US Patent 9526547 Bone screw

A threaded fastener for embedment into bone is disclosed. Threads are formed on cylindrical stock. The thread pattern features upper and lower surfaces. The upper surface includes (in section) two facets which intersect to form a “V” shaped contour and a lower surface which is undercut below an upper facet nearest a root of the fastener thread. The fastener includes a self-tapping cutter at a distal extremity and a driving head at its proximal extremity. The cylindrical stock contemplates two variants: it may be hollow from the proximal end to the self-tapping cutter or from the self-tapping cutter to its distal end. The self-tapping cutter is configured to feed bone shards into the hollow.