Tensile Test of Human Lumbar Ligamentum Flavum: Age-Related Changes of Stiffness

The most common cause of lumbar spinal canal stenosis is age-related degenerative changes. The ligamentum flavum is said to become thicker and stiffer with age, based on several histological and cadaver studies. However, there are no studies determining the age-related changes of the mechanical properties of the ligamentum flavum in live patients. We examined the mechanical properties of the ligamentum flavum of live patients and evaluated the age-related changes. A total of 44 patients undergoing decompression surgery due to lumbar disease at our institute were included. The ligamentum flavum was harvested from the decompression site as a part of a necessary procedure for decompression. The tensile test was performed for the harvested ligamentum flavum within 24 h of harvest. Age-related changes in the stiffness of the ligamentum flavum were evaluated. Age was the only factor that showed a significant correlation with stiffness on multiple regression analysis. We demonstrated that the mechanical properties of the ligamentum flavum change with age.