Augmented Reality-Guided osteotomies for a simulated mandibular reconstruction with fibular bone using virtual cutting guides and 3D navigation

In the last decades, maxillomandibular reconstruction has been revolutionised by the use of free flaps and virtual surgical planning technologies. However, the currently available applied physical cutting guides provide no intraoperative flexibility, and adjustments based on intraoperative findings are not possible. A novel augmented reality (AR)-guided technique is presented that allows for quick intraoperative surgical planning adaptations. A mandibular reconstruction using fibular bone was simulated and an application for Microsoft's HoloLens 2 developed for modelling the fibular segments. The application provided real-time feedback on the position of the saw with respect to the virtual planned osteotomy planes projected on the fibular bone. The technique was investigated in a validation test using 3-dimensional printed fibular models. Mean (SD) deviations from the planned osteotomy plane, expressed in degrees and segment length deviation, were 4.1° (2.6) and 2.0 mm (1.1), respectively, for session one, and 3.1° (2.3) and 2.3 mm (1.4), respectively, for session two. The feasibility of the AR-guided technique to perform osteotomies of fibular bone was established in this workflow simulation. The technique can improve the transfer of the preoperative plan to the intraoperative situation. Further development is, however, necessary since conventional cuttings guides are, so far, superior.