Prostheses, systems and methods for replacement of natural facet joints with artifical facet joint surfaces

• US 20030028250A1
• Filed: 05/30/2002
• Published: 02/06/2003
• Est. Priority Date: 10/22/1999
• Status: Active Grant

• Current Assignee: Globus Medical, Inc.
• Original Assignee: Archus Orthopedics, Inc. (Globus Medical, Inc.)
• Inventors: Scribner, Robert M., Reiley, Mark A., Davidson, James
• Granted Patent: US 6,974,478 B2
• Time in Patent Office: Days
• US Class Current: 623/17.11
• CPC Class Codes: A61B 17/7064 Devices acting on, attached to, or simulating the effect of, vertebral facets; Tools therefor
• CPC Class Codes: A61B 17/86 Pins or screws or threaded wires; nuts therefor A61B17/72 take precedence
• CPC Class Codes: A61F 2/28 Bones joints A61F2/30
• CPC Class Codes: A61F 2/4405 for apophyseal or facet joints, i.e. between adjacent spinous or transverse processes devices implanted between spinous or transverse processes A61B17/7062
• CPC Class Codes: A61F 2002/30387 Dovetail connection
• CPC Class Codes: A61F 2002/30433 using additional screws, bolts, dowels, rivets or washers e.g. connecting screws
• CPC Class Codes: A61F 2002/305 Snap connection
• CPC Class Codes: A61F 2002/30537 adjustable
• CPC Class Codes: A61F 2002/30604 modular
• CPC Class Codes: A61F 2002/30777 Oblong apertures
• CPC Class Codes: A61F 2002/30873 Threadings machined on non-cylindrical external surfaces
• CPC Class Codes: A61F 2002/449 comprising multiple spinal implants located in different intervertebral spaces or in different vertebrae
• CPC Class Codes: A61F 2002/4631 the prosthesis being specially adapted for being cemented
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0041 using additional screws, bolts, dowels or rivets, e.g. connecting screws
• CPC Class Codes: A61F 2250/0004 adjustable
• CPC Class Codes: A61F 2310/00017 Iron- or Fe-based alloys, e.g. stainless steel
• CPC Class Codes: A61F 2310/00023 Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00029 Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium
• CPC Class Codes: A61F 2310/00131 Tantalum or Ta-based alloys
• CPC Class Codes: A61F 2310/00179 : Ceramics or ceramic-like structures
• CPC Class Codes: A61F 2310/00329 : Glasses, e.g. bioglass
• CPC Class Codes: A61F 2310/00604 : Coating made of aluminium oxide or hydroxides
• CPC Class Codes: A61F 2310/00634 : Coating made of zirconium oxide or hydroxides
• CPC Class Codes: A61F 2310/0097 : Coating or prosthesis-covering structure made of pharmaceutical products, e.g. antibiotics
• CPC Class Codes: A61F 2310/00976 : Coating or prosthesis-covering structure made of proteins or of polypeptides, e.g. of bone morphogenic proteins BMP or of transforming growth factors TGF
• CPC Class Codes: Y10S 606/907 : Composed of particular material or coated
• CPC Class Codes: Y10S 606/91 : Polymer

Abstract

Cephalad and caudal vertebral facet joint prostheses and methods of use are provided. The prostheses provide an artificial facet joint structure including an artificial articular configuration unlike the preexisting articular configuration. The radii and material stress values of the prostheses are configured to sustain contact stress. The cephalad prosthesis provides for posterior-anterior adjustment. Both prostheses permit lateral adjustment and adjustment to accomodate interpedicle distance. Further, the prostheses may be customized to provide a pre-defined lordotic angle and a pre-defined pedicle entry angle.

Claims

1. A facet joint prosthesis to replace, on a vertebral body, a portion of a natural facet joint, the prosthesis comprising a component sized to be fixed to the vertebral body and including an artificial facet joint structure adapted to replace the portion of the natural facet joint, a fixation region on the component being configured and arranged to receive a fixation element to fix the component to the vertebral body on or near a pedicle, the fixation region being sized to accommodate adjustment of the component on the vertebral body.

2. A facet joint prosthesis according to claim 1

wherein the fixation region is sized to accommodate lateral adjustment of the component on the vertebral body.

3. A facet joint prosthesis according to claim 1

wherein the fixation region is sized to accommodate inferior-superior adjustment of the component on the vertebral body.

4. A facet joint prosthesis according to claim 1

wherein the artificial facet joint structure comprises a generally convex surface.

5. A facet joint prosthesis according to claim 1

wherein the artificial facet joint structure comprises a generally concave surface.

6. A facet joint prosthesis according to claim 1

wherein the artificial facet joint structure comprises a surface adapted to articulate with another facet joint structure.

7. A facet joint prosthesis according to claim 1

wherein the artificial facet joint structure comprises a surface adapted to articulate with another artificial facet joint structure.

8. A facet joint prosthesis according to claim 1

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

9. A facet joint prosthesis according to claim 1

wherein the artificial facet joint structure is adapted to replace a caudal portion of the natural facet joint.

10. A facet joint prosthesis according to claim 1

wherein the fixation region is configured and arranged to support the fixation element at a desired pedicle entry angle.

11. A facet joint prosthesis according to claim 1

wherein the fixation region is configured and arranged to support the fixation element at an angle that approximates a desired lardotic angle.

12. A facet joint prosthesis according to claim 1

further including a second fixation region on the component being configured and arranged to fix the component to the vertebral body on or near a spinous process.

47. A method of replacing, on a vertebral body, a portion of a natural facet joint using the prosthesis as defined in claim 1, the method comprising the steps of

(i) removing at least a 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 facet joint with the artificial facet joint structure.

55. A method of replacing, on a vertebral body, a portion of a natural facet joint using the prosthesis as defined in claim 46, the method comprising the steps of

(i) removing at least a 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 facet joint with the artificial facet joint structure.

13. A facet joint prosthesis to replace, on a vertebral body, a portion of a natural facet joint, the prosthesis comprising a component sized to be fixed to the vertebral body and including an artificial facet joint structure adapted to replace the portion of the natural facet joint, the artificial facet joint structure being mounted for movement on the component.

14. A facet joint prosthesis according to claim 13

wherein the artificial facet joint structure is mounted for posterior-anterior movement on the component.

15. A facet joint prosthesis according to claim 13

wherein the artificial facet joint structure comprises a generally convex surface.

16. A facet joint prosthesis according to claim 13

wherein the artificial facet joint structure comprises a generally concave surface.

17. A facet joint prosthesis according to claim 13

wherein the artificial facet joint structure comprises a surface adapted to articulate with another facet joint structure.

18. A facet joint prosthesis according to claim 13

wherein the artificial facet joint structure comprises a surface adapted to articulate with another artificial facet joint structure.

19. A facet joint prosthesis according to claim 13

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

20. A facet joint prosthesis according to claim 13

wherein the fixation region is configured and arranged to support the fixation element at a desired pedicle entry angle.

21. A facet joint prosthesis according to claim 13

wherein the fixation region is configured and arranged to support the fixation element at an angle that approximates a desired lardotic angle.

22. A facet joint prosthesis according to claim 13

further including a second fixation region on the component being configured and arranged to fix the component to the vertebral body on or near a spinous process.

48. A method of replacing, on a vertebral body, a portion of a natural facet joint using the prosthesis as defined in claim 13, the method comprising the steps of

(i) removing at least a portion of the natural facet joint from the vertebral body, and

(ii) fixing the prosthesis as defined in claim 13 to the vertebral body to replace the removed portion of the natural facet joint with the artificial facet joint structure.

23. A prosthesis assembly for replacing the inferior and superior halves of a natural facet joint comprising

a cephalad prosthesis comprising a component sized to be fixed to a vertebral body and including a first artificial facet joint structure adapted to replace the inferior half of the natural facet joint, a first fixation region on the component being configured and arranged to receive a fixation element to fix the component to the vertebral body on or near a pedicle, a caudal prosthesis comprising a component sized to be fixed to a vertebral body and including a second artificial facet joint structure adapted to replace the superior half of the natural facet joint, a second fixation region on the component being configured and arranged to receive a fixation element to fix the component to the vertebral body on or near a pedicle,

the first and second artificial facet joint structures articulating to form, respectively, the superior and inferior halves of an artificial facet joint, and

at least one of the first and second fixation regions being sized to accommodate adjustment of the respective component on the respective vertebral body.

24. A prosthesis assembly according to claim 23

wherein the at least one fixation region is sized to accommodate lateral adjustment of the respective component on the respective vertebral body.

25. A prosthesis assembly according to claim 23

wherein the at least one fixation region is sized to accommodate inferior-superior adjustment of the respective component on the respective vertebral body.

26. A prosthesis assembly according to claim 23

wherein the first artificial facet joint structure comprises a generally convex surface, and

wherein the second artificial facet joint structure comprises a generally concave surface articulating with the generally convex surface.

27. A prosthesis assembly according to claim 23

wherein the first artificial facet joint structure comprises a generally concave surface, and

wherein the second artificial facet joint structure comprises a generally convex surface articulating with the generally concave surface.

28. A prosthesis assembly according to claim 23

wherein the first and second artificial facet joint structures comprise articulating metal surfaces having a contact stress less than about 25,000 psi.

29. A prosthesis assembly according to claim 28

wherein the contact stress is less than about 12,000 psi.

30. A prosthesis assembly according to claim 23

wherein at least one of the first and second artificial facet joint structures comprises an articulating polymer surface having a contact stress less than about 10,000 psi.

31. A prosthesis assembly according to claim 30

wherein the contact stress is less than about 5,000 psi.

32. A prosthesis assembly according to claim 23

wherein at least one of the first and second fixation regions is configured and arranged to support the respective fixation element at a desired pedicle entry angle.

33. A facet joint prosthesis according to claim 23

wherein at least one of the first and second fixation regions is configured and arranged to support the respective fixation element at an angle that approximates a desired lardotic angle.

34. A prosthesis assembly according to claim 23

wherein the cephalad prosthesis further includes an auxiliary fixation region on the respective component configured and arranged to fix the respective component to the respective vertebral body on or near a spinous process.

35. A prosthesis assembly according to claim 23

wherein the first artificial facet joint structure is mounted for movement on the cephalad prosthesis.

36. A prosthesis assembly for replacing the inferior and superior halves of a natural facet joint comprising

a cephalad prosthesis comprising a component sized to be fixed to a vertebral body and including a first artificial facet joint structure adapted to replace the inferior half of the natural facet joint, a caudal prosthesis comprising a component sized to be fixed to a vertebral body and including a second artificial facet joint structure adapted to replace the superior half of the natural facet joint, the first and second artificial facet joint structures articulating to form, respectively, the superior and inferior halves of an artificial facet joint, and

the first and second artificial facet joint structures comprise articulating metal surfaces having a contact stress less than about 25,000 psi.

37. A prosthesis assembly according to claim 36

wherein the contact stress is less than about 12,000 psi.

38. A prosthesis assembly for replacing the inferior and superior halves of a natural facet joint comprising

a cephalad prosthesis comprising a component sized to be fixed to a vertebral body and including a first artificial facet joint structure adapted to replace the inferior half of the natural facet joint, a caudal prosthesis comprising a component sized to be fixed to a vertebral body and including a second artificial facet joint structure adapted to replace the superior half of the natural facet joint, the first and second artificial facet joint structures articulating to form, respectively, the superior and inferior halves of an artificial facet joint, and

at least one of the first and second artificial facet joint structures comprises an articulating polymer surface having a contact stress less than about 10,000 psi.

39. A prosthesis assembly according to claim 38

wherein the contact stress is less than about 5,000 psi.

40. A facet joint prosthesis to replace, on a vertebral body, a portion of a natural facet joint, the prosthesis comprising a component sized to be fixed to the vertebral body and including an artificial facet joint structure adapted to replace the portion of the natural facet joint, a fixation element on the component being configured and arranged to engage a portion of the lamina to fix the component to the vertebral body.

41. A facet joint prosthesis according to claim 40

wherein the fixation element comprises a hook.

53. A method of replacing, on a vertebral body, a portion of a natural facet joint using the prosthesis as defined in claim 40, the method comprising the steps of

(i) removing at least a portion of the natural facet joint from the vertebral body, and

(ii) fixing the prosthesis as defined in claim 40 to the vertebral body to replace the removed portion of the natural facet joint with the artificial facet joint structure.

42. A facet joint prosthesis to replace, on a vertebral body, a portion of a natural facet joint, the prosthesis comprising a component sized to be fixed to the vertebral body and including an artificial facet joint structure adapted to replace the portion of the natural facet joint, a fixation region on the component being configured and arranged to receive a fixation element to fix the component to the vertebral body on or near a pedicle, the fixation region being configured and arranged to support the fixation element at a desired pedicle entry angle.

43. A facet joint prosthesis according to claim 42

wherein the component includes laterally spaced first and second fixation regions each being configured and arranged to support a fixation element at a desired pedicle entry angle.

44. A facet joint prosthesis according to claim 43

wherein the desired pedicle entry angle for the first fixation region differs from the desired pedicle entry region for the second fixation region.

45. A facet joint prosthesis according to claim 42

wherein the fixation region is configured and arranged to support the fixation element at an angle that approximates a desired lardotic angle.

54. A method of replacing, on a vertebral body, a portion of a natural facet joint using the prosthesis as defined in claim 42, the method comprising the steps of

(i) removing at least a portion of the natural facet joint from the vertebral body, and

(ii) fixing the prosthesis as defined in claim 42 to the vertebral body to replace the removed portion of the natural facet joint with the artificial facet joint structure.

46. A facet joint prosthesis to replace, on a vertebral body, a portion of a natural facet joint, the prosthesis comprising a component sized to be fixed to the vertebral body and including an artificial facet joint structure adapted to replace the portion of the natural facet joint, a fixation region on the component being configured and arranged to receive a fixation element to fix the component to the vertebral body on or near a pedicle, the fixation region being configured and arranged to support the fixation element at an angle that approximates a desired lardotic angle.

49. A method for replacing the inferior and superior halves of a natural facet joint comprising the steps of

removing the inferior and superior halves of the natural facet joint,

fixing a cephalad prosthesis to a vertebral body that includes a first artificial facet joint structure to replace the inferior half of the natural facet joint,

fixing a caudal prosthesis to a vertebral body that includes a second artificial facet joint structure to replace the superior half of the natural facet joint, the first and second artificial facet joint structures articulating to form, respectively, the superior and inferior halves of an artificial facet joint, and

selecting for the first and second artificial facet joint structures articulating metal surfaces having a contact stress less than about 25,000 psi.

50. A method according to claim 49

wherein the contact stress is less than about 12,000 psi.

51. A method for replacing the inferior and superior halves of a natural facet joint comprising the steps of

removing the inferior and superior halves of the natural facet joint,

fixing a cephalad prosthesis to a vertebral body that includes a first artificial facet joint structure to replace the inferior half of the natural facet joint,

fixing a caudal prosthesis to a vertebral body that includes a second artificial facet joint structure to replace the superior half of the natural facet joint, the first and second artificial facet joint structures articulating to form, respectively, the superior and inferior halves of an artificial facet joint, and selecting for the first and second artificial facet joint structures at least one articulating polymer surface having a contact stress less than about 10,000 psi.

52. A method according to claim 51

wherein the contact stress is less than about 5,000 psi.