Double cortical line in the acetabular roof: a sign of disuse osteoporosis.

Abstract

A double cortical line (DCL) was observed in the acetabular roofs during interpretation of the abdominal radiographs and intravenous pyelograms of patients with paraplegia and quadriplegia. This was investigated by review of the radiographs of 40 paralyzed patients, by postmortem radiographic and histologic examination of the acetabula of one quadriplegic and three nonparalyzed patients, and by observation of the subchondral cortices of various long bones on radiographs of paralyzed and nonparalyzed patients. The DCL resulted from intracortical bone loss caused by severe disuse osteoporosis. It was most prominent in the acetabulum and most frequently found in patients with paraplegia or quadriplegia. The DCL also occurred in other bones, however, and in other conditions associated with severe disuse osteoporosis.