Eddy Current System for Finding Distal Transverse Screw Holes of an Intramedullary Nail

This report describes an eddy current system for finding distal transverse screw holes of an intramedullary nail. Although conventional X-ray methods can visualize screw holes in the bone, they pose a danger due to X-ray exposure. Therefore, a system to find screw holes without X-ray exposure is required. This problem was solved using an eddy current system and applying a method that calculates local maximum values of the searching signal obtained by the eddy current system. Characteristics of screw holes were revealed in the waveform and amplitude of the searching signal. As a result, the screw hole positions could be identified within an error of 1.3 mm when the distance between the probe and the intramedullary nail was 4 mm.