[Aging process of the acetabular labrum--an electron-microscopic study].

We have studied the aging process of the labrum of the hip using scanning and transmission electron-microscopes. The materials consisted of 22 human hip joint acetabula. Disruption and irregular ridges were evident on the uppermost superficial layer and the superficial layer of the labrum in their fifties of age. Collagen fibers composing the labrum increased in density and sectional area in the specimens of subjects up to their twenties, but decreased in those of subjects in their thirties. At the joint of the labrum and articular cartilage, a bundle of fibers approximately 20 microns in diameter was observed to extend from the labrum to the cartilage, reinforcing the bond of these components. Disruption of this area starting on the acetabular side and leaving fibers of the labrum of about 400 to 500 microns on the cartilage side was more frequent in the specimens of subjects in their fifties of age. The changes with aging in the collagen fibers along with concentration of the stress of weight bearing at the point where the labrum meets the cartilage, may have some effect on the well-fitting of the acetabulum and femoral head.