Procedure and apparatus for screwing implants into bones

摘要

An artificial hinge pin having a self-cutting threaded portion is inserted into a prepared bone with reduced reaction moment by a hand-held power tool which imposes a rotary oscillating movement on the pin during the insertion process. The tool has an output shaft driven by an overriding ratchet type coupling providing repeated impacts to the output shaft. A plurality of elastic rods connected to the output shaft are arranged coaxially around the shaft and are anchored to a rotary brake disk. Braking force on the disk is controlled by an adjustable compression spring. The eigenfrequency of the elastic system comprising the rods and output shaft may be adjusted to the impact frequency of the ratchet coupling.