Evaluation of Heat Generation in Unidirectional Versus Oscillatory Modes During K-Wire Insertion in Bone.

Heat generation during insertion of Kirschner wires (K-wires) may lead to thermal osteonecrosis and can affect the construct fixation. Unidirectional and oscillatory drilling modes are options for K-wire insertion, but understanding of the difference in heat generation between the two modes is lacking. The goal of this study was to compare the temperature rise during K-wire insertion under these two modes and provide technical guidelines for K-wire placement to minimize thermal injury. Ten orthopedic surgeons were instructed to drill holes on hydrated ex vivo bovine bones under two modes. The drilling trials were evaluated in terms of temperature, thrust force, torque, drilling time, and tool wear. The analysis of variance showed that the oscillatory mode generated significantly lowered peak bone temperature rise (13% lower mean value, p = 0.036) over significantly longer drilling time (46% higher mean time, p < 0.001) than the unidirectional mode. Drilling time had significant effect on peak bone temperature rise under both modes (p < 0.001) and impact of peak thrust force was significant under oscillatory mode (p < 0.001). These findings suggest that the drilling mode choice is a compromise between peak temperature and bone exposure time. Shortening the drilling time was the key under both modes to minimize temperature rise and thermal necrosis risk. To achieve faster drilling, technique analysis found that "shaky" and intermittent drilling with moderate thrust force are preferred techniques by small vibration of the drill about the K-wire axis and slight lift-up of the K-wire once or twice during drilling. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1903-1909, 2019.