Outcomes of Circumferential Minimally-Invasive Technique vs. 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 with severe deformity has not been assessed.

Methods: Operative ASD patients ≥18yrs with complete BL/2Y radiographic/HRQL data were assessed. Patients aged 80y≥were isolated for analysis and compared by surgical technique: Open vs cMIS. BL and peri/postoperative factors were assessed using ANOVA and Bonferroni-adjusted ANCOVA while controlling for BL CCI and posterior levels fused. Propensity score matching(PSM) aligned cMIS vs Open groups by BL CCI, C7-S1 SVA, PI-LL, and C7PL.

Results: Of 1542 patients(62.85±13.93years, 75.7%F, 29.23±6.64kg/m2), 19.5%(n=34) octogenarians split evenly between cMIS and Open. 19.5%(n=34) were octogenarians. At baseline, patients were comparable in gender, BMI, and prior history of spine surgery(all p>.05). When assessing baseline frailty, Passias et al. and Miller et al. frailty scores were not significantly different(both p>.05), and Chi-square analysis revealed equal distribution of frailty in cMIS vs Open patients(χ2(2)=.446,p=.788). cMIS patients were less likely to require SICU care(p <.001), and had lower mean LOS(p=.013). Postoperatively, Open patients reported significantly 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). No significant differences were noted in peri/postoperative major/minor complications(all p>.05), cMIS patients were significantly more likely to require reoperation for radiographic sagittal imbalance by 2Y when controlling for CCI and levels fused(p <.001). By 2Y, there were no recorded deaths in the cMIS nor Open octogenarians.

Conclusion : Octogenarians present a unique challenge to spine surgeons due to the potential for decreased physiologic reserve, and heightened risk for complications. Our comparison of 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.