Posterior spinal implant

• US 6,077,262 A
• Filed: 02/20/1997
• Issued: 06/20/2000
• Est. Priority Date: 06/04/1993
• Status: Expired due to Term

• Current Assignee: Synthes USA LLC (Johnson & Johnson)
• Original Assignee: Synthes USA LLC (Johnson & Johnson)
• Inventors: Schlapfer, Johannes F., Hagmann, Ralf, Schelker, Rene, Hess, Martin
• Primary Examiner(s): SNOW, BRUCE EDWARD
• Application Number:
  US08/803,550
• Time in Patent Office: 1,216 Days
• Field of Search: 623/17.11, 606/61, 606/66, 606/69, 606/72-73
• US Class Current: 606/305
• CPC Class Codes: A61B 17/7032 Screws or hooks with U-shaped head or back through which longitudinal rods pass

Abstract

A spinal screw or hook has a slotted head to receive a support rod. A two-piece rod retainer is provided with an outer ring-like collar locked into the interior of the slotted head and a fastener extending through the collar to contact a support rod in the bottom of the slot.

Claims

1. A spinal implant kit for attachment of the implant to the spine and for clamping a support rod, said implant kit comprising

(a) an anchoring segment for attachment to the spine,

(b) a head attached to said anchoring segment, said head comprising two legs defining a transverse slot for receiving a support rod,

(c) a cylindrical closure element having an aperture and locking means adapted for engagement with said legs, and

(d) a fastener adapted to be inserted through said aperture and to clamp within said slot at least the largest diameter cylindrical support rod capable of passing through said slot, and

(e) a safety bush element adapted to surround at least a portion of said legs;

said head further comprising a stop located at a position preventing said safety bush from clamping any cylindrical support rod capable of passing through said slot.

2. The implant kit claimed in claim 1 wherein the aperture is centrally located in said closure element and has an internal thread.

3. The implant kit claimed in claim 2, wherein the fastener has an external thread matching the internal thread of the aperture.

4. The implant kit claimed in claim 1 wherein the outside diameter of the closure element is not greater than the outer diameter of the head.

5. The implant kit claimed in claim 1 wherein each of said legs has an end remote from said anchoring segment, the ends of the legs are narrowed, and the bush has an inner diameter such that it can be slipped over the ends of the legs and an outer diameter no greater than the outer diameter of the head.

6. The implant kit claimed in claim 5, wherein the safety bush comprises a collar having an opening large enough to allow passage of the fastener.

7. The implant kit claimed in claim 5, wherein the safety bush comprises a flange having a aperture large enough to accommodate the fastener.

8. The implant kit claimed in claim 1 wherein the safety bush and closure element are formed integrally.

9. The implant kit claimed in claim 1 wherein the bush and closure element are connected to one another.

10. The implant kit claimed in claim 1 wherein the closure element has an outer thread and the slot has a matching inner thread.

11. The implant kit claimed in claim 1 wherein the closure element comprises a stud and a leg of the slot has a matching arcuate transverse channel to receive said stud thus to form a bayonet type closure element.

12. The implant kit claimed in claim 1 wherein the closure element comprises a transverse channel and two longitudinal channels connecting to said transverse channel and the inner surfaces of the legs have studs for insertion into said channels to lock said closure element in said slot.

13. The implant kit claimed in claim 11 wherein the transverse channel extends over less than the full circumference of the head.

14. The implant kit claimed in claim 12 wherein the transverse channel extends over less than the full circumference of the closure element.

15. The implant kit claimed in claim 1 wherein the fastener is a set screw having a central aperture.

16. The implant kit claimed in claim 15 wherein the aperture of the fastener is threaded.

17. The implant kit claimed in claim 15 wherein the set screw comprises a convex surface.

18. The implant kit claimed in claim 17 wherein the convex surface has a countersink.

19. The implant kit claimed in claim 18 wherein the countersink is conical.

20. The implant kit claimed in claim 15, wherein the set screw tapers to a point.

21. The implant kit claimed in claim 1 wherein the base of the slot is serrated.

22. The implant kit claimed in claim 1 wherein the base of the slot has a first, relatively small radius in a central region at the bottom of the slot and a second, relatively larger radius on either side of said central region.

23. The implant kit claimed in claim 1 wherein the diameter of the closure element is in the range of 8 to 12 mm.

24. The implant kit claimed in claim 23 wherein the diameter of the closure element is in the range 9.5 to 10.5 mm.

25. The implant kit claimed in claim 1 wherein the diameter of the fastener is in the range of 7 to 9 mm.

26. The implant kit claimed in claim 25 wherein the fastener diameter is in the range 7.5 to 8.5 mm.

27. The implant kit claimed in claim 1 wherein the width of the slot is in the range of 5 to 7 mm.

28. The implant kit claimed in claim 27 wherein the width of the slot is in the range 5.5 to 6.5 mm.

29. The implant kit claimed in claim 1 wherein the base of the slot comprises a recess for receiving a movable element for contacting a support rod inserted in said slot.

30. A spinal implant kit for attachment of the implant to the spine and for clamping a support rod, said implant kit comprising

(a) an anchoring segment for attachment to the spine,

(b) a head attached to said anchoring segment, said head comprising two legs defining a transverse slot for receiving a support rod,

(c) a cylindrical closure element having an aperture and locking means adapted for engagement with said legs,

(d) a fastener adapted to be inserted through said aperture and to clamp within said slot at least the largest diameter cylindrical support rod capable of passing through said slot, and

(e) a safety bush element adapted to surround at least a portion of said legs;

said head further comprising a stop located at a position preventing said safety bush from clamping any cylindrical support rod capable of passing through said slot,

wherein the fastener comprises a rotatable, spheroidal contacting element.

31. The implant kit claimed in claim 30 wherein the fastener comprises a spherical contact element having a portion cut away to provide a surface for contacting said support rod.

32. A spinal implant kit for attachment of the implant to the spine and for clamping a support rod, said implant kit comprising

(a) an anchoring segment for attachment to the spine,

(b) a head attached to said anchoring segment, said head comprising two legs defining a transverse slot for receiving a support rod,

(c) a cylindrical closure element having an aperture and locking means adapted for engagement with said legs, and

(d) a fastener adapted to be inserted through said aperture and to clamp within said slot at least the largest diameter cylindrical support rod capable of passing through said slot, and

(e) a safety bush element adapted to surround at least a portion of said legs;

said head further comprising a stop located at a position preventing said safety bush from clamping any cylindrical support rod capable of passing through said slot,

wherein the fastener comprises a flange at the end of said fastener closest to the anchoring segment.

33. The implant kit claimed in claim 32, wherein the flange has a chamfered surface on the side away from the anchoring element comprising an angle between 0 and 90°

.

34. The implant kit claimed in claim 33 wherein the angle is between 45°

and 60°

.

35. The implant kit claimed in claim 33 wherein the closure element comprises a countersink matching the chamfered surface of the flange.

36. A spinal implant kit for attachment of the implant to the spine and for clamping a support rod, said implant kit comprising

(a) an anchoring screw for attachment to the spine, and

(b) a cylindrical head attached at one end to and coaxial with said anchoring screw, said head comprising

(1) two legs defining a transverse slot for receiving a support rod, and

(2) an internally threaded recess between said legs,

(c) a cylindrical closure element having a central, axial aperture and having external threads adapted for engagement with said internally threaded recess,

(d) a fastener adapted for insertion through said aperture to clamp a support rod within said slot,

(e) a safety bush adapted for surrounding at least a portion of the legs, said safety bush having an outer diameter no greater than the outer diameter of the head, and

said head further comprising a stop adapted to prevent said safety bush from contacting the largest diameter cylindrical support rod which can be clamped in said slot by said fastener.

37. A spinal implant kit for attachment of the implant to the spine and for clamping a support rod, said implant kit comprising

(a) an anchoring segment for attachment to the spine,

(b) a head attached to said anchoring segment, said head comprising two legs defining a transverse slot for receiving said support rod,

(c) a cylindrical closure element having an aperture and locking means adapted for engagement with said legs, and

(d) a fastener comprising an externally threaded member adapted to be inserted in said aperture and a rotatable contacting element.

38. The implant kit claimed in claim 37 wherein said fastener is adapted to clamp within said slot at least the largest diameter cylindrical support rod capable of passing through said slot.

39. The implant kit claimed in claim 37 wherein a major portion of said contacting element is spherical.

40. The implant kit claimed in claim 37 wherein a portion of said contacting element is cut away to provide a surface for contacting said support rod.

41. The implant kit claimed in claim 37 wherein the base of said slot is serrated.

42. The implant kit claimed in claim 37 wherein the base of the slot has a first, relatively small radius in a central region at the bottom of the slot and a second, relatively larger radius on either side of said central region.

43. The implant kit claimed in claim 37 wherein said fastener is adapted to clamp within said slot at least the largest diameter cylindrical support rod capable of passing through said slot, a major portion of said contacting element is spherical and a portion of said contacting element is cut away to provide a surface for contacting said support rod.

44. The implant kit claimed in claim 43 wherein the base of said slot is serrated.

45. The implant kit claimed in claim 43 wherein the base of said slot has a plurality of radii.

46. A spinal implant kit for attachment of the implant to the spine and for clamping a support rod, said implant kit comprising

(a) an anchoring segment for attachment to the spine,

(b) a head attached to said anchoring segment, said head comprising two legs defining a transverse slot for receiving a support rod,

(c) a cylindrical closure element having an aperture and locking means adapted for engagement with said legs, and

(d) a fastener adapted to be inserted in said aperture and to clamp within said slot at least the largest diameter cylindrical rod capable of passing through said slot, and wherein the fastener comprises a flange at the end of said fastener closest to the anchoring segment.

47. The implant kit claimed in claim 46 wherein the flange has a chamfered surface on the side away from the anchoring element comprising an angle between 0 and 90°

.

48. The implant kit claimed in claim 47 wherein the angle is between 45°

and 60°

.

49. The implant kit claimed in claim 47 wherein the closure element comprises a countersink matching the chamfered surface on said flange.

50. The implant kit claimed in claim 48 wherein the closure element comprises a countersink matching the chamfered surface on said flange.