ALEXANDRIA, Va., June 18 -- United States Patent no. 12,324,614, issued on June 10, was assigned to Stryker European Operations Holdings LLC (Portage, Mich.).
"Self-holding screw head" was invented by Nils Zander (Eckernforde, Germany) and Manfred Wieland (Kiel, Germany).
According to the abstract* released by the U.S. Patent & Trademark Office: "A screw insertion system has a screw having a threaded shaft and a head. The head has a conically tapered outer surface, the taper increasing in distance from a central longitudinal axis of the screw from a free end of the head towards a larger diameter adjacent the connection between the head and the threaded shaft. The conically tapered head outer surface has preferably two helically extending ...