43. The trends in robot related complications, operative efficiency, radiation exposure, and clinical outcomes after robot-assisted spine surgery: a multicenter study of 722 patients and 5,005 screws from 2015 to 2019

Abstract

<h3>BACKGROUND CONTEXT</h3> Although there has been a growing amount of literature that suggests robots are safe and can achieve comparable outcomes to conventional techniques, much of this literature is limited by small sample sizes and single-surgeon or single center series. Furthermore, it is unclear what the impact of robotic technology has made on operative and clinical outcomes over time. This is the first and largest multicenter study to examine the trends in outcomes and complications after robot-assisted spine surgery over a 5-year period. <h3>PURPOSE</h3> To examine trends in outcomes and complications after robot-assisted spine surgery from 2015-2019. <h3>STUDY DESIGN/SETTING</h3> Multicenter cohort. <h3>PATIENT SAMPLE</h3> Adult (≥18 years old) patients who underwent robot-assisted (Mazor Renaissance, X, and Stealth) spine surgery from 2015 to 2019. <h3>OUTCOME MEASURES</h3> Outcomes of interest included operative efficiency (robot time per screw), radiation exposure (fluoroscopy time per screw), robot complications (eg, screw exchange, robot abandonment), clinical outcomes (eg, length of stay, 90-day reoperations), and other nonrobot-related complications (eg, dural tear, loss of motor/sensory function, blood transfusion). <h3>METHODS</h3> In this multicenter study, we included adult (≥18 years old) patients who underwent robot-assisted spine surgery between 2015 and 2019 at four geographically diverse institutions. The robotic systems used included the Mazor Renaissance, Mazor X, and Mazor Stealth Edition. Patients with missing data were excluded from this study. The minimum follow-up was 90 days after the index surgery. This study was approved by the institutional review board. Chi-square/fisher exact test and t-test/ANOVA were used for categorical and continuous variables, respectively. The Cochran-Armitage test was used to examine statistically significant trends. Statistical significance was defined as a P-value <0.05. SAS Studio Version 3.4 (SAS Institute Inc, Cary, NC) was used for all statistical analyses. <h3>RESULTS</h3> 722 adult patients were included (117 Renaissance, 477 X, 128 Stealth). Mean (standard deviation) Charlson comorbidity index (CCI) was 1.5 (1.5). The most common diagnoses included high grade spondylolisthesis (grade>2) (40.6%), degenerative disc disease (18.4%), and degenerative scoliosis (17.6%). Mean (standard deviation) number of instrumented levels was 3.8(3.4). Most patient and operative factors (eg, gender, smoking status, total instrumented levels, and pelvic fixation,) were similar across the years. From 2015-2019, mean robot time per screw decreased from 7.2 minutes to 5.5 minutes (P=0.004, R2=0.65). Mean fluoroscopy time per screw decreased from 15.2 seconds to 9.4 seconds (P=0.002, R2=0.83). Rates of both intraoperative screw exchange for misplaced screw (2015-2016: 2.7%, 2019: 0.8%, P=0.0115, R2=0.13) and robot abandonment (2015-2016: 7.1%, 2019: 1.1%, P=0.011, R2=0.22) improved significantly over time. The incidence of other intraoperative nonrobot related complications (eg, dural tear, loss of motor/sensory function, blood transfusion) remained consistently low, but similar between years. The LOS decreased by nearly 1 day from 2015-2019(P=0.007, R2=0.78). 90-day reoperation rates did not change significantly. <h3>CONCLUSIONS</h3> Current trends demonstrate that robot screw accuracy, reliability, operative efficiency, and radiation exposure have improved significantly over the last five years. This is likely the result of increased surgeon experience with robots and the recent advances in robotic technology. The 90-day surgical complication rates remain consistently low and the mean length of stay has reduced significantly with time, which may offset the cost of robot-assisted spine surgery; however, future work specifically focusing on cost analyses are needed. Nevertheless, these findings further validate the continued usage of robot-assisted spine surgery and the potential path toward improved value-based care. <h3>FDA DEVICE/DRUG STATUS</h3> Medtronic Renaissance, Mazor X and Mazor X stealth are FDA approved in the US.