PLANNING AND INSERTION OF PEDICLE SCREWS WITH COMPUTER-ASSISTANCE

Transpedicular screw fixation relies on thorough knowledge of the pedi cular anatomy and a reliable intraoperative technique. To enhance the safety and accuracy of screw insertion, computer-assisted systems have been introduced. Our in vitro study investigated the potential benefi ts of such a system for the preoperative planning and the intraoperati ve visualization. In part 1, the potentially possible range of screw p aths (trajectories) through lumbar pedicles was analyzed. In part 2, t he accuracy of actual pedicle-hole preparation with and without preope rative planning was assessed. It was shown that, especially in the low er lumbar regions, the possible range of trajectories is considerable, with inclinations of less than or equal to 40 degrees in the transver se plane and a range of angulation in the sagittal plane of >20 degree s. The computer assistance in preparation of 100 pedicle holes resulte d in cortex perforation in only one case. Computer assistance therefor e may be used as a valuable tool to minimize the risks of transpedicul ar screw insertion. It furthermore may assist in determining the desir ed screw orientation and length and transform this planning into the i ntraoperative pedicle-hole preparation.