US Patent 7018378 Screw

An element with a thread is created, in which both partial flanks enclose a negative angle with a plane extending perpendicular to the screw axis. Further, a screw or a hook for connecting to a rod, as used in particular in spinal column surgery, is created, wherein the inner thread of a holder, to which the rod is connected, and the associated thread of a nut comprise the thread according to the invention.