Monitoring the Quality of Robot-Assisted Pedicle Screw Fixation in the Lumbar Spine by Using a Cumulative Summation Test

Study Design. Prospective randomized controlled trial. Objective. The aim of this study was to monitor the quality control of robot-assisted pedicle screw fixation accuracy by using a cumulative summation (CUSUM) test at the initial stage of its application. Summary of Background Data. Although robot-assisted pedicle screw fixation reduces screw misplacement rates and provides critical support for minimally invasive surgical procedures, there have been no reports relating to the monitoring of quality control of the accuracy of this robot-assisted pedicle screw fixation procedure. Methods. Patients with lumbar spinal stenosis scheduled to undergo surgery were randomly and equally assigned through 1:1 allocation to a robot-assisted minimally invasive posterior lumbar interbody fusion (Rom-PLIF) group or a conventional open posterior PLIF using freehand technique group. The accuracy of pedicle screw placement was evaluated using postoperative computed tomography. The primary outcome was the CUSUM analysis for monitoring the quality control of the accuracy of pedicle screw insertion between the Rom-PLIF and conventional open posterior PLIF using freehand technique groups. Results. Of the 80 pedicle screws inserted in each group, 4 screws in the Rom-PLIF group, and 7 in the conventional open PLIF group, breached the pedicle. Of these 11 offending screws, 4 cases were categorized as grade B in the Rom-PLIF group, whereas 6 were grade B and 1 case was grade C in the Com-PLIF group, using the Gertzbein and Robbins classification. Throughout the monitoring period, there was no CUSUM test-derived indication that the quality of performance of the pedicle screw fixation procedure was inadequate in either group. Conclusion. First, this study demonstrates the adequacy of quality control of robot-assisted pedicle screw fixation even early in the application period based on the CUSUM analysis. Second, the CUSUM test can be a useful tool for monitoring of the quality of procedures related with spine surgery.