Comparison of Cytokine Profiles in Ligamentum Flavum from Patients Undergoing Surgery for Lumbar Disc Herniation and Lumbar Spinal Stenosis: An Exploratory Study

In spinal pathology, lumbar disc herniation (LDH) is typically contrasted with lumbar spinal stenosis (LSS) based on either its pathophysiology (structural compression vs. dynamic/vascular/degenerative changes) or its clinical presentation (acute radiculopathy vs. chronic claudication). We compared the ligamentum flavum (LF) tissue, primary LF cells, and serum cytokine profiles using human cytokine antibody arrays and Western blotting between patients with LDH (n = 17) and LSS (n = 23). LF specimens underwent hematoxylin–eosin, Masson’s trichrome, and immunohistochemical staining. Compared with LSS, LDH specimens showed relatively preserved LF architecture and higher tissue levels of IL-7, IL-10, eotaxin-3, HGF, and TGF-β2, suggesting an earlier immune-regulatory and reparative phase. In contrast, LSS specimens showed fragmented elastic fibers, increased collagen accumulation, and significantly elevated OPG in primary LF cell cultures. Serum cytokine profiles did not differ significantly between groups. These findings suggest that LDH-associated LF changes may involve immunoregulatory and repair-related cytokine expression, whereas LSS represents a more fibrotic, OPG-enriched remodeling phenotype. TGF-β2, eotaxin-3, and the RANKL/OPG pathway merit further evaluation as stage-specific biomarkers.