172 A Critical Analysis of Sagittal Plane Deformity Correction With Minimally Invasive Surgery: A 2-Year Follow-up Study of Deformity Patients Categorized by the SRS-Schwab Classification. (August 2015) - Mundis, Gregory
Abstract : INTRODUCTION: Sagittal plane realignment is critical to achieve desirable clinical outcomes in adult spinal deformity (ASD). Increasingly minimally invasive (MIS) techniques are being used to treat ASD. This study's objective was to evaluate circumferential MIS (cMIS) techniques and their ability to treat sagittal plane imbalance. METHODS: Multicenter database was queried for the following inclusion criteria: minimum 2-year follow-up, coronal cobb = 20°, SVA > 5 cm, or PT > 25°. Patients were stratified by SRS-Schwab global alignment modifier (GAM) as "Scoli, " "+, " or "++" depending on their preoperative sagittal plane deformity, and then analyzed for demographic, radiographic, and health-related quality-of-life (HRQoL) measures. A "+" modifier denoted moderate and "++" denoted marked sagittal deformity whereas "Scoli" signified nonpathological sagittal alignment. RESULTS: Eighty-six of 91 potential patients had complete 2-year follow-up data ("Scoli" = 51, "+" = 21, and "++" = 14). The "Scoli" group was significantly younger than "++" group (mean 57.6 vs 70.5 years). There were no differences in baseline HRQoL and operative data. Postoperatively "Scoli" and "+" had improved Oswestry Disability Index (ODI), Visual Analog Scale (VAS) back and leg. "Scoli" group had no differences radiographically while "+" saw improvement in PI-LL mismatch (21.1°-15.4°; P = .025) and LL (33.6°-39.9°; P = .016). "++" had improvement in VAS back but not ODI, VAS leg, PT, PI-LL mismatch, SVA, LL. Of 51 patients in "Scoli, " 42 (81%) remained "Scoli, " 9 (17%) deteriorated (5 to "+, " 4 to "++"). Thirteen of 21 (61.9%) "+" patients remained "+" while 3 changed to "++, " and 5 to "Scoli." Nine of 14 (64.3%) "++" patients remained "++, " 3 improved to "+" and 2 to "Scoli." CONCLUSION: MIS techniques successfully treated patients with Scoli and "+" deformities with improved HRQoL. Patients with "++" showed less improvement clinically, and, as a sequela of fusion surgery, were left with a fixed sagittal plane deformity. These results suggest that with severe sagittal plane deformities, an open rather than MIS approach should be considered.