Orthopedic screw with break away drive
Embodiments of break off screws are disclosed, configured so that when one head or screw portion is broken off, a complete screw with head remains.
1 . An orthopedic screw, comprising:
a first screw portion comprising;
a first distal end;
a first proximal end having a first head portion; and
a threaded region between the first distal and proximal ends;
wherein the first head portion is an external drive head portion;
a second screw portion comprising;
a second distal end; and
a second proximal end having a second head portion;
wherein the second head portion is an internal drive head portion; and wherein the second distal end and first proximal end are adapted to separate from one another upon application of a prescribed force to the second head portion.
2 . The orthopedic screw as in claim 1 wherein the first head portion comprises a star-shaped screw head portion.
3 . The orthopedic screw as in claim 1 wherein the second head portion comprises a hexagonal-shaped screw head portion.
4 . The orthopedic screw as in claim 1 wherein the second head portion has an outer diameter greater than a first head portion outer diameter.
5 . The orthopedic screw as in claim 1 wherein the first and second screw portions are coaxially aligned.
6 . The orthopedic screw as in claim 1 wherein the first and second screw portions are coupled together at a separation region, the separation region adapted to shear upon the application of the prescribed force.
7 . The orthopedic screw as in claim 1 wherein the first and second screw portions are integrally formed together.
8 . The orthopedic screw as in claim 1 wherein the first and second screw portions comprise a non-metallic material.
9 . The orthopedic screw as in claim 8 wherein the non-metallic material is an implantable grade polymer.
10 . The orthopedic screw as in claim 8 wherein the first screw portion further comprises at least one radiopaque marker.
11 . The orthopedic screw as in claim 10 wherein the at least one radiopaque marker is disposed in the first distal end.
12 . The orthopedic screw as in claim 10 wherein the at least one radiopaque marker is disposed in the first head portion.
13 . The orthopedic screw as in claim 12 wherein the at least one radiopaque marker is disposed proximal to the threaded region.
14 . The orthopedic screw as in claim 1 wherein the second screw portion is a nonthreaded screw portion.
15 . An elongate bone screw for engaging a vertebral body, the screw comprising:
a distal region comprising a bone engaging tip and a threaded portion extending proximally from the bone engaging tip;
an intermediate region comprising an external drive head portion and a radiopaque marker; and
a proximal region comprising an internal drive head portion.
16 . The elongate bone screw as in claim 15 wherein the proximal region is adapted to separate from the intermediate region when a prescribed rotational force is applied to the internal drive head portion.
17 . The elongate bone screw as in claim 15 wherein the proximal region is a non-threaded region.
18 . An orthopedic system, comprising:
a bone plate having at least one hole disposed therethrough, the hole adapted to receive a bone screw; and
a bone screw for coupling the bone plate to a bone, the bone screw comprising:
a distal region, an intermediate region, and a proximal region, wherein the intermediate region comprises an external drive head portion and the proximal region comprises an internal drive head portion; and
wherein the proximal region is adapted to separate from the intermediate region when a prescribed force is applied to the internal drive head portion.
19 . A method of attaching a plate to a vertebral body, the method comprising:
positioning the plate adjacent the vertebral body;
inserting a bone screw through a hole in the plate, the bone screw comprising a distal region, an intermediate region, and a proximal region, wherein the intermediate region comprises an external drive head portion and the proximal region comprises an internal drive head portion;
rotating the bone screw at least partially into the vertebral body using a tool adapted to engage the internal drive head portion; and
separating the proximal region of the bone screw from the intermediate region using a rotational force which exceeds the shear strength of an interface between the proximal region and the intermediate region.
20 . The method as in claim 19 further comprising engaging the external drive head portion and further rotating the bone screw into the vertebral body.
21 . The method as in claim 19 further comprising imaging a location of the bone screw relative to the vertebral body by imaging at least one radiopaque marker disposed in the bone screw.
22 . An orthopedic screw, comprising:
a first screw portion comprising;
a first distal end;
a first proximal end having a first head portion; and
a threaded region between the first distal and proximal ends;
wherein the first head portion is an external drive head portion;
a second screw portion comprising;
a second distal end; and
a second proximal end having a second head portion;
wherein the second head portion is a threaded drive head portion; and wherein the second distal end and first proximal end are adapted to separate from one another upon application of a prescribed force to the second head portion.