Device for securing spinal rods

1. A device for securing a spinal rod to the spine comprising:

a) a head portion defining a central axis extending from an upper end to a lower end of the head portion, the head portion having a channel extending therethrough oriented perpendicular to the central axis and configured to receive a spinal rod;

b) a locking cap including an upper portion engageable with an interior surface of the head portion and a lower portion having an elongated recess for engaging an exterior surface of a spinal rod received by the channel to secure the position of the head portion relative to the spinal rod upon rotation of the upper portion relative to the lower portion about the central axis of the head portion, wherein the upper portion and the lower portion of the locking cap are coupled together by an axial post that facilitates relative rotational movement of the upper portion relative, to the lower portion; and

c) a fastener portion depending from the lower end of the head portion to engage the spine and mounted for angular movement relative to the central axis of the head portion.

2. A device as recited in claim 1 , wherein the channel in the head portion is bounded by opposed side walls each having an arcuate engagement slot formed therein.

3. A device as recited in claim 2 , wherein the upper portion of the locking cap has opposed arcuate engagement flanges.

4. A device as claimed in claim 3 , wherein the opposed arcuate engagement flanges are spaced from one another.

5. A device as claimed in claim 3 , wherein the upper portion of the locking cap is rotatable relative to the head portion so that the opposed arcuate engagement flanges are disposed in the respective arcuate engagement slots in the opposed side walls.

6. A device as claimed in 1 , wherein the elongated recess has a shape that matches the shape of the exterior surface of the spinal rod.

7. A device as claimed in claim 1 , wherein the fastener portion is movable relative to the head portion when the locking cap is in an unlocked position and the fastener portion is fixed relative to the head portion when the locking cap is in a locked position.

8. The device as claimed in claim 1 , wherein the axial post mechanically joins the upper and lower portions of the locking cap.

9. The device as claimed in claim 8 , wherein the axial post has an arcuate exterior surface.

10. The device as claimed in claim 8 , wherein the axial post has a lower end permanently fixed to the lower portion of the locking cap and an upper end inserted into an opening at an underside of the upper portion of the locking cap.

11. A device as recited in claim 1 , wherein the upper portion of the locking cap is configured to cammingly engage the interior surface of the head portion.

12. A device as recited in claim 11 , wherein the arcuate engagement flanges have inclined flange surfaces.

13. A device as recited in claim 12 , wherein the angle of the inclined flange surface of one engagement flange is opposite that of the opposed engagement flange.

14. A device for securing a spinal rod to the spine comprising:

a head portion having an upper end, a lower end and a channel extending therethrough for receiving a spinal rod, the channel in the head portion being bounded by opposed side walls each having an arcuate engagement slot formed therein;

a locking cap having a first portion and a second portion, the first portion of the locking cap having opposed arcuate engagement flanges receivable in the arcuate engagement slots of the head portion, the second portion of the locking cap having an elongated recess engageable with the exterior surface of the spinal rod, the first and second portions of the locking cap being mechanically joined for rotation relative to one another, wherein the first portion of the locking cap is located above the second portion of the locking cap as the locking cap moves from an unlocked position to a locked position, and the locking cap is a two-part locking cap consisting of the first portion and the second portion; and

a fastener portion depending from the lower end of the head portion for engaging the spine.

15. The device as claimed in claim 14 , wherein the fastener portion is movable relative to the head portion when the locking cap is in an unlocked position.

16. The device as claimed in claim 14 , wherein the first portion of the locking cap is spaced from the spinal rod when the locking cap is in the locked position.

17. The device as claimed in claim 14 , wherein the opposed arcuate engagement flanges are spaced from one another.

18. The device as claimed in claim 14 , wherein the opposed arcuate engagement flanges comprise a first flange projecting from a first side of the first portion of the locking cap and a second flange projecting from a second side of the first portion of the locking cap that is opposite the first side.

19. The device as claimed in claim 14 , wherein the locking cap further comprises a post extending between the first and second portions thereof for mechanically joining the first and second portions.

20. The device as claimed in claim 19 , wherein the post extending between the first and second portions of the locking cap has an arcuate exterior surface.

21. The device as claimed in claim 19 , wherein the post extending between the first and second portions of the locking cap has a lower end permanently fixed to the second portion of the locking cap and an upper end inserted into an opening at an underside of the first portion of the locking cap.

22. The device as claimed in claim 14 , wherein the head portion is formed monolithic with the fastener portion.

23. The device as claimed in claim 14 , wherein the head portion defines a central axis extending perpendicular to the channel and the fastener portion is adapted for angular movement relative to the central axis of the head portion.

24. The device as claimed in claim 23 , wherein the fastener portion includes a spherical head and a threaded body depending from the spherical head.

25. The device as claimed in claim 24 , wherein the head portion defines a seat for receiving the spherical head of the fastener portion and an aperture for accommodating the threaded body depending from the spherical head.

26. The device as claimed in claim 14 , wherein each of the opposed engagement flanges has an inclined surface.

27. The device as claimed in claim 26 , wherein the angle of the inclined surface of one of the engagement flanges is opposite the angle of the inclined surface of the opposed engagement flange.

28. The device as claimed in claim 14 , wherein each of the opposed arcuate engagement flanges has a leading end and a trailing end, and wherein the leading ends of the opposed arcuate engagement flanges include inclined surfaces.

29. The device as claimed in claim 14 , wherein the fastener portion is movable relative to the head portion when the locking cap is in an unlocked position.

30. The device as claimed in claim 29 , wherein the fastener portion is fixed relative to the head portion when the locking cap is in a locked position.

31. The device as claimed in claim 30 , wherein the opposed arcuate engagement flanges are disposed in the arcuate engagement slots when the locking cap is rotated into the locked position.

32. A device as recited in claim 14 , wherein the opposed arcuate engagement flanges of the first portion of the locking cap are configured to cammingly engage the arcuate engagement slots formed in the opposed side walls of the head portion.

33. A device as recited in claim 32 , wherein the arcuate engagement flanges of the first portion of the locking cap comprise inclined flange surfaces.

34. A device as recited in claim 33 , wherein the angle of the inclined flange surface of one engagement flange is opposite that of the opposed engagement flange.