Augmented Reality application for guided mandibular reconstruction surgery

Mandibular reconstruction is one of the most complex challenges in maxillofacial surgery, especially when bone segments must be replaced following trauma, tumors or other pathologies. The mandible’s intricate anatomy and its functional and aesthetic importance require high precision to restore it. Nowadays, patient-specific surgical guides are commonly employed to perform osteotomies, providing high precision, reliability and reproducibility. However, these guides are strictly dependent on the patient’s preoperative anatomy, which entails significant time and cost for their design and manufacturing, and makes them unusable in case of intraoperative anatomical changes. Moreover, they lack flexibility, as the cutting planes cannot be easily adjusted or reoriented during surgery. Recent technological advances have introduced new opportunities to enhance surgical outcomes. Among these, augmented reality (AR) has proven particularly promising, allowing surgeons to visualize anatomical structures and preoperative plans as holograms directly within the operative field. This provides useful visual support, however it does not offer any physical feedback regarding the correct positioning or manipulation of surgical instruments. This study aims to analyse two case studies to evaluate the effectiveness of a hybrid technique, which combines an adjustable experimental cutting guide, designed for mandibular reconstruction with fibular grafts, with augmented reality visualization. The primary objective is to quantify the accuracy of this technique by analysing the deviations between the expected results and the actual final result, considering that both surgical guides and AR application are still in an early stage of development. The first chapter provides an overview of the mandibular and fibular anatomy, focusing on the main causes that necessitate reconstruction, and reviews current techniques, from conventional grafting to free flap procedures combined with patient-specific surgical guides. The second chapter introduces the concept of augmented reality and provides a comprehensive review of AR applications in surgery in combination with HoloLens2 device, discussing both the technological capabilities and the practical benefits. Chapter three describes in detail the tools and methods used for the study. Starting from the description of the experimental surgical guides in exame, to an overview of the AR application, developed to assist the surgeon during operative procedures. It also discusses the choice of the number and position of the reference points to permit a best alignment procedure and gives information about the instruments used to prepare the 3D models and to take the scan. Chapter four focuses on the execution of the experiments, detailing the preparation of the test bench, the procedures, data collection and data processing methods. It includes an analysis of deviations between the planned and achieved outcomes, allowing for a precise evaluation of the technique’s accuracy. Finally, the last chapter presents the conclusions and critical discussion of the results, summarizing the key findings and their implications for clinical practice. It highlights the strengths and limitations of the proposed method and outlines possible future developments to further enhance surgical accuracy and workflow efficiency.