Prosthetic disc for intervertebral insertion

• US 20050021145A1
• Filed: 05/26/2004
• Published: 01/27/2005
• Est. Priority Date: 05/27/2003
• Status: Active Grant

• Current Assignee: Simplify Medical Pty. Ltd. (Nuvasive Incorporated)
• Original Assignee: SpinalMotion, Inc.
• Inventors: de Villiers, Malan, Hahnle, Ulrich
• Granted Patent: US 7,753,956 B2
• Time in Patent Office: Days
• US Class Current: 623/17.140
• CPC Class Codes: A61F 2/30771 applied in original prostheses, e.g. holes or grooves
• CPC Class Codes: A61F 2/44 for the spine, e.g. vertebrae, spinal discs
• CPC Class Codes: A61F 2/4425 made of articulated components
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/30052 differing in electric or magnetic properties
• CPC Class Codes: A61F 2002/3008 radio-opaque, e.g. radio-opaque markers
• CPC Class Codes: A61F 2002/30331 made by longitudinally pushing a protrusion into a complementarily-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30462 retained or tied with a rope, string, thread, wire or cable
• CPC Class Codes: A61F 2002/30574 with an integral complete or partial collar or flange
• CPC Class Codes: A61F 2002/30649 Ball-and-socket joints
• CPC Class Codes: A61F 2002/30662 with rotation-limiting means
• 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 2002/30884 Fins or wings, e.g. longitudinal wings for preventing rotation within the bone cavity
• CPC Class Codes: A61F 2002/30899 Protrusions pierced with apertures
• CPC Class Codes: A61F 2002/30904 serrated profile, i.e. saw-toothed
• CPC Class Codes: A61F 2002/443 having two transversal endplates and at least one intermediate component
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0033 made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2220/0075 sutured, ligatured or stitched, retained or tied with a rope, string, thread, wire or cable
• CPC Class Codes: A61F 2230/0071 : spherical
• CPC Class Codes: A61F 2250/0045 : differing in electromagnetical properties
• CPC Class Codes: A61F 2250/0098 : radio-opaque, e.g. radio-opaque markers
• 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 2310/00179 : Ceramics or ceramic-like structures
• CPC Class Codes: A61F 2310/00604 : Coating made of aluminium oxide or hydroxides
• CPC Class Codes: A61F 2310/0088 : Coating made of titanium nitride

Abstract

A prosthetic disc for insertion between adjacent vertebrae includes a core having upper and lower curved surfaces, upper and lower plates, and peripheral restraining structure on at least one of the upper plate, the lower plate and the core. Each plate has an outer surface which engages a vertebra and an inner curved surface which slides over the curved surface of the core. The peripheral restraining structure serves to hold the core against a curved surface of at least one of the plates during sliding movement of the plates over the core.

Claims

1. A prosthetic disc for insertion between adjacent vertebrae, the prosthetic disc comprising:

a core having upper and lower curved surfaces;

upper and lower plates, each plate having an outer surface which engages a vertebra and an inner curved surface which slides over the curved surface of the core; and

;

peripheral restraining structure on at least one of the upper plate, the lower plate and the core to hold the core against a curved surface of at least one of the plates during sliding movement of the plates over the core.

2. A prosthetic disc as in claim 1, wherein at least one of the curved surfaces is spherical.

3. A prosthetic disc as in claim 2, wherein both curved surfaces are spherical.

4. A prosthetic disc as in claim 1, wherein movement of the core within the peripheral restraining structure is unconstrained.

5. A prosthetic disc as in claim 1, wherein the peripheral restraining structure defines a stop structure to limit relative inclination of the plates during sliding movement of the plates over the core.

6. A prosthetic disc as in claim 1, wherein the peripheral restraining structure will engage one side of the core to lift an opposite side of the core during sliding movement of the plates over the core.

7. A prosthetic disc as in claim 1, wherein the peripheral restraining structure comprises:

an annular structure extending over at least a portion of the periphery of the core; and

a ring structure on one of the upper and lower plates, which ring structure engages and retains the annular structure.

8. A prosthetic disc as in claim 7, wherein the ring structure comprises a flange which defines an overhang, and wherein at least part of the annular structure on the core extends into the overhang to provide an interference fit of the core with the flange.

9. A prosthetic disc as in claim 8, wherein the annular structure comprises a rim which extends continuously around a lateral circumference of the core, the rim having a greater width at at least some locations than a width of an inner edge of the flange to provide said interference fit.

10. A prosthetic disc as in claim 1, wherein the peripheral restraining structure comprises:

a groove around a lateral edge of the core; and

a ring structure on at least one of the upper and lower plates, said ring structure having a lip which engages the groove.

11. A prosthetic disc as in claim 10, wherein the lip extends into the groove to form an interference fit between the ring structure and the core.

12. A prosthetic disc as in claim 1, wherein the outer surfaces of the upper and lower plates have at least one surface feature for promoting attachment of the outer surfaces to the vertebrae.

13. A prosthetic disc as in claim 12, wherein the at least one surface feature comprises a plurality of serrations disposed along the outer surfaces.

14. A prosthetic disc as in claim 13, wherein the at least one surface feature further comprises a surface coating.

15. A prosthetic disc as in claim 14, wherein the surface coating comprises plasma sprayed titanium.

16. A prosthetic disc as in claim 13, wherein the at least one surface feature further comprises a plurality of concavities formed by aluminum oxide blasting.

17. A prosthetic disc as in claim 13, wherein the at least one surface feature further comprises at least one fin disposed on each of the outer surfaces.

18. A prosthetic disc as in claim 17, wherein each fin includes at least one hole for further promoting attachment to the vertebrae.

19. A prosthetic disc as in claim 17, wherein each fin is oriented in a straight line in an anterior-posterior direction.

20. A prosthetic disc as in claim 17, wherein each fin is rotated away from an anterior-posterior axis of the disc.

21. A prosthetic disc as in claim 1, wherein the plates comprise at least one metal selected from the group consisting of cobalt chrome molybdenum and titanium.

22. A prosthetic disc as in claim 1, wherein each plate comprises an MRI compatible material coupled with a hardened material forming the inner surface.

23. A prosthetic disc as in claim 22, wherein the MRI-compatible material comprises titanium and the hardened material comprises cobalt chrome molybdenum.

24. A prosthetic disc as in claim 22, wherein the MRI-compatible material comprises titanium and the hardened material titanium nitride.

25. A prosthetic disc as in claim 22, wherein the MRI-compatible material and the hardened material are coupled together using a process selected from the group consisting of lamination, slip fitting, interference fitting and adhesion.

26. A prosthetic disc as in claim 1, wherein the core comprises two oppositely facing convex low-friction surfaces which slidably engage the inner curved surfaces of the upper and lower plates.

27. A prosthetic device as in claim 26, wherein the core comprises at least one material selected from the group consisting of polymers and ceramics.

28. A prosthetic disc for insertion between adjacent vertebrae, the prosthetic disc comprising:

upper and lower plates having outer surfaces locatable against the respective vertebrae and inner, curved surfaces, wherein at least one of the upper and lower plates includes a peripheral restraining structure extending about a periphery of the inner surface(s); and

a mobile core disposed between the curved surfaces to allow the plates to slide over the core,

wherein the core includes at least one peripheral protrusion for engaging with the peripheral restraining structure(s) to hold the core captive between the plates during sliding movement of the plates over the core.

29. A prosthetic disc as in claim 28, wherein the peripheral restraining structure comprises a flange, and wherein at least part of the protrusion on the core extends into the flange to provide an interference fit of the core with the flange.

30. A prosthetic disc as in claim 29, wherein the protrusion comprises a rim around a lateral circumference of the core, the rim having a greater diameter than a diameter of an inner edge of the flange.

31. A prosthetic disc as in claim 28, wherein the inner surfaces of the plates are concave and the core comprises two convex surfaces for slidably contacting the concave inner surfaces.

32. A prosthetic disc as in claim 31, wherein the concave and convex curved surfaces are spherical.

33. A prosthetic disc as in claim 28, wherein the core comprises a material selected from the group consisting of polymers and ceramics.

34. A prosthetic disc as in claim 28, further including at least one fin extending from each of the outer surfaces of the plates.

35. A prosthetic disc as in claim 34, wherein each fin includes at least one hole for promoting attachment of the fin to vertebral bone.

36. A prosthetic disc as in claim 34, wherein each fin is oriented in a straight line in an anterior-posterior direction.

37. A prosthetic disc as in claim 34, wherein each fin is rotated away from an anterior-posterior axis of the disc.

38. A prosthetic disc as in claim 28, wherein the outer surfaces of the plates are textured to enhance attachment of the plates to the vertebrae.

39. A prosthetic disc as in claim 38, wherein the textured surfaces comprise serrated surfaces.

40. A prosthetic disc as in claim 39, wherein the serrated surfaces further include a plurality of concavities formed by aluminum oxide blasting.

41. A prosthetic disc as in claim 38, wherein the outer surfaces further comprise a surface coating.

42. A prosthetic disc as in claim 41, wherein the surface coating comprises plasma sprayed titanium.

43. A prosthetic disc as in claim 38, wherein the outer surfaces of the plates are flat.

44. A prosthetic disc as in claim 28, wherein each plate comprises an MRI compatible material coupled with a hardened material forming the inner surface.

45. A prosthetic disc as in claim 44, wherein the MRI-compatible material comprises titanium and the hardened material comprises cobalt chrome molybdenum.

46. A prosthetic disc as in claim 44, wherein the MRI-compatible material comprises titanium and the hardened material titanium nitride.

47. A prosthetic disc as in claim 44, wherein the MRI-compatible material and the hardened material are coupled together using a process selected from the group consisting of lamination, slip fitting, interference fitting and adhesion.

48. A prosthetic disc as in claim 28, wherein the flange of one of the upper and lower plates is adapted to contact the other plate adjacent its inner surface during sliding movement of the plates over the core.

50. A prosthetic disc as in claim 48, wherein the peripheral restraining structure comprises a flange adapted to extend into the groove on the core to provide an interference fit of the core with the flange.

51. A prosthetic disc as in claim 50, wherein a portion of the core immediately adjacent the groove has a greater diameter than a diameter of an inner edge of the flange.

52. A prosthetic disc as in claim 48, wherein the inner surfaces of the plates are concave and the core comprises two convex surfaces for slidably contacting the inner surfaces.

53. A prosthetic disc as in claim 52, wherein the concave and convex curved surfaces are spherical.

54. A prosthetic disc as in claim 48, wherein the core comprises a material selected from the group consisting of polymers and ceramics.

55. A prosthetic disc as in claim 48, further including at least one fin extending from each of the outer surfaces of the plates.

56. A prosthetic disc as in claim 55, wherein each fin includes at least one hole for promoting attachment of the fin to vertebral bone.

57. A prosthetic disc as in claim 48, wherein the outer surfaces of the plates are textured to enhance attachment of the plates to the vertebrae.

58. A prosthetic disc as in claim 57, wherein the textured surfaces comprise serrated surfaces.

59. A prosthetic disc as in claim 57, wherein the outer surfaces further comprise a surface coating.

60. A prosthetic disc as in claim 59, wherein the surface coating comprises plasma sprayed titanium.

61. A prosthetic disc as in claim 57, wherein the outer surfaces of the plates are flat.

62. A prosthetic disc as in claim 48, wherein the flange of one of the upper and lower plates is adapted to contact the other plate adjacent its inner surface during sliding movement of the plates over the core.

49. A prosthetic disc for insertion between adjacent vertebrae, the prosthetic disc comprising:

upper and lower plates having outer surfaces locatable against the respective vertebrae and inner, curved surfaces, wherein at least one of the upper and lower plates includes a peripheral restraining structure extending about a periphery of the inner surface(s); and

a mobile core disposed between the curved surfaces to allow the plates to slide over the core,

wherein the core includes a lateral groove for engaging with the peripheral restraining structure(s) to hold the core captive between the plates during sliding movement of the plates over the core.

63. A method for restraining spacing between adjacent vertebrae, the method comprising:

implanting an upper plate against a lower surface of an upper vertebral body;

implanting a lower plate against an upper surface of a lower vertebral body; and

disposing a core between the upper and lower plates,

wherein the core floats between spherical cavities in each of the upper and lower plates, the plates restraining peripheral movement of the core using at least one peripheral restraining member.

64. A method as in claim 63, wherein implanting each of the plates comprises sliding a fin on each plate into a corresponding groove formed in its respective vertebral body.

65. A method as in claim 64, wherein sliding the fin is performed in a direction from posterior to anterior.

66. A method as in claim 64, wherein sliding the fin is performed in a lateral direction.

67. A method as in claim 64, wherein sliding the fin is performed in angled direction between posterior-anterior and lateral.

68. A method as in claim 64, wherein implanting further comprises contacting textured outer surfaces of the upper and lower plates with the upper and lower surfaces of the vertebral bodies.

69. A method for assembling a prosthetic disc for insertion between adjacent vertebrae, the method comprising:

movably coupling a core with a first endplate to form an interference fit between the core and the first endplate; and

contacting the core with a second endplate.

70. A method as in claim 69, wherein coupling the core with the first endplate comprises snap fitting the core into the endplate.

71. A method as in claim 69, wherein coupling the core with the first endplate comprises forming the endplate around the core.

72. A method as in claim 69, wherein coupling the core with the first endplate comprises engaging a peripheral protrusion of the core with a peripheral restraining structure of the first endplate.