Background <p>Current research on Modic Changes (MCs) in Posterior Lumbar Interbody Fusion (PLIF) has predominantly focused on types 1, 2, and 3; however, findings remain inconsistent. To address this gap, we introduce a novel classification system based on endplate sclerosis status (sclerotic vs. non-sclerotic) to better evaluate the influence of MCs on PLIF outcomes.</p> Methods <p>Patients were divided into Group A (normal endplates), Group B (MCs without endplate sclerosis), and Group C (MCs with endplate sclerosis), with fifty patients in each group. VAS and ODI scores were recorded preoperatively, postoperatively, and during follow-up to assess clinical outcomes. At least one year after surgery, CT scans were performed to evaluate postoperative cage subsidence and bony fusion.</p> Results <p>The postoperative cage subsidence rate recorded were 4% for Group A, 16% for Group B, and 2% for Group C, with a statistically significant difference (<i>P</i> &lt; 0.05). The postoperative bony fusion rate were 98% for Group A, 96% for Group B, and 80% for Group C, with a statistically significant difference (<i>P</i> &lt; 0.05). At the final follow-up, the Visual Analog Scale(VAS) and Oswestry Disability Index(ODI) scores in Group C were significantly higher than those in Groups A and B (<i>P</i> &lt; 0.05), indicating worse clinical outcomes.</p> Conclusion <p>MCs without endplate sclerosis increase the risk of cage subsidence after PLIF surgery but do not effect clinical outcomes. MCs with endplate sclerosis are associated with a reduced bony fusion rate following PLIF surgery, leading to worse long-term clinical outcomes.</p>