Comparison of pull-out resistance of Kirschner wires and Imex™ miniature interface fixation half pins in polyurethane foam

Abstract

SummaryThe pin-bone interface is critical in maintaining a stable external skeletal fixator to allow bony union and prevent complications related to loose pins (3, 7, 13, 14, 16, 17). Threaded pins have increased pull-out strength in comparison to smooth pins and have improved the bone-pin interface (1, 2, 4, 12, 16, 21). Pull-out strengths were compared between smooth Kirschner size pins and Imex™ Miniature Interface Fixation Half Pins in a polyurethane foam bone model. The negative profile end threaded pins had significantly higher pull-out strengths (p <0.001) than smooth pins. Increasing the diameter of the pin and the length of engagement also increased the pull-out strengths of both pin types. Improving the pull-out strength of pins should minimize morbidity of external skeletal fixators used in repair of mandibular/maxillary fractures or long bone repairs on small and exotic patients.