Effects of Drill Geometry and Penetration Angle on Temperature and Holes Surfaces for Cortical Bovine Bone: An in Vitro Study☆

Abstract Drilling of bone is the most important part of the internal and external fixation processes in orthopaedic surgery. This surgical procedure usually is performed manually with a hand-held tool and is greatly dependent on the surgeon skill. Imprecise manipulation of the hand-held tool can cause the drill skidding across the bone surface and leads to a localized increase in temperature resulting a thermal necrosis on the soft tissue surrounding the hole surface. The magnitudes of the friction energy are greatly dependent with the drill geometry design and the penetration angle. For the sake of importance on studying this phenomenon, this paper aim to investigate the effects of drill geometry on temperatures rise and hole surface in bone drilling procedure. Totals of 17 drills were designed and tested with different geometry namely point angle, helix angle and web thickness on different penetration angle (0 0 , 15 0 , and 30 0 ) to mimic the manually control penetration by the surgeon. From the conducted investigation, the most significant parameter that affects the temperature rise and holes surface quality was the penetration angle followed by the point angle. In addition, the interaction between helix angle and web thickness also controlled the drilling temperature and the performance of the hole surface.