The Effect of Drill Design Elements on Drilling Characteristics when Drilling Bone

Abstract

Twist drills are often used to prepare implant sites for the internal fixation of fractures, and the stability of the fixation, which depends directly on how securely the implants are held, depends on the quality of the bone around the pilot holes after implant site preparation. To optimize the design of surgical drills, this study evaluated the effects of the drill design elements (thinning, and the helix and point angles) on drilling characteristics (thrust force and temperature increase and duration) when drilling bone. We used mature porcine femurs because porcine bone resembles human bone, and measured the thrust force and bone temperature at three points during the drilling test using drills with different designs and a standard surgical drill. We found that types X, N, and R thinning were effective in reducing the thrust force, and a quick helix was effective in reducing temperature increase and duration when drilling cortical bone. However, no obvious relationship was observed between the drill design elements and the drilling characteristics, perhaps because the cutting system of a drill is complex. In the future, creating a more efficient evaluation method to overcome the complexity of the cutting system and examining the relationship between the drill design elements and the drilling characteristics should be carried out to improve the drilling performance of bone. © 2010, The Japan Society of Mechanical Engineers. All rights reserved.