[Growth of the human acetabulum--with a comparison of cartilaginous proliferation in acetabular and triradiate physeal cartilages].

For the purpose of investigation on the human acetabular growth, proliferation of cartilage cells as well as extent and degree of maturation of newly formed trabeculae in both acetabular and triradiate physeal plates were observed. The material consisted of 13 acetabula of the left hip joints from necropsies whose age distribution ranged from the period of neonate to adolescence. The acetabulum was divided into 5 parts by radial lines. Histological sections were then prepared from each of these parts. The growth of the acetabulum was mainly based on the development of the acetabular and triradiate physeal cartilages, and it seemed that the course of newly formed trabeculae from both physeal plates showed centripetally directed arrangement, with convergence upon a point. These trabecular arrangement was most conspicuous in the neonatal period in which active new bone formation progressed. Based on these findings it would be reasonable to consider that the acetabular physeal cartilage takes a large part of increase in depth of the acetabulum, while the triradiate one is mainly responsible for increase in its diameter. From neonatal period to about 1 year of age there was an active growth of both acetabular and triradiate cartilages. With age the growth rate of physeal plates showed a decrease, and there was a tendency to a predominance of triradiate cartilage proliferation over acetabular one. On reaching adolescence cessation of cartilage growth occurred in both physeal plates.