Bone reinforcement lines in chronic adult osteopenia: a hypothesis.

Although linear bands of increased radiodensity have been described in the tubular bones of children, similar but less often reported structures are frequent in the osteopenic skeleton of middle-aged and elderly patients. In this study, the radiology, pathology, and histology of osseous bands in the mature skeleton were analyzed in 20 cadavers, 29 macerated ancient and modern bone specimens, and 100 recent radiographs. These radiodense areas represent complete or incomplete, horizontally or obliquely oriented bars composed of compact lamellar bone. Although their precise pathogenesis is not clear, they are associated with long-standing (vs. acute) osteopenia. In some instances, bone bars appear to be formed during skeletal growth, remain hidden in the adult because of adjacent trabeculae, and are unmasked by osseous resorption. In other instances, bone bars appear to be formed initially in the mature skeleton as a response to chronic mechanical stress and, as such, are not identical with growth recovery lines observed in children. They are more accurately considered bone reinforcement lines.