Navigated control in functional endoscopic sinus surgery.

This study designs and evaluates a mechatronic system to assist ENT surgery, taking as an example a navigation controlled shaver as used in paranasal sinus surgery. The on/off status of the shaver is regulated automatically, depending on the current position of the shaver tip. The working space for the navigation controlled shaver is planned preoperatively as a three-dimensional model and is based on the individual patient's CT data. Within this area the shaver reacts to signals from the surgeon. If the tip of the shaver moves outside the predefined working space, the shaver's automatic drive control is interrupted by an electrical pulse. The planning software was evaluated using CT data sets from 32 patients. The accuracy of the registration was analysed on an anatomical model with the aid of 451 measurements on titanium screws attached endonasally, whilst the implementation of the working space was evaluated on 5 technical models. The average time taken for segmenting the working space was found to be 4.23 minutes. The average accuracy of the shaver registration was 1.08 mm. The selected cavity was to be resected without any restrictions. The preoperatively determined working space was implemented with a mean deviation of 3.1 mm over all levels. The study proves the feasibility of a mechatronic assistance system taking as an example the navigation controlled shaver used in paranasal sinus surgery. In contrast to isolated CAS solutions, this conceptual approach provides for the redundancy of the surgeon and eases their cognitive burden. We can foresee numerous applications in ENT surgery of the future following the principle presented here, in the control systems of power tools such as cutters, high frequency scalpels and lasers. Copyright 2005 John Wiley & Sons, Ltd.