Cross-sectional area of lumbar vertebrae in peri- and postmenopausal patients with and without osteoporosis.

The purpose of this study was to analyze the midvertebral area of lumbar vertebrae in osteoporotic and nonosteoporotic female patients and to find out whether the midvertebral area may be used as an additional parameter in the diagnosis of osteoporosis. In 195 peri- and postmenopausal patients (average age 51.7 +/- 5.2 years) trabecular and cortical bone mineral density (BMD) were determined using quantitative CT (QCT) in L2-4. In addition, midvertebral cross-sectional area was measured in a standardized fashion on the CT sections and the height of the second lumbar vertebra was determined on the lateral digital radiographs. Body height and weight were obtained and vertebral fracture status was determined. According to WHO criteria 29 patients (average age 57.2 years) were considered osteoporotic, 93 osteopenic (average age 52.2 years) and 73 normal (average age 48.6 years). Body weight and size did not show significant differences between the individual groups. Average midvertebral area was 1278 +/- 173 mm2 in the osteoporotic patients, 1186 +/- 125 mm2 in the osteopenic patients and 1126 +/- 127 mm2 in the normals. A correlation of r = -0.39 (p < 0.05) was obtained between BMD and area. Thirty-six of 195 patients showed osteoporotic vertebral fractures. Midvertebral area in these patients was 1266 +/- 171 mm2 versus 1159 +/- 133 mm2 in the nonfractured females (p < 0.05). We therefore conclude that the lumbar midvertebral area is larger in osteoporotic and osteopenic patients compared with women with normal BMD. In contrast to biomechanical considerations midvertebral area seems not to be suited as an additional measure of bone strength in vivo.