilament fibers, monofilament fibers, and encapsulated fibers.