INTRODUCTION: As the complexity of the craniofacial (CF) surgery increases, cases become more challenging for less-experienced surgeons to perform advanced procedures. Surgical teleconsulting/telementoring by an expert physician, as a subset of telemedicine, can provide real-time guidance to inexperienced surgeons at remote medical centers. Mixed reality head-mounted displays like HoloLens (Microsoft, Seattle, WA)—modern, untethered, a network-enabled headset which “augments” computer-generated 3-dimensional virtual image/information to the real physical environment/surgical site—are potentially easier to use than the conventional high-cost 2-dimensional telestrator-based systems.
OBJECTIVE: To validate that a collaborative surgical planning application developed for HoloLens meets ease-of-use criterion on a system usability scale (SUS) criteria (mean Likert scale >3.0 with P ≤ 0.05; 1: strongly disagree; 5: strongly agree), whereas 2 plastic surgeons, in the roles of mentor and mentee, use shared interactive annotation and linear measurement tools on CF holograms.
METHODS: To demonstrate the use of mixed reality headsets for telementoring in CF surgery, HoloLens was utilized to evaluate its usability. Teleconsulting/telementoring application with CF surgical planning tools was developed for HoloLens. Seven adult dry human skulls with several main types of facial fractures were selected. Computerized tomographic imaging data were acquired, bone structures were segmented, and resulting surface mesh files were loaded onto HoloLenses. Ten surgeons (ranging from second-year residents to experienced surgeons [>300 surgeries]) were enrolled in the study. Each session consisted of 2 surgeons at different geographical locations wearing HoloLenses networked via an internet connection. A set of interactive dimensional measurements was performed on disfigured holographic skulls to evaluate the CF defect for collaborative surgical planning. A previously verified distance measurement tool calibrated with a holographic phantom for HoloLens was used.1 Optimal reconstructive options were discussed via a Voice over Internet Protocol and holographic annotation. The SUS was evaluated using a Likert scale questionnaire and analyzed with a Student’s t test. The latency of interaction was evaluated by comparing the navigation of shared holographic cursors from the 2 participants.
RESULTS: Holograms provided enhanced visualization of 3-dimensional spatial relationships and depth perception within and between anatomic structures which could not be observed by the conventional 2-dimensional display monitors. Mean SUS score of overall participants was 3.92 ± 0.73 (P ≤ 0.05, 1-sided). Surgeons evaluated the defects and shared surgical plans using interactive holographic annotations and linear measurements facilitating discussion of bone reduction direction, incision, and osteotomy design in true 3-dimensions. Latencies were acceptable for both shared holograms and Voice over Internet Protocol.
CONCLUSION: The novel telementoring application met usability acceptance criteria and enabled effective holographic telementoring during collaborative CF surgical planning. Future telementoring studies will include spatially registering and augmenting patient-specific holograms on the physical surgical site to provide real-time intraoperative guidance. This will improve educational access to surgeons to enhance surgical competency and patient safety in addition to facilitating the teaching of advanced surgical skills worldwide.
1. Cho K, Yanof J, Schwarz GS, et al. Abstract: craniofacial surgical planning with augmented reality: accuracy of linear 3D cephalometric measurements on 3D holograms. Plast Reconstr Surg Glob Open. 2017;5(9 Suppl):204. Published October 2, 2017. doi:10.1097/01.GOX.0000526460.64463.87.