Comparison of Cortical Bone Drilling Induced Heat Production Among Common Drilling Tools

Objectives: Significant data exist regarding heat production of twist drills; however, there are little data regarding cannulated drills or Kirschner (K) wires. This study compared the heat produced during bone drilling with twist drills, K wires, and a cannulated drill. It was hypothesized that drilling temperature would increase with tool sizes used in orthopaedic surgery; with twist drills producing the least amount of heat followed by cannulated drills and K wires. Methods: Twist drills (2.0, 2.5, and 3.5 mm), K wires (1.25, 1.6, and 2.0 mm), and a cannulated drill (2.7 mm) were driven into warmed human cadaveric tibia by a battery-powered hand drill. The drill was secured on a servo-controlled linear actuator to provide a constant advancing speed (1 mm/s) during drilling. Two thermocouples were embedded 2 mm from the surface at 0.5 and 1.5 mm from the drill hole margin. Eight tests were performed for each tool. Results: Twist drills exhibited a positive trend between size and heat production. The size effect was less significant with K wires. K wires resulted in significantly (P = 0.008 at 0.5 mm) higher peak temperatures than twist drills of the same size. A 2.7-mm cannulated drill produced more than double the temperature rise of a 2.5-mm twist drill. Conclusions: Twist drills produced the smallest temperature rise among all bit types. Thermal effects should not be a reason for choosing K-wire size. The cannulated drill showed significantly higher temperatures when compared with standard drills, reaching maximal temperatures comparable with K wires.