Distal bone anchors for bone fixation with secondary compression
View Patent ↗Disclosed is a bone fracture fixation device, such as for reducing and compressing fractures in the proximal femur. The fixation device includes an elongate body with a helical cancellous bone anchor on a distal end. An axially moveable proximal anchor is carried by the proximal end of the fixation device. The device is rotated into position across the fracture or separation between adjacent bones and into the adjacent bone or bone fragment, and the proximal anchor is distally advanced to apply secondary compression and lock the device into place. The device may also be used for soft tissue attachments.
1. A spinal fusion device, comprising:
an elongate body, having a proximal end and a distal end; a helical anchor on the distal end; a first retention structure on the body, proximal to the anchor; and an axial lumen extending from the proximal end to the distal end of the elongate body to accommodate placement of the elongate body over a placement wire;
a proximal anchor, moveably carried by the body, the proximal anchor comprising a tubular sleeve having a radially outwardly extending transverse flange, the transverse flange having a curved surface;
a second retention structure on the interior of the tubular sleeve for cooperating with the first retention structure on the body; and
a washer, moveably carried by the flange of the proximal anchor, the washer comprising an aperture, an indented surface generally corresponding to the curved surface of the flange, and a base surface, the aperture being configured with the proximal anchor being moveably received therethrough with the curved surface of the flange contacting the indented surface of the washer for distributing a load exerted by the proximal anchor across the base surface of the washer, the base surface of the washer being adjustable relative to a longitudinal axis of the proximal anchor for maximizing bone contact with the base surface;
wherein the proximal anchor and the transverse flange thereof are movable in the distal direction with respect to the body without rotation, and wherein both the first retention structure and second retention structure resist proximal movement of the proximal anchor with respect to the body; and
wherein the washer remains adjustable relative to the longitudinal axis of the proximal anchor as the entirety of the proximal anchor is moved in the distal direction with respect to the body.
2. A spinal fusion device as in claim 1 , wherein the first retention structure comprises an annular structure.
3. A spinal fusion device as in claim 1 , wherein the first retention structure comprises a flange.
4. A spinal fusion device as in claim 1 , wherein the curved surface of the proximal anchor generally corresponds with the indented surface of the washer.
5. A spinal fusion device as in claim 1 , wherein the indented surface of the washer is concave.
6. A spinal fusion device as in claim 1 , wherein the indented surface of the washer is generally semi-spherical.
7. A spinal fusion device as in claim 1 , wherein the curved surface of the proximal anchor is generally semi-spherical.
8. A spinal fusion device as in claim 1 , wherein the transverse flange of the proximal anchor is annular.
9. A spinal fusion device as in claim 1 , wherein a range of motion of the proximal anchor for providing compression is at least approximately 10% of the length of the body.
10. A spinal fusion device as in claim 1 , wherein a range of motion of the proximal anchor for providing compression is approximately 10% to approximately 30% of the length of the body.
11. A spinal fusion device, comprising:
an elongate body having a proximal end and a distal end, the elongate body comprising a helical anchor on the distal end and a first retention structure, the first retention structure being disposed proximal to the anchor; and an axial lumen extending from the proximal end to the distal end of the elongate body to accommodate placement of the elongated body over a placement wire;
a proximal anchor being moveably carried by the body, the proximal anchor comprising a second retention structure and an outwardly extending flange, the second retention structure being operative interact with the first retention structure of the elongate body to resist proximal movement of the proximal anchor relative to the elongate body and to facilitate distal movement thereof relative to the elongate body; and
a washer being disposed about the flange of the proximal anchor, the washer comprising an aperture and a concave flange seat disposed about the aperture, the aperture being configured with the proximal anchor being moveably received therethrough and the flange being received within the flange seat such that the flange is at least rotatable within the flange seat;
wherein the flange of the proximal anchor is movable in the distal direction with respect to the body without rotation; and
wherein the washer is adjustable relative to a longitudinal axis of the proximal anchor as the entirety of the proximal anchor is moved in the distal direction with respect to the body.
12. A spinal fusion device as in claim 11 , wherein the flange of the proximal anchor comprises a curved surface generally corresponding with the flange seat of the washer.
13. A spinal fusion device as in claim 2 , wherein the curved surface of the flange is generally semi-spherical.
14. A spinal fusion device as in claim 12 , wherein the flange seat is generally semi-spherical.
15. A spinal fusion device as in claim 11 , wherein the flange of the proximal anchor is annular.
16. A spinal fusion device as in claim 11 , wherein a range of motion of the proximal anchor for providing compression is at least approximately 10% of the length of the body.
17. A spinal fusion device as in claim 11 , wherein a range of motion of the proximal anchor for providing compression is approximately 10% to approximately 30% of the length of the body.
18. A spinal fusion device as in claim 11 , wherein the washer further comprises a base surface being adjustable relative to a longitudinal axis of the proximal anchor.
19. A spinal fusion device as in claim 18 , wherein the base surface is generally flat.
20. A spinal fusion device as in claim 18 , wherein the base surface is adjustable relative to a longitudinal axis of the proximal anchor.