Apparatus for Implanting Prosthetic Intervertebral Discs in a Spine
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 . An apparatus for implanting a prosthetic disc between two adjacent vertebrae in a patient's spinal column, comprising: a first pusher having an attachment member for selectively attaching a first endplate of the prosthetic disc, a second pusher having a first chisel, and a spacer located between said first pusher and said second pusher, said spacer being adapted to provide a force separating said attachment member and said first chisel.
2 . The apparatus of claim 1 , further comprising: a third pusher attached to said spacer, and an advancement member connected to said third pusher and adapted to cause the spacer to move relative to one or both of the first pusher and the second pusher.
3 . The apparatus of claim 2 , further comprising a base member attached to a first end of said first pusher and a first end of said second pusher, said base member including a pivot pin to which is attached one or the other of said first pusher and said second pusher.
4 . The apparatus of claim 2 , wherein said advancement member comprises a gear adapted to engage a plurality of teeth formed on said third pusher.
5 . The apparatus of claim 2 , wherein said first chisel comprises at least one blade member adapted to engage a surface of one of said two adjacent vertebrae.
6 . The apparatus of claim 1 , wherein said spacer comprises a generally flat plate having one or more first grooves for engaging said first pusher and one or more second grooves for engaging said second pusher.
7 . The apparatus of claim 3 , wherein said first pusher is attached to said pivot pin such that said first pusher is capable of rotating about the pivot axis of said pivot pin.