P132. How does the Mazor X stealth edition compare with the Mazor X for robot-assisted spine surgery? A multicenter, propensity matched analysis of 2,800 screws and 372 patients

BACKGROUND CONTEXT Robot-assisted spine surgery continues to rapidly develop as evidenced by the growing literature in the last few years. Numerous reports demonstrate excellent pedicle screw accuracy and early studies have explored the impact of robot-assisted spine surgery on reducing radiation exposure, length of hospital stay, operative time, and perioperative complications in comparison to conventional freehand technique. Recently, the Mazor X Stealth Edition was introduced in 2018. This robotic system integrates Medtronic's Stealth navigation technology into the Mazor X platform. It is unclear what the impact of these advancements have made on clinical outcomes. PURPOSE This is the first study to compare the outcomes and complications between the most recent iterations of the Mazor Robot systems: Mazor X and the Mazor X Stealth Edition. STUDY DESIGN/SETTING Multicenter cohort. PATIENT SAMPLE Among four different institutions, we included adult (≥18 years old) patients who underwent robot-assisted spine surgery with either the Mazor X or Stealth platforms. OUTCOME MEASURES Primary outcomes included robot time per screw, robot abandonment, screw accuracy, radiation exposure and 90-day reoperation rate. METHODS A propensity-score matching algorithm based on perioperative factors (eg, demographics, comorbidities, primary diagnosis, prior spine surgery, pelvic fixation, instrumented levels, number of planned robot screws) was employed to control for the potential selection bias between the two robotic systems. The minimum follow-up was 90 days after surgery. Chi-square/fisher exact test and t-test/ANOVA were used for categorical and continuous variables, respectively. RESULTS A total of 372 adult patients were included in this study (Stealth: 186, X: 186). The mean number of instrumented levels was 4.3. The mean number of planned robot screws was 7.8. Similar total operative time (Stealth: 197 minutes vs X: 211, p=0.591) and robot time per screw (Stealth: 6.1 minutes/screw vs X: 6.1 minutes/screw, p=0.930) occurred between cohorts. However, Stealth achieved a significantly lower robot abandonment rate (Stealth: 0% vs X: 2.2%, p=0.044). The screw accuracy for both robots was excellent (Stealth: 99.6% vs X: 99.1%, p=0.120). Stealth achieved significantly shorter radiation time than X (Stealth: 7.2 seconds/screw vs X: 10.4 seconds/screw, p 0.05). The 90-day reoperation rates were low and similar between robot cohorts. CONCLUSIONS In this multicenter study, both robot systems achieved excellent screw accuracy and low robot time per screw. However, Stealth achieved significantly less radiation exposure, lower robot abandonment rates, and reduced blood transfusion rates than Mazor X. Other factors including LOS, and 90-day reoperation rates were similar. FDA DEVICE/DRUG STATUS Medtronic Mazor X and Mazor X stealth are FDA approved in the US.