25. The collective influence of lumbopelvic mismatch and proportional shape on clinical outcomes and proximal junctional kyphosis following adult spinal deformity corrective surgery

Abstract

BACKGROUND CONTEXT The age-adjusted alignment ideal alignment was proposed in order reduce the occurrence of proximal junctional kyphosis (PJK) in an adult spinal deformity (ASD) population. The normative postoperative age ideal value for the mismatch between pelvic incidence and lumbar lordosis (PI-LL) has yet to be related to the global alignment and proportion (GAP) score postop proportionality. PURPOSE To assess the impact of normative age-adjusted PI-LL and proportionality via GAP score on postoperative patient-reported outcomes. STUDY DESIGN/SETTING Retrospective review of single-surgeon adult spinal deformity (ASD) database PATIENT SAMPLE 140 ASD patients. OUTCOME MEASURES Health-related quality-of-life (HRQLs); SRS-22r; PJK. METHODS ASD patients with baseline (BL) and 2-year postoperative (2Y) radiographic and HRQL data were included. Age-adjusted correction groups generated at postoperative follow-up for actual alignment compared to age-adjusted values for PI-LL-adjusted ideal values (matched, overcorrected, undercorrected). GAP Score in the literature includes the four parameters, and an age factor to formulate a sagittal plane score out of 13 (proportional, moderately disproportional [MD], severely disproportional [SD]). GAP improvement scores were noted as less at 2Y compared to BL. Patients were grouped by age-adjusted and 2Y GAP results: Match PI-LL/Proportional GAP, Match PI-LL/Disproportional GAP, Unmatch PI-LL/Proportional GAP, Unmatch PI-LL/Disproportional GAP. Means comparison and chi-squared ANOVA analyses assessed the outcomes between age-adjusted and GAP groups. RESULTS Included: 140 ASD patients (55.5±16.4 years, 81% female, 25.2±4.7kg/m2). At BL, mean sacral slope: 30.7°, pelvic tilt: 23°, pelvic incidence: 53.5°, PI-LL: 13.3°, SVA: 61.6 mm, and L1-S1: 40.4°. BL GAP proportionality: 17.8% proportional, 27.1% MD, 55% SD. PI-LL by baseline GAP proportionality groups: -6.4° Proportional, -4.6° MD, 26.8° SD, p CONCLUSIONS Collectively over or undercorrecting in age-adjusted mismatch pelvic incidence and lumbar lordosis and becoming disproportional in spinal shape at 2 years led to increased postoperative proximal junctional kyphosis and significantly worse patient-reported outcomes. Surgeons should be wary of the double mal-correction when utilizing these complex realignment schemas. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.