Anchor screw assembly for joint prosthesis cup implant

摘要

The screw (4) suitable for spongy bone material has a thread (6) of large pitch along its shaft and a finer thread (10) around its head or proximal end. The implant cup (1) is formed with a number of screw passage holes which include a thread (3) on their inner edge faces corresponding to that of the screw heads. The threads on the cup hole edges also correspond to a thread on a drill guide (5) which may be temporarily screwed into the hole while a guide hole for the screw is formed in the spongy bone tissue. The bone screws may alternatively have smooth shafts (7), and the edges of the cap holes may only be partially threaded.