The reliability of diagnosing osteoporosis from spinal radiographs.

In order to assess the value of spine radiographs in the diagnosis of osteoporosis, we have measured lumbar-spine bone mineral density (BMD) in 33 women aged 33-74 years whose radiographs were reported as showing 'osteopenia' only and 41 women aged 39-78 with radiological evidence of vertebral deformation. These results were compared with the normal range for young women and with control groups of 41 normal elderly women aged 65-70 and 15 normal younger women aged 50-60. Women with radiological osteopenia had a significantly lower BMD than the younger (p < 0.001) but not the older control group. The BMD in women with vertebral deformation was significantly lower than in both control groups (p < 0.001) and women with radiological osteopenia (p < 0.01). Only 67% of women with radiological osteopenia had a bone density below the normal range for young women, compared with 81% of those with vertebral deformation, though the latter may be an underestimate because of the artefactual elevation of bone mass caused by vertebral fractures in the lumbar spine. Our study suggests that a radiological report of reduced bone density may be misleading. Bone density measurements should be performed to confirm that patients so identified require treatment for osteoporosis. For patients with vertebral deformation after minimal or no trauma, bone density measurements are probably not required.