Device for fixing a longitudinal carrier to a bone fixing element
View Patent ↗The device is used for mutually securing or clamping a longitudinal carrier (e.g., a spinal rod) to a bone fixing element (e.g., a pedicle screw). The device includes a body having a channel that is open along its longitudinal axis on one side for receiving the longitudinal carrier. The body has a bore that extends fully through the body and at least partially intersects the channel. The bore is conical in form and has a large opening, a small opening, and an inner thread. The head of the bone fixing element has an outer thread that corresponds to the inner thread. As the fixing element is secured in the bore, it locks the longitudinal carrier to the device.
1. A three piece device consisting of:
a longitudinal carrier;
a body including a channel having a longitudinal axis and an opening along the longitudinal axis for receiving the longitudinal carrier, the body having a bore extending completely there through, the channel and the bore partially intersecting each other, the bore constructed conically and having a first opening on one side of the body and a second opening on another side of the body, the first opening larger than the second opening, and the bore having an internal thread; and
a bone screw including a tip, a threaded shaft for threadably engaging bone, and an externally threaded conical head portion for engaging the internally threaded conical bore such that rotation of the bone screw causes the threaded shaft to engage the bone, the externally threaded head portion to engage the internally threaded bore and the externally threaded head portion to contact the longitudinal carrier positioned with the channel so that the longitudinal carrier is fixed between an inner surface of the channel and the head portion of the bone screw.
2. The device of claim 1 wherein the bore has a conical angle ranging from 5 degrees to 25 degrees.
3. The device of claim 1 wherein the bore has a conical angle ranging from 8 degrees to 15 degrees.
4. The device of claim 1 wherein:
the conical bore tapers inward towards the channel; and
the smaller second opening of the bore is on the same side of the body as the channel.
5. The device of claim 1 wherein
the conical bore expands towards the channel; and
the larger first opening of the bore is on the same side of the body as the channel.
6. The device of claim 1 wherein the external thread has a pitch from about 0.1 to 3.0 millimeters.
7. The device of claim 1 wherein the external thread has a pitch from about 0.25 to 1.50 millimeters.
8. The device of claim 1 wherein the head of the bone screw tapers conically toward the tip.
9. The device of claim 8 wherein the head has a conical angle ranging from 5 degrees to 25 degrees.
10. The device of claim 1 wherein the longitudinal axis of the channel and the bore are perpendicular to each other.