In-vitro analysis of forces in conventional and ultrasonically assisted drilling of bone

Background: Drilling of bone is widely performed in orthopaedics for repair and reconstruction of bone. Current paper is focused on the efforts to minimize force generation during the drilling process. Ultrasonically Assisted Drilling (UAD) is a possible option to replace Conventional Drilling (CD) in bone surgical procedures. Objective: The purpose of this study was to investigate and analyze the effect of drilling parameters and ultrasonic parameters on the level of drilling thrust force in the presence of water irrigation. Methods: Drilling tests were performed on young bovine femoral bone using different parameters such as spindle speeds, feed rates, coolant flow rates, frequency and amplitudes of vibrations. Results: The drilling force was significantly dropped with increase in drill rotation speed in both types of drilling. Increase in feed rate was more influential in raising the drilling force in CD compared to UAD. The force was significantly dropped when ultrasonic vibrations up to 10 kHz were imposed on the drill. The drill force was found to be unaffected by the range of amplitudes and the amount of water supplied to the drilling region in UAD. Conclusions: Low frequency vibrations with irrigation can be successfully used for safe and efficient drilling in bone.