Intraoperative navigation for single-splint two-jaw orthognathic surgery: From model to actual surgery.

OBJECTIVE: This study reported an intraoperative navigation system for single-splint two-jaw orthognathic surgery, and assessed the accuracy of transferring the computer assisted surgical simulation. METHODS: A skull model was used for validation, and twenty patients receiving such procedure were enrolled. The procedure contained five phases, including virtual surgery on three-dimensional images, fabrication of surgical positioning guides, preparation of registration and validation landmarks, confirmation of bony position during surgery, and postoperative assessment. Target registration error (TRE) and differences between simulation (T0) and postoperative images (T1) were measured from landmarks to Frankfort horizontal plane (FHP), mid-sagittal plane (MSP), and coronal plane (COP). RESULTS: For the model experiment, mean TRE was lowest using the hard tissue landmarks (0.60 +/- 0.27 mm), and the mean difference (T1-T0) was less than 1 mm to all three planes. For the patients, mean TRE was 1.07 +/- 0.18 mm from the hard tissue landmarks. The mean difference was 0.96. +/- 0.60 mm from MSP, 1.39 +/- 1.11 mm from FHP, and 2.12 +/- 1.82 mm from COP. The differences were not significant. Both surgeons and patients were satisfied with the surgical outcome. CONCLUSION: This study showed that the navigation system had acceptable accuracy and was useful for the two-jaw orthognathic surgery using single-splint method.