The Learning Curve of Robotic-Assisted Pedicle Screw Placements Using the Cumulative Sum Analysis: A Study of the First 50 Cases at a Single Center

INTRODUCTION: The purpose of this study was to clarify how many cases surgeons need to experience to pass the learning phase of robotic-assisted spine surgery using the cumulative sum (CUSUM) analysis. METHODS: A retrospective review was conducted on the initial 50 consecutive patients who underwent robotic-assisted pedicle screw placements with open procedures using a spine robotic system (Mazor X Stealth Edition) at a single center from April 2021 to January 2022. There were 19 male and 31 female patients with a mean age of 58.7 (range, 13-86) years. To split the surgeries into the early and late phases using the CUSUM analysis of screw insertion time, we compared the screw insertion time, the robot setting time, the registration time, and the operation time in the early and late phases. RESULTS: The screw insertion time, the robot setting time, and the registration time declined as the number of surgical cases increased. The operation time did not decline as the number of surgical cases increased. The learning curve for screw insertion time can be separated into two stages based on the CUSUM analysis. The first 23 cases were in the early phase, and the later 27 cases were in the late phase. The mean screw insertion time was reduced from 3.2 min in the first 23 cases to 2.7 min in the subsequent 27 cases. The robot setting time and registration time in the late phase were also significantly shorter than those in the early phase. CONCLUSIONS: The screw insertion time, robot setting time, and registration time decreased with experience. After 23 cases, surgeons passed the learning phase of robotic-assisted spine surgery and became more proficient.