Slotted head pedicle screw assembly

• US 6,554,834 B1
• Filed: 10/07/1999
• Issued: 04/29/2003
• Est. Priority Date: 10/07/1999
• Status: Expired due to Term

• Current Assignee: Stryker European Operations Holdings, LLC (Stryker Corporation)
• Original Assignee: Stryker Spine
• Inventors: Crozet, Yves, Martin, Gregory
• Primary Examiner(s): Philogene, Pedro
• Application Number:
  US09/414,272
• Time in Patent Office: 1,300 Days
• Field of Search: 606/61, 606/60, 606/69, 606/65, 606/70, 606/71, 606/72, 606/73, 606/54, 606/59, 606/66, 606/104, 623/16.11, 623/17.11
• US Class Current: 606/65
• CPC Class Codes: A61B 17/7032 Screws or hooks with U-shaped head or back through which longitudinal rods pass
• CPC Class Codes: A61B 17/7037 wherein pivoting is blocked when the rod is clamped
• CPC Class Codes: A61B 17/7082 for driving, i.e. rotating, screws or screw parts specially adapted for spinal fixation, e.g. for driving polyaxial or tulip-headed screws driving other bone screws A61B17/8875
• CPC Class Codes: A61B 17/861 specially shaped for gripping driver

Abstract

A pedicle screw assembly includes a fastener having an expandable head. The expandable head has an outer surface including a convex portion, a recess having an inner surface and defining an inner dimension, and at least one slot extending between the inner and outer surfaces thereof. The assembly also has an insert positionable at least partially in the recess having an outer surface defining an outer dimension that is greater than the inner dimension of the recess. The assembly includes a coupling element including a rod receiving opening, a bore for the fastener, and a seat for receiving the head of the fastener and allowing the fastener and coupling element to pivot relative to one another before being locked in place. After an orthopedic rod is positioned within the coupling element, a locking element associated with the coupling element locks the orthopedic rod in the rod-receiving opening. The locking element applies a force onto the rod to in turn force the insert into the recess of the expandable head for expanding the outer surface of the head against the seat of the coupling element and locking the coupling element and fastener from further pivotal movement relative to one another.

Claims

1. A pedicle screw assembly comprising:

a. a fastener including a tip end for insertion into bone and an expandable head at the opposite end thereof, said head having an outer surface including a convex portion, and a recess having an inner surface and defining an inner dimension;

b. an insert which can be positioned at least partially in the recess, said insert having an outer surface and defining an outer dimension that is greater than the inner dimension of the recess;

c. a coupling element including a rod receiving opening, a bore for receiving said head of said fastener, and a seat for receiving said head of said fastener, said seat including a concave portion for receiving the convex portion of said head and allowing said fastener to pivot relative to said coupling element before being locked therein; and

d. a locking element associated with said coupling element, said locking element being adapted to be forced against an orthopedic rod arranged in said rod receiving opening, to in turn force said insert into the recess of said head so that the outer dimension of said insert bears against the inner dimension of said head, whereby said head expands against the seat of said coupling element for preventing said coupling element from moving pivotally relative to said fastener.

2. The assembly as claimed in claim 1, wherein said head includes at least one slot extending between the inner and outer surfaces thereof for allowing expansion of said head.

3. The assembly as claimed in claim 2, wherein said fastener has a longitudinal axis.

4. The assembly as claimed in claim 2, wherein said at least one slot extends toward the tip end of said fastener.

5. The assembly as claimed in claim 3, wherein said at least one slot includes a plurality of slots.

6. The assembly as claimed in claim 5, wherein said plurality of slots subdivide said screw head into a plurality of flexible arms extending away from the tip end of said fastener.

7. The assembly as claimed in claim 6, wherein each said flexible arm includes a tab at an upper end thereof extending toward the longitudinal axis of said fastener.

8. The assembly as claimed in claim 7, wherein said at least one tab includes a plurality of tabs.

9. The assembly as claimed in claim 8, wherein said recess has an outer circumference and the plurality of tabs are arranged in an annular configuration around the outer circumference of said recess.

10. The assembly as claimed in claim 3, wherein the flexible arms of said head are adapted for flexing away from the longitudinal axis for expanding said head.

11. The assembly as claimed in claim 3, wherein the flexible arms of said head are adapted for flexing toward the longitudinal axis for compressing said head.

12. The assembly as claimed in claim 3, wherein the recess in said head is substantially centered on the longitudinal axis of said fastener.

13. The assembly as claimed in claim 3, wherein the inner and outer surfaces of said screw head are substantially centered on the longitudinal axis of said fastener.

14. The assembly as claimed in claim 8, wherein said insert has an upper end, a lower end and the outer surface extending therebetween, the outer surface of said insert including a flange.

15. The assembly as claimed in claim 14, wherein the tabs are adapted for engaging the flange for retaining said insert within the recess of said fastener.

16. The assembly as claimed in claim 8, wherein said insert has an upper end and an outer surface extending from the upper end that is substantially spherical in shape.

17. The assembly as claimed in claim 16, wherein said insert has a minimum diameter section adjacent the upper end and wherein the tabs are adapted for engaging the minimum diameter section for retaining said insert within the recess of said fastener.

18. The assembly as claimed in claim 1, wherein said insert has an upper end, a lower end and the outer surface extending therebetween, the outer surface of said insert including a flange for retaining said insert within said recess of said fastener.

19. The assembly as claimed in claim 18, wherein the outer surface of said insert tapers inwardly from the flange toward the lower end thereof.

20. The assembly as claimed in claim 19, wherein the lower end of said insert has a substantially spherical shape.

21. The assembly as claimed in claim 19, wherein the lower end of said insert is substantially flat.

22. The assembly as claimed in claim 18, wherein the upper end of said insert extends beyond said head for preventing said orthopedic rod from contacting said head.

23. The assembly as claimed in claim 18, wherein the upper end of said insert has a radial surface.

24. The assembly as claimed in claim 23, wherein the radial surface at the upper end of said insert is adapted for engaging said orthopedic rod.

25. The assembly as claimed in claim 18, wherein the outer surface of said insert is substantially conical.

26. The assembly as claimed in claim 18, wherein the outer surface of said insert is substantially polygon-shaped.

27. The assembly as claimed in claim 18, wherein the outer surface of said insert is substantially cylindrical.

28. The assembly as claimed in claim 1, wherein said insert includes at least one radial projection, whereby said at least one projection extends into said at least one slot when said insert is at least partially positioned in the recess.

29. The assembly as claimed in claim 28, wherein said at least one radial projection includes a plurality of radial projections.

30. The assembly as claimed in claim 18, wherein said insert includes a socket at an upper end thereof adapted for receiving a driver.

31. The assembly as claimed in claim 30, wherein the socket is adapted for receiving a hexagonal wrench.

32. The assembly as claimed in claim 30, wherein the socket is adapted for receiving a screwdriver.

33. The assembly as claimed in claim 1, wherein said insert includes an axial bore extending therethrough.

34. The assembly as claimed in claim 33, wherein the recess in said head includes a socket formed therein adapted to receive a driver for driving said fastener.

35. The assembly as claimed in claim 34, wherein when said insert is positioned in said recess, the axial bore of said insert is substantially aligned with the socket in the recess of said head.

36. The assembly as claimed in claim 1, wherein said insert has an upper end and an outer surface extending from the upper end that is substantially spherical in shape.

37. The assembly as claimed in claim 1, wherein said locking element comprises threads formed at an upper end of said coupling element.

38. The assembly as claimed in claim 37, wherein the coupling element threads are internal threads formed on an interior surface of said coupling element.

39. The assembly as claimed in claim 38, wherein said locking element further comprises a set screw having external threads for threadably engaging the internal threads of said coupling element.

40. The assembly as claimed in claim 37, wherein the coupling element threads are exterior threads formed on an exterior surface of said coupling element.

41. The assembly as claimed in claim 40, wherein said locking element further comprises a nut having internal threads for threadably engaging the exterior threads of said coupling element.

42. The assembly as claimed in claim 1, wherein the exterior surface of said coupling element includes one or more notches formed therein for securing said coupling element.

43. The assembly as claimed in claim 1, wherein said fastener includes a threaded portion having a diameter, the threaded portion extending from the tip end toward said head.

44. The assembly as claimed in claim 43, wherein said fastener includes a neck portion extending between the threaded portion thereof and said head, the neck portion having a diameter less than the diameter of the threaded portion for facilitating pivotal movement of said coupling element relative to said fastener.

45. The assembly as claimed in claim 44, wherein the neck of said fastener has a concave surface.

46. The pedicle screw assembly as claimed in claim 1, wherein said coupling element includes an exterior surface having a gripping surface.

47. The pedicle screw assembly as claimed in claim 1, wherein said coupling element includes an exterior surface having gripping means for maneuvering said coupling element.

48. The pedicle screw assembly as claimed in claim 47, wherein said gripping means includes one or more depressions formed in the exterior surface of said coupling element.

49. A driver for screwing the fastener of claim 5 into a bone, said driver comprising a shaft having a lower end and a plurality of prongs extending from the lower end of the shaft, wherein said prongs are adapted for being inserted into said slots.

50. The driver as claimed in claim 49, wherein said driver includes external threads provided on the shaft.

51. The driver as claimed in claim 50, wherein said locking element comprises internal threads formed on an interior surface of said coupling element.

52. The driver as claimed in claim 51, wherein the external threads of said driver are adapted for engaging the internal threads of said coupling element.

53. A pedicle screw assembly comprising:

a. a fastener including a tip end for insertion into bone and a head at the opposite end thereof, said head having an outer surface with a convex portion and said head having a recess defining an inner surface having an inner dimension;

b. an insert secured at least partially in said recess and having an outer surface in contact with the inner surface of said recess, wherein said insert pivots simultaneously with said fastener after being secured at least partially therein;

c. a coupling element including a rod receiving opening, a bore for receiving said fastener, and a seat for receiving said head of said fastener, said seat including a concave portion for receiving the convex portion of said head and allowing said fastener to pivot relative to said coupling element before being locked therein; and

d. a locking element for locking an orthopedic rod in the rod receiving opening, said locking element being associated with said coupling element to force said insert into the recess of said head so that the outer surface of said insert bears against the inner surface of said head, wherein said head engages the seat of said coupling element for preventing said coupling element from moving pivotally relative to said fastener.

54. The assembly as claimed in claim 53, wherein said head includes at least one slot extending between the inner and outer surfaces thereof for allowing expansion of said head.

55. The assembly as claimed in claim 54, wherein said at least one slot extends from an upper end of said fastener toward the tip end thereof.

56. The assembly as claimed in claim 55, wherein said at least one slot includes a plurality of slots.

57. The assembly as claimed in claim 54, wherein the outer surface of said insert includes an outer dimension that is greater than the inner dimension of the recess so that when said insert is forced into the recess the outer dimension of said insert bears against the inner dimension of said head for expanding said head.

58. The assembly as claimed in claim 57, wherein said insert has an upper end, a lower end and a flange therebetween extending around the outer dimension.

59. The pedicle screw assembly as claimed in claim 53, wherein said coupling element includes an exterior surface having a gripping surface.

60. The pedicle screw assembly as claimed in claim 53, wherein said coupling element includes an exterior surface having gripping means for maneuvering said coupling element.

61. The pedicle screw assembly as claimed in claim 60, wherein said gripping means includes one or more depressions formed in the exterior surface of said coupling element.

62. A pedicle screw assembly for use in conjunction with an orthopedic rod, said assembly comprising:

a. a fastener including a tip end for insertion into bone and an expandable head at the opposite end thereof having an outer surface including a convex portion, a recess formed in said head defining an inner surface having an inner dimension; and

b. a coupling element including a rod receiving opening, a bore for receiving said fastener, and a seat for receiving said head of said fastener, said seat including a concave portion for receiving the convex portion of said head and allowing said fastener to pivot relative to said coupling element before being locked therein.

63. The assembly as claimed in claim 62, wherein said expandable head includes at least one slot extending between the inner and outer surfaces of said head for allowing expansion of said head.

64. The assembly as claimed in claim 63, wherein said at least one slot extends from an upper end of said fastener toward the tip end thereof.

65. The assembly as claimed in claim 64, wherein said at least one slot includes a plurality of slots.

66. The assembly as claimed in claim 65, wherein said plurality of slots subdivide said head into a plurality of flexible arms at the upper end of said fastener.

67. The assembly as claimed in claim 66, wherein said flexible arms are adapted for flexing away from one another for expanding said screw head.

68. The assembly as claimed in claim 67, further comprising an insert which can be positioned at least partially in the recess, said insert having an outer dimension that is greater than the inner dimension of said head.

69. The assembly as claimed in claim 62, wherein said coupling element includes an exterior surface having one or more notches formed therein for securing said coupling element.

70. The assembly as claimed in claim 68, further comprising a locking element for locking an orthopedic rod in the rod receiving opening, said locking element being associated with said coupling element to force said insert into the recess of said head so that the outer dimension of said insert bears against the inner dimension of said head, wherein said head expands against the seat of said coupling element for preventing said fastener from moving pivotally relative to said coupling element.

71. The pedicle screw assembly as claimed in claim 62, wherein said coupling element includes an exterior surface having a gripping surface.

72. The pedicle screw assembly as claimed in claim 62, wherein said coupling element includes an exterior surface having gripping means for maneuvering said coupling element.

73. The pedicle screw assembly as claimed in claim 72, wherein said gripping means includes one or more depressions formed in the exterior surface of said coupling element.

74. A pedicle screw assembly comprising:

a. a fastener including a tip end for insertion into bone and an expandable head at the opposite end thereof, said head including an outer surface having an outer dimension and a recess having an inner surface, the inner surface defining an inner dimension of said head; and

b. a coupling element including a rod receiving opening, a bore having upper and lower ends for receiving said fastener, and a seat for receiving said head of said fastener, the bore having a minimum diameter section with an inner dimension that is less than the outer dimension of said head and defining an expansion cavity between the upper and lower ends thereof having an inner dimension greater than the outer dimension of said head, wherein said screw can be pivotally connected with said coupling element by passing the tip end of said fastener through the upper end of said bore toward the lower end thereof while compressing said head as said head passes through the minimum diameter section of said bore.

75. The assembly as claimed in claim 74, wherein said expandable head includes at least one slot extending between the inner and outer surfaces thereof for allowing expansion and compression of said expandable head.

76. The pedicle screw assembly as claimed in claim 74, wherein said coupling element includes an exterior surface having a gripping surface.

77. The pedicle screw assembly as claimed in claim 74, wherein said coupling element includes an exterior surface having gripping means for maneuvering said coupling element.

78. The pedicle screw assembly as claimed in claim 77, wherein said gripping means includes one or more depressions formed in the exterior surface of said coupling element.