Devices and methods for the correction and treatment of spinal deformities

• US 20030088251A1
• Filed: 05/02/2002
• Published: 05/08/2003
• Est. Priority Date: 11/05/2001
• Status: Active Grant

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Inventors: Sherman, Michael C., Drewry, Troy D., Braun, John T., Molz, Fred J.
• Granted Patent: US 7,285,121 B2
• Time in Patent Office: Days
• US Class Current: 606/73
• CPC Class Codes: A61B 17/7007 Parts of the longitudinal elements, e.g. their ends, being specially adapted to fit around the screw or hook heads
• CPC Class Codes: A61B 17/7022 Tethers, i.e. longitudinal elements capable of transmitting tension only, e.g. straps, sutures or cables A61B17/702 takes precedence
• CPC Class Codes: A61B 17/7083 Tools for guidance or insertion of tethers, rod-to-anchor connectors, rod-to-rod connectors, or longitudinal elements
• CPC Class Codes: A61B 17/864 hollow, e.g. with socket or cannulated
• CPC Class Codes: A61B 2017/00867 shape memory effect for prostheses A61F2210/0014

Abstract

One or more anchors are engaged intravertebrally for attachment of one more constructs thereto to correct or treat spinal conditions or deformities. Methods for inserting the anchors are also provided along with constructs for attachment to the anchors.

Claims

1. A bone anchor, comprising:

a body engageable intravertebrally to a vertebra, said body having a proximal end, a distal end, and a thread form extending along at least a portion of said body, said body further defining a chamber and having a tapered profile from said proximal end to said distal end such that said thread form is at least partially engageable with undisturbed bone of the vertebra; and

a head extending from said proximal end of said body and positioned outside the vertebra when said body is engaged to the vertebra.

2. The bone anchor of claim 1, wherein said thread form extends between said proximal end and said distal end of said body.

3. The bone anchor of claim 2, wherein said entire thread form is engageable to undisturbed bone along said body.

4. The bone anchor of claim 2, wherein said thread form has a self-tapping configuration.

5. The bone anchor of claim 1, wherein said tapered body has a frusto-conical shape extending between said proximal end and said distal end.

6. The bone anchor of claim 5, wherein said frusto-conical, tapered body forms a taper angle.

7. The bone anchor of claim 6, wherein said taper angle is the range from 5 degrees to 45 degrees.

8. The bone anchor of claim 6, wherein said taper angle is about 5 degrees.

9. The bone anchor of claim 1, wherein said body has a minimum size at said distal end and a maximum size at said proximal end.

10. The bone anchor of claim 1, wherein said head has a proximal end and said chamber extends through said head and opens at said proximal end of said head.

11. The bone anchor of claim 10, wherein said chamber defines a tool engaging portion adjacent said proximal end of said head.

12. The bone anchor of claim 10, further comprising a cap engageable to said head such that said cap is located proximally of said head.

13. The bone anchor of claim 12, wherein said cap includes a stem engageable to said head in said chamber.

14. The bone anchor of claim 13, wherein said stem compresses bone material in said chamber when said cap is engaged to said head.

15. The bone anchor of claim 12, wherein said cap includes an end member extending radially about said proximal end of said head.

16. The bone anchor of claim 1, wherein said head includes a recessed surface extending between said proximal end of said body and a proximal end of said head.

17. The bone anchor of claim 16, wherein said head further includes a lip extending around said recessed surface separating said recessed surface into a proximal platform and a distal platform.

18. The bone anchor of claim 16, wherein said recessed surface has a concave profile extending between said proximal end of said body and said proximal end of said head.

19. The bone anchor of claim 1, wherein said distal end of said body is beveled to facilitate insertion of said body into the vertebra.

20. The bone anchor of claim 1, wherein said thread form is interrupted by a number of openings extending through said body and in communication with said chamber, wherein bone material cut by said thread form as said body is threadingly engaged to the vertebra is deposited through said openings into said chamber, whereby bone growth occurs through said body to fuse said body with the vertebra.

21. The bone anchor of claim 20, wherein said number of openings is in the range from one to three openings.

22. The bone anchor of claim 20, wherein each of said number of openings has an oval shape centered on and extending along said thread form.

23. The bone anchor of claim 20, wherein said number of openings are staggered about said body.

24. The bone anchor of claim 20, wherein said number of openings are spaced along said thread form such that when a first one of said number of openings is positioned at a first depth in the vertebra at least one complete revolution of said body along said thread form is required before a second one of said number of openings is positioned at said first depth in the vertebra.

25. The bone anchor of claim 20, wherein each of said number of openings has a triangular shape with an apex of said shape oriented toward said distal end of said body.

26. The bone anchor of claim 20, wherein each of said number of openings has a rectangular shape.

27. A bone anchor, comprising:

a head; and

a body extending distally from said head, said body engageable intravertebrally to a vertebra by a thread form extending at least partially along said body, said body having a proximal end, a distal end, and a tapered profile extending therebetween, said body defining a chamber and a number of openings interrupting said thread form in communication with said chamber, wherein bone material cut by said thread form as said body is threadingly engaged to the vertebra is deposited through said openings into said chamber whereby fusion of the bone anchor to the vertebra occurs through said chamber.

28. The bone anchor of claim 27, wherein:

said chamber opens at said distal end and receives bone material from the vertebra therethrough as said body is threadingly engaged to the vertebra.

29. The bone anchor of claim 28, wherein the bone material deposited through said number of openings provides bony continuity between bone material received through said distal end opening of said chamber and bone material of the vertebra around said body.

30. The bone anchor of claim 29, wherein said tapered profile is configured so that said thread form is at least partially engageable with undisturbed bone to secure the bone anchor in the vertebra.

31. The bone anchor of claim 27, wherein said number of openings is in the range from one to three openings.

32. The bone anchor of claim 27, wherein each of said number of openings has an oval shape centered on and extending along said thread form.

33. The bone anchor of claim 27, wherein said number of openings are staggered about said body.

34. The bone anchor of claim 27, wherein said number of openings are spaced along said thread form such that when a first one of said number of openings is positioned at a first depth in the vertebra at least one complete revolution of said body along said thread form is required before a second one of said number of openings is positioned at said first depth in the vertebra.

35. The bone anchor of claim 27, wherein each of said number of openings has a triangular shape with an apex of said shape oriented toward said distal end of said body.

36. The bone anchor of claim 27, wherein each of said number of openings has a rectangular shape.

37. The bone anchor of claim 27, wherein said thread form extends between said proximal end and said distal end of said body.

38. The bone anchor of claim 37, wherein said thread form is entirely engageable to undisturbed bone along said body.

39. The bone anchor of claim 37, wherein said thread form has a self-tapping configuration.

40. The bone anchor of claim 27, wherein said tapered body has a frusto-conical shape extending between said proximal end and said distal end.

41. The bone anchor of claim 40, wherein said frusto-conical, tapered body forms a taper angle in the range from about 5 degrees to about 45 degrees.

42. The bone anchor of claim 27, further comprising a cap having a stem engageable to said head in said chamber, wherein said stem compresses bone material in said chamber.

43. The bone anchor of claim 42, further comprising graft material in said chamber, wherein said graft material is compressed by said stem.

44. A bone anchor, comprising:

a head; and

a body extending distally from said head, said body extending between a proximal end adjacent said head and a distal end, said body including;

a thread form configured for at least partial engagement with undisturbed bone of a vertebra to which said body is intravertebrally engaged;

a chamber opening at said distal end;

at least one opening interrupting said thread form in communication with said chamber, wherein;

bone material cut by said thread form as said body is threadingly engaged to the vertebra is deposited through said at least one opening into said chamber;

bone material from the vertebra is received into said chamber through said distal end opening as said body is threadingly engaged to the vertebra; and

the bone material deposited through said number of openings provides bony continuity between bone material received through said distal end opening of said chamber and bone material of the vertebra around said body for fusion of said body with the vertebra.

45. The bone anchor of claim 44, wherein said chamber extends through said head and opens at a proximal end thereof.

46. The bone anchor of claim 44, wherein the bone material deposited through said number of openings provides continuity between bone material received through said distal end opening of said chamber and bone material of the vertebra around said body.

47. The bone anchor of claim 44, wherein said body has a tapered profile extending from said proximal end to said distal end.

48. A spinal stabilization system, comprising:

a first bone anchor having a body defining a chamber, said body intravertebrally fuseable with a first vertebra;

a second bone anchor having a body defining a chamber, said body intravertebrally fuseable to a second vertebra; and

a stabilization construct extending along the exterior of the first and second vertebrae and connecting said first bone anchor and said second bone anchor.

49. The system of claim 48, wherein said stabilization construct is a looped tether.

50. The system of claim 49, wherein said lopped tether includes:

a first portion extending along a first side of said first and second bone anchors;

a second portion spaced from said first portion extending along a second side of said first and second bone anchor; and

at least one crimp extending around said looped tether loop and securing the first and second portions in a position more proximate one another.

51. The system of claim 50, wherein said at least one crimp increases the compressive force applied by said looped tether between said first bone anchor and said second bone anchor.

52. The system of claim 50, wherein said at least one crimp includes a number of crimps spaced along said looped tether between said first and second anchors.

53. The system of claim 49, wherein said looped tether applies a compressive force between said first bone anchor and said second bone anchor.

54. The system of claim 48, wherein:

said first bone anchor includes a head extending from said body;

said second bone anchor includes a head extending from said body; and

said stabilization construct being engaged to said head of said first anchor and said head of said second anchor.

55. The system of claim 54, further comprising:

a third bone anchor having a body defining a chamber, said body intravertebrally fuseable with a third vertebra, said third bone anchor including a head extending from said body; and

said stabilization construct being engaged to said head of said third anchor.

56. The system of claim 54, wherein each of said heads of said first and second bone anchors includes a recessed surface to which said stabilization construct is engaged.

57. The system of claim 56, wherein each of said heads of said first and second bone anchors includes a lip extending around said recessed surface, said lip defining a proximal platform and a distal platform on said recessed surface.

58. The system of claim 57, wherein said stabilization construct includes a first looped tether positionable on one of said proximal and distal platforms of said recessed surface and a second looped tether positionable on the other one of said proximal and distal platforms.

59. A method for stabilizing a portion of the spine, comprising:

intravertebrally engaging a first bone anchor for fusion with a first vertebra;

intravertebrally engaging a second bone anchor for fusion with a second vertebra;

connecting a tether to the first bone anchor and to the second bone anchor, the tether applying a compressive force between the first and second bone anchors; and

crimping the tether between the first bone anchor and the second bone anchor to increase a compressive force applied by the tether between the first bone anchor and the second bone anchor.

60. The method of claim 59, wherein said first bone anchor is intravertebrally engaged to undisturbed bone of the first vertebra and said second bone anchor is intravertebrally engaged to undisturbed bone of the second vertebra.

61. The method of claim 59, wherein connecting the tether includes looping the tether around a head of the first bone anchor and looping the tether around a head of the second bone anchor.

62. The method of claim 61, wherein the looped tether includes:

a first portion extending along a first side of said first and second bone anchors;

a second portion spaced from said first portion extending along a second side of said first and second bone anchor; and

crimping the tether includes securing the first and second portions in a position more proximate one another.

63. A method for stabilizing a portion of the spine, comprising:

intravertebrally engaging a first bone anchor for fusion with a first vertebra;

intravertebrally engaging a second bone anchor for fusion with a second vertebra;

placing a first anchor extension extending proximally from the first anchor;

placing a second anchor extension extending proximally from the second bone anchor;

applying a compressive force between the first bone anchor and the second bone anchor adjacent the first and second bone anchors;

placing a tether over proximal ends of and around the first and second anchor extensions;

advancing the tether along the anchor extensions toward the first and second bone anchors;

applying a compressive force between the first bone anchor and the second bone anchor adjacent the proximal ends of the first and second anchor extensions;

removing the compressive force applied adjacent the first and second bone anchors; and

securing the tether to the first and second bone anchors.

64. The method of claim 63, further comprising removing the compressive force applied adjacent the proximal ends of the anchor extensions.

65. The method of claim 63, further comprising removing the first and second anchor extensions from the anchors.

66. The method of claim 63, further comprising crimping the tether between the first bone anchor and the second bone anchor to increase a compressive force applied by the tether between the first bone anchor and the second bone anchor.