Facet arthroplasty devices and methods

1 . A prosthesis to replace all or a portion of a cephalad portion of a natural facet joint on a vertebral body comprising

a prosthesis body accommodating fixation to the vertebral body at or near a pedicle and without support by a lamina, and

an artificial facet joint structure carried by the prosthesis body adapted and configured to replace all or a portion of a cephalad portion of a natural facet joint.

2 . A prosthesis according to claim 1

wherein the artificial facet joint structure is adapted and configured to replace a natural articular process of a cephalad portion of a natural facet joint.

3 . A prosthesis according to claim 1

wherein the artificial facet joint structure is adapted and configured to replace a natural articular process of a cephalad portion of a natural facet joint after removal of at least some of a lamina from the vertebral body.

4 . A prosthesis according to claim 1

wherein the artificial facet joint structure is adapted and configured to replace a natural articular process of a cephalad portion of a natural facet joint after removal of at least part of an accessory process from the vertebral body

5 . A prosthesis according to claim 1

wherein the artificial facet joint structure is adapted and configured to replace a natural articular process of a cephalad portion of a natural facet joint after removal of at least part of a transverse process from the vertebral body.

6 . A prosthesis according to claim 1

wherein the artificial facet joint structure is adapted and configured to replace a natural articular process of a cephalad portion of a natural facet joint after removal of at least part of a pedicle from the vertebral body.

7 . A prosthesis according to claim 1

wherein the artificial facet joint structure is adapted and configured to replace a natural articular process of a cephalad portion of a natural facet joint after removal of at least some of the natural articular process from the vertebral body.

8 . A prosthesis according to claim 1

wherein the artificial facet joint structure is adapted and configured to replace a natural articular process of a cephalad portion of a natural facet joint after removal of at least some of the natural articular process and of at least some of a lamina from the vertebral body.

9 . A prosthesis according to claim 1

wherein the artificial facet joint structure is adapted and configured to replace a natural articular process of a cephalad portion of a natural facet joint after removal of at least some of the natural articular process and of at least some of an accessory process from the vertebral body.

10 . A prosthesis according to claim 1

wherein the artificial facet joint structure is adapted and configured to replace a natural articular process of a cephalad portion of a natural facet joint after removal of at least some of the natural articular process and of at least part of a transverse process from the vertebral body.

11 . A prosthesis according to claim 1

wherein the artificial facet joint structure is adapted and configured to replace a natural articular process of a cephalad portion of a natural facet joint after removal of at least some of the natural articular process and of at least part of a pedicle from the vertebral body.

12 . A prosthesis according to claim 1

wherein the artificial facet joint structure is adapted and configured to replace a natural articular process of a cephalad portion of a natural facet joint, and

wherein the prosthesis body is adapted and configured to replace at least some of a lamina of the vertebral body.

13 . A prosthesis according to claim 1

wherein the artificial facet joint structure is adapted and configured to replace a natural articular process of a cephalad portion of a natural facet joint, and

wherein the prosthesis body is adapted and configured to replace at least some of a mamillary process of the vertebral body.

14 . A prosthesis according to claim 1

wherein the prosthesis body is adapted and configured to replace at least some of a lamina of the vertebral body.

15 . A prosthesis according to claim 1

wherein the prosthesis body is adapted and configured to replace at least some of a mamillary process of the vertebral body.

16 . A prosthesis according to claim 1

wherein the artificial facet joint structure is adapted and configured to articulate with a caudal portion of a facet joint of an adjoining vertebral body.

17 . A prosthesis according to claim 1

wherein the artificial facet joint structure is made of at least one selected prosthetic material.

18 . A prosthesis according to claim 17

wherein the selected prosthetic material includes polyethylene, rubber, tantalum, titanium, chrome cobalt, surgical steel, bony in-growth material, ceramic, artificial bone, or a combination thereof.

19 . A method of replacing, on a vertebral body, all or a portion of a cephalad portion of a natural facet joint using the prosthesis defined in claim 1 to provide improved support for the spinal column, the method comprising the steps of

(i) removing all or a portion of a natural articular process of the cephalad portion of the natural facet joint from the vertebral body, and

(ii) fixing the prosthesis as defined in claim 1 to the vertebral body to replace the removed portion of the natural articular process with the artificial facet joint structure.

20 . A method according to claim 19

further including a step of removing at least part of an accessory process from the vertebral body.

21 . A method according to claim 19

further including a step of removing at least part of a transverse process from the vertebral body.

22 . A method according to claim 19

further including a step of removing at least part of a pedicle from the vertebral body.