Authors: Jang Yoon, MD; John Paul Kolcun, BS; Michael Wang, MD (Miami, FL)

Introduction: Endoscopic transforaminal lumbar interbody fusion under conscious sedation (ENDO-TLIF) has been shown to reduce surgical morbidity while achieving clinical outcomes and arthrodesis rates comparable to those of conventional minimally invasive TLIF (MIS-TLIF). In patients with advanced age, obesity, or significant medical co-morbidities, reducing surgical burden and hastening postoperative recovery may have a greater clinical impact than in average patients. We therefore sought to confirm the advantages of the ENDO-TLIF in clinically high-risk patients. Methods: A consecutive series of 132 patients underwent ENDO-TLIF. A matched cohort of 66 patients underwent conventional MIS-TLIF by the same surgeon. Medical co-morbidity was assessed by the Charlson Co-morbidity Index (CCI). Patients were stratified by advanced age (≥70 years), obesity (BMI ≥30), and significant co-morbidity (CCI >2). Acute surgical outcomes, including estimated blood loss (EBL), operating time (OR time), and hospital length of stay (LOS), were compared between ENDO-TLIF and MIS-TLIF cohorts. Results: There were no significant differences in baseline characteristics between cohorts. In patients of advanced age, ENDO-TLIF was associated with reduced EBL (77.0±89.3 vs. 176.9±107.0mL, p = 0.001), OR time (88.6±22.8 vs. 157.4±39.2min, p < 0.001), and LOS (1.7±1.3 vs. 4.4±2.7 days, p < 0.001). These effects held in obese patients, with reduced EBL (88.4±100.9 vs. 148.9±94.0mL, p = 0.010), OR time (82.7±23.3 vs. 182.2±52.1min, p < 0.001), and LOS (1.6±1.0 vs. 3.9±2.4 days, p <0.001), as well as patients with significant co-morbidity, with reduced EBL (77.1±100.4 vs. 131.2±92.9, p = 0.03), OR time (90.1±30.9 vs. 156.9±46.5, p = 0.004), and LOS (1.6±1.1 vs. 3.9±2.7, p = 0.002). Conclusion: ENDO-TLIF is associated with superior acute surgical outcomes as compared to conventional MIS-TLIF in clinically high-risk patients. Future studies are required to demonstrate generalizability of our results and sustainable clinical and radiographic outcomes over time.