Frameless computer-aided surgery system for revision endoscopic sinus surgery

To increase the intraoperative safety factor and to acquire anatomic assist ance during revision endoscopic sinus surgery (RESS), we used an optical co mputer-aided surgery (CAS) system that we developed collaboratively in Bern , Switzerland. During 1 year, 25 RESSs were performed with GAS: recurrent p olyposis (n = 20), recurrent frontal recess stenosis (n = 3), and recurrent frontal recess stenosis with mucocele (n = 2). These patients were compare d with a control group of 10 patients undergoing RESS without GAS. The same surgeon (M.C.) performed all operations, and there were no minor or major complications in either group. The clinical inaccuracy of our system is bet ween 0.5 and 2 mm with paired-point and surface matching. The navigation sy stem is an important aid to surgeons in identifying anatomic landmarks that are typically difficult to visualize in this type of surgery, thus reducin g the stress placed on the surgeon.