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.

Osteodystrophia fibrosa in two guinea pigs

“…4 One of the few pathognomonic radiographic signs of osteopenia is the double cortical line, which has been described in disuse osteoporosis in humans. 5 Because of the arrangement of the arterial blood supply, there is preferential bone resorption of the middle layers of the cortex, resulting in a residual outer and inner cortical layer of bone. To the authors' knowledge, this characteristic finding has been described radiographically in animals in only 1 report, 1 where it was apparent in 3 cats and 1 dog.…”

Radiology of Osteoporosis

“…The latter is responsible for the "double cortical line" in the acetabulum that has been described as a sign of disuse osteoporosis. 6 It should be noted, however, that this may be seen in bones other than the acetabulum and with other causes of osteoporosis ( Fig. 8).…”

“…In the spine, this may give rise to a well-demarcated outline of the vertebral body, which has been aptly described as "picture-framing," and in the acetabulum, this may give rise to the "double-cortical line" appearance. 6…”