Full-Endoscopic Surgery for Lumbar Disc Herniation: Comparative Outcomes and Risk Factors Between Lumbar Levels—The EndoLEVEL Study

<sec><title>Background</title> Upper lumbar disc herniation (ULDH) represents a rare but distinct subset of lumbar disc herniation (LDH), often presenting with atypical symptoms, older patient age, and greater surgical complexity due to the narrower spinal canal. While full-endoscopic lumbar discectomy (FELD) is increasingly used for LDH, robust data on its outcomes in ULDH remain limited. </sec><sec><title>Objective</title> This study aimed primarily to compare clinical outcomes of FELD between ULDH and lower lumbar disc herniation (LLDH). Secondary objectives included identifying risk factors associated with ULDH and describing perioperative differences between groups. </sec><sec><title>Methods</title> We retrospectively analyzed a single-center cohort of 806 patients undergoing FELD (TESSYS or iLESSYS) for LDH. Patients were stratified by level: ULDH (L1–L2, L2–L3, and L3–L4) vs LLDH (L4–L5 and L5–S1). Demographic, operative, and clinical data were compared, including visual analog scale pain scores, Oswestry Disability Index, Short Form-12, complications, and reoperation rates. Statistical analysis used <italic>χ</italic>² tests, <italic>t</italic> tests, and analysis of covariance adjusted for baseline scores. </sec><sec><title>Results</title> ULDH patients comprised 13% of the cohort and were significantly older than LLDH patients (57.3 ± 12.0 vs 46.0 ± 13.5 years). Patients in the ULDH group showed shorter symptom duration, longer operative times, and higher rates of postoperative persistent neurological deficits compared with those in the LLDH group (36.0% vs 25.6%, <italic>P</italic> = 0.0293). Despite these challenges, both groups demonstrated similar, significant reductions in leg and back pain (mean change = –4.9 and –2.5 points), comparable Oswestry Disability Index improvements (–33 points), and high satisfaction rates (>90% reporting good or excellent outcomes). </sec><sec><title>Conclusion</title> FELD offers effective, well-tolerated treatment for ULDH, achieving comparable clinical outcomes to LLDH despite anatomical complexity. These findings support the broader use of endoscopic techniques for all lumbar levels while underscoring the need for cautious surgical planning and further prospective studies. </sec><sec><title>Clinical Relevance</title> FELD provides effective pain relief and functional improvement for patients with ULDH, with outcomes comparable to those with LLDH. Despite anatomical challenges and a higher risk of persistent neurological deficits, FELD is a safe, minimally invasive option, supporting its broader use across all lumbar levels with careful surgical planning. </sec><sec><title>Level of Evidence</title> 3. </sec>