Modelling and optimization of temperature in orthopaedic drilling: An in vitro study

This present investigation uses the Taguchi and response surface methodology (RSM) for modelling and optimization of the tem-perature produced during bone drilling. The drilling of bone is a common procedure in orthopaedic surgery to produce hole for screw insertion to fixate the fracture devices and implants. A major problem which is encountered during such a procedure is the increase in temperature of the bone due to the plastic deformation of chips and the friction between the bone and the drill. The increase in tempera-ture can result in thermal osteonecrosis which may delay healing or reduce the stability and strength of the fixation. The drilling experi-ments are conducted on poly-methyl-meth-acrylate (PMMA) (as a substitute for bone) using Taguchi’s L27 experimental design tech-nique. The cutting parameters used are drill diameter, feed rate and cutting speed. The optimum cutting parameters for minimum temperature are determined by using S/N ratios and the effect of individual cutting parameters on temperature produced is evaluated using analysis of variance (ANOVA). A second-order model is established between the drilling parameters and temperature using RSM. The experimental results show that the drill diameter is the most significant drilling parameter affecting the temperature during drilling followed by cutting speed and feed, respectively. The values predicted and the values obtained from experiment are fairly close, which indicates that the developed RSM model can be effectively used to predict the temperature in orthopaedic drilling. Key words: analysis of variance (ANOVA), orthopaedic surgery, response surface methodology, Taguchi method, thermal osteonecrosis 1