Under Correction of Sagittal Deformities Based on Age-adjusted Alignment Thresholds Leads to Worse Health-related Quality of Life Whereas Over Correction Provides No Additional Benefit

Retrospective review of prospectively-collected database. This study aims to compare 2-year clinical outcomes of patients who underwent surgical reconstructions based on their achievement to age-adjusted alignment ideals. Recent research in sagittal plane has proposed age-adjusted alignment thresholds. However, the impact of these thresholds on postoperative health-related quality of life (HRQOL) is yet to be investigated. Patients were included if they were more than 18-years old and underwent surgical correction of adult spinal deformity with a complete 2-year follow-up. Patients were stratified into three groups based on achievement of age-adjusted thresholds in pelvic tilt (PT), pelvic incidence minus lumbar lordosis (PI-LL), and sagittal vertical axis (SVA). First group included patients who reached the exact age-adjusted threshold ± 10 years (MATCHED), other two groups included patients who were over corrected (OVER), and under corrected (UNDER). Clinical outcomes including actual value and offset from age-adjusted Oswestry Disability Index, Short-Form-36 (SF-36) -physical component summary, and Scoliosis Research Society-22r (SRS-22r) were compared between groups at 2 years follow-up. A total of 343 patients (mean, 57 yrs and 83% females) were included. Sagittal profile of the population was: PT = 23.6°, SVA = 65.8 mm, and PI-LL = 15.6°. At 2-year follow-up, there was significant improvement in all sagittal modifiers with 25.7%, 24.3%, and 33.1% of the patients matching their age alignment targets in terms of PT, PI-LL, and SVA, respectively. For PT and PI-LL, the three groups (MATCHED, OVER, and UNDER) had comparable values and offsets from age-adjusted patient reported outcome. However, for SVA groups, patients in UNDER had significantly worse HRQOL than the two other groups. Patients in PT, PI-LL, and SVA UNDER groups were significantly younger than the other groups, P