Validation of a Wearable Device Based on Augmented Reality For Surgical Maxillary Repositioning

Aim: We present a newly designed, localiser-free, head-mounted system featuring augmented reality (AR) as an aid to maxillofacial bone surgery, and assess the potential utility of the device by conducting a feasibility study and validation. Also, we implement a novel and ergonomic strategy designed to present AR information to the operating surgeon (hPnP). Methods: The head-mounted wearable system was developed as a stand- alone, video-based, see-through device in which the visual features were adapted to facilitate maxillofacial bone surgery. The system is designed to exhibit virtual planning overlaying the details of a real patient. We implemented a method allowing performance of waferless, AR-assisted maxillary repositioning. In vitro testing was conducted on a physical replica of a human skull. Surgical accuracy was measured. The outcomes were compared with those expected to be achievable in a three-dimensional environment. Data were derived using three levels of surgical planning, of increasing complexity, and for nine different operators with varying levels of surgical skill. Results: The mean linear error was 1.70±0.51mm. The axial errors were 0.89±0.54mm on the sagittal axis, 0.60±0.20mm on the frontal axis, and 1.06±0.40mm on the craniocaudal axis. Mean angular errors were also computed. Pitch: 3.13°±1.89°; Roll: 1.99°±0.95°; Yaw: 3.25°±2.26°. No significant difference in terms of error was noticed among operators, despite variations in surgical experience. Feedback from surgeons was acceptable; all tests were completed within 15 min and the tool was considered to be both comfortable and usable in practice. Conclusion: Our device appears to be accurate when used to assist in waferless maxillary repositioning. Our results suggest that the method can potentially be extended for use with many surgical procedures on the facial skeleton. Further, it would be appropriate to proceed to in vivo testing to assess surgical accuracy under real clinical conditions.