137. Surgical overcorrection relative to ideal spinopelvic alignment reduces rates of pelvic nonresponse for severely malaligned adult spinal deformity patients

BACKGROUND CONTEXT Persistent lumbopelvic malalignment following ASD-corrective surgery may impair quality of life and result in persistent pathologic compensation in the lower extremities. Patient-specific age- and BMI-adjusted alignment targets have been proposed to improve alignment outcomes; however, it is unclear whether reaching these postop targets reduces rates of pelvic nonresponse following surgery. PURPOSE Assess the relationship between pelvic nonresponse to ASD-corrective surgery and persistent lower-extremity compensation. STUDY DESIGN/SETTING Single center retrospective review. PATIENT SAMPLE Fifty-eight ASD patients. OUTCOME MEASURES Sagittal alignment. METHODS Included: surgical ASD patients with full-spine X-ray imaging at pre- and early postop follow-up ( RESULTS Following propensity score matching, PNR (N=29) and PR (N=29) patients did not differ in age, sex, BMI or preop sagittal spinal alignment (all p>0.05); however, PNR patients presented with less knee flexion (9° vs 14°, p=0.043). Groups did not differ in levels fused (10.8 vs 10.8, p=0.974) or osteotomy (93% vs 92%, p=0.902). Postop, PNR patients had inferior lumbopelvic alignment in PT (30° vs 17°), PI-LL (17° vs 3°), and greater global malalignment for TPA (27° vs 15°, all p 0.05). For patients with severe preop SVA deformity, overcorrection relative to ideal postop PT targets was associated with lower rates of pelvic non-response (under: 12%, match: 18%, over: 71%, p CONCLUSIONS Pelvic nonresponders following ASD-corrective surgery had higher rates of persistent compensatory action in the lower extremities. Patients with severe preop PT deformity who were surgically overcorrected with respect to ideal PI-LL had lower rates of postop pelvic nonresponse, indicating that for severely malalignmed patients, existing alignment targets may need to be adjusted to optimize alignment outcomes. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.