Operative time and learning curve between fluoroscopy-based instrument tracking and robot-assisted instrumentation for patients undergoing minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF)

Introduction: Instrument-navigation modalities including CT-guided and robot-assisted methods claim both efficacy and accuracy when applied to spine surgery, yet often increase setup and operating times which can translate to increased costs. To see the impact of different technologies on surgical efficiency, we studied the impact of a single surgeon's experience with a multitude of instrument navigational technologies. Methods: Consecutive patients undergoing minimally invasive transforaminal lumbar interbody fusion (MISTLIF) were analyzed. Consecutive cases were done with assistance of a robot (Mazor, Medtronic, Minneapolis, MN), with the assistance of fluoroscopic instrument-tracking (TrackX, North Carolina, USA), or fluoroscopy alone without adjunctive navigation in consecutive blocks of time. The cases done without assistance were used to normalize for number of interbody implants and decompressions performed as well as hardware removal if needed. Age, body mass index (BMI), sex, operative levels, laminectomy, need for hardware removal, and total operative time were recorded. Results: A total of 119 cases (74 conventional, 13 robot-assisted, 32 instrument-tracking) were included in analysis. There were no significant differences in age, sex, or BMI between modalities. Average total operative time for robot-assisted, and instrument-tracking-assisted cases was 175.46 +/- 46.86 min 119.63 +/- 34.33 min, respectively, for each level (p < 0.05 across each group). After normalization against operative times from similar cases performed with conventional fluoroscopy, robotic-navigation added an average of 42.25 +/- 28.35 min while use of instrument-tracking saved an average of 13.88 +/- 38.69 min. There was no learning curve seen using robotic navigation, as operative times remained consistently longer than similar cases using conventional fluoroscopy and showed no sign of improvement over time. Cases using instrument-tracking were initially slower but trended downwards through approximately 11 patients, at which point operative times were consistently quicker (R-2 = 0.39). None of the assisted cases were abandoned in favor of standard fluoroscopy or required hardware revision. Conclusion: Enabling technology can have a significant impact on surgical efficiency. Compared to MIS-TLIFs performed with standard fluoroscopy, those done with robotic-assistance consistently negatively impacted operative times while instrument-tracking was associated with a short learning curve and in the majority of cases studied showed improved operative times.