Bone fixation with a pin and a collar
System, including methods and devices, for bone fixation with a pin and a collar. In exemplary embodiments, the system may comprise a pin configured to be inserted into a bone, and a deformable collar to retain the pin in the bone. The collar may be configured to be operatively disposed on the pin such that the collar extends more than halfway and less than completely around the pin. The pin and the collar may have complementary surface features that discourage sliding of the collar along a long axis of the pin. In some embodiments, the collar may be configured to be operatively disposed on the pin at a plurality of discrete, alternative axial positions along the long axis of the pin. The pin may be cut to a desired length.
1. A system for bone fixation, comprising:
a pin configured to be inserted into a bone; and
a deformable collar to retain the pin in the bone;
wherein the collar is configured to be operatively disposed on the pin such that the collar extends more than halfway and less than completely around the pin,
wherein the collar defines a through-axis and has an axial dimension measured along the through-axis, wherein the collar includes an inner surface configured to face the pin, wherein the inner surface defines a surface feature that is complementary to each surface feature of a plurality of surface features of the pin, wherein the surface feature of the collar has an axial extent that is less than the axial dimension of the collar, and wherein the collar is configured to be seated on the pin without threaded engagement between the collar and the pin.
2. The system of claim 1 , wherein the surface feature of the collar is curved along the through-axis of the collar.
3. The system of claim 1 , wherein the collar has a first end opposite a second end and defines a hole extending through the collar from the first end to the second end, wherein the hole is open on one side of the collar from the first end to the second end to form a gap that is contiguous to the hole, and wherein a size of the gap is configured to change as the collar is being operatively disposed on the pin.
4. The system of claim 1 , wherein the collar is configured to be operatively disposed on the pin by movement of the pin and the collar relative to one another transverse to a long axis of the pin.
5. The system of claim 1 , wherein the pin is formed of metal and the collar is formed of polymer.
6. The system of claim 1 , wherein each surface feature of the plurality of surface features of the pin is configured to discourage sliding of the collar along a long axis of the pin after the collar is operatively disposed on the pin at the surface feature of the pin.
7. The system of claim 6 , wherein the plurality of surface features of the pin includes a longitudinal array of notches or protrusions defined by the pin, and wherein each notch or protrusion extends at least partway around the long axis of the pin in a plane that is orthogonal to a long axis of the pin.
8. The system of claim 1 , wherein the collar is configured to be operatively disposed on the pin at only a finite plurality of discrete, predefined, alternative axial positions defined by the surface features of the pin along a long axis of the pin.
9. The system of claim 1 , wherein the collar includes an outer surface forming one or more asymmetrical ridges that selectively restrict translational movement of the collar with respect to the bone.
10. A system for bone fixation, comprising:
a pin configured to be inserted into a bone; and
a deformable collar to retain the pin in the bone;
wherein the collar is configured to be operatively disposed on the pin such that the collar extends more than halfway and less than completely around the pin,
wherein the collar defines a through-axis and has an axial dimension measured along the through-axis, wherein the collar includes an inner surface configured to face the pin, wherein the inner surface defines a surface feature that is complementary to each surface feature of a plurality of surface features of the pin, wherein the surface feature of the collar has an axial extent that is less than the axial dimension of the collar, wherein the pin defines a long axis, and wherein each surface feature of the plurality of pin surface features extends completely and uniformly around the long axis in a respective plane that is orthogonal to the long axis.
11. A method of fixing bone with the system of claim 1 , the method comprising, in any order:
inserting the pin of claim 1 into a bone;
disposing the collar of claim 1 operatively on a section of the pin such that the collar extends more than halfway and less than completely around the section of the pin; and
driving the collar into the bone to retain the pin in the bone with the collar.
12. The method of claim 11 , wherein the step of disposing the collar includes a step of deforming the collar with the pin.
13. The method of claim 11 , further comprising a step of shortening the pin by cutting or breaking the pin.
14. The method of claim 11 , wherein the step of disposing the collar includes a step of moving the pin and the collar relative to one another transverse to a long axis of the pin.
15. The method of claim 11 , wherein the step of driving the collar into the bone includes a step of driving the collar into contact with a wall of a pre-formed bore in the bone.
16. The method of claim 11 , wherein the step of driving the collar into the bone causes the section of the pin and the collar to travel into the bone as a unit.