Abstract
Thickening of the yellow ligament is clinically important as the main factor of backward compression in spinal canal stenosis and is known to be one of the main causes of lumbar spinal canal stenosis. Histologically, the ligament contains elastic fibers and a large amount of elastin that is a component of the fibers, and its metaplastic changes such as proliferation of collagen fibers and cartilaginous tissue occur with age. However, the molecular biological mechanism of such tissue changes has not been clarified in several respects. On the other hand, f ibroblast growth factor (FGF) is known to stimulate growth of cells of mesodermal origin such as fibroblasts, vascular endothelial cells and epithelial cells. At present there are at least 23 species of FGF attracting attention. In the present study, we examined FGF-1 in the yellow ligament and comparatively examined the relation of the FGF-1 expression with lateral images of simple roentgenogram and MR images. The subjects were 11 patients who underwent operations for lumbar spinal canal stenosis, degenerative lumbar sliding and lumbar disk herniation. Sixteen extracted yellow ligament specimens were examined. At the time of operation, the patients were 24-79 years old or 65.7 years old on average and consisted of 6 males and 5 females. During extended fenestration or discectomy performed on lumbar spinal canal stenosis, degenerative lumbar sliding and lumbar disk herniation, specimens of yellow ligament tissue were collected and examined. After collection, each specimen was embedded in O.T.C compound and fixed by freezing. Thereafter, 4μ m-thick sections were routinely prepared and stained with H-E and Alcian blue. In addition, immunostaining of FGF-1 was performed, and each tissue section was classified based on the number of FGF-1-positive cells. Images of the yellow ligament were classified according to the degree of osteophyte formation on simple roentgenogram lateral images, thickness of the yellow ligament and degree of stenosis of the spinal canal on MRI; furthermore, the relation to FGF-1 was examined. A high FGF-1 expression rate was found in the vertebral arch side where degeneration of yellow ligament was severe. The rate of FGF-1 expression rose with increasing thickness of the ligament on MR images. No clear relation to the degree of spinal canal stenosis or the degree of osteophyte formation was observed. In brief, FGF-1 was involved in degeneration of yellow ligament and showed a high correlation with changes in MR images.
