The Learning Curve of Endoscopic Lumbar Interbody Fusion: A Systematic Review.

Background/Objectives: Endoscopic lumbar interbody fusion (ELIF) represents a key milestone in minimally invasive spinal surgery, offering reduced tissue trauma, lower complication rates, and faster recovery compared with open fusion. However, its steep learning curve remains a major barrier to widespread adoption. This systematic review aimed to synthesize current evidence on the ELIF learning curve and identify factors that influence the acquisition of surgical proficiency. Methods: A comprehensive literature search of PubMed, Embase, and the Cochrane Library was conducted for studies reporting quantitative analyses of the ELIF learning curve. Eligible articles included clinical data describing operative performance, complication rates, and learning curve cutoff points. Study quality was evaluated using the Newcastle-Ottawa Scale. Pooled data were analyzed to determine the mean cutoff point between the early and proficient phases and to compare outcomes across surgical approaches. Results: Five eligible studies encompassing 425 patients were included. Operative time was the most frequently assessed outcome, followed by hospital stay and complication rates. The pooled cutoff point for operative time was 23.4 ± 8.9 (range, 12-29) cases. Full-endoscopic ELIF tended to require longer operative times but resulted in shorter hospital stays than biportal techniques. Conclusions: ELIF reflects the evolution of endoscopic fusion techniques. The proficiency threshold varies according to the outcome parameters and the type of endoscopic system. Structured training programs and standardized educational pathways are essential for optimizing the learning process and ensuring safe and efficient implementation.