210. Comparing and contrasting the clinical utility of sagittal spine alignment classification frameworks: Roussouly vs SRS-Schwab

Abstract

BACKGROUND CONTEXT For surgical adult spinal deformity (ASD) patients, incorporating restoration of appropriate Roussouly Classificaion shape into surgical planning may improve outcomes. With the introduction and use of the SRS-Schwab ASD classification system, it is important to compare the utility of both classification frameworks as they relate to surgical outcomes. PURPOSE Compare outcomes of surgical ASD patients classified by both Roussouly and Schwab systems. STUDY DESIGN/SETTING Retrospective review of prospective ASD database. PATIENT SAMPLE A total of 515 ASD patients. OUTCOME MEASURES Complications; Health-related quality of life (HRQL): ODI, SF-36 PCS, SRS-22r. METHODS ASD patients with pre- and 2-year postop (2Y) radiographic/HRQL data were grouped by “theoretical” Roussouly type (Type 1: PI 60°) and “current” Roussouly type (1: SS 45°), as published. Means comparison tests assessed outcomes of those that mismatched “theoretical” and “current” types at both pre- and 2Y intervals (mismatched) to those of preoperative mismatched patients that matched at 2-years (matched). Subanalysis assessed outcomes of patients that improved in Schwab modifiers, and patients that both improved in both Schwab modifiers and matched Roussouly type by 2Y. RESULTS Included 515 ASD patients (59±14yrs, 80%F). The overall cohort showed moderate preoperative global and lumbo-pelvic deformity: SVA(64mm±73), PT(25°±11), PI-LL(16°±21). Preoperative breakdown of “current” Roussouly types: Type 1 (10%), Type 2 (54%), Type 3 (24%), Type 4 (12%). Preoperative mismatch between “current” and “theoretical” types was 60%. By 2Y, 16% of patients matched Roussouly types. Matched and Mismatched groups did not differ in rates of reaching MCID for any HRQL metrics by 2Y(all p>0.1). Reop, PJK and complications did not differ between matched and mismatched(all p>0.1), though mismatched patients showed a trend of increased instrumentation failure(17% vs 26%, p=0.080). By 2Y, 28% of patients improved in PT Schwab modifier, 37% in SVA, and 46% in PI-LL. Patients that improved in PT modifier had lower instrumentation failure rates (16% vs 24%) and higher rates of reaching 2Y MCID for ODI (58% vs 48%) and SRS Activity (75% vs 64%) than patients that did not improve. Patients that both Matched Roussouly at 2Y and improved in all Schwab modifiers met MCID for ODI and SRS Activity at higher rates than patients that did not. Roussouly Match patients that improved in Schwab PT met SRS Activity MCID at a higher rate, and had less renal, infection, and neurologic complications than patients that did not. Roussouly Match patients that improved in Schwab SVA also had superior SF-36 scores and fewer cardiopulmonary complications(all p CONCLUSIONS For surgical ASD patients, isolated restoration of sagittal spinal shape per the Roussouly system was not associated with superior clinical outcomes or complications by 2 years. In contrast, improvement in PT, per the SRS-Schwab system, was associated with substantial improvement in low-back disability by 2 years. Collectively, patients that both matched Roussouly sagittal type and improved in Schwab modifiers had superior complication and patient-reported outcomes by 2 years. These results suggest that concurrent consideration of both existing systems may offer utility in establishing optimal realignment targets. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.