gms | German Medical Science

Objective: Accuracy of pedicle screw placement has direct impact on surgical results regarding stability, fusion and clinical outcome. Intraoperative navigation could already show significant improvement of accuracy. We report about our results and experience with the latest generation of robot-guided screw placement.

Method: Between January and September 2014 93 patients with one- and multilevel instabilities w/o stenosis of thoracic and lumbar spine were operated at our institution with the most recent generation of a miniature robot (Renaissance, Fa. Mazor Robotics, Israel). Screw placement was performed percutaneously with fluoroscopic aid in all patients. Screw accuracy was determined on postoperative CT scans using the Gertzbein-Robbins scale.

Results: In one case coregistration was not feasible because of bad fluoroscopic imaging due to a BMI of 43. 402 screws were inserted percutaneously. In the postoperative CT scans the robot-guided screws showed an ideal position in 98.6 % and an acceptable position in 1.4 % of cases. There was no need of intra- or postoperative screw replacement. There were no new neurological deficits. X-ray exposition and blood loss were reduced significantly compared to freehand technique. There was a steep learning curve regarding operation time and x-ray reduction. We observed limitations of the technique with Ala- and Ileum-screws and detected avoidable beginner’s mistakes.

Conclusions: Robot-guided pedicle screw placement is a highly accurate and favourable method. We report on our experience and show the limitations of this technique. Advantages of this method are the high precision, the preoperative planning, the perfect suitability for percutaneous approach and a significant reduction of x-ray exposure and blood loss. We reveal typical mistakes and provide tips and advice for the novice.