Aim:This study aims to evaluate the incidence, risk factors, and spinopelvic alignment parameters associated with distal junctional failure (DJF) following posterior thoracolumbar stabilization surgery. The focus is on understanding how lumbar lordosis (LL), pelvic incidence (PI), and PI-LL mismatch contribute to the development of DJF. Material and Methods:This retrospective cohort study included 40 patients who underwent thoracolumbar stabilization between 2018 and 2024. Patients were divided into two groups: those who developed DJF (n=20) and those who did not (n=20, control group). Radiographic evaluations, including pre- and postoperative lateral radiographs, were used to assess spinopelvic parameters such as LL, PI, and PI-LL mismatch. Statistical analyses were conducted to examine the correlation between these parameters and DJF occurrence. Results:The analysis revealed that the DJF group exhibited a significant postoperative reduction in LL and an increase in PI-LL mismatch compared to the control group, which maintained better sagittal alignment postoperatively (p<0.05). Patients with higher preoperative PI-LL mismatch were more likely to develop DJF, highlighting the importance of preoperative planning and correction to prevent this complication. Conclusion:Optimizing spinopelvic alignment, particularly LL and PI-LL mismatch, is crucial for reducing the risk of DJF after thoracolumbar stabilization surgery. Future studies should aim to refine surgical techniques and strategies to enhance postoperative outcomes and minimize complications.