System and method for replacing degenerated spinal disks

• US 7,217,291 B2
• Filed: 12/08/2003
• Issued: 05/15/2007
• Est. Priority Date: 12/08/2003
• Status: Active Grant

• Current Assignee: Kyphon SARL (Medtronic Plc)
• Original Assignee: St. Francis Medical Technologies, Inc. (Medtronic Plc)
• Inventors: Flynn, John J., Zucherman, James F., Winslow, Charles J., Markwart, John A., Hsu, Ken Y., Yerby, Scott A., Mitchell, Steve
• Primary Examiner(s): Stewart; Alvin J.
• Application Number:
  US10/730,717
• Publication Number:
  US 20050125061A1
• Time in Patent Office: 1,254 Days
• Field of Search: 623 1711- 1716
• US Class Current: 623/17.15
• CPC Class Codes: A61F 2/30965 Reinforcing the prosthesis by embedding particles or fibres during moulding or dipping
• CPC Class Codes: A61F 2/4425 made of articulated components
• CPC Class Codes: A61F 2002/3037 Translation along the common longitudinal axis, e.g. piston
• CPC Class Codes: A61F 2002/30433 using additional screws, bolts, dowels, rivets or washers e.g. connecting screws
• CPC Class Codes: A61F 2002/30471 connected by a hinged linkage mechanism, e.g. of the single-bar or multi-bar linkage type
• CPC Class Codes: A61F 2002/305 Snap connection
• CPC Class Codes: A61F 2002/30563 having elastic means or damping means, different from springs, e.g. including an elastomeric core or shock absorbers
• CPC Class Codes: A61F 2002/30566 Helical springs
• 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 2002/30785 parallel
• CPC Class Codes: A61F 2002/30884 Fins or wings, e.g. longitudinal wings for preventing rotation within the bone cavity
• CPC Class Codes: A61F 2002/30904 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 2002/448 comprising multiple adjacent spinal implants within the same intervertebral space or within the same vertebra, e.g. comprising two adjacent spinal implants
• 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 2220/0041 using additional screws, bolts, dowels or rivets, e.g. connecting screws
• CPC Class Codes: A61F 2220/0091 connected by a hinged linkage mechanism, e.g. of the single-bar or multi-bar linkage type
• 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 2310/00796 : Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite
• 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

Abstract

A system and method for replacing degenerated spinal disks in accordance with the present invention can substitute for interbody fusion techniques by replacing degenerated spinal disks with artificial spinal disks. In one embodiment, the system can comprise one or more artificial spinal disks, each comprising an upper and lower housing, a first spacer and a second spacer partially enclosed by a cavity formed by the housings, and a shaft with a spring positioned between the first spacer and the second spacer such that the spacers are urged apart.

Claims

1. An artificial replacement disk that is positionable between vertebrae comprising:

an upper housing including an upper cavity;

a lower housing including a lower cavity;

a first spacer and a second spacer, said first and second spacers mounted on a shaft with a resisting member located between the first and the second spacers and arranged concentrically on the shaft, which resisting member can urge said first and second spacers apart; and

said first and second spacers partially located in said upper cavity and partially located in said lower cavity.

2. The disk of claim 1 wherein at least one of said upper cavity and said lower cavity includes a ramp and at least one of said first spacer and said second spacer can slide relative to said ramp.

3. The disk of claim 1 wherein at least one of said upper cavity and said lower cavity includes a ramp and at least one of said first spacer and said second spacer can slide relative to said ramp in order to allow said first housing to move relative to said second housing.

4. The disk of claim 1 wherein at least one of said upper cavity and said lower cavity includes a ramp and at least said first spacer and said second spacer includes a ramp with can mate with the ramp of the at least one of said upper cavity and said lower cavity.

5. The disk of claim 1 wherein when the upper housing and the lower housing are urged together, said first spacer and said second spacer move relative to each other.

6. The disk of claim 1 wherein when the upper housing and the lower housing are urged together, one of the first spacer and the second spacer moves toward the other of the first spacer and the second spacer.

7. The disk of claim 1 wherein when the upper housing and the lower housing are urged together, the first spacer and the second spacer moves toward each other.

8. The disk of claim 1 including a retainer that maintains no more that a maximum distance between the upper housing and the lower housing.

9. The disk of claim 1 wherein at least one of the upper cavity and the lower cavity is concave in shape.

10. The disk of claim 1 wherein at least one of the upper cavity and the lower cavity has a first sloping end, a central cylindrical portion, and a second sloping end.

11. The disk of claim 1 wherein at least one of the upper cavity and the lower cavity is kidney shaped.

12. The disk of claim 1 wherein at least one of the upper cavity and the lower cavity is substantially elliptically shaped.

13. The disk of claim 1 wherein at least one of the first spacer and the second spacer includes a ramp.

14. The disk of claim 1 wherein at least one of the first spacer and the second spacer is oval-shaped.

15. The disk of claim 1 wherein at least one of the first spacer and the second spacer is bell-shaped.

16. The disk of claim 1 wherein at least one of the housings includes a keel adapted to be positioned in a vertebral body of a vertebra.

17. The disk of claim 1 wherein at least one of the housings includes a keel that is positioned on said at least one housing so that with the disk implanted in a spine the keel is oriented laterally with respect to the spine.

18. The disk of claim 1 wherein at least one of the housings includes a keel that is positioned on said at least one housing so that with the disk implanted in a spine the keel is substantially perpendicular to a sagittal plane of the spine.

19. The disk of claim 1 wherein said upper and lower housings with no force on the disk are spaced apart a maximum amount and force on any portion of the disk does not space the housings apart beyond said maximum amount.

20. The disk of claim 1 wherein with the disk implanted in a spine the shaft is adapted to be oriented along a lateral line with respect to the spine.

21. The disk of claim 1 wherein with the disk implanted in a spine the shaft is adapted to be oriented along an anterior/posterior line.

22. The disk of claim 1 including BMP provided thereon.

23. An artificial replacement disk that is positionable between vertebrae comprising:

a first housing including a first cavity;

a second housing including a second cavity;

a first spacer and a second spacer, said first and second spacers mounted on a shaft with a resisting member located between the first and the second spacers and arranged concentrically on the shaft, which resisting member can urge said first and second spacers apart; and

said first and second spacers partially located in said first cavity and partially located in said second cavity; and

when the first housing is urged toward the second housing by one or both of an extension and flexion motion of the vertebrae, the first and the second spacers move relative to each other and against the resisting member.

24. The disk of claim 23 wherein said first and said second housings have first and second elongated sides respectively, and wherein at least one of the first and second spacers can move along a direction of the first and second elongated sides, such that when the first and second housing are urged together at an angle that is non-parallel to at least one of the first and second elongated sides, the at least one of the first and second spacers move along the direction of the first and the second elongated sides.

25. The disk of claim 23 wherein at least one of the first cavity and the second cavity has a first sloping end, a central cylindrical portion, and a second sloping end.

26. The disk of claim 23 including at least one of said first and second housings including a keel that is adapted to be positioned in a vertebral body of the spine.

27. The disk of claim 23 wherein at least one of the housings includes a keel that is positioned on said at least one housing so that with the disk implanted in a spine the keel is oriented laterally with respect to the spine.

28. The disk of claim 23 wherein at least one of the housings includes a keel that is positioned on said at least one housing so that with the disk implanted in a spine the keel is substantially perpendicular to a sagittal plane of the spine.

29. The disk of claim 23 wherein said first and second housings with no force on the disk are spaced apart a maximum amount and force on any portion of the disk does not space the housings apart beyond said maximum amount.

30. The disk of claim 23 wherein with the disk implanted in a spine the shaft is adapted to be oriented along a lateral line with respect to the spine.

31. The disk of claim 23 wherein with the disk implanted in a spine the shaft is adapted to be oriented along an anterior/posterior line.

32. The disk of claim 23 including BMP provided thereon.

33. An artificial replacement disk that is positionahle between vertebrae comprising:

a first housing including a cavity;

a second housing;

a first spacer and a second spacer, said first and second spacers mounted on a shaft with a resisting member located between the first and the second spacers, which resisting member can urge said first and second spacers apart;

said first and second spacers at least partially located in said cavity;

wherein the cavity has a sloping portion, and a cylindrical portion; and

when the first housing is urged toward the second housing, by one or both of an extension and flexion motion of the vertebrae the first and the second spacers move relative to each other and against the resisting member with one of the first and second spacers moving along the sloping portion of the cavity and toward the cylindrical portion.

34. An artificial spinal disk adapted to be positioned between adjacent vertebrae of a spine, comprising:

an upper plate;

a lower plate positioned opposite the upper plate such that a gap having a maximum width exists between the lower plate and the upper plate;

a device arranged between the upper plate and the lower plate for urging the upper and lower plates apart, the device including;

a shaft,

a first spacer slidably associated with the shaft,

a second spacer associated with the shaft, and

a resisting mechanism disposed between the first spacer and the second spacer such that the first spacer and the second spacer are urged apart; and

wherein when the upper plate and the lower plate are urged together and the resisting mechanism is overcome by one or both of an extension and flexion motion of the vertebrae, the first spacer and the second spacer are urged together such that at least a portion of the gap collapses.

35. The artificial spinal disk of claim 34,

wherein when the upper plate and lower plate are urged together, one or both of the first spacer and the second spacer slide toward the other of the first spacer and the second spacer.

36. The artificial spinal disk of claim 35, wherein a cavity of at least one of the upper plate and the lower plate within which the device is at least partially disposed includes a ramp.

37. The artificial spinal disk of claim 36, wherein the first spacer has a substantially ovoid-shaped cross-section such that the first spacer substantially conform to the ramp of at least one of the upper plate and the lower plate.

38. The artificial spinal disk of claim 36, wherein the first spacer has a substantially bell-shaped cross-section such that the first spacer substantially conforms to the ramp of at least one of the upper plate and the lower plate.

39. The artificial spinal disk of claim 35, wherein a cavity of at least one of the upper plate and the lower plate within which the device is at least partially disposed is kidney shaped.

40. The artificial spinal disk of claim 39, wherein the first spacer has a substantially oval-shaped cross-section such that the first spacer substantially conforms to at least one of the upper plate and the lower plate.

41. The artificial spinal disk of claim 39, wherein the first spacer has a substantially bell shaped cross-section such that the first spacer substantially conform to at least on of the upper plate and the lower plate.

42. The artificial spinal disk of claim 35, wherein the first spacer and the second spacer each comprise one of titanium, stainless steel, or PEEK.

43. The artificial spinal disk of claim 34, wherein the resisting mechanism is a spring.

44. The artificial spinal disk of claim 34, wherein the upper plate and lower plate each comprise one of titanium, stainless steel, or PEEK.

45. The artificial spinal disk of claim 34, further comprising:

a plurality of ridges on at least one of the upper plate and lower plate adapted to grip an associated vertebra.

46. The disk of claim 34 wherein:

the first and second spacers have shapes of revolution.

47. The disk of claim 34 wherein:

said first and second spacers have first and second spacer ramps respectively.

48. The disk of claim 34 wherein:

said first and second spacers each have housing contact surfaces that are wider than the spacers are tall.

49. The disk of claim 34 wherein:

said first and second spacers are conically-shaped with rounded edges.

50. A artificial spinal disk for substituting at least a portion of a spinal disk between adjacent vertebrae, comprising:

an upper housing adapted to be positioned adjacent to a first vertebra;

a lower housing positioned opposite the upper housing, the lower housing adapted to be positioned adjacent to a second vertebra;

an first spacer positioned between the upper housing and the lower housing;

a second spacer positioned between the upper housing and the lower housing;

wherein the first spacer and the second spacer urge a gap between the upper housing and the lower housing;

a shaft;

the first spacer and the second spacer mounted on the shaft, one or both of the first spacer and the second spacer being movable along the shaft;

a resisting mechanism adapted to urge the first and second spacer apart; and

wherein when a force is applied to the upper housing and the lower housing such that the resisting mechanism is overcome, the gap is reduced.

51. The artificial spinal disk of claim 50, wherein the shaft includes a spring for applying the load.

52. The artificial spinal disk of claim 50, wherein a cavity of at least one of the upper housing and the lower housing has a ramp.

53. The artificial spinal disk of claim 52, wherein the first spacer has a substantially oval-shaped cross-section such that the first spacer substantially conforms to the ramp at least one of the upper housing and the lower housing.

54. The artificial spinal disk of claim 52, wherein the first spacer has a substantially bell-shaped cross-section such tat the first spacer substantially conforms to the ramp of at least one of the upper housing and the lower housing.

55. The artificial spinal disk of claim 50, wherein a cavity of at least one of the upper housing and the lower housing is kidney-shaped.

56. The artificial spinal disk of claim 50, wherein when the upper housing and the lower housing are urged together, the first spacer slides along the upper housing and the lower housing and in a cavity to reduce the space between the first spacer and the second spacer.

57. The artificial spinal disk of claim 50, wherein the upper housing and lower housing each comprise one of titanium, stainless steel, or PEEK.

58. The artificial spinal disk of claim 50, wherein the first spacer and the second spacer each comprise one of titanium, stainless steel, or PEEK.

59. The artificial spinal disk of claim 50, further comprising:

a ridge on at least one of the upper housing and lower housing for gripping an associated vertebra.

60. An artificial spinal disk that is adapted to be placed between adjacent vertebral bodies of a spine, comprising:

an upper elongated housing;

a lower elongated housing;

a first spacer and a second spacer positioned relative to an elongated shaft between the first and second housings with the elongated shaft being about parallel to the upper and lower elongated housings;

a spring mechanism positioned along said shaft in order to urge said first and second spacers apart; and

wherein when the upper and lower housings are urged together, by one or both of an extension and flexion motion of the vertebrae at least one of the first and second spacers can move relative to the other against the spring mechanism.

61. The disk of claim 60 wherein:

the first and second spacers have shapes of revolution.

62. The disk of claim 60 wherein:

said first and second spacers have first and second spacer ramps respectively.