Comparison of Post-Operative Mobilization After Minimally Invasive Transforaminal Lumbar Interbody Fusion and Traditional Open Posterolateral Fusion Using Objective Gait Analysis Data

Study DesignProspectively Enrolled Cohort Study.ObjectiveTo compare the time of return to baseline ambulatory function after undergoing minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) vs traditional open posterolateral fusion (OF).MethodsPatients undergoing TLIF or OF with an iPhone were prospectively enrolled. Participants voluntarily shared information from the pre-installed Apple Healthkit package, which provided baseline activity data. Daily steps and distance were tracked until a patient returned to within 90% of their pre-operative baseline for 2 consecutive days. Patient-reported outcome measure scores (PROMs) were collected at the pre-operative and subsequent follow-up visits.ResultsA total of 23 MIS-TLIF and 25 OF patients were enrolled. Patients undergoing MIS-TLIF had an average preoperative baseline of 3576 steps (SD 2185); these patients returned to 90% of baseline steps at an average of 10.57 days. Those undergoing OF had an average preoperative baseline of 2280 steps (SD 1295) and required 15.32 days to return to 90% of pre-operative step count. There were no significant correlations between pre-operative demographic factors or PROMs with time to return to 90% of baseline ambulation. After matched analysis was performed, the average treatment effect of MIS vs OF operation was estimated, though this was not statistically significant.ConclusionsThis study quantifies pre- and post-operative ambulatory function for 2 cohorts of patients undergoing lumbar surgery. This work further builds on the existing uses of Apple HealthKit data to establish ambulatory baseline in the lumbar spine surgery population, as well as comparison of objective ambulation data with PROMs.