Spinal facet implants with mating articulating bearing surface and methods of use

• US 20050131538A1
• Filed: 06/02/2004
• Published: 06/16/2005
• Est. Priority Date: 12/10/2003
• Status: Active Grant

• Current Assignee: Globus Medical, Inc.
• Original Assignee: Gmedelaware 2 LLC (Globus Medical, Inc.)
• Inventors: Hoy, Robert W., Triplett, Daniel J., Fallin, T. Wade, Chervitz, Alan
• Granted Patent: US 8,419,770 B2
• Time in Patent Office: Days
• US Class Current: 623/17.110
• 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 facet prosthesis system for replacing an inferior facet of a first vertebra of a spine, and a superior facet of a second vertebra of the spine, the system comprising:

an inferior prosthesis shaped to be coupled to the first vertebra, the inferior prosthesis having an inferior articulating surface; and

a superior prosthesis shaped to be coupled to the second vertebra, the superior prosthesis having a superior articulating surface;

wherein the articulating surfaces of the inferior and superior prostheses are shaped and relatively positioned to articulate against each other such that a medial-lateral range of relative motion between the first and second vertebrae decreases significantly with extension of the spine.

2. The system of claim 1, wherein each of the articulating surfaces has a curved shape, wherein one of the articulating surfaces has a cephalad end and a caudal end, and a radius of curvature about an axis extending generally from the cephalad end to the caudal end, wherein the radius of curvature changes along the axis to provide greater clearance between the articulating surfaces when the spine is flexed.

3. The system of claim 2, wherein the articulating surface of the superior prosthesis has a concave shape having the cephalad end, caudal end, and radius of curvature, wherein the radius of curvature increases toward the cephalad end.

4. The system of claim 1, wherein each of the articulating surfaces has a curved shape, wherein one of the articulating surfaces has a cephalad end and a caudal end, and a radius of curvature about an axis extending generally from the cephalad end to the caudal end, wherein the prosthesis is shaped such that, when the prosthesis is coupled to the vertebra, the axis is significantly anteriorly inclined to provide greater clearance between the articulating surfaces when the spine is flexed.

5. The system of claim 4, wherein the articulating surface of the superior prosthesis has a concave shape having the cephalad, caudal end, and radius of curvature, wherein the axis is anteriorly inclined toward the cephalad end.

6. The system of claim 5, wherein the axis is inclined at an angle of at least five degrees with respect to a longitudinal axis of the spine.

7. The system of claim 1, wherein each of the articulating surfaces has a curved shape, wherein one of the articulating surfaces has a cephalad end and a caudal end, and a radius of curvature about an axis extending generally from the cephalad end to the caudal end, wherein the radius of curvature varies along a medial-lateral direction of the articulating surface.

8. The system of claim 7, wherein the articulating surface of the superior prosthesis has a concave shape having the cephalad end, caudal end, and radius of curvature, wherein the articulating surface of the superior prosthesis has a medial end, a lateral end, and a central portion between the medial and lateral ends, wherein the radius of curvature is larger toward the medial and lateral ends than at the central portion.

9. The system of claim 8, wherein the radius of curvature is substantially infinite toward the medial and lateral ends, such that the articulating surface of the superior prosthesis has a curved region proximate the central portion, a first tangent flat disposed medially of and tangent to the curved region, and a second tangent flat disposed laterally of and tangent to the curved region.

10. The system of claim 7, wherein the articulating surface of the superior prosthesis has a concave shape and the articulating surface of the inferior prosthesis has a convex shape.

11. The system of claim 10, wherein the articulating surface of the inferior prosthesis has a three-dimensionally curved elliptical shape.

12. The system of claim 1, wherein at least one of the articulating surfaces is constructed of a material selected from a group consisting of a polymeric material, a polymeric bearing material attached to a metal substrate, a ceramic bearing material, a metal bearing material, and combinations thereof.

13. A prosthesis for replacing at least a portion of a facet of a vertebra of a spine, the prosthesis comprising:

a fixation element implantable into the vertebra;

a coupling portion shaped to be coupled to the fixation element, the coupling portion having a bone engaging surface positioned to abut the vertebra; and

an articulating surface attached to the coupling portion;

wherein the articulating surface is positioned and shaped to articulate against an articulating surface of an adjacent vertebra such that a medial-lateral range of relative motion between the vertebra and the adjacent vertebra decreases significantly with extension of the spine.

14. The prosthesis of claim 13, wherein the articulating surface of the prosthesis has a curved shape with a cephalad end and a caudal end, and a radius of curvature about an axis extending generally from the cephalad end to the caudal end, wherein the radius of curvature changes along the axis to provide greater clearance between the articulating surfaces when the spine is flexed.

15. The prosthesis of claim 14, wherein the prosthesis comprises a superior prosthesis, wherein the articulating surface of the prosthesis has a concave shape, wherein the radius of curvature increases toward the cephalad end.

16. The prosthesis of claim 13, wherein the articulating surface of the prosthesis has a curved shape with a cephalad end and a caudal end, and a radius of curvature about an axis extending generally from the cephalad end to the caudal end, wherein the prosthesis is shaped such that, when the prosthesis is coupled to the vertebra, the axis is significantly anteriorly inclined to provide greater clearance between the articulating surfaces when the spine is flexed.

17. The prosthesis of claim 16, wherein the prosthesis comprises a superior prosthesis, wherein the articulating surface of the prosthesis has a concave shape, wherein the axis is anteriorly inclined toward the cephalad end.

18. The prosthesis of claim 17, wherein the prosthesis is shaped such that, when the prosthesis is coupled to the vertebra, the axis is inclined at an angle of at least five degrees with respect to a longitudinal axis of the spine.

19. The prosthesis of claim 13, wherein the articulating surface of the prosthesis has a curved shape with a cephalad end and a caudal end, and a radius of curvature about an axis extending generally from the cephalad end to the caudal end, wherein the radius of curvature varies along a medial-lateral direction of the articulating surface.

20. The prosthesis of claim 19, wherein the prosthesis comprises a superior prosthesis, wherein the articulating surface of the prosthesis has a concave shape, wherein the articulating surface of the prosthesis has a medial end, a lateral end, and a central portion between the medial and lateral ends, wherein the radius of curvature is larger toward the medial and lateral ends than at the central portion.

21. The prosthesis of claim 20, wherein the radius of curvature is substantially infinite toward the medial and lateral ends, such that the articulating surface of the prosthesis has a curved region proximate the central portion, a first tangent flat disposed medially of and tangent to the curved region, and a second tangent flat disposed laterally of and tangent to the curved region.

22. The prosthesis of claim 13, wherein the articulating surface of the prosthesis is constructed of a material selected from a group consisting of a polymeric bearing material attached to a metal substrate, a ceramic bearing material, a metal bearing material, and combinations thereof.

23. A prosthesis for replacing at least a portion of a facet of a vertebra of a spine, the prosthesis comprising:

a fixation element implantable into the vertebra;

a coupling portion shaped to be coupled to the fixation element, the coupling portion having a bone engaging surface positioned to abut the vertebra; and

an articulating surface attached to the coupling portion to articulate against an articulating surface of an adjacent vertebra, the articulating surface of the prosthesis having a cephalad end and a caudal end, wherein the articulating surface has a radius of curvature about an axis extending generally from the cephalad end to the caudal end;

wherein the axis is significantly anteriorly inclined toward the cephalad end.

24. The prosthesis of claim 23, wherein the prosthesis comprises a superior prosthesis, wherein the articulating surface of the prosthesis has a concave shape

25. The prosthesis of claim 24, wherein the prosthesis is shaped such that, when the prosthesis is coupled to the vertebra, the axis is inclined at an angle of at least five degrees with respect to a longitudinal axis of the spine.

26. The prosthesis of claim 23, wherein the articulating surface of the prosthesis has a medial end, a lateral end, and a central portion between the medial and lateral ends, wherein the radius of curvature is larger toward the medial and lateral ends than at the central portion.

27. A superior prosthesis for replacing at least a portion of a superior facet of a vertebra of a spine, the prosthesis comprising:

a fixation element implantable into the vertebra;

a coupling portion shaped to be coupled to the fixation element, the coupling portion having a bone engaging surface positioned to abut the vertebra; and

an articulating surface attached to the coupling portion to articulate against an articulating surface of an adjacent vertebra, the articulating surface of the prosthesis having a concave shape with a variable radius of curvature, wherein the articulating surface is positioned to articulate against an inferior facet of an adjacent vertebra.

28. The superior prosthesis of claim 27, wherein the articulating surface of the prosthesis has a curved shape with a cephalad end and a caudal end, and a radius of curvature about an axis extending generally from the cephalad end to the caudal end, wherein the radius of curvature varies along a medial-lateral direction of the articulating surface.

29. The prosthesis of claim 28, wherein the prosthesis comprises a superior prosthesis, wherein the articulating surface of the prosthesis has a concave shape, wherein the articulating surface of the prosthesis has a medial end, a lateral end, and a central portion between the medial and lateral ends, wherein the radius of curvature is larger toward the medial and lateral ends than at the central portion.

30. The prosthesis of claim 29, wherein the radius of curvature is substantially infinite toward the medial and lateral ends, such that the articulating surface of the prosthesis has a curved region proximate the central portion, a first tangent flat disposed medially of and tangent to the curved region, and a second tangent flat disposed laterally of and tangent to the curved region.

31. The prosthesis of claim 27, wherein the articulating surface of the adjacent vertebra has a convex shape and the articulating surface of the prosthesis has a concave shape selected to articulate against the articulating surface of the adjacent vertebra in a manner that approximates articulation of a natural facet joint.

32. A method for replacing at least one facet of a first vertebra of a spine, the method comprising:

resecting the first vertebra to provide a resected portion of the first vertebra; and

attaching a coupling portion of a prosthesis to the first resected portion to position an articulating surface of the prosthesis to articulate against an articulating surface of a second vertebra;

wherein positioning the articulating surface of the prosthesis comprises providing a medial-lateral range of relative motion between the first and second vertebrae that decreases significantly with extension of the spine.

33. The method of claim 32, wherein the articulating surface of the prosthesis has a curved shape with a cephalad end and a caudal end, and a radius of curvature about an axis extending generally from the cephalad end to the caudal end, wherein the radius of curvature changes along the axis, wherein providing the medial-lateral range of relative motion between the first and second vertebrae comprises providing greater clearance between the articulating surfaces when the spine is flexed.

34. The method of claim 33, wherein the prosthesis comprises a superior prosthesis, wherein the articulating surface of the prosthesis has a concave shape, wherein the radius of curvature increases toward the cephalad end, wherein resecting the first vertebra comprises removing at least a portion of a natural superior facet.

35. The method of claim 32, wherein the articulating surface of the prosthesis has a curved shape with a cephalad end and a caudal end, and a radius of curvature about an axis extending generally from the cephalad end to the caudal end, wherein positioning the articulating surface of the prosthesis comprises significantly anteriorly inclining the axis to provide greater clearance between the articulating surfaces when the spine is flexed.

36. The method of claim 35, wherein the prosthesis comprises a superior prosthesis, wherein the articulating surface of the prosthesis has a concave shape, wherein resecting the first vertebra comprises removing at least a portion of a natural superior facet, wherein significantly anteriorly inclining the axis comprises inclining the axis toward the cephalad end.

37. The method of claim 36, wherein significantly anteriorly inclining the axis comprises inclining the axis at an angle of at least five degrees with respect to a longitudinal axis of the spine.

38. The prosthesis of claim 32, wherein the articulating surface of the prosthesis has a curved shape with a cephalad end and a caudal end, and a radius of curvature about an axis extending generally from the cephalad end to the caudal end, wherein the radius of curvature varies along a medial-lateral direction of the articulating surface, wherein providing the medial-lateral range of relative motion between the first and second vertebrae comprises providing greater clearance between the articulating surfaces when the spine is flexed.

39. The prosthesis of claim 38, wherein the prosthesis comprises a superior prosthesis, wherein the articulating surface of the prosthesis has a concave shape, wherein the articulating surface of the prosthesis has a medial end, a lateral end, and a central portion between the medial and lateral ends, wherein the radius of curvature is larger toward the medial and lateral ends than at the central portion, wherein resecting the first vertebra comprises removing at least a portion of a natural superior facet.

40. The prosthesis of claim 39, wherein the radius of curvature is substantially infinite toward the medial and lateral ends, such that the articulating surface of the prosthesis has a curved region proximate the central portion, a first tangent flat disposed medially of and tangent to the curved region, and a second tangent flat disposed laterally of and tangent to the curved region.

41. A method for replacing at least one facet of a first vertebra of a spine, the method comprising:

resecting the first vertebra to provide a resected portion of the first vertebra; and

attaching a coupling portion of a prosthesis to the resected portion to position an articulating surface of the prosthesis to articulate against a second articulating surface of a second vertebra;

wherein the articulating surface of the vertebra comprises a cephalad end and a caudal end and a radius of curvature about an axis extending generally from the cephalad end to the caudal end, wherein positioning the articulating surface of the prosthesis comprises significantly inclining the axis anteriorly toward the cephalad end.

42. The method of claim 41, wherein the prosthesis comprises a superior prosthesis, wherein the articulating surface of the prosthesis has a concave shape, wherein resecting the first vertebra comprises removing at least a portion of a natural superior facet.

43. The method of claim 42, wherein significantly anteriorly inclining the axis comprises inclining the axis at an angle of at least five degrees with respect to a longitudinal axis of the spine.

44. The method of claim 41, wherein the articulating surface of the prosthesis has a medial end, a lateral end, and a central portion between the medial and lateral ends, wherein the radius of curvature is larger toward the medial and lateral ends than at the central portion.