Reduction thermal damage to cortical bone using ultrasonically-assisted drilling

BACKGROUND: Thermal damage induced by bone drilling is a common problem during surgical procedures. A recent and promising method utilizes high-frequency low-amplitude vibration in the feed direction during drilling and has the potential to reduce drilling temperature, minimizing the risk of thermal damage. OBJECTIVE: The purpose of this study was to investigate the effects of ultrasonically-assisted drilling (UAD) on cortical bone temperature. METHODS: A series of experiments was conducted to compare the cortical bone temperature during UAD with that during conventional drilling (CD). A thermo-mechanical 3D finite element model (FEM) of UAD was developed, using ABAQUS, to help understand temperature changes during drilling of cortical bone. The numerical simulation results of FEM showed good agreement with the experimental data. Subsequently, a predictive model was developed for bone temperature during drilling, using multiple regression analysis based on the results from numerical simulation. RESULTS: The results showed drill diameter had the greatest influence on drilling temperature, followed by the rotational speed of the drill. Additionally, the variation of vibration frequency had more influence on the drilling temperature than did the amplitude. CONCLUSIONS: Ultrasonically-assisted drilling is helpful to lower drilling temperature to reduce the thermal damage of bone tissue.