A new Modic Changes classification and its impact on Posterior Lumbar Interbody Fusion

Background 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. Methods Patients were categorized into Group A (normal endplate), Group B ༈MCs without endplate sclerosis༉, and Group C (MCs with endplate sclerosis). 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. Results 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 (P < 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 (P < 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 (P < 0.05), indicating worse clinical outcomes. Conclusion 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.