The role and predictive value of Th17/Treg imbalance and inflammatory factors in sagittal imbalance after VCD for ankylosing spondylitis.

Background: This study aimed to explore the impact of T helper 17 (Th17)/regulatory T (Treg) cells imbalance and inflammatory factors (IL-1b, IL-18, and TNF-a) on sagittal balance in patients with thoracolumbar kyphosis due to ankylosing spondylitis (AS) following vertebral column decancellation (VCD), to clarify the predictive efficacy of the Th17/Treg ratio and IL-1b, IL-18, and TNF-a in post-operative sagittal imbalance. Methods: A total of 134 AS patients undergoing VCD were enrolled and categorised into an imbalance group (46 cases) and a balance group (88 cases), depending on post-operative sagittal balance. Measurements of the Th17/Treg ratio and inflammatory factor levels were conducted at three time points: preoperatively (T0), 24 hours postoperatively (T1), and 4 weeks postoperatively (T2). These data were analysed alongside sagittal parameters (SVA, PI-LL, and PT) to assess their correlations and predictive potential. Results: At 4 weeks after surgery, the imbalance group showed significantly elevated Th17/Treg ratios and higher levels of IL-1b, IL-18, and TNF-a compared to the balance group (P<0.05). Th17/Treg ratios and inflammatory factors (IL-1b, IL-18, TNF-a) showed significant positive correlations with SVA, PI-LL, and PT (P<0.05). Notably, the combined assessment of Th17/Treg ratio and inflammatory factors sagittal imbalance had a sensitivity of 52.17% and specificity of 90.91 (P<0.001). Conclusions: The findings suggest that Th17/Treg imbalance and excessive expression of IL-1b, IL-18, and TNF-a are strongly linked to postoperative sagittal imbalance in AS patients. These biomarkers may serve as valuable early predictors for assessing surgical outcomes.