Compression bone staple
The present invention relates to devices and techniques for securing bone segments across a fracture site, and more particularly relates to bone staples for achieving compression between segments. A method and apparatus for interosseous bone fixation uses a compression staple, generally U-shaped, having a pair of legs with proximal ends interconnected by a bridge portion that is resilient and bowed, the staple having an initial configuration and capable of a tensioned configuration by spreading apart the legs by a certain amount causing the curvature of the bowed bridge to lessen and the legs to move towards each other with certain compressive spring force.
1. A compression staple comprising:
a bridge having a first end, a second end, and an elongate body with one or more curves between the first end and the second end;
a first leg having a proximal end, a distal end, and an elongate body between the proximal end and the distal end, wherein the proximal end of the first leg is connected to the first end of the bridge, and wherein the first leg is solid in cross-section and has a first elongate groove on an exterior surface thereof, the first elongate groove extending along the elongate body of the first leg from the distal end of the first leg to the bridge and is partially defined by perimetric surfaces of the bridge, the first elongate groove configured to be contacted by a first guide on at least one of a staple loading mechanism and a delivery mechanism when the staple is loaded on one of the staple loading mechanism or the delivery mechanism in a tensioned state; and
a second leg having a proximal end, a distal end, and an elongate body between the proximal end and the distal end, wherein the proximal end of the second leg is connected to the second end of the bridge, and wherein the second leg is solid in cross-section and has a second elongate groove on an exterior surface thereof, the second elongate groove extending along the elongate body of the second leg from the distal end of the second leg to the bridge and is partially defined by perimetric surfaces of the bridge, the second elongate groove configured to be contacted by a second guide on at least one of the staple loading mechanism and the delivery mechanism when the staple is loaded on one of the staple loading mechanism or the delivery mechanism in the tensioned state,
wherein the staple is movable from a relaxed state to the tensioned state by spreading apart the first leg and the second leg from one another which lessens a curvature of the one or more curves of the elongate body of the bridge, the first leg and the second leg being resiliently urged toward one another when the staple is in the tensioned state.
2. The staple of claim 1 wherein the elongate body of the bridge is gull-wing shaped.
3. The staple of claim 1 wherein the first groove is provided along an inner surface of the first leg facing the second leg, and the second groove is provided along an inner surface of the second leg facing the first leg.
4. The staple of claim 1 , wherein the staple is configured to achieve a force to staple width or force to staple height ratio of between about 25-45 lbs of compression force to 20 mm width or 20 mm height upon insertion into bone segments.
5. The staple of claim 4 , wherein the amount of compression force upon insertion into bone segments varies by less than 80% along a length of the staple legs.
6. The staple of claim 1 , wherein the one or more curves comprising a laterally curved shape, and wherein said bridge lies in a plane normal to axes of the staple legs.
7. The staple of claim 6 , wherein the bridge forms a gull-wing shape, S-shape, Z-shape, or U-shape.
8. The staple of claim 1 , wherein the first and second staple legs are moved apart by a distance of less than about 1 mm between the tensioned state and the relaxed state.
9. The staple of claim 1 , wherein the staple legs have a flat base at the distal end of each of the first and second staple legs.
10. The staple of claim 1 , wherein the staple legs contain at least one serrated barb.
11. The staple of claim 1 , wherein the bridge includes a flat surface on one side such that a bridge height is greater than a bridge width.
12. The staple of claim 1 , wherein the one or more curves of the bridge comprise at least three curves between the first end and second end.
13. The staple of claim 1 , wherein the staple legs are moved apart by a distance of less than about 2 mm between the tensioned state and the relaxed state.
14. The staple of claim 1 , further comprising:
a third groove on the exterior surface of the first leg, wherein the third groove is oriented substantially perpendicular to and intersects with the first elongate groove; and
a fourth groove on the exterior surface of the second leg, wherein the fourth groove is oriented substantially perpendicular to and intersects with the second elongate groove.
15. A compression staple comprising:
a bridge having a first end, a second end, and an elongate body with one or more curves between the first end and second end;
a first leg having a proximal end, a distal end, and an elongate body between the proximal end and the distal end, wherein the proximal end of the first leg is connected to the first end of the bridge, and wherein the first leg is solid in cross-section and has a first elongate groove on an exterior surface thereof, the first elongate groove being circumferentially open for an entire length thereof and extending along the first leg from the distal end of the first leg to the proximal end of the first leg, the first elongate groove extending along a side surface of the bridge to a top surface of the bridge; and
a second leg having a proximal end, a distal end, and an elongate body between the proximal end and the distal end, wherein the proximal end of the second leg is connected to the second end of the bridge, wherein the second leg is solid in cross-section and has a second elongate groove on an exterior surface thereof, the second elongate groove being circumferentially open for an entire length thereof and extending along the second leg from the distal end of the second leg to the proximal end of the second leg, the second elongate groove extending along the side surface of the bridge to the top surface of the bridge.
16. The staple of claim 15 , wherein the one or more curves comprising a laterally curved shape, and wherein said bridge lies in a plane normal to axes of the staple legs.
17. The staple of claim 16 , wherein the bridge forms a gull-wing shape, S-shape, Z-shape, or U-shape.
18. The staple of claim 15 , further comprising:
a third groove on the exterior surface of the first leg, wherein the third groove is oriented substantially perpendicular to and intersects with the first elongate groove; and
a fourth groove on the exterior surface of the second leg, wherein the fourth groove is oriented substantially perpendicular to and intersects with the second elongate groove.
19. A compression staple comprising:
a bridge having a first end, a second end, and an elongate body with one or more curves between the first end and second end;
a first leg having a proximal end, a distal end, and an elongate body between the proximal end and the distal end, wherein the proximal end of the first leg is connected to the first end of the bridge, and wherein the first leg is solid in cross-section and has a first elongate groove on an exterior surface thereof, the first elongate groove extending an entire length of the elongate body from the distal end to the proximal end thereof, and wherein the first groove further extends into the first end of the bridge and is partially defined by perimetric surfaces of the bridge; and
a second leg having a proximal end, a distal end, and an elongate body between the proximal end and the distal end, wherein the proximal end of the second leg is connected to the second end of the bridge, wherein the second leg is solid in cross-section and has a second elongate groove on an exterior surface thereof, the second elongate groove extending an entire length of the elongate body from the distal end to the proximal end thereof, and wherein the second groove further extends into the second end of the bridge and is partially defined by perimetric surfaces of the bridge.
20. The staple of claim 19 , wherein the one or more curves comprising a laterally curved shape, and wherein said bridge lies in a plane normal to axes of the staple legs.
21. The staple of claim 19 , further comprising:
a third groove on the exterior surface of the first leg, wherein the third groove is oriented substantially perpendicular to and intersects with the first elongate groove; and
a fourth groove on the exterior surface of the second leg, wherein the fourth groove is oriented substantially perpendicular to and intersects with the second elongate groove.