Impact of Arthroscopic Experience on the Learning Curve in Interlaminar Endoscopic Lumbar Discectomy: A Single-Center Prospective Cohort Study of 240 Patients

Study Design: Prospective single-center observational cohort study. Objectives: To evaluate whether prior arthroscopic experience shortens the learning curve in interlaminar endoscopic lumbar discectomy (IELD) and influences complication rates and patient-reported outcomes (PROs). Methods: In accordance with STROBE guidelines, 240 consecutive patients with single-level lumbar disc herniation (MSU A/B, non-calcified, symptom duration ≤ 3 months) underwent IELD between 2021 and 2023 at the University Orthopedic and Rehabilitation Hospital in Zakopane, affiliated with the Department and Clinic of Orthopedics and Rehabilitation, Collegium Medicum, Jagiellonian University. Procedures were performed by three spine surgeons with no prior endoscopic experience; one had completed > 300 shoulder arthroscopies. Operative times were analyzed using cumulative sum (CUSUM) and linear regression. Missing data were managed using last available observation. Complications were stratified by type, phase, and surgeon. Oswestry Disability Index (ODI) and Visual Analog Scale (VAS) for back and leg pain were assessed preoperatively and at 3 and 12 months. Results: All surgeons demonstrated a three-phase learning curve (learning, improvement, stabilization). Technical stabilization occurred after approximately 50 cases. The arthroscopy-experienced surgeon reached improvement earlier (case 12) than others (cases 24–26). Overall complication rate was 9.2%, highest during the learning phase (up to 25%). A single postoperative epidural hematoma was confirmed on MRI and resolved conservatively. ODI and VAS improved significantly at 3 and 12 months (p < 0.001), with no between-surgeon differences at final follow-up. Conclusions: Prior arthroscopic experience facilitates early adaptation to endoscopic visualization and may reduce initial neurological risk, but long-term outcomes remain comparable among surgeons. The study confirms IELD as a safe, effective technique with a reproducible ~50-case learning curve. Level of Evidence: III