SPINAL FACET COMPRESSION SCREW WITH VARIABLE PITCH THREAD ZONES AND BUTTRESS HEAD

• US 20120022603A1
• Filed: 07/18/2011
• Published: 01/26/2012
• Est. Priority Date: 07/20/2010
• Status: Active Grant

• Current Assignee: X-Spine Systems Incorporated (OrbiMed Advisors LLC (China))
• Original Assignee: X-Spine Systems Incorporated (OrbiMed Advisors LLC (China))
• Inventors: Kirschman, David Louis
• Granted Patent: US 8,992,587 B2
• Time in Patent Office: Days
• US Class Current: 606/305
• CPC Class Codes: A61B 17/7064 Devices acting on, attached to, or simulating the effect of, vertebral facets; Tools therefor
• CPC Class Codes: A61B 17/861 specially shaped for gripping driver
• CPC Class Codes: A61B 17/862 at the periphery of the screw head
• CPC Class Codes: A61B 17/863 with thread interrupted or changing its form along shank, other than constant taper
• CPC Class Codes: A61B 17/864 hollow, e.g. with socket or cannulated
• CPC Class Codes: A61B 17/8891 at its periphery
• CPC Class Codes: A61B 2017/681 Alignment, compression, or distraction mechanisms
• CPC Class Codes: A61B 2017/8655 with special features for locking in the bone

Abstract

A surgical implant comprising a screw element having a screw head, a first thread having a first thread pitch, a second thread having a second thread pitch and an intermediate portion coupling the first and second thread pitches with the first and second thread pitches being different. The implant has a buttressing head associated with the first thread, and it is dimensioned to be larger than a diameter of the first threads to provide external buttressing as the first and second threads compress a first bone and a second bone together.

Claims

1. A surgical implant comprising:

a screw element having a screw head, a first thread having a first thread pitch, a second thread having a second thread pitch and an intermediate portion coupling said first and second thread pitches, said first and second thread pitches being different; and

said screw head defining a tool attachment zone;

a buttressing head associated with said first thread and being dimensioned to be larger than a diameter of said first threads to provide external buttressing as said first and second threads compress a first bone and a second bone together.

2. The surgical implant as recited in claim 1 wherein said first thread pitch is smaller than said second thread pitch.

3. The surgical implant as recited in claim 1 wherein said intermediate portion and said buttressing head are not threaded.

4. The surgical implant as recited in claim 1 wherein said screw element comprises at least one locking slot to facilitate allowing for bone growth over said screw element and helping to prevent said screw element from loosening.

5. The surgical implant as recited in claim 4 wherein said at least one locking slot is linear.

6. The surgical implant as recited in claim 4 wherein said screw element comprises a plurality of locking slots.

7. The surgical implant as recited in claim 6 wherein said plurality of locking slots are located in at least one or both of said first and second threads.

8. The surgical implant as recited in claim 7 wherein said plurality of locking slots are located in said first thread.

9. The surgical implant as recited in claim 1 wherein said screw head comprises third threads at said tool attachment zone to allow for engagement of a tool locking sleeve.

10. The surgical implant as recited in claim 9 wherein said third threads have a handedness that is opposite the handedness of each of the first and second threads.

11. The surgical implant as recited in claim 1 wherein said first thread pitch and said second thread pitch are different so that when said first thread threadably engages and drives said first bone to be fused at a first rate and said second thread threadably engages and drives said second bone to be fused toward said first bone at a second rate, wherein said second rate is greater than said first rate.

12. The surgical implant as recited in claim 1 wherein said buttressing head has a generally planar bone-engaging surface at an end of said first threads.

13. The surgical implant as recited in claim 1 wherein said first threads are proximal threads and said second threads are distal threads, said first and second threads driving said first bone and second bone, respectively, towards said buttressing head at different rates.

14. The surgical implant as recited in claim 13 wherein said buttressing head is located between said tool attachment zone and said buttressing head.

15. A surgical implant comprising:

an elongated body having a first end and a second end;

a screw head associated with said first end;

a first thread having a first thread pitch associated with said first end, a second thread having a second thread pitch and an intermediate portion coupling said first and second thread pitches, said first and second thread pitches being different; and

said screw head defining a tool attachment zone;

a buttressing head situated between said first thread and said screw head;

said buttressing head being dimensioned to be larger than a diameter of said first threads to provide external buttressing to a first bone as said first and second threads compress a second bone against said first bone.

16. The surgical implant as recited in claim 15 wherein said first thread pitch is smaller than said second thread pitch.

17. The surgical implant as recited in claim 15 wherein said intermediate portion and said buttressing head are not threaded.

18. The surgical implant as recited in claim 15 wherein said screw head comprises at least one locking slot to facilitate allowing for bone growth into the thread and helping to prevent said screw head from loosening.

19. The surgical implant as recited in claim 18 wherein said at least one locking slot is linear.

20. The surgical implant as recited in claim 15 wherein said elongated body comprises a plurality of locking slots.

21. The surgical implant as recited in claim 20 wherein said plurality of locking slots are located in at least one or both of said first and second threads.

22. The surgical implant as recited in claim 20 wherein said plurality of locking slots are located in said first thread.

23. The surgical implant as recited in claim 15 wherein said screw head comprises third threads to allow for engagement of a tool locking sleeve.

24. The surgical implant as recited in claim 23 wherein said third threads have a handedness that is opposite the handedness of each of the first and second threads.

25. The surgical implant as recited in claim 15 wherein said first thread pitch and said second thread pitch are different so that when said first thread threadably engages and drives said first bone to be fused at a first rate and said second thread threadably engages and drives said second bone to be fused toward said first bone at a second rate, wherein said second rate is greater than said first rate.

26. The surgical implant as recited in claim 15 wherein said buttressing head has a generally planar bone-engaging surface at an end of said first threads.

27. The surgical implant as recited in claim 15 wherein said first threads are proximal threads and said second threads are distal threads, said first and second threads driving said first bone and second bone, respectively, towards said buttressing head at different rates.

28. The surgical implant as recited in claim 27 wherein said buttressing head is located between said tool attachment zone and said buttressing head.

29. The surgical implant as recited in claim 24 wherein said surgical implant is provided with a screw driver having a screw driver locking sleeve having threads that mate with the third threads and that has an internal screw driver for rotatably driving said surgical implant.