A Retrospective Analysis of S2 Iliosacral Screw Fixation Using Robot-Assisted Navigation for Unstable Pelvic Injuries and Sacral Dysmorphism: a Report of 16 Cases

Objective The second sacral segment iliosacral screw (S2 screw) insertion is a demanding technique, with a high rate of screw malposition due to the complex pelvic anatomy. TiRobot™ is an orthopedic surgery robot which can be used for S2 screw fixation. We carried out a retrospective analysis of the accuracy of S2 screws using robot-assisted navigation.Methods A retrospective analysis of 16 patients admitted and managed by S2 screw fixation for unstable pelvic fractures was carried out for evaluation of its efficacy and safety. all patients with pelvic ring disruptions and sacral dysmorphism were evaluated radiographically and S2 screws were placed using a robot-assisted navigation technique. Screw position was assessed and classified using postoperative computed tomography. Fisher’s exact probabilities test was used to analyse the screws’ positions. Surgical time after reduction of the pelvis, insertion time for guide wire, number of guide wire attempts, and radiation exposure without pelvic reduction were also assessed.Results The excellent and good rate of screw placement was 100%. The fluoroscopy time after pelvic reduction was 7 (7, 9) seconds. The operation time after reduction of the pelvis was 29 (27,33). Time for guide wire insertion was 2.0 (2, 2) minutes. The number of guide wire attempts was 0.0 (0, 0). No postoperative complications or revisions were reported.Conclusion S2 iliosacral screws can be safely and accurately accomplished using a robot-assisted navigation technique in patients with unstable posterior pelvic ring disruptions and sacral dysmorphism.