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.