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Objectives and questions: Full-Endoscopic Spine-Surgery is a well-established cornerstone of contemporary spine surgery. However, long-term data regarding cumulative incidence of and risk factors associated with revision surgery after full endoscopic lumbar spine surgery are lacking.

Material and methods: We conducted a retrospective analysis of adults undergoing their first endoscopic spine surgery via the transforaminal (TELD) or interlaminar endoscopic (IELD) approach between 2014 and 2021 at two national high-volume centers. The primary outcome was any reoperation at the index surgical level. Parallel analyses were conducted due to data heterogeneity. We conducted post-discharge follow-up phone calls to collect data on current health status for all patients with less than 2 years of follow-up. Cumulative incidence functions were used to estimate the cumulative probability of revision surgery and multivariate cause-specific hazard models were used to adjust for relevant covariates while accounting for patient loss to follow up and death.

Results: 558 patients were included with median follow-up time of 3.7 years (IQR: 1.8–5.6) and mean age of 59.3 years (SD: 16.0). 48% of patients were lost to follow up at 2 years after initial surgery. 424 patients (76%) underwent surgery at hospital 1 and 134 (24%) at hospital 2. 67.6% of patients were surgery-naïve and the remainder underwent surgery at the same level of or immediately adjacent to the level of a previous non-endoscopic surgery. 15% (95%CI: 12–18%) underwent reoperation within 6 months after the first endoscopic lumbar discectomy and 20% (95%CI: 16–23), 25% (95%CI: 22–29), and 28% (95%CI: 24–32) did so after 1, 2, and 3 years, respectively. We did not find associations between obesity, age, or surgical disc level and risk of reoperation in either cohort. However, ASA classification emerged as an independent risk factor for reoperation in both locations.

Discussion and conclusions: Most reoperations following TELD and IELD occur within six months post-surgery. We report a conservative cumulative incidence for revision surgery of 15% at six months and 25% at two years. Interestingly, no association for age, obesity, or level of surgery and risk of reoperation was found.