‏ ‏Samples of ligamenta flava were obtained after surgical operations from 50 patients with a ‎lumbar disc herniation, another 50 patients with a lumbar canal stenosis, and 25 patients with ‎spinal fractures who were used as control group. ‎
‎ Ligamenta flava from control patients aged below 46 years consisted of large elastic fibers, ‎thin bundles of collagen fibers, and few spindle-shaped fibroblast cells.‎
In close proximity to the laminal insertion, the ligamentum flavum had fibrocartilagineous ‎features. in the control patients who were aged 46 or older, the areas that had fewer and thinner ‎elastic fibers and a more abundant collagen component were visible occasionally. The spindle-‎shaped fibroblast cells were fewer compared with control patients aged below 46 years. Also ‎remnants of necrotic cells and few, short, thin, interwoven, fragmented, non-branching elastic ‎fibers, as well as small calcified areas, were occasionally visible. ‎
‎ In close proximity to the laminal insertion, the ligamentum flavum had larger fibrocartilaginous ‎features with more collagen fibers compared with younger patients. ‎
‎ In patients with disc herniation, the ligamenta flava had nearly similar morphologic features to ‎those of the control patients of similar ages. The ligamenta flava from patients with lumbar ‎spinal stenosis aged below 46 years showed areas of fibrosis in which the cells were often ‎represented by fibroblast cells and in stenotic patients older than 46 years, central portion of ‎ligamentum flavum showed areas of fibrosis, in which the elastic fibers appear normal in some ‎areas, showed little changes in others and in most of these areas showed great changes. ‎Fibrous septa, degenerating elastic fibers as well as small calcified areas were observed often.‎
‎ In conclusion, Lumbar ligamentum flavum as any tissue in human body undergo degenerative ‎changes during aging. In lumbar canal stenosis, the degenerative changes were more obvious ‎compared with normal spine or lumbar disc herniation. In stenotic patients, ligamenta flava ‎show a significant decrease in the elastic component as a result of fibrosis and chondroid ‎metaplasia of the tissue, as well as degeneration of the elastic fibers. These changes, and the ‎presence of calcified areas within the tissue, decrease the elasticity of the ligaments. An elastic ‎tissue can be deformed under traction and gradually return to its normal size, proportional to ‎the decrease of the elastic tension. Ligamenta flava do not normally bulge into the spinal canal ‎when spine is in the neutral position.‎