Electromagnetically Navigated Forearm Fracture Plating

Abstract

Electromagnetic (EM) tracking is currently a feasible tracking modality to navigated surgical operations on delicate bone structures, but how accurate and consistent could the navigation be in the case of forearm fracture plating? Recent studies, on artificial models, that used tracked personalized guides showed accuracy that was comparable to optical tracking - the gold standard of surgical navigation in orthopedics. This work explored whether electromagnetic tracking can fit a plate onto the human forearm with clinically acceptable accuracy and precision. Tracked personalized guides were used to navigate eleven human forearm cadavers, demonstrating the consistency, accuracy, and reliability of EM based surgical navigation. Preoperative plans were made by a board certified surgeon for placement of two 2.25mm cortical screws along the mid-shaft in eleven soft-embalmed cadaveric upper extremity specimens for volar mid-shaft radius plating. Each tracked guide was calibrated, with errors measured as fiducial localization error between the calibration holes and an EM tracked probe. A resident surgeon drilled the eleven specimens, according to the preoperative plans, using EM navigation technology, in an environment that was included typical surgical instruments. Solid aluminum rods were placed in the screw holes for imaging contrast. Postoperative CT scans were acquired and segmented to compare drilling trajectories, manifested by the placement of the rods, to the preoperative plans. Positional and angular target registration errors were calculated between actual and planned placement locations for each specimen. Visual inspection of plating quality was done by fitting a plate onto the drilled cadavers. This work suggested that, in orthopedic surgical procedures where optical navigation systems cannot feasibly be used, EM navigation with precisely calibrated personalized guides may be an accurate and reliable alternative. EM navigation with personal guides shows promise towards surgical navigated fracture reduction.