Evaluating the learning curve and operative time of interlaminar and transforaminal endoscopic lumbar discectomy.

Introduction: Lumbar disc herniation is common in spine surgery, and endoscopic lumbar discectomy (ELD) offers a minimally invasive alternative with reduced complications. However, the learning curve of ELD, particularly between interlaminar and transforaminal techniques, remains a challenge. Research question: To determine the learning curve for both interlaminar and transforaminal ELD in terms of operative time, and analyze factors that affect it. Materials and methods: Single-center retrospective study of 376 patients who underwent ELD between January 2013 and March 2024. In the cohort, 319 were in the interlaminar group and 57 in the transforaminal group. The learning curves were analyzed by CUSUM. The data regarding surgical technique, operative time, and postoperative outcome were analyzed. Results: The learning curve reached a plateau at 50 cases for the interlaminar technique and 23 cases for the transforaminal technique. Operative time was significantly lower for the transforaminal approach compared to the interlaminar approach: 69.18 ± 28.85 min versus 78.71 ± 28.86 min, p = 0.022. A second learning curve could not be demonstrated for the interlaminar approach in the long term. Operative time was influenced variably by factors such as age, gender, and level of herniated disc between the two techniques. Discussion and conclusion: Both the interlaminar and transforaminal ELD are minimally invasive techniques with different learning curves. The transforaminal approach shows a steeper learning curve and shorter operative time. The interlaminar approach did not show a second learning curve in the long term.