Intervertebral nucleus prosthesis and surgical procedure for implanting the same
An intervertebral nucleus prosthesis is proposed, which is characterized in that it consists of at least one, in particular, spherical body movable in two directions of a plane and made of a rigid, non-oxidizing, biocompatible material with a diameter adapted to the biological nucleus, the spherical body being mounted non-displaceably but freely rotatably about its center in a cage and protruding at both opposite sides in the form of a spherical cap from the cage. Also proposed is a method for implanting such a prosthesis.
1. Intervertebral nucleus prosthesis having dimensions adapted to a biological intervertebral nucleus and comprising:
at least one cage comprising a plurality of substantially spherical recesses and a horizontal center plane; and
a plurality of substantially identical substantially spherical bodies or balls made of a substantially rigid, substantially non-oxidizing, biocompatible material, each of said substantially spherical bodies or balls
being disposed with its center substantially along said horizontal center plane in one of said substantially spherical recesses,
being rotatable about at least two axes through its center, and protruding through opposite sides of said cage in the form of substantially spherical caps.
2. Prosthesis according to claim 1 , wherein the substantially spherical bodies or balls are each rotatably captured in one of said substantially spherical recesses.
3. Prosthesis according to claim 1 wherein the at least one cage comprises plural substantially identical cages, each formed, in transverse section, substantially in the shape of an isosceles trapezoid.
4. Prosthesis according to claim 3 , wherein the prosthesis has a volume which, taking into consideration the function of the plural substantially identical cages as holders for the substantially spherical bodies or balls, is adapted to the volume of the biological nucleus to facilitate a self-positioning of the prosthesis and allow the prosthesis to be in the anatomical position and the natural movements between two vertebral bodies to be restored.
5. Prosthesis according to claim 1 , wherein the at least one cage has a volume which, taking into consideration the function of the cage as holder for the substantially spherical bodies or balls, is adapted to the volume of the biological nucleus to facilitate a self-positioning of the prosthesis and allow the prosthesis to be in the anatomical position and the natural movements between two vertebral bodies to be restored.
6. Intervertebral nucleus prosthesis having dimensions adapted to a biological intervertebral nucleus and comprising:
plural substantially identical cages each comprising a plurality of substantially spherical recesses and a horizontal center plane, the recesses arranged to form an isosceles triangle having corners and a base and disposed along the horizontal center plane, with said isosceles triangles of adjacent substantially identical cages being oppositely oriented and defining a longitudinal axis of the prosthesis substantially parallel to the bases of the isosceles triangles; and
a plurality of substantially identical substantially spherical bodies or balls made of a substantially rigid, substantially non-oxidizing, biocompatible material, each of said substantially spherical bodies or balls
being disposed with its center substantially along said horizontal center plane in one of said substantially spherical recesses of one of said substantially identical cages,
being rotatable about at least two axes through its center,
protruding through opposite sides of said one of said substantially identical cages in the form of substantially spherical caps; and
being located at a corner of the isosceles triangle of the one of said substantially identical cages, and
at least two elastic connecting elements connecting adjacent substantially identical cages, each of the two elastic connecting elements extending at right angles to the horizontal center planes of the adjacent substantially identical cages, and each of the elastic connecting elements being located near a corner of the isosceles triangles or near an end of the longitudinal axis of the prosthesis.
7. Prosthesis according to claim 6 , wherein the prosthesis has a volume which, taking into consideration the function of the plural substantially identical cages as holders for the substantially spherical bodies or balls, is adapted to the volume of the biological nucleus to facilitate a self-positioning of the prosthesis and allow the prosthesis to be in the anatomical position and the natural movements between two vertebral bodies to be restored.