Analysis of the milling response of an artificial temporal bone developed for otologic surgery in comparison with human cadaveric samples

Temporal-bone milling is a delicate process commonly performed during otologic surgery to gain access to the middle and inner ear structures. Because of the numerous at-risk structures of this anatomic area, extensive surgeon training is required. Artificial temporal bones offer an interesting alternative to cadaveric training. However, the evaluation of such simulators has not been systematic, with an absence of objective validation of their milling response, especially in a surgical context. By measuring the milling forces obtained during the classical steps of otologic surgery on six 3D-printed and three cadaveric temporal bones, this work aims at evaluating the ability of the OTOtwin® synthetic temporal bone to reproduce human bone behavior. A better repeatability was obtained for artificial bones than for cadaveric ones. However, the level of forces recorded during artificial bone milling was close to the one measured with cadaveric samples. The effects of both surgical phase and irrigation on milling force levels were also quantified. The experiments conducted in this study confirmed the suitability of OTOtwin® temporal bone model for both otologic surgery training and research purposes. Valuable insights were also gained from this study regarding the understanding of the otologic milling process.