A light and electron microscopic study of osteogenesis imperfecta bone samples, with reference to collagen chemistry and clinical phenotype

A detailed morphological study was carried out using light and electron mic roscopy on 36 bone specimens from patients suffering from osteogenesis impe rfecta (OI) and 20 age- and site-matched control bone specimens. The findin gs were grouped into the clinical types of OI according to the Sillence cla ssification. The morphological and ultrastructural alterations observed in OI bone correlate well with clinical severity. Thus, OI type I, the mildest type, showed the least abnormalities in bone ultrastructure. OI type IV cl osely resembled type I, with only minor abnormalities in the bone cells and osteoid. OI type III showed abnormalities in the structure and distributio n of osteoid collagen fibrils, whilst OI type II, the lethal form, revealed many varied abnormalities such as thin cortical bone, sparse trabecular bo ne, increased numbers of osteoclasts and osteocytes, thin osteoid with thin collagen fibrils, and patchy mineralization. Copyright (C) 2000 John Wiley & Sons, Ltd.