365 Outcomes of Circumferential Minimally-Invasive Technique Versus Open Technique in Adult Spinal Deformity Surgery Patients Over 80 Years of Age: A Propensity-Matched Analysis

INTRODUCTION: Circumferential minimally-invasive surgery (cMIS) techniques in ASD surgery may provide benefit in reducing physiologic burden, but the utility of such surgeries in patients greater than 80 years of age has not been assessed. METHODS: Operative ASD patients 18yrs with complete pre-(BL) and 2-year(2Y) data were assessed. Patients aged =80years were isolated and compared by surgical technique: Open vs cMIS. BL and peri/post-operative factors were assessed using ANOVA and Bonferroni-adjusted ANCOVA while controlling for BL CCI and posterior levels fused. Propensity score matching (PSM) was used to align cMIS vs Open groups by BL CCI, C7-S1 SVA, PI-LL, and C7PL. RESULTS: 174 ASD patients were included (62.85 ± 13.93 years, 75.7% female), split evenly between cMIS and Open. 19.5% (n = 34) were octogenarians; 29.4% operated via cMIS vs 70.6% Open. At baseline, patients were comparable in gender, BMI, and history of spine surgery (all p > .05). At BL, frailty scores were comparable (both p > .05). Post-operatively, Open patients reported higher SRS-22 Appearance and Mental domain scores (both p < .005), and were more likely to reach MCID in both domains by 2Y (p = .025, .024, respectively). In terms of post-operative complications, cMIS patients were more likely to require reoperation for radiographic sagittal imbalance by 2Y when controlling for CCI and levels fused (20.0% vs 8.3%, p < .001). By 2Y, there were no recorded deaths in the cMIS nor Open octogenarians. CONCLUSIONS: Our comparison of octogenarian adult spinal deformity patients undergoing circumferential minimally-invasive versus open surgery demonstrates that while cMIS patients benefit from decreased blood loss, operative time, and SICU and hospital length of stay, both Open and cMIS patients benefit from similar improvement in patient-reported outcomes. Likewise, Open technique, though more invasive, may also reduce the risk for reoperation due to radiographic instability by 2Y post-operatively.