Adult Dysplasia Research Articles

Variation of Quantitative and Qualitative Changes of Enchondral Ossification in Heterozygous Achondroplasia

Whereas the radiologic features of achondroplasia--the most common type of skeletal dysplasia in adults--are clearly defined there is still some debate about the severity and the type of histologic changes. Earlier descriptions reported severe disturbance of enchondral ossification to be typical of achondroplasia: They are, however, misleading by dealing mostly with cases of lethal neonatal dwarfism (e.g. thanatophoric dysplasia). Newer findings confirmed that only minor, quantitative lesions are typical of heterozygous achondroplasia. But even in recent years some observers noted more severe changes of enchondral ossification. An extensive histologic skeletal survey in a newborn achondroplastic male revealed remarkable findings: It clearly showed that in addition to a generalized, but moderate narrowing of the zones of enchondral ossification focal severe changes were present in various epiphyseal plates including clusterlike arrangement of enlarged chondrocytes, vacuolization, premature calcification and important fibrosis of cartilagineous matrix with membranous ossification. Our findings thus enable us to reconcile the seemingly divergent statements made before.

Occipital Dysplasia in Infancy

MANY of the congenital abnormalities around the foramen magnum are accompanied and manifested by dysplasia of the occipital bone. Hypoplasia of the basiocciput can be found in manifestations of the occipital vertebra, in atlas assimilation, in atlanto-occipital fusion, and in such conditions as platybasia and basilar impression. Schmidt and Fischer (25) in their rather complete monograph covering the literature up to 1960, classified and analyzed in detail the many aspects of this condition. These abnormalities can occur in an endless variation. With the application of standard lines in multiple, special projections and with function films, the diagnosis of occipital dysplasia in adults and older children is not too difficult. Because this abnormality is congenital, it might logically be expected and the diagnosis entertained in infancy. To the author's knowledge, however, such a diagnosis has not as yet been reported. Probably this is the result of the incomplete ossification and calcification of the cho...