Accuracy and Safety of Robot-Assisted versus Fluoroscopy-Guided Posterior C1 Lateral Mass and C2 Pedicle Screw Internal Fixation for Atlantoaxial Dislocation: A Preliminary Study

Abstract

Objective. To compare the accuracy, efficiency, and safety of robotic assistance (RA) and conventional fluoroscopy guidance for the placement of C1 lateral mass and C2 pedicle screws in posterior atlantoaxial fusion. Methods. The data of patients who underwent posterior C1–C2 screw fixation (Goel-Harm’s technique) in our hospital from August 2014 to March 2021 were retrospectively evaluated, including 14 cases under fluoroscopic guidance and 11 cases under RA. The hospital records, radiographic results, surgical data, and follow-up records were reviewed. Accuracy of screw placement was assessed using the Gertzbein and Robbins scale, and clinical outcomes were evaluated by Japanese Orthopedic Association (JOA) score, visual analogue scale (VAS), modified MacNab criteria, and postoperative complications. Results. Baseline characteristics of both groups were similar. The mean estimated blood loss in the fluoroscopic guidance and RA groups was $205.7\pm 80.3\text{mL}$ and $120.9\pm 31.9\text{mL}$ , respectively ( $p=0.03$ ). The mean surgical duration was 34 min longer with RA compared to that performed with free-hand (FH) method ( $p=0.15$ ). In addition, lower intraoperative radiation exposure was detected in the RA group ( $12.4\pm 1.4$  mGy/screw) versus the FH ( $19.9\pm 2.1$  mGy/screw) group ( $p=0.01$ ). The proportion of “clinically acceptable” screws (graded 0 and I) was higher in the RA group (93.2%) than that in the FH group (87.5%, $p=0.04$ ). There was no significant difference in the increase of JOA score and decrease of VAS score between the two surgical procedures. Furthermore, there were no significant differences in overall clinical outcome between the two groups and no neurovascular complications associated with screw insertion. Conclusions. RA is a safe and potentially more accurate alternative to the conventional fluoroscopic-guided FH technique for posterior atlantoaxial internal fixation.