Supporting Maxillo-Facial surgical guides positioning with Mixed Reality - an HoloLens2 application.

Following an oncological resection or trauma it may be necessary to reconstruct the normal anatomical and functional structures of the mandible to ensure the effective and complete social reintegration of patients. In most surgical procedures, reconstruction of the mandibular shape and its occlusal relationship is performed using a free fibula flap. The bone segments must be taken with extreme accuracy and, for this reason, it is often done using a cutting guide which allows the surgeon to easily identify the cutting point and angle. This thesis focused on the development of a mixed reality headset application that facilitates the process of positioning the cutting guide on the fibula during surgery. By projecting a virtual model of the guide onto the fibula, the holographic viewer allows the user to know its correct allocation in space, providing in real time the distance and rotation between the real and the virtual guide. The application was tested to estimate the accuracy of the system, evaluating the error on positioning in terms of both distance and rotation. Results show greater accuracy in positioning the guide, while errors increase in finding the right rotation. Furthermore, qualitative tests were performed to assess the usability of the system. Although performance was not excellent, overall, the application was judged by users to be innovative, helpful, and satisfying. These results confirm what emerged from the related literature review, encouraging the use of mixed reality to support Maxillo-facial surgery. Future work will include different technologies for object tracking and recognition to improve the performance of the system. Moreover, also surgeons’ validation will be performed to validate the application from a medical perspective.