Study of the Correlation between Adjacent Segment Disease and Segmental Lordosis After Lumbar Facet Joint Fusion Surgery

Objective Segmental lordosis is an important risk factor for spinal diseases. The purpose of this study was to investigate the relationships between segmental lordosis-related parameters and adjacent segment disease (ASD) after lumbar interarticular fusion. Methods This was a retrospective analysis of 27 patients with ASDs who underwent revision surgery in our hospital after lumbar interarticular fusion from February 2012 to February 2025. We included these 27 patients with ASD and matched them with 27 non-ASD controls on the basis of the initial surgery age, sex, surgical segment, and follow-up duration. Preoperative, postoperative, and final follow-up lumbar spine radiographs (anteroposterior and lateral radiographs) were analyzed. Parameters, including lumbar lordosis (LL), segmental lordosis (SL), sacral slope (SS), and the relative height of the intervertebral space adjacent to the fusion segment, were compared. Preoperative data, radiographic parameters at 3 days postsurgery, and final follow-up data were compared between the two groups. Significant parameters were further analyzed via multivariate logistic regression. The optimal predictive threshold for ASD was determined via receiver operating characteristic (ROC) curve analysis. Results No significant differences in the general demographic data were found between the two groups ( P  > 0.05). Compared with the control group, the ASD group presented significantly lower postoperative lumbar LL, SS, and intervertebral space height ( P  < 0.05), along with a significantly reduced relative change in segmental lordosis (r△SL) during the early postoperative period ( P  < 0.05). Multivariate regression analysis confirmed that r△SL was an independent risk factor for ASD ( AUC  = 0.713, 95% CI : 0.577–0.850), with an optimal predictive threshold of 2.8%. Conclusion Insufficient local curvature correction during fusion surgery accelerates degenerative changes in adjacent segments, and segmental lordosis is a critical risk factor for ASD.