Differential compression bone screw
A differential compression bone screw and a method are provided for compressing adjacent bone portions together to encourage bone fusion. The compression bone screw is comprised of a head portion and a shank. A center hole extends from the head portion to a distal end of the shank. A superior end of the head portion includes a shaped opening that receives a tool for driving the compression bone screw into a hole drilled in a patient's bone. An inferior end of the head portion includes barbs that engage with surrounding bone tissue. A smooth portion of the shank is disposed between proximal threads and distal threads that rotatably engage within the hole in the patient's bone. A thread pitch of the distal threads is greater than a thread pitch of the proximal threads, such that the compression bone screw comprises a differential pitch configured to compress the adjacent bone portions.
1 . A method for a bone compression screw, comprising:
forming a shank having a head portion;
extending a center hole through the head portion and the shank;
forming at least one barb on a tapered portion of the head portion; and
forming threads along the shank;
wherein forming the threads includes forming at least distal threads near a distal end of the shank and proximal threads near the head portion;
wherein forming the threads includes arranging a differential pitch that comprises a distal thread pitch that is greater than a proximal thread pitch.
2 . The method of claim 1 , wherein arranging the differential pitch includes adapting the differential pitch for compressing bone fractures, fixating osteotomies, and joining fusions.
3 . The method of claim 1 , wherein arranging the differential pitch includes arranging the distal thread pitch to be between substantially 1 to 3 times greater than the proximal thread pitch.
4 . The method of claim 3 , wherein arranging the distal thread pitch comprises arranging the distal thread pitch to be substantially 2 times greater than the proximal thread pitch.
5 . The method of claim 1 , wherein arranging the differential pitch includes configuring the distal thread pitch to push a distal bone portion toward a proximal bone portion.
6 . The method of claim 5 , wherein forming the threads includes disposing a smooth portion between the distal threads and the proximal threads to allow the distal bone portion and the proximal bone portion to be compressed together.
7 . The method of claim 1 , wherein forming the threads includes forming intermediate threads between the distal threads and the proximal threads.
8 . The method of claim 7 , wherein forming the intermediate threads includes extending the intermediate threads from the distal threads to the proximal threads, such that a continuous series of threads is disposed along substantially an entirety of the shank.
9 . The method of claim 8 , wherein forming the intermediate threads includes arranging an intermediate thread pitch that changes along the length of the shank.
10 . The method of claim 9 , wherein forming the intermediate threads includes increasing the intermediate thread pitch from the proximal thread pitch to the distal thread pitch.
11 . The method of claim 10 , wherein forming the intermediate threads includes increasing the intermediate thread pitch from a first thread pitch that is substantially the same as the proximal thread pitch to a second thread pitch that ranges between substantially 1 to 3 times greater than the proximal thread pitch.
12 . The method of claim 11 , wherein forming the intermediate threads includes configuring the first thread pitch and the second thread pitch to cause the intermediate threads to contribute to compressing a distal bone portion against a proximal bone portion.
13 . The method of claim 11 , wherein forming the intermediate threads includes configuring the second thread pitch to be about 2 times greater than the first thread pitch.
14 . The method of claim 1 , wherein forming the shank includes tapering a diameter of the shank between the distal threads and the distal end of the shank.
15 . The method of claim 14 , wherein tapering the diameter includes adapting the distal end to minimize resistance to forward movement of the compression bone screw within a hole drilled in bone.
16 . The method of claim 14 , wherein tapering the diameter includes extending one or more flutes and cutting edges from the center hole to the distal threads.
17 . The method of claim 16 , wherein extending the one or more flutes and cutting edges includes bordering each of the one or more flutes with a pair of cutting edges.
18 . The method of claim 17 , wherein tapering the diameter includes extending three flutes and six cutting edges from the center hole to the distal threads.