The research method was a “retrospective cohort” study. The study’s primary aim was to check if a patient’s lumbar lordosis (LL) and segmental lordosis (SL) changed on the operating table during surgery and if these changes were consistent with those seen postoperatively. Clinical outcomes are expected to improve in tandem with adjustments to sagittal alignment. Therefore, it is essential to determine if LL or SL improvements may be predicted from intraoperative radiographs. Patients more than or equal to 18 years who had a single- or double-level anterior lumbar interbody fusion with posterior instrumentation between 2016 and 2020 were included in the analysis of electronic medical information. 

Preoperative, intraoperative, and postoperative radiographs were analyzed using paired t tests to compare LL, SL, and the lordosis distribution index. The influence of subsidence on LL and SL was analyzed using a linear model. As a whole, 118 people were eligible for the study. From that group, 75 had single-level fusions, and 43 had double-level fusions. (Delta (Δ): 5.7°, P<0.001) indicates a statistically significant increase in LL after being placed on the table. But LL was shown to have dropped significantly from intraoperative to postoperative radiographs at 2 to 6 weeks (Δ: -3.4°, P=0.001), while no change was found between intraoperative and more than 3 months postoperative radiographs (Δ: -1.6°, P=0.143). From preoperative to intraoperative radiographs, SL was observed to considerably increase (Δ: 10.9°, P<0.001), although it subsequently reduced (Δ: -2.7°, P<0.001) and finally reached a new low (Δ: -4.1°, P<0.001) by the end of the follow-up period. 

It was found that cage subsidence/allograft resorption was a significant predictor of the ΔSL (β=0.55; 95% CI: 0.16-0.94; P=0.006), but not the LL (β=0.10; -0.44 to 0.65; P=0.708). Predictive of long-term lumbar sagittal alignment, even if they may not reflect the improvement in LL seen on intraoperative radiographic imaging. Although LL is not considerably affected by subsidence, SL is decreased by 0.55 degrees for every millimeter of cage sinking or allograft resorption.