Bone fixation system

• US 9,861,406 B2
• Filed: 08/19/2016
• Issued: 01/09/2018
• Est. Priority Date: 08/23/2012
• Status: Active Grant

• Current Assignee: Depuy Synthes Products Incorporated (Johnson & Johnson)
• Original Assignee: Depuy Synthes Products Incorporated (Johnson & Johnson)
• Inventors: Appenzeller, Andreas, Fluri, Daniel, Fierlbeck, Johann, Niederberger, Alfred
• Primary Examiner(s): Bates, David
• Assistant Examiner(s): Chang, Olivia C
• Application Number:
  US15/241,827
• Publication Number:
  US 20170000535A1
• Time in Patent Office: 508 Days
• 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 17/8057 the interlocking form comprising a thread
• CPC Class Codes: A61B 17/8061 specially adapted for particular bones A61B17/70 and A61B17/74 take precedence
• CPC Class Codes: A61B 17/8605 Heads, i.e. proximal ends projecting from bone
• CPC Class Codes: A61B 17/869 characterised by an open form, e.g. wire helix

Abstract

A bone fixation system has a bone implant with an implant body. The implant body defines an upper surface, a bone-facing surface spaced from the upper surface along a transverse direction, and at least one aperture defined by an inner wall. A bone fixation element is configured for insertion at least partially through the aperture. The bone fixation element defines a proximal end and a distal end spaced from the proximal end along a central axis. The bone fixation element has a head and a shaft that extends relative to the head toward the distal end. The head defines a first ridge, a second ridge spaced from the first ridge, and a groove disposed between the first and second ridges. The groove can receive at least a portion of the inner wall to couple the bone fixation element to the bone implant.

Claims

1. A method of attaching a fixation element to an implant, the method comprising:

inserting a shaft of the fixation element between respective inner surfaces of first and second wire segments of the implant along a transverse direction, wherein

     1) the inner surfaces are curved as they extend along the transverse direction and define a first threaded region, and

     2) the fixation element defines a head and the shaft extends from the head in a distal direction along a central axis of the fixation element;

further inserting the fixation element between the inner surfaces along the transverse direction so as to cause a second threaded region of the fixation element to threadedly engage the first threaded region; and

further inserting the fixation element between the inner surfaces along the transverse direction until

     1) the second threaded region is disengaged from, and spaced in the distal direction from, the first threaded region, and

     2) the first threaded region is aligned with an unthreaded groove of the head along a lateral direction that is perpendicular to the transverse direction,

wherein the groove extends along the transverse direction between a

     1) first ridge of the head, the first ridge extending out with respect to the central axis, and

     2) a second ridge of the head, the second ridge extending out with respect to the central axis and defining the second threaded region.

2. The method of claim 1, further comprising placing an exterior surface of the implant adjacent a bone such that the transverse direction intersects the bone.

3. The method of claim 2, further comprising driving the shaft of the fixation element into bone during at least one of the inserting steps.

4. The method of claim 3, further comprising retaining the inner surfaces of the first and second wire segments within the groove after the second threaded region is disengaged from, and spaced in the distal direction from, the first threaded region.

5. The method of claim 4, further comprising, after the retaining step, repositioning the fixation element relative to the bone along the central axis so as to responsively reposition the implant relative to the bone relative to the transverse direction.

6. The method of claim 5, wherein repositioning the fixation element comprises rotating the fixation element so as to drive the fixation element into the bone so as to reduce a space between the implant and the bone in the transverse direction.

7. The method of claim 5, wherein repositioning the fixation element comprises rotating the fixation element so as to back the head of the fixation element away from the bone so as to increase a space between the implant and the bone in the transverse direction.

8. The method of claim 4, wherein:

the first ridge has a proximal end and a distal end spaced from the first ridge proximal end along the central axis, and

the method further comprises abutting the distal end of the first ridge against at least one of the inner surfaces of the first and second wire segments after the second threaded region is disengaged from, and spaced in the distal direction from, the first threaded region.

9. The method of claim 4, wherein:

the second ridge has a proximal end and a distal end spaced from the second ridge proximal end along the central axis, and

the method further comprises abutting the proximal end of the second ridge against at least one of the inner surfaces of the first and second wire segments after the second threaded region is disengaged from, and spaced in the distal direction from, the first threaded region.

10. The method of claim 4, wherein the first threaded region comprises threads having peaks that lie in a convex path along the transverse direction.

11. The method of claim 10, wherein the threads have valleys positioned between adjacent peaks along the transverse direction, wherein the valleys lie on a linear path along the transverse direction.

12. The method of claim 1, wherein the first ridge is unthreaded.

13. The method of claim 1, wherein the inner wall is curved along a longitudinal direction that is perpendicular to the transverse and lateral directions.

14. The method of claim 1, wherein the first and second wire segments each have a substantially circular cross section.

15. The method of claim 1, wherein the first ridge defines a first cross-sectional dimension between diametrically opposed, radially outermost points of the first ridge, and the second ridge defines a second cross-sectional dimension between diametrically opposed, radially outermost points of the second ridge, and the second cross-sectional dimension is no greater than the first cross-sectional dimension.

16. The method of claim 1, wherein at least a portion of the groove is curved along the transverse direction.

17. The method of claim 1, wherein the groove is concave.

18. The method of claim 1, wherein, when the first threaded region is aligned with the unthreaded groove along the lateral direction, the groove and at least one of the inner surfaces defines a gap extending therebetween in the lateral direction.

19. The method of claim 1, wherein the inner surfaces each define a protrusion along the lateral direction, and the first threaded region is disposed on at least a portion of the protrusion.

20. The method of claim 1, wherein the inner surfaces each include a portion that extends linearly along the transverse direction.