Aim:Degenerative disc disease (DDD) is a common spinal disorder associated with low-back pain (LBP) and leg pain, leading to significant disability. MRI in DDD often shows Modic changes (MCs), which are vertebral marrow alterations classified into three types based on bone pathology. This study aimed to assess the association between MCs and clinical outcomes in patients undergoing one-level lumbar fusion surgery.Material and Methods:A retrospective cohort study included patients (>18 years) with single-level DDD treated with one-level lumbar fusion from 2016 to 2020 at a single center. Preoperative and 2-year postoperative outcomes were collected, including the Visual Analog Scales (VAS-back and VAS-leg), Oswestry-Disability-Index (ODI), Core-Outcome-Measures-Index (COMI-back) and Short-Form-Health-Survey-36 (SF-36). The association of patient reported outcomes measurements (PROMs) with preoperative MCs on MRI were assessed. Subjects with MC2 and MC3 were pooled in the No-MC1 group and compared to MC1 group. Continuous variables were compared using independent or paired t-tests, and non-parametric data with Mann–Whitney U or Wilcoxon signed-rank tests. Categorical variables were analyzed with Chi-square or Fisher’s exact test.Results:Preoperatively, the MC1 group exhibited higher ODI scores (47.05±14.60 vs. 36.84±13.12; p=0.026) and lower SF-36-PCs (30.80±7.22 vs. 35.61±5.17; p=0.021) compared to the No-MC1 group. Postoperatively, no significant intergroup differences were observed. However, the MC1 group demonstrated greater improvements in ΔODI, ΔVAS-back, and ΔSF-36-PCs. Intra-group analysis revealed significant postoperative improvements in ODI, VAS-back, and VAS-leg in the MC1 group (e.g., ΔODI= 29.14±13.27; p= 0.007), while the No-MC1 group improved in ODI and SF-36-Mental Components (ΔODI= 21.10±12.26; p= 0.023; ΔSF-36-MCs= 5.98±12.44; p= 0.003). Notably, 7 patients did not reach the ΔODI minimum clinically important difference, with higher prevalence in the No-MC1 group (71.4%).Conclusion:One-level spinal fusion improves clinical outcomes in symptomatic DDD. Patients with MC1 demonstrate greater functional and pain-related improvements compared to those with MC2 or MC3.