Clinical correlation of postoperative reduction magnitude in patients with degenerative scoliosis

Background: Degenerative scoliosis is a three-dimensional spinal deformity frequently observed in the elderly population, often associated with pain, functional impairment, and reduced health-related quality of life (HRQoL). Although surgical correction aims to restore spinal alignment and improve clinical outcomes, the relationship between the magnitude of coronal correction and postoperative functional improvement remains unclear. This study aimed to evaluate the correlation between postoperative coronal reduction and clinical outcomes in patients undergoing long-segment posterior fusion for degenerative scoliosis, with particular emphasis on spinopelvic parameters. Methods: This retrospective cross-sectional study included 16 patients treated surgically for degenerative scoliosis between January 2018 and December 2024. Inclusion criteria comprised age >40 years, Cobb angle >20°, and posterior instrumentation with fusion of ≥4 segments. Radiographic parameters (Cobb angle, sagittal vertical axis [SVA], pelvic incidence [PI], pelvic tilt [PT], sacral slope [SS], and PI–LL mismatch) and clinical outcomes (VAS, ODI, and SRS-22) were assessed preoperatively and at 1-year follow-up. Pre–post comparisons were analyzed using the Wilcoxon signed-rank test. Correlations were assessed with Spearman analysis (p<0.05 considered significant). Results: The mean preoperative Cobb angle significantly decreased from 26.5° ± 9.8 to 12.3° ± 6.2 postoperatively, corresponding to a 54% correction (p<0.001). Significant improvements were observed in VAS (7.94 ± 0.93 to 4.00 ± 2.10), ODI (70.4% ± 11.6 to 28.5% ± 24.4), and all SRS-22 domains (pain, self-image, function, and mental health) (p<0.001). No significant preoperative correlations were found between radiographic parameters and HRQoL scores. However, at 1-year follow-up, postoperative SVA showed significant positive correlations with VAS (r=0.522, p=0.038) and ODI (r=0.530, p=0.035), and significant negative correlations with SRS-22 self-image (r=−0.534, p=0.033), function (r=−0.560, p=0.024), and mental health (r=−0.768, p=0.001). In contrast, the degree of coronal correction did not significantly correlate with HRQoL outcomes. Conclusions: Long-segment posterior fusion provides significant radiographic and clinical improvement in degenerative scoliosis. However, the magnitude of coronal correction does not appear to predict postoperative quality of life. Restoration of sagittal alignment, particularly optimization of SVA, plays a more decisive role in functional recovery and patient-reported outcomes. These findings suggest that surgical success in degenerative scoliosis should be evaluated beyond coronal deformity correction, with greater emphasis placed on global sagittal balance. Keywords: Degenerative scoliosis; coronal correction; sagittal balance; spinopelvic parameters; sagittal vertical axis; quality of life.