Optimal Choice of Surgical Drill Design

Optimally designed surgical drills are necessary to avoid thermal damage to osseous tissues and to ensure rapid and accurate drilling during bone fracture surgery. Bony necrosis is believed to occur at temperatures of 50℃ or more and is strongly related to the length of exposure to high temperatures. A drill with a low thrust force that suppresses heat generation is thus necessary to avoid bone necrosis. This study quantitatively examined the effects of surgical drill geometry on heat generation and thrust force using experimental design, analysis of variances and statistical technique. The helix angle, web thickness, and point angle of the fundamental drill elements were evaluated to determine the optimal drill geometry at various cutting and feed speeds. Thrust force and drilling temperature were measured while drilling porcine femoral bone to examine the influence of drill geometry on these factors. A 40° helix angle, 23% web thickness, and 90° point angle were found to be the optimal choices for suppressing heat generation.