Thermomechanical characterization, heat transfer modeling, and statistical analysis of bovine cortical bone drilling for orthopedic applications

Bone drilling is a critical step in orthopaedic surgery. Excessive heat generation during drilling can induce thermal osteonecrosis, which can compromise implant stability and hinder bone healing. This study experimentally investigated the thermomechanical behaviour of bovine cortical bone during dry drilling using a 3.2 mm diameter, 316L stainless steel drill bit. Four drilling conditions, combining two rotational speeds (100 and 200 rpm) and two feed rates (30 and 60 mm/min), were evaluated. Temperature evolution was monitored using eight type-T thermocouples arranged in a spiral around the drilling site in order to characterize heat propagation within the cortical bone. The results showed that the maximum temperature decreased exponentially with increasing distance from the drilling site. This demonstrates that heat transfer was predominantly governed by thermal conduction, in accordance with Fourier's law. Thermal descriptors, including maximum temperature, heating rate, cooling rate, time to reach the maximum temperature, and activation energy, consistently indicated localised heat generation and diffusion around the drill–bone interface. An exponential mathematical model accurately described the spatial temperature distribution under all drilling conditions (0.979 ≤ R 2 ≤ 0.999). A one-way analysis of variance (ANOVA) showed that the drilling conditions had a significant effect on the maximum temperature (F = 64.219, p = 3.852 × 10 −9 ). Tukey's HSD post hoc analysis revealed significant differences between the N100Vf30 condition and the other drilling conditions. However, no significant differences were observed between N100 V f 60, N200Vf30 and N200 V f 60. These results suggest that heat generation is the result of the combined influence of rotational speed and feed rate on friction, drilling time, and heat dissipation. Overall, this study provides experimental evidence and statistical validation, as well as a predictive thermal model, all of which contribute to a better understanding of heat generation during orthopaedic bone drilling. The proposed approach could help to optimize drilling parameters and improve the thermal safety of orthopaedic surgical procedures.