Multiplexed screws
A bone fixation element comprises a shaft extending substantially along a longitudinal axis of the fixation element in combination with a head including a plurality of fixation element openings distributed about a perimeter thereof. Each of the fixation element openings extends through the head from a proximal surface thereof to a distal surface of the head. Each of the fixation element openings extends through the head along an opening axis.
1. A bone fixation element, comprising:
a shaft extending substantially along a longitudinal axis of the fixation element; and
a head extending from and integrally formed with the shaft, the head defining a plurality of fixation element openings distributed about a perimeter thereof, each of the fixation element openings extending through the head from a proximal surface thereof to a distal surface of the head, each of the fixation element openings extending through the head along an opening axis, wherein at least two of the fixation element openings are only partially enclosed by the head, wherein a first one of the openings includes a threading along an inner surface thereof to lockingly engage a corresponding threading on a head of a bone fixation element to be inserted therethrough.
2. The fixation element of claim 1 , wherein each of the fixation element openings is angled relative to the longitudinal axis so that points of intersection of the opening axes and the longitudinal axis are proximal of the head.
3. The fixation element of claim 2 , wherein the proximal surface is substantially concave and the distal surface is substantially convex such that the opening axis of each of the openings is substantially perpendicular to the proximal surface.
4. The fixation element of claim 2 , wherein an angle of intersection between a first one of the opening axes and the longitudinal axis is less than 70°.
5. The fixation element of claim 1 , wherein each of the fixation element openings is angled relative to the longitudinal axis so that points of intersection of the opening axes and the longitudinal axis are distal of the head.
6. The fixation element of claim 5 , wherein the proximal surface is substantially convex and such that the opening axis of each of the openings is substantially perpendicular to the proximal surface.
7. The fixation element of claim 5 , wherein an angle of intersection between a first one of the opening axes and the longitudinal axis is smaller than −45°.
8. The fixation element of claim 1 , wherein at least two of the openings are partially enclosed by the head.
9. The fixation element of claim 8 , wherein the at least two openings are surrounded by a surface formed by the head over an angle of between 240° and 270°.
10. The fixation element of claim 1 , wherein an angle of a first opening axis is equal to an angle of a second opening axis.
11. The fixation element of claim 1 , wherein the opening axis of each of the fixation element openings is substantially parallel to the longitudinal axis of the fixation element.
12. The fixation element of claim 1 , wherein the head further includes a locking hole extending therethrough from the proximal surface to the distal surface along a locking axis, the locking hole being adapted and configured for receiving a locking element.
13. The fixation element of claim 12 , wherein the locking axis intersects the longitudinal axis at a point proximal of the proximal surface of the head.
14. The fixation element of claim 13 , wherein an angle of intersection of the locking axis and the longitudinal axis is approximately 30°.
15. The fixation element of claim 1 , wherein the shaft is threaded to threadably engage the bone.
16. The bone fixation element of claim 1 , wherein the bone fixation element is a bone screw.
17. The bone fixation element of claim 1 , wherein the circumference of the at least two fixation element openings is enclosed more than 180 degrees.
18. The bone fixation element of claim 17 , wherein the circumference of the at least two fixation element openings is enclosed between 240 and 270 degrees.
19. A system for treating a bone, comprising:
a master fixation element including:
a shaft extending substantially along a longitudinal axis of the fixation element, wherein the shaft is threaded to threadably engage the bone; and
a head extending from and integrally formed with the shall, the head defining a plurality of fixation element openings distributed about a perimeter thereof, each of the fixation element openings extending through the head from a proximal surface thereof to a distal surface of the head, each of the fixation element openings extending through the head along an opening axis, wherein at least two of the openings are only partially enclosed by the head; and
a plurality of supplemental bone fixation elements sized and shaped for insertion through respective ones of the fixation element openings, a first one of the supplemental bone fixation elements including a threading on a head thereof adapted to lockingly mate with a corresponding thread on the one of the fixation element openings into which it is to be inserted.
20. The system of claim 19 , wherein the opening axis is angled relative to the longitudinal axis so that points of intersection of the opening axes and the longitudinal axis are proximal of the head.
21. The system of claim 19 , wherein the opening axis is angled relative to the longitudinal axis so that points of intersection of the opening axes and the longitudinal axis are distal of the head.
22. The system of claim 19 , a surface of the head surrounding the at least two openings extending around an angle between 240° and 270°.
23. The system of claim 19 , wherein the opening axis is substantially perpendicular to the longitudinal axis.
24. The system of claim 19 , wherein the head further includes a locking hole extending therethrough from the proximal surface to the distal surface along a locking axis, the locking hole being adapted and configured for receiving a locking element.
25. A device for bone fixation, comprising:
a shaft extending along a longitudinal axis; and
a head permanently attached to the shaft, wherein the shaft is rotatable relative to the head about the longitudinal axis and axially locked thereto, the head defining a plurality of fixation element openings distributed about a perimeter thereof, each of the fixation element openings extending through the head from a proximal surface thereof to a distal surface of the head, each of the fixation element openings extending through the head along an opening axis, wherein at least two of the openings are partly open only partially enclosed by the head.
26. The device of claim 25 , wherein the shaft is received within a central opening of the head.
27. The device of claim 25 , wherein a proximal end of the shaft includes an increased diameter portion received within a corresponding recess formed in the head, the increased diameter portion preventing the shaft from being inserted distally through the head.
28. The device of claim 27 , wherein the shaft includes a reduced diameter neck received in a corresponding recess formed in the head, the reduced diameter neck preventing the shaft from being withdrawn proximally through the head.
29. The device of claim 28 , wherein the reduced diameter neck is threaded.
30. The device of claim 28 , wherein the head further comprises an unthreaded position receiving a threaded distal portion of the shaft, engagement of the threads with a distal end of the reduced diameter neck preventing the shaft from being withdrawn proximally from the head.