Load distribution crown

• US 20050228387A1
• Filed: 04/08/2004
• Published: 10/13/2005
• Est. Priority Date: 04/08/2004
• Status: Active Grant

• Current Assignee: Globus Medical, Inc.
• Original Assignee: Globus Medical, Inc.
• Inventors: Paul, David C.
• Granted Patent: US 7,615,069 B2
• Time in Patent Office: Days
• US Class Current: 606/246
• CPC Class Codes: A61B 17/86 Pins or screws or threaded wires; nuts therefor A61B17/72 take precedence
• CPC Class Codes: A61B 17/8695 Washers surrounding screw head in plate hole A61B17/8047, between bone plate and bone A61B17/8028

Abstract

An apparatus for distributing the load caused by the insertion of a fastening device into bony tissue is disclosed. In one embodiment, the apparatus comprises a crown having a plurality of protrusions. The protrusions may have any desired physical properties, and function to obtain purchase in the bony tissue. Preferably, the crown includes an opening that is selectively engageable with a spherical head of the fastening device. The opening preferably comprises a spherical curvature that allows the surfaces of the spherical head and the opening to maintain flush contact, even when the fastening device is inserted into the bony tissue at a non-orthogonal angle. When the fastening device is inserted into the bony tissue, the crown distributes the load over a wider section of the bone, allowing the bone to maintain its structural integrity.

Claims

1. An apparatus for distributing a load in bony tissue, comprising:

a crown comprising one or more protrusions and an opening having a spherical curvature; and

a fastener including a head that interferes with the spherical curvature of the opening;

wherein the fastener is selectively engageable with the opening to allow the crown to distribute the load caused by the insertion of the fastener into bony tissue.

2. The apparatus according to claim 1, wherein the length of the protrusions is between about 0.7 and about 1.2 mm.

3. The apparatus according to claim 1, wherein the average peak-to-peak distance between the one or more protrusions is between about 0.7 mm to about 1.0 mm.

4. The apparatus according to claim 1, wherein the one or more protrusions include a base, wherein the average base to base distance between neighboring protrusions is between about 0.5 and 1.0 mm.

5. The apparatus according to claim 1, wherein the protrusions comprise an angle, wherein the angle from a base of the protrusion to a peak of the protrusion is between about 55 degrees and about 65 degrees.

6. The apparatus according to claim 1, wherein the spherical curvature is configured and dimensioned to evenly distribute the load caused by the insertion of the fastener into the bony tissue at a non-orthogonal angle.

7. The apparatus according to claim 1, wherein tangents to the spherical curvature of the opening intersect.

8. The apparatus according to claim 1, wherein the total surface area of the base of the crown is about 10 square mm or greater.

9. The apparatus according to claim 1, wherein the crown is capable of being deformed by a predetermined amount.

10. The apparatus according to claim 1, wherein a force necessary to deform the crown is greater than the force necessary to insert the screw into the bony tissue.

11. The apparatus according to claim 10, wherein the deformation is based on an incision.

12. The apparatus according to claim 1, wherein the diameter of the opening is between about 5% and 10% smaller than the diameter of the head of the fastener.

13. The apparatus according to claim 1, wherein the head of the fastener comprises a spherical head, and wherein an inner portion of the opening and the surface of the spherical head comprise a plurality of ridges.

14. An apparatus for distributing a load in bony tissue, comprising:

a fastener; and

a crown comprising an opening;

wherein the fastener is selectively engageable with the opening to allow the crown to distribute the load caused by the insertion of the fastener into bony tissue at a plurality of angles.

15. The apparatus according to claim 14, wherein the crown comprises at least one protrusion.

16. The apparatus according to claim 15, wherein the number of protrusions is about 40 or less.

17. The apparatus according to claim 15, wherein the length of the protrusions is between about 0.1 and about 4 mm.

18. The apparatus according to claim 15, wherein the average peak-to-peak distance between the one or more protrusions is between about 0.4 mm to about 2.5 mm.

19. The apparatus according to claim 15, wherein the one or more protrusions include a base, wherein the average base to base distance between neighboring protrusions is between about 0.1 and 1.5 mm.

20. The apparatus according to claim 15, wherein the protrusions comprise an angle, wherein the angle from a base of the protrusion to a peak of the protrusion is between about 50 degrees and about 70 degrees.

21. The apparatus according to claim 14, wherein opening comprises a spherical curvature configured and dimensioned to evenly distribute the load caused by the insertion of the fastener into the bony tissue at a non-orthogonal angle.

22. The apparatus according to claim 21, wherein tangents to the spherical curvature of the opening intersect.

23. The apparatus according to claim 14, wherein the total surface area of the base of the crown is about 10 square mm or greater.

24. The apparatus according to claim 14, wherein the crown is capable of being deformed by a predetermined amount.

25. The apparatus according to claim 24, wherein a force necessary to deform the crown is greater than the force necessary to insert the screw into the bony tissue.

26. The apparatus according to claim 25, wherein the deformation is based on an incision.

27. The apparatus according to claim 14, wherein the fastener comprises a spherical head having a diameter that is between about 5% and 30% larger than the diameter of the opening.

28. The apparatus according to claim 27, wherein an inner portion of the opening and the surface of the spherical head comprise a plurality of ridges.

29. An apparatus for distributing a load in a spinal fixation system, comprising:

a fastener;

a crown including a plurality of protrusions and an opening;

wherein the opening is configured and dimensioned to distribute the load caused by insertion of the fastener into bony tissue.

30. The apparatus according to claim 29, wherein the number of protrusions is about 40 or less.

31. The apparatus according to claim 29, wherein the length of the protrusions is between about 0.1 and about 4 mm.

32. The apparatus according to claim 29, wherein the average peak-to-peak distance between the one or more protrusions is between about 0.4 mm to about 2.5 mm.

33. The apparatus according to claim 29, wherein the one or more protrusions include a base, wherein the average base to base distance between neighboring protrusions is between about 0.1 and 1.5 mm.

34. The apparatus according to claim 29, wherein the protrusions comprise an angle, wherein the angle from a base of the protrusion to a peak of the protrusion is between about 50 degrees and about 70 degrees.

35. The apparatus according to claim 29, wherein the opening comprises a spherical curvature configured and dimensioned to evenly distribute the load caused by the insertion of the fastener into the bony tissue at a non-orthogonal angle.

36. The apparatus according to claim 35, wherein tangents to the spherical curvature of the opening intersect.

37. The apparatus according to claim 29, wherein the total surface area of the base of the crown is about 10 square mm or greater.

38. The apparatus according to claim 29, wherein the crown is capable of being deformed by a predetermined amount.

39. The apparatus according to claim 38, wherein a force necessary to deform the crown is greater than the force necessary to insert the screw into the bony tissue.

40. The apparatus according to claim 39, wherein the deformation is based on an incision.

41. The apparatus according to claim 29, wherein the fastener comprises a spherical head having a diameter that is between about 5% and 30% larger than the diameter of the opening.

42. The apparatus according to claim 41, wherein an inner portion of the opening and the surface of the spherical head comprise a plurality of ridges.