A system for ultrasound based intraoperative navigation in spine surgery

An ultrasound-based intraoperative navigation system was developed for a robotic device that places and inserts pedicle screws in spine surgery. The navigation system provides real-time-information about the exact position and location of the tool within the operation field and the possibility to track the robot if there is a motion of the bone during the procedure. The navigation method combines preoperative CT or MRT with intraoperative ultrasonic imaging. The precision of the placement and insertion of the screws strongly depends on the imaging quality and how accurate the vertebral bone is depicted by the modalities used. It is also governed by the mathematical 'patient-model' and the algorithm used for the intraoperative registration. First in-vitro-measurements were performed to study and quantify the influence of the imaging modalities and the segmentation on the precision of the robot-control. It has been demonstrated that the combination of preoperative CT and intraoperative ultrasound (US) fulfils the requirements as long as special procedures are kept.