Linked bilateral spinal facet implants and methods of use

• US 7,753,937 B2
• Filed: 06/02/2004
• Issued: 07/13/2010
• Est. Priority Date: 12/10/2003
• Status: Active Grant

• Current Assignee: Globus Medical, Inc.
• Original Assignee: Facet Solutions, Inc. (Globus Medical, Inc.)
• Inventors: Justin, Daniel F., Hoy, Robert W., Fallin, T. Wade, Chervitz, Alan
• Primary Examiner(s): Robert; Eduardo C
• Assistant Examiner(s): HARVEY, JULIANNA NANCY
• Application Number:
  US10/860,495
• Publication Number:
  US 20050131409A1
• Time in Patent Office: 2,232 Days
• Field of Search: 623 1611- 1716, 606247-253, 606/256, 606/266
• US Class Current: 606/247
• CPC Class Codes: A61B 17/7049 Connectors, not bearing on the vertebrae, for linking longitudinal elements together A61B17/7055, A61B17/7053, A61B17/7019 take precedence
• CPC Class Codes: A61B 17/7064 Devices acting on, attached to, or simulating the effect of, vertebral facets; Tools therefor
• CPC Class Codes: A61B 17/7067 Devices bearing against one or more spinous processes and also attached to another part of the spine; Tools therefor
• CPC Class Codes: A61B 17/8625 Shanks, i.e. parts contacting bone tissue
• CPC Class Codes: A61B 17/8695 Washers surrounding screw head in plate hole A61B17/8047, between bone plate and bone A61B17/8028
• CPC Class Codes: A61B 2017/8655 with special features for locking in the bone
• CPC Class Codes: A61F 2/30771 applied in original prostheses, e.g. holes or grooves
• 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 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/30125 elliptical or oval
• CPC Class Codes: A61F 2002/30154 square
• CPC Class Codes: A61F 2002/30156 triangular
• CPC Class Codes: A61F 2002/30171 rosette- or star-shaped
• CPC Class Codes: A61F 2002/30179 X-shaped
• CPC Class Codes: A61F 2002/30426 Bayonet coupling
• CPC Class Codes: A61F 2002/30433 using additional screws, bolts, dowels, rivets or washers e.g. connecting screws
• CPC Class Codes: A61F 2002/30448 using adhesives
• CPC Class Codes: A61F 2002/30514 using a locking washer
• CPC Class Codes: A61F 2002/30574 with an integral complete or partial collar or flange
• CPC Class Codes: A61F 2002/30576 with extending fixation tabs
• CPC Class Codes: A61F 2002/30578 : having apertures, e.g. for receiving fixation screws
• CPC Class Codes: A61F 2002/30579 : with mechanically expandable devices, e.g. fixation devices
• CPC Class Codes: A61F 2002/30616 : Sets comprising a plurality of prosthetic parts of different sizes or orientations
• CPC Class Codes: A61F 2002/30663 : multiaxial, e.g. biaxial; multipolar, e.g. bipolar or having an intermediate shell articulating between the ball and the socket
• CPC Class Codes: A61F 2002/3082 : Grooves
• CPC Class Codes: A61F 2002/30841 : Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/3085 : with a threaded, e.g. self-tapping, bone-engaging surface, e.g. external surface
• CPC Class Codes: A61F 2002/30934 : Special articulating surfaces
• 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 2220/005 : using adhesives
• CPC Class Codes: A61F 2230/0008 : elliptical or oval
• CPC Class Codes: A61F 2230/0021 : square
• CPC Class Codes: A61F 2230/0023 : triangular
• CPC Class Codes: A61F 2230/005 : Rosette-shaped, e.g. star-shaped
• 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 2310/00203 : containing alumina or aluminium oxide
• CPC Class Codes: A61F 2310/00239 : containing zirconia or zirconium oxide ZrO2
• CPC Class Codes: A61F 2310/00796 : Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite
• CPC Class Codes: A61F 2310/00928 : Coating or prosthesis-covering structure made of glass or of glass-containing compounds, e.g. of bioglass

Abstract

Superior and/or inferior facets of one or more facet joints may be replaced by superior and/or inferior facet joint prostheses. In one embodiment, a kit of superior or inferior prostheses is provided, in which the prostheses have at least two dimensions that vary among members of the kit independently of each other. Each prosthesis may have a bone engaging surface having a surface that is polyaxially rotatable against a corresponding resection of a vertebra. Each prosthesis may also have an articulating surface shaped such that, after attachment to the spine, the replaced or partially replaced facet joints provide a larger medial-lateral range of motion when the spine is flexed than when the spine is extended. Crosslinks may be used to connect left and right prosthesis together in such a manner that they are stabilized in a position in which they are seated directly against the vertebra.

Claims

1. A bilateral facet prosthesis system for replacing facets of a mammalian vertebra, the system comprising:

a first prosthesis mountable to a vertebra proximate a first facet of an adjacent vertebra, the first prosthesis having a first articulating surface for articulating against the first facet of the adjacent vertebra and a first mounting feature, wherein, when the first prosthesis is mounted to the vertebra and the first articulating surface articulates against the first facet of the adjacent vertebra, the mounting feature is on the posterior side of the first prosthesis;

a second prosthesis mountable to the vertebra proximate a second facet of the adjacent vertebra, the second prosthesis having a second articulating surface for articulating against the second facet of the adjacent vertebra and a second mounting feature, wherein, when the second prosthesis is mounted to the vertebra and the second articulating surface articulates against the second facet of the adjacent vertebra, the mounting feature is on the posterior side of the second prosthesis; and

a crosslink adjustably attachable to the first and second mounting features to extend between the first and second prostheses to fix a displacement between the first and second prostheses at any of a plurality of displacement values, wherein the crosslink provides at least one of cephalad-caudal and anterior-posterior adjustability between the relative positions of the first and second prostheses;

wherein, when the prostheses are mounted to the vertebra proximate the facets of the adjacent vertebra and the articulating surfaces articulate against the facets of the adjacent vertebra, the system provides relative axial rotation between the vertebra and the adjacent vertebra.

2. The system of claim 1, wherein the crosslink comprises a rod having a substantially rigid construction.

3. The system of claim 2, further comprising a first coupling coupled to the first prosthesis, the first coupling having a first gripping mechanism configured to grip the crosslink to couple the first prosthesis to the crosslink at any of a plurality of positions along an axis of the crosslink.

4. The system of claim 3, further comprising a second coupling coupled to the second prosthesis, the second coupling having a second gripping mechanism configured to grip the crosslink to couple the second prosthesis to the crosslink at any of a plurality of positions along the axis.

5. The system of claim 3, wherein the first gripping mechanism comprises flanges positionable on either side of the crosslink such that the crosslink is gripped between the flanges.

6. The system of claim 5, wherein the first gripping mechanism further comprises a first turnbuckle that is rotatable to urge the flanges together to grip the crosslink.

7. The system of claim 5, wherein the first coupling enables the first prosthesis to lockably pivot with respect to the crosslink to enable fixation of an angular displacement between the prostheses about a first axis at any of a plurality of angular displacement values.

8. The system of claim 7, wherein the flanges engage a semispherical member of the first prosthesis to provide a ball-and-socket joint.

9. The system of claim 8, wherein the semispherical member has surface features selected from a group consisting of divots, splines, knurling, longitudinal grooves, circumferential grooves, facets, nubs, and combinations thereof, wherein the surface features resist relative rotation between the first coupling and the semispherical member in response to pressure urging the surface features against the flanges.

10. The system of claim 8, wherein at least one of the flanges is formed of a material that is softer than a material from which the semispherical member is formed.

11. The system of claim 5, wherein at least one of the flanges is formed of a material that is softer than a material from which the crosslink is formed.

12. The system of claim 1, wherein the first prosthesis is a first inferior prosthesis and the second prosthesis is a second inferior prosthesis, the system further comprising a first superior prosthesis replacing the first superior facet of the adjacent vertebra, and a second superior prosthesis replacing the second superior facet of the adjacent vertebra.

13. The system of claim 12, wherein an articulating surface of the first inferior prosthesis is convex and an articulating surface of the first superior facet prosthesis is concave.

14. The system of claim 1, wherein the crosslink compresses the prostheses against the vertebra to which the first and second prostheses are mounted.

15. A bilateral facet prosthesis system for replacing facets of a mammalian vertebra, the system comprising:

a first inferior prosthesis shaped to be coupled to the vertebra proximate a first superior facet of an adjacent vertebra, the first inferior prosthesis having a first articulating surface for articulating against the first superior facet of the adjacent vertebra and a first mounting feature, wherein, when the first inferior prosthesis is coupled to the vertebra and the first articulating surface articulates against the first superior facet of the adjacent vertebra, the mounting feature is on the posterior side of the first inferior prosthesis;

a second inferior prosthesis shaped to be coupled to the vertebra proximate a second superior facet of the adjacent vertebra, the second inferior prosthesis having a second articulating surface for articulating against the second superior facet of the adjacent vertebra and a second mounting feature, wherein, when the second inferior prosthesis is coupled to the vertebra and the second articulating surface articulates against the second superior facet of the adjacent vertebra, the mounting feature is on the posterior side of the second inferior prosthesis;

a first fixation member comprising a proximal end, and a distal end shaped to be embedded in the vertebra;

a second fixation member comprising a proximal end, and a distal end shaped to be embedded in the vertebra; and

a crosslink adjustably attachable to the first and second mounting features to extend between the first and second inferior prostheses to fix a displacement between the first and second prostheses at any of a plurality of displacement values, wherein the crosslink is adjustably attachable to the first and second inferior prostheses such that the crosslink is offset from the first and second fixation members when the bilateral facet prosthesis system is coupled to the vertebra;

wherein, when the inferior prostheses are mounted to the vertebra proximate the superior facets of the adjacent vertebra and the articulating surfaces articulate against the superior facets of the adjacent vertebra, the system provides relative axial rotation between the vertebra and the adjacent vertebra.

16. The system of claim 15, wherein the crosslink comprises a rod having a substantially rigid construction.

17. The system of claim 16, further comprising a first coupling coupled to the first prosthesis, the first coupling having a first gripping mechanism configured to grip the crosslink to couple the first prosthesis to the crosslink at any of a plurality of positions along an axis of the crosslink.

18. The system of claim 17, further comprising a second coupling coupled to the second prosthesis, the second coupling having a second gripping mechanism configured to grip the crosslink to couple the second prosthesis to the crosslink at any of a plurality of positions along the axis.

19. The system of claim 17, wherein the first gripping mechanism comprises flanges positionable on either side of the crosslink such that the crosslink is gripped between the flanges.

20. The system of claim 19, wherein the first gripping mechanism further comprises a first turnbuckle that is rotatable to urge the flanges together to grip the crosslink.

21. The system of claim 19, wherein the flanges engage a semispherical member of the first inferior prosthesis to provide a ball-and-socket joint.

22. The system of claim 21, wherein the semispherical member has surface features selected from a group consisting of divots, splines, knurling, longitudinal grooves, circumferential grooves, facets, nubs, and combinations thereof, wherein the surface features resist relative rotation between the first coupling and the semispherical member in response to pressure urging the surface features against the flanges.

23. The system of claim 15, further comprising a first superior prosthesis having the first superior facet of the adjacent vertebra, and a second superior prosthesis having the second superior facet of the adjacent vertebra.

24. The system of claim 15, wherein the crosslink compresses the inferior prostheses against the vertebra to which the first and second prostheses are coupled.

25. A bilateral facet prosthesis system for replacing facets of a mammalian vertebra, the system comprising:

a first prosthesis mountable to a vertebra proximate a first facet of an adjacent vertebra,

the first prosthesis having a first articulating surface for articulating against the first facet of the adjacent vertebra and a first mounting feature, wherein, when the first prosthesis is coupled to the vertebra and the first articulating surface articulates against the first facet of the adjacent vertebra, the mounting feature is on the posterior side of the first prosthesis;

a first fixation member implantable in the vertebra;

a first fastener securable to the first fixation member to secure the first prosthesis to the vertebra;

a second prosthesis mountable to the vertebra proximate a second facet of the adjacent vertebra, the second prosthesis having a second articulating surface for articulating against the second facet of the adjacent vertebra and a second mounting feature, wherein, when the second prosthesis is coupled to the vertebra and the second articulating surface articulates against the second facet of the adjacent vertebra, the mounting feature is on the posterior side of the second prosthesis;

a second fixation member implantable in the vertebra;

a second fastener securable to the second fixation member to secure the second prosthesis to the vertebra; and

a crosslink adjustably attachable to the first and second mounting features to extend between the first and second prostheses to fix an angular displacement between the prostheses about a first axis at any of a plurality of angular displacement values;

wherein, when the prostheses are mounted to the vertebra proximate the facets of the adjacent vertebra and the articulating surfaces articulate against the facets of the adjacent vertebra, the system provides relative axial rotation between the vertebra and the adjacent vertebra.

26. The system of claim 25, wherein the crosslink comprises a rod having a substantially rigid construction.

27. The system of claim 26, further comprising a first coupling coupled to the first prosthesis, the first coupling having a first gripping mechanism configured to grip the crosslink to couple the first prosthesis to the crosslink at any of a plurality of positions along an axis of the crosslink.

28. The system of claim 27, further comprising a second coupling coupled to the second prosthesis, the second coupling having a second gripping mechanism configured to grip the crosslink to couple the second prosthesis to the crosslink at any of a plurality of positions along the axis of the crosslink.

29. The system of claim 27, wherein the first gripping mechanism comprises flanges positionable on either side of the crosslink such that the crosslink is gripped between the flanges.

30. The system of claim 29, wherein the first gripping mechanism further comprises a first turnbuckle that is rotatable to urge the flanges together to grip the crosslink.

31. The system of claim 29, wherein the first coupling enables the first prosthesis to lockably pivot with respect to the crosslink to enable fixation of the angular displacement between the prostheses.

32. The system of claim 31, wherein the first coupling further enables fixation of an angular displacement between the prostheses about a second axis perpendicular to the first axis, at any of a plurality of angular displacement values.

33. The system of claim 31, wherein the flanges engage a semispherical member of the first prosthesis to provide a ball-and-socket joint.

34. The system of claim 33, wherein the semispherical member has surface features selected from a group consisting of divots, splines, knurling, longitudinal grooves, circumferential grooves, facets, nubs, and combinations thereof, wherein the surface features resist relative rotation between the first coupling and the semispherical member in response to pressure urging the surface features against the flanges.

35. The system of claim 25, wherein the first prosthesis comprises a first inferior prosthesis and the second prosthesis comprises a second inferior prosthesis, the system further comprising a first superior prosthesis having the first superior facet of the adjacent vertebra, and a second superior prosthesis having the second superior facet of the adjacent vertebra.

36. The system of claim 25, wherein the crosslink compresses the prostheses against the vertebra to which the first and second prostheses are coupled.

37. A bilateral facet prosthesis system for replacing facets of a mammalian vertebra, the system comprising:

a first prosthesis shaped to be coupled to the vertebra proximate a first facet of an adjacent vertebra, the first prosthesis having a first articulating surface for articulating against the first facet of the adjacent vertebra and a first mounting feature, wherein, when the first prosthesis is coupled to the vertebra and the first articulating surface articulates against the first facet of the adjacent vertebra, the mounting feature is on the posterior side of the first prosthesis;

a first fixation member implantable in the vertebra;

a first fastener securable to the first fixation member to secure the first prosthesis to the vertebra;

a second prosthesis shaped to be coupled to the vertebra proximate a second facet of the adjacent vertebra, the second prosthesis having a second articulating surface for articulating against the second facet of the adjacent vertebra and a second mounting feature, wherein, when the second prosthesis is coupled to the vertebra and the second articulating surface articulates against the second facet of the adjacent vertebra, the mounting feature is on the posterior side of the second prosthesis;

a second fixation member implantable in the vertebra;

a second fastener securable to the second fixation member to secure the second prosthesis to the vertebra;

a crosslink adjustably attachable to the first and second mounting features to extend between the first and second prostheses; and

a first coupling coupled to the first prosthesis, the first coupling having a first gripping mechanism configured to grip the crosslink to couple the first prosthesis to the crosslink;

wherein, when the prostheses are mounted to the vertebra proximate the facets of the adjacent vertebra and the articulating surfaces articulate against the facets of the adjacent vertebra, the system provides relative axial rotation between the vertebra and the adjacent vertebra.

38. The system of claim 37, wherein the crosslink comprises a rod having a substantially rigid construction, wherein the first gripping mechanism is further configured to couple the first prosthesis to the crosslink at any of a plurality of positions along an axis of the crosslink.

39. The system of claim 38, further comprising a second coupling coupled to the second prosthesis, the second coupling having a second gripping mechanism configured to grip the crosslink to couple the second prosthesis to the crosslink at any of a plurality of positions along the axis.

40. The system of claim 38, wherein the first gripping mechanism comprises flanges positionable on either side of the crosslink such that the crosslink is gripped between the flanges.

41. The system of claim 40, wherein the first gripping mechanism further comprises a first turnbuckle that is rotatable to urge the flanges together to grip the crosslink.

42. The system of claim 40, wherein the first coupling enables the first prosthesis to lockably pivot with respect to the crosslink to enable fixation of an angular displacement between the prostheses about a first axis at any of a plurality of angular displacement values.

43. The system of claim 42, wherein the flanges engage a semispherical member of the first prosthesis to provide a ball-and-socket joint.

44. The system of claim 43, wherein the semispherical member has surface features selected from a group consisting of divots, splines, knurling, longitudinal grooves, circumferential grooves, facets, nubs, and combinations thereof, wherein the surface features resist relative rotation between the first coupling and the semispherical member in response to pressure urging the surface features against the flanges.

45. The system of claim 37, wherein the first prosthesis comprises a first inferior prosthesis and the second prosthesis comprises a second inferior prosthesis, the system further comprising a first superior prosthesis having the first superior facet of the adjacent vertebra, and a second superior prosthesis having the second superior facet of the adjacent vertebra.

46. The system of claim 37, wherein the crosslink compresses the prostheses against the vertebra to which the first and second prostheses are coupled.

47. A bilateral facet prosthesis system for replacing facets of a mammalian vertebra, the system comprising:

a first prosthesis mountable to a vertebra, the first prosthesis having a first articulating surface for articulating against a first facet of an adjacent vertebra and a first mounting feature, wherein, when the first prosthesis is mounted to the vertebra and the first articulating surface articulates against the first facet of the adjacent vertebra, the mounting feature is on the posterior side of the first prosthesis;

a second prosthesis mountable to the vertebra, the second prosthesis having a second articulating surface for articulating against a second facet of the adjacent vertebra and a second mounting feature, wherein, when the second prosthesis is mounted to the vertebra and the second articulating surface articulates against the second facet of the adjacent vertebra, the mounting feature is on the posterior side of the second prosthesis;

a crosslink adjustably attachable to the first and second mounting features to extend between the first and second prostheses to fix a displacement between the first and second prostheses at any of a plurality of displacement values, wherein the crosslink provides at least one of cephalad-caudal and anterior-posterior adjustability between the relative positions of the first and second prostheses, wherein the crosslink comprises a rod having a substantially rigid construction; and

a first coupling coupled to the first prosthesis, the first coupling having a first gripping mechanism configured to grip the crosslink to couple the first prosthesis to the crosslink at any of a plurality of positions along an axis of the crosslink, wherein the first gripping mechanism comprises flanges positionable on either side of the crosslink such that the crosslink is gripped between the flanges, wherein the first gripping mechanism further comprises a first turnbuckle that is rotatable to urge the flanges together to grip the crosslink.

48. A bilateral facet prosthesis system for replacing facets of a mammalian vertebra, the system comprising:

a first prosthesis mountable to a vertebra, the first prosthesis having a first articulating surface for articulating against a first facet of an adjacent vertebra and a first mounting feature, wherein, when the first prosthesis is mounted to the vertebra and the first articulating surface articulates against the first facet of the adjacent vertebra, the mounting feature is on the posterior side of the first prosthesis;

a second prosthesis mountable to the vertebra, the second prosthesis having a second articulating surface for articulating against a second facet of the adjacent vertebra and a second mounting feature, wherein, when the second prosthesis is mounted to the vertebra and the second articulating surface articulates against the second facet of the adjacent vertebra, the mounting feature is on the posterior side of the second prosthesis;

a crosslink adjustably attachable to the first and second mounting features to extend between the first and second prostheses to fix a displacement between the first and second prostheses at any of a plurality of displacement values, wherein the crosslink provides at least one of cephalad-caudal and anterior-posterior adjustability between the relative positions of the first and second prostheses, wherein the crosslink comprises a rod having a substantially rigid construction; and

a first coupling coupled to the first prosthesis, the first coupling having a first gripping mechanism configured to grip the crosslink to couple the first prosthesis to the crosslink at any of a plurality of positions along an axis of the crosslink, wherein the first gripping mechanism comprises flanges positionable on either side of the crosslink such that the crosslink is gripped between the flanges, wherein the first coupling enables the first prosthesis to lockably pivot with respect to the crosslink to enable fixation of an angular displacement between the prostheses about a first axis at any of a plurality of angular displacement values, wherein the flanges engage a semispherical member of the first prosthesis to provide a ball-and-socket joint.

49. The system of claim 48,

wherein the semispherical member has surface features selected from a group consisting of divots, splines, knurling, longitudinal grooves, circumferential grooves, facets, nubs, and combinations thereof,

wherein the surface features resist relative rotation between the first coupling and the semispherical member in response to pressure urging the surface features against the flanges.

50. The system of claim 48,

wherein at least one of the flanges is formed of a material that is softer than a material from which the semispherical member is formed.

51. A bilateral facet prosthesis system for replacing facets of a mammalian vertebra, the system comprising:

a first inferior prosthesis shaped to be coupled to the vertebra, the first inferior prosthesis having a first articulating surface for articulating against a first superior facet of an adjacent vertebra and a first mounting feature, wherein, when the first inferior prosthesis is coupled to the vertebra and the first articulating surface articulates against the first superior facet of the adjacent vertebra, the mounting feature is on the posterior side of the first inferior prosthesis;

a first fixation member comprising a proximal end, and a distal end shaped to be embedded in the vertebra;

a second inferior prosthesis shaped to be coupled to the vertebra, the second inferior prosthesis having a second articulating surface for articulating against a second superior facet of the adjacent vertebra and a second mounting feature, wherein, when the second inferior prosthesis is coupled to the vertebra and the second articulating surface articulates against the second superior facet of the adjacent vertebra, the mounting feature is on the posterior side of the second inferior prosthesis;

a second fixation member comprising a proximal end, and a distal end shaped to be embedded in the vertebra;

a crosslink adjustably attachable to the first and second mounting features to extend between the first and second inferior prostheses to fix a displacement between the first and second prostheses at any of a plurality of displacement values, wherein the crosslink is adjustably attachable to the first and second inferior prostheses such that the crosslink is offset from the first and second fixation members when the bilateral facet prosthesis system is coupled to the vertebra, wherein the crosslink comprises a rod having a substantially rigid construction; and

a first coupling coupled to the first prosthesis, the first coupling having a first gripping mechanism configured to grip the crosslink to couple the first prosthesis to the crosslink at any of a plurality of positions along an axis of the crosslink, wherein the first gripping mechanism comprises flanges positionable on either side of the crosslink such that the crosslink is gripped between the flanges, wherein the first gripping mechanism further comprises a first turnbuckle that is rotatable to urge the flanges together to grip the crosslink.

52. A bilateral facet prosthesis system for replacing facets of a mammalian vertebra, the system comprising:

a first inferior prosthesis shaped to be coupled to the vertebra, the first inferior prosthesis having a first articulating surface for articulating against a first superior facet of an adjacent vertebra and a first mounting feature, wherein, when the first inferior prosthesis is coupled to the vertebra and the first articulating surface articulates against the first superior facet of the adjacent vertebra, the mounting feature is on the posterior side of the first inferior prosthesis;

a first fixation member comprising a proximal end, and a distal end shaped to be embedded in the vertebra;

a second inferior prosthesis shaped to be coupled to the vertebra, the second inferior prosthesis having a second articulating surface for articulating against a second superior facet of the adjacent vertebra and a second mounting feature, wherein, when the second inferior prosthesis is coupled to the vertebra and the second articulating surface articulates against the second superior facet of the adjacent vertebra, the mounting feature is on the posterior side of the second inferior prosthesis;

a second fixation member comprising a proximal end, and a distal end shaped to be embedded in the vertebra;

a crosslink adjustably attachable to the first and second mounting features to extend between the first and second inferior prostheses to fix a displacement between the first and second prostheses at any of a plurality of displacement values, wherein the crosslink is adjustably attachable to the first and second inferior prostheses such that the crosslink is offset from the first and second fixation members when the bilateral facet prosthesis system is coupled to the vertebra, wherein the crosslink comprises a rod having a substantially rigid construction; and

a first coupling coupled to the first prosthesis, the first coupling having a first gripping mechanism configured to grip the crosslink to couple the first prosthesis to the crosslink at any of a plurality of positions along an axis of the crosslink, wherein the first gripping mechanism comprises flanges positionable on either side of the crosslink such that the crosslink is gripped between the flanges, wherein the flanges engage a semispherical member of the first inferior prosthesis to provide a ball-and-socket joint.

53. The system of claim 52,

wherein the semispherical member has surface features selected from a group consisting of divots, splines, knurling, longitudinal grooves, circumferential grooves, facets, nubs, and combinations thereof,

wherein the surface features resist relative rotation between the first coupling and the semispherical member in response to pressure urging the surface features against the flanges.

54. A bilateral facet prosthesis system for replacing facets of a mammalian vertebra, the system comprising:

a first prosthesis having a first articulating surface for articulating against a first facet of an adjacent vertebra and a first mounting feature, wherein, when the first prosthesis is coupled to the vertebra and the first articulating surface articulates against the first facet of the adjacent vertebra, the mounting feature is on the posterior side of the first prosthesis;

a first fixation member implantable in the vertebra;

a first fastener securable to the first fixation member to secure the first prosthesis to the vertebra;

a second prosthesis having a second articulating surface for articulating against a second facet of the adjacent vertebra and a second mounting feature, wherein, when the second prosthesis is coupled to the vertebra and the second articulating surface articulates against the second facet of the adjacent vertebra, the mounting feature is on the posterior side of the second prosthesis;

a second fixation member implantable in the vertebra;

a second fastener securable to the second fixation member to secure the second prosthesis to the vertebra;

a crosslink adjustably attachable to the first and second mounting features to extend between the first and second prostheses to fix an angular displacement between the prostheses about a first axis at any of a plurality of angular displacement values, wherein the crosslink comprises a rod having a substantially rigid construction; and

a first coupling coupled to the first prosthesis, the first coupling having a first gripping mechanism configured to grip the crosslink to couple the first prosthesis to the crosslink at any of a plurality of positions along an axis of the crosslink, wherein the first gripping mechanism comprises flanges positionable on either side of the crosslink such that the crosslink is gripped between the flanges, wherein the first gripping mechanism further comprises a first turnbuckle that is rotatable to urge the flanges together to grip the crosslink.

55. A bilateral facet prosthesis system for replacing facets of a mammalian vertebra, the system comprising:

a first prosthesis having a first articulating surface for articulating against a first facet of an adjacent vertebra and a first mounting feature, wherein, when the first prosthesis is coupled to the vertebra and the first articulating surface articulates against the first facet of the adjacent vertebra, the mounting feature is on the posterior side of the first prosthesis;

a first fixation member implantable in the vertebra;

a first fastener securable to the first fixation member to secure the first prosthesis to the vertebra;

a second prosthesis having a second articulating surface for articulating against a second facet of the adjacent vertebra and a second mounting feature, wherein, when the second prosthesis is coupled to the vertebra and the second articulating surface articulates against the second facet of the adjacent vertebra, the mounting feature is on the posterior side of the second prosthesis;

a second fixation member implantable in the vertebra;

a second fastener securable to the second fixation member to secure the second prosthesis to the vertebra;

a crosslink adjustably attachable to the first and second mounting features to extend between the first and second prostheses to fix an angular displacement between the prostheses about a first axis at any of a plurality of angular displacement values, wherein the crosslink comprises a rod having a substantially rigid construction; and

a first coupling coupled to the first prosthesis, the first coupling having a first gripping mechanism configured to grip the crosslink to couple the first prosthesis to the crosslink at any of a plurality of positions along an axis of the crosslink, wherein the first gripping mechanism comprises flanges positionable on either side of the crosslink such that the crosslink is gripped between the flanges, wherein the first coupling enables the first prosthesis to lockably pivot with respect to the crosslink to enable fixation of the angular displacement between the prostheses, wherein the flanges engage a semispherical member of the first prosthesis to provide a ball-and-socket joint.

56. The system of claim 55,

wherein the semispherical member has surface features selected from a group consisting of divots, splines, knurling, longitudinal grooves, circumferential grooves, facets, nubs, and combinations thereof,

wherein the surface features resist relative rotation between the first coupling and the semispherical member in response to pressure urging the surface features against the flanges.

57. A bilateral facet prosthesis system for replacing facets of a mammalian vertebra, the system comprising:

a first prosthesis shaped to be coupled to the vertebra, the first prosthesis having a first articulating surface for articulating against a first facet of an adjacent vertebra and a first mounting feature, wherein, when the first prosthesis is coupled to the vertebra and the first articulating surface articulates against the first facet of the adjacent vertebra, the mounting feature is on the posterior side of the first prosthesis;

a first fixation member implantable in the vertebra;

a first fastener securable to the first fixation member to secure the first prosthesis to the vertebra;

a second prosthesis shaped to be coupled to the vertebra, the second prosthesis having a second articulating surface for articulating against a second facet of the adjacent vertebra and a second mounting feature, wherein, when the second prosthesis is coupled to the vertebra and the second articulating surface articulates against the second facet of the adjacent vertebra, the mounting feature is on the posterior side of the second prosthesis;

a second fixation member implantable in the vertebra;

a second fastener securable to the second fixation member to secure the second prosthesis to the vertebra;

a crosslink adjustably attachable to the first and second mounting features to extend between the first and second prostheses; and

a first coupling coupled to the first prosthesis, the first coupling having a first gripping mechanism configured to grip the crosslink to couple the first prosthesis to the crosslink, wherein the crosslink comprises a rod having a substantially rigid construction, wherein the first gripping mechanism is further configured to couple the first prosthesis to the crosslink at any of a plurality of positions along an axis of the crosslink, wherein the first gripping mechanism comprises flanges positionable on either side of the crosslink such that the crosslink is gripped between the flanges, wherein the first gripping mechanism further comprises a first turnbuckle that is rotatable to urge the flanges together to grip the crosslink.

58. A bilateral facet prosthesis system for replacing facets of a mammalian vertebra, the system comprising:

a first prosthesis shaped to be coupled to the vertebra, the first prosthesis having a first articulating surface for articulating against a first facet of an adjacent vertebra and a first mounting feature, wherein, when the first prosthesis is coupled to the vertebra and the first articulating surface articulates against the first facet of the adjacent vertebra, the mounting feature is on the posterior side of the first prosthesis;

a first fixation member implantable in the vertebra;

a first fastener securable to the first fixation member to secure the first prosthesis to the vertebra;

a second prosthesis shaped to be coupled to the vertebra, the second prosthesis having a second articulating surface for articulating against a second facet of the adjacent vertebra and a second mounting feature, wherein, when the second prosthesis is coupled to the vertebra and the second articulating surface articulates against the second facet of the adjacent vertebra, the mounting feature is on the posterior side of the second prosthesis;

a second fixation member implantable in the vertebra;

a second fastener securable to the second fixation member to secure the second prosthesis to the vertebra;

a crosslink adjustably attachable to the first and second mounting features to extend between the first and second prostheses; and

a first coupling coupled to the first prosthesis, the first coupling having a first gripping mechanism configured to grip the crosslink to couple the first prosthesis to the crosslink, wherein the crosslink comprises a rod having a substantially rigid construction, wherein the first gripping mechanism is further configured to couple the first prosthesis to the crosslink at any of a plurality of positions along an axis of the crosslink, wherein the first gripping mechanism comprises flanges positionable on either side of the crosslink such that the crosslink is gripped between the flanges, wherein the first coupling enables the first prosthesis to lockably pivot with respect to the crosslink to enable fixation of an angular displacement between the prostheses about a first axis at any of a plurality of angular displacement values, wherein the flanges engage a semispherical member of the first prosthesis to provide a ball-and-socket joint.

59. The system of claim 58,

wherein the semispherical member has surface features selected from a group consisting of divots, splines, knurling, longitudinal grooves, circumferential grooves, facets, nubs, and combinations thereof,

wherein the surface features resist relative rotation between the first coupling and the semispherical member in response to pressure urging the surface features against the flanges.