Basrah Journal of Surgery (Dec 2005)
HISTOLOGICAL CHANGES OF LIGAMENTA FLAVA IN LUMBAR DISC HERNIATION AND SPINAL CANAL STENOSIS
Abstract
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.
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