3D finite-element modelling of drilling cortical bone: Temperature analysis

Bone drilling is a key part of major orthopaedic surgeries for fixing fractured bones and replacing damaged joints. One of the main problems in bone drilling is thermal necrosis of tissue, which can occur due to elevated temperatures in the drilling zone. Investigation of the temperatures arising in bone drilling is necessary to analyse the extent of bone necrosis. This paper presents a three-dimensional thermo-mechanical finite-element model of a bone-drilling process to study the effect of drilling parameters (cutting speed and feed rate) and cooling conditions (air and saline solution) on the temperature in drilled bone. The drilling speed was found to have a higher effect compared to that of the feed rate in inducing thermal necrosis in bone for the tested cooling environments. The level of necrosis penetration into bone was strongly affected by the drilling speed and the application of saline cooling (irrigation) in the drilling zone. A considerable extent of necrosis was predicted even at lower drilling speeds when no cooling was used. Drilling experiments were performed on real cortical bone to measure temperatures near the immediate vicinity of the drill. Calculated temperatures were compared with experimental values and were found to be in good agreement with them.