Glycosaminoglycans Composition Associated with Ligamentum Flavum Hypertrophy in Degenerative Lumbar Spine Diseases

Introduction: hypertrophy of the ligamentum flavum, also called yellow ligament, is a major contributor to lumbar spinal canal stenosis in degenerative spine diseases. Elastic fibers, collagen, proteoglycans and glycosaminoglycans are key components of the extracellular matrix of the ligamentum flavum, playing essential roles in maintaining its structural integrity and function. However, the molecular mechanisms underlying ligamentum flavum hypertrophy, particularly those involving alterations in glycosaminoglycans composition, remain poorly understood. Objective: to analyze the composition of glycosaminoglycans in the ligamentum flavum of patients with degenerative lumbar spine diseases, with the aim of identifying molecular alterations associated with ligamentum flavum hypertrophy. Methods: thirty Ligamentum flavum samples were surgically obtained from patients diagnosed with either lumbar disc herniation or spinal canal stenosis. Sulfated glycosaminoglycans were extracted, identified, and quantified using agarose gel electrophoresis and specific glycosidases digestion. Ligamentum flavum thickness was measured using magnetic resonance imaging, and statistical analyses were performed to assess correlations between ligamentum flavum thickness and glycosaminoglycans composition. Results: a significant increase in chondroitin sulfate level was detected and found to be positively correlated with the degree of ligamentum flavum thickening. In contrast, dermatan sulfate levels did not show significant variation across different degrees of ligamentum flavum hypertrophy. Conclusion: ligamentum flavum hypertrophy in degenerative lumbar spine conditions is associated with specific alterations in glycosaminoglycans composition, particularly an increase in chondroitin sulfate content. These findings suggest that chondroitin sulfate, a highly anionic constituent of the extracellular matrix, may play a pivotal role in the pathophysiology of ligamentum flavum thickening observed in degenerative lumbar spine disease.