Bone plate and resilient screw system allowing bi-directional assembly

• US 20040127904A1
• Filed: 12/31/2002
• Published: 07/01/2004
• Est. Priority Date: 12/31/2002
• Status: Active Grant

• Current Assignee: Depuy Acromed Incorporated (Johnson & Johnson)
• Original Assignee: Depuy Acromed Incorporated (Johnson & Johnson)
• Inventors: Doherty, Thomas V., Konieczynski, David D.
• Granted Patent: US 7,048,739 B2
• Time in Patent Office: Days
• US Class Current: 606/70
• CPC Class Codes: A61B 17/8038 the additional component being inserted in the screw head
• CPC Class Codes: A61B 17/8047 wherein the additional element surrounds the screw head in the plate hole A61B17/8052 takes precedence
• CPC Class Codes: A61B 17/8052 immobilised relative to screws by interlocking form of the heads and plate holes, e.g. conical or threaded
• CPC Class Codes: A61B 17/8605 Heads, i.e. proximal ends projecting from bone

Abstract

Bone screws and bone plates are provided that offer the surgeon the ability to either assemble the screws to the plate, or the plate to the screws, depending on the surgeon'"'"'s preference and the patient'"'"'s circumstances. The bone screws and bone plates of the present invention include a combination of geometric configurations that allow the screws and plates to fit together from different assembly directions. Additionally, the bone screws and bone plates can include material resilience features to allow expansion/contraction during assembly to allow bi-directional attachment to one another.

Claims

1. A bone plate and resilient screw system for the stabilization of bone segments, comprising:

a bone plate having a first surface, a second, bone-contacting surface opposed to the first surface, and an aperture extending through the first and second surfaces, the aperture having a predefined shape and size, and being configured to receive a bone screw; and

a resilient screw configured to be inserted into bone, the screw having a head region at a proximal end, the head region being defined by a top flange, a bottom flange, and a groove extending therebetween, and an elongated body extending from the head region to a distal end of the screw, the elongated body including a threaded portion;

wherein at least one of the top and bottom flanges of the screw is resilient.

2. The system of claim 1, wherein both the top and bottom flanges are resilient.

3. The system of claim 1, wherein at least one of the top and bottom flanges includes a relief slit extending therethrough.

4. The system of claim 3, wherein the relief slit is S-shaped.

5. The system of claim 1, wherein a proximal surface of the top flange is chamfered.

6. The system of claim 1, wherein a distal surface of the bottom flange is chamfered.

7. The system of claim 1, wherein the aperture of the bone plate further includes a seating groove therein.

8. The system of claim 7, further including an attachment member for securing the bone plate to the screw, the attachment member being configured to be captured within the seating groove of the aperture, and further being sized and shaped to mate with the groove of the screw.

9. The system of claim 8, wherein the attachment member is a closed ring.

10. The system of claim 1, wherein the screw has an open head region, the region including a tool-engaging bore extending from an upper surface thereof.

11. The system of claim 10, wherein the tool-engaging bore is a threaded bore.

12. The system of claim 10, wherein the tool-engaging bore is a hexagonal bore.

13. The system of claim 10, further including a cap configured to engage the tool-engaging bore.

14. The system of claim 13, wherein the cap comprises a head region and a threaded body extending therefrom.

15. The system of claim 13, wherein the cap further includes a tool-engaging bore extending from an upper surface of the head region.

16. The system of claim 13, wherein the aperture includes a countersunk rim on the first surface of the bone plate.

17. The system of claim 16, wherein the countersunk rim includes a nested region for capturing the cap.

18. The system of claim 17, wherein the nested region includes surface features to restrict movement of the cap.

19. The system of claim 17, wherein the cap restricts translation and/or rotation of the screw with respect to the aperture.

20. The system of claim 1, wherein the predefined shape of the aperture is selected from the group consisting of a hole and an oblong slot.

21. The system of claim 1, further being capable of assembly using a plate first and/or an anchors first construction.

22. A resilient bone screw for use with a bone plate, comprising:

a head region at a proximal end, the head region being defined by a top flange having a compressible diameter, a bottom flange, and a groove extending therebetween about a circumference of the head region, and an elongated body extending from the head region to a distal end of the screw, the elongated body including a threaded portion.

23. The bone screw of claim 22, wherein the bottom flange has a compressible diameter.

24. The bone screw of claim 22, wherein a proximal surface of the top flange is chamfered.

25. The bone screw of claim 22, wherein a distal surface of the bottom flange is chamfered.

26. The bone screw of claim 22, wherein at least one of the top and bottom flanges includes a relief slit extending therethrough.

27. The bone screw of claim 26, wherein the relief slit is S-shaped.

28. The bone screw of claim 22, wherein the groove is configured to engage with a ring for locking engagement to the bone plate.

29. The bone screw of claim 22, wherein the groove is configured to engage directly with the bone plate for locking engagement.

30. The bone screw of claim 22, further having an open head region, the region including a tool-engaging bore extending from an upper surface thereof.

31. The bone screw of claim 30, wherein the tool-engaging bore is a threaded bore.

32. The bone screw of claim 30, wherein the tool-engaging bore is a hexagonal bore.

33. A method of attaching a bone plate to a resilient bone screw using a screws first construction, comprising the steps of:

providing a bone plate and resilient screw system, comprising;

a bone plate having a first surface, a second, bone-contacting surface opposed to the first surface, and an aperture extending through the first and second surfaces, the aperture having a predefined shape and size, and being configured to receive a bone screw; and

a resilient screw configured to be inserted into bone, the screw having a head region at a proximal end, the head region being defined by a resilient top flange, a bottom flange, and a groove extending therebetween, and an elongated body extending from the head region to a distal end of the screw, the elongated body including a threaded portion, the screw further having a tool-engaging bore extending from an upper surface of the head region;

inserting the screw into a bone segment to be fixed;

disposing an aperture of the bone plate over a post attached to the screw;

sliding the bone plate down the post and onto the screw;

securing the aperture around the screw; and

removing the post from the screw.

34. The method of claim 33, wherein the post is attached to the tool-engaging bore prior to insertion of the screw.

35. The method of claim 33, wherein the post is attached to the tool-engaging bore after insertion of the screw.

36. The method of claim 33, wherein the step of securing the aperture around the screw further includes passing the aperture over the top flange, and nesting the aperture within the groove of the screw.

37. The method of claim 33, wherein the bone plate includes a seating groove within the aperture, and further including the step of capturing an attachment member within the seating groove of the bone plate.

38. The method of claim 37, wherein the attachment member is captured prior to assembly.

39. The method of claim 38, wherein the step of disposing the aperture over the post includes disposing the captured attachment member within the aperture over the post.

40. The method of claim 39, wherein the step of securing the aperture around the screw further includes the step of nesting the captured attachment member within the groove of the screw.

41. The method of claim 33, wherein the tool-engaging bore comprises a threaded bore and the post includes a threaded tip for attaching to the threaded bore.

42. The method of claim 41, further including the step of engaging a threaded cap onto the threaded bore of the bone screw.

46. The system of claim 40, wherein the upper surface of the head region is chamfered.

43. A bone plate and resilient screw system for the stabilization of bone segments, comprising:

a bone plate having a first surface, a second, bone-contacting surface opposed to the first surface, and an aperture extending through the first and second surfaces, the aperture having a predefined shape and size, and being configured to receive a bone screw; and

a resilient screw configured to be inserted into bone, the screw including a head region at a proximal end, the head region having a compressible diameter and being defined by an upper surface, a lower surface, and a sidewall extending therebetween and connecting the upper surface and lower surface, and further comprising an elongated body extending from the head region to a distal end of the screw, the elongate body including a threaded portion.

44. The system of claim 43, wherein the head region includes at least one relief slit extending therethrough.

45. The system of claim 44, wherein the at least one relief slit is S-shaped.

47. The system of claim 43, wherein the lower surface of the head region is chamfered.

48. The system of claim 43, wherein the sidewall extends at a perpendicular angle with respect to the upper and lower surfaces of the head region.

49. The system of claim 43, wherein the head region includes a tool-engaging recess.

50. The system of claim 43, wherein the screw has an open head region, the region including a tool-engaging bore extending from the upper surface thereof.

51. The system of claim 50, wherein the tool-engaging bore is a threaded bore.

52. The system of claim 50, wherein the tool-engaging bore is a hexagonal bore.

53. The system of claim 50, further including a cap configured to engage the tool-engaging bore.

54. The system of claim 53, wherein the cap comprises a head region and a threaded body extending therefrom.

55. The system of claim 54, wherein the cap further includes a tool-engaging bore extending from an upper surface of the head region.

56. The system of claim 53, wherein the aperture includes a countersunk rim on the first surface of the bone plate.

57. The system of claim 56, wherein the countersunk rim includes a nested region for capturing the cap.

58. The system of claim 57, wherein the nested region includes surface features to restrict movement of the cap.

59. The system of claim 53, wherein the cap restricts translation and/or rotation of the screw with respect to the aperture.

60. The system of claim 43, wherein the aperture of the bone plate further includes a seating groove therein.

61. The system of claim 60, wherein the head region of the screw is configured to nest within the seating groove.

62. The system of claim 43, wherein the aperture is countersunk on at least one of the first and second surfaces of the bone plate.

63. The system of claim 43, further being capable of assembly using a plate first and/or an anchors first construction.

64. The system of claim 60, further including an attachment member for securing the bone plate to the screw, the attachment member having a top surface, a bottom surface, and an outer wall extending therebetween and connecting the top surface to the bottoms surface, the attachment member being configured to be captured within the seating groove of the aperture, and further including a channel extending about the inner circumference, the channel being sized and shaped to capture the head region of the screw.

65. The system of claim 64, wherein the top surface of the attachment member extends along a downward slope from an outer edge to an inner edge of the top surface.

66. The system of claim 64, wherein the bottom surface of the attachment member extends along an upward slope from an outer edge to an inner edge of the bottom surface.

67. The system of claim 64, wherein the channel of the attachment member comprises a top side, a bottom side, and an inner wall connecting the top and bottom sides together, the top side and the bottom side extending at right angles with respect to the inner wall.

68. The system of claim 43, wherein the predefined shape of the aperture is selected from the group consisting of a hole and an oblong slot.

69. A method of attaching a bone plate to a resilient bone screw using a screws first construction, comprising the steps of:

providing a bone plate and resilient screw system, comprising;

a bone plate having a first surface, a second, bone-contacting surface opposed to the first surface, and an aperture extending through the first and second surfaces, the aperture having a predefined shape and size, and being configured to receive a bone screw; and

a resilient screw configured to be inserted into bone, the screw including a head region at a proximal end, the head region having a compressible diameter and being defined by an upper surface, a lower surface, and a sidewall extending therebetween and connecting the upper surface and lower surface, and further including an elongated body extending from the head region to a distal end of the screw, the elongated body having a threaded portion, wherein the screw further includes a tool-engaging bore extending from the upper surface thereof;

inserting the screw into a bone segment to be fixed;

disposing the aperture of the bone plate over a post attached to the screw;

sliding the bone plate down the post and onto the screw;

securing the head region of the screw within the aperture; and

removing the post from the screw.

70. The method of claim 69, wherein the post is attached to the tool-engaging bore prior to insertion of the screw.

71. The method of claim 69, wherein the post is attached to the tool-engaging bore after insertion of the screw.

72. The method of claim 69, wherein the aperture of the bone plate further includes a seating groove therein, and the step of securing the head region of the screw includes nesting the head region within the seating groove.

73. The method of claim 72, further including the step of capturing an attachment member within the seating groove, wherein the attachment member has a top surface, a bottom surface, and an outer wall extending therebetween and connecting the top surface to the bottom surface, and further including a channel extending about the inner circumference, the channel being sized and shaped to capture the head region of the screw.

74. The method of claim 73, wherein the attachment member is captured within the seating groove prior to assembly.

75. The method of claim 74, wherein the step of sliding the bone plate includes sliding the attachment member down the post and onto the head region of the screw.

76. The method of claim 75, wherein the step of securing the head region within the aperture includes disposing the head region within the channel of the captured locking member.

77. The method of claim 69, wherein the tool-engaging bore comprises a threaded bore and the post includes a threaded tip.

78. The method of claim 77, further including the step of engaging a threaded cap onto the threaded bore of the screw.