Axial tension screw

Abstract

A screw having a root and threads formed on the root. The screw is configured to generate and/or maintain axial compression between threads formed in leading and trailing sections of the screw either by virtue of pitch differential in the threads or the way in which the screw is installed.

1 . A method of compressing a bone, comprising:
 boring a hole through a first bone fragment, across a fracture, and into a second bone fragment;   placing a leading end of a fastener into the hole, where the fastener has a root portion, the root portion having a leading end, a trailing end, and an elongate axis extending therebetween, and a single continuous thread formed on the root portion and extending between the leading end and the trailing end of the root portion, the thread having an outside diameter which, moving from the leading end toward the trailing end, increases over several revolutions, then decreases, then increases again, wherein the pitch of the thread measured between corresponding points on consecutive threads near the leading end is larger than the pitch of the threads near the trailing end; and   driving the fastener into the hole such that the thread spans the fracture.