Effects of gender and age differences on the distribution of bone content in the third lumbar vertebra

Study Design. A cross-sectional study on the distribution of bone mineral c ontent in the third lumbar. Objectives. To evaluate the effects of age and gender on the distribution o f bone mineral content in the third lumbar vertebrae. Summary of Background Data. Compression fractures occur mainly at the verte bral body. Variations in the distribution of bone mass in a vertebra, if un defined, may bias the ability of the acquired bone mineral density values, which was usually measured posteroanteriorly, to predict the risk of fractu res. Methods. The bone mineral content of the whole L3. including the L3 vertebr al body and the posterior segment, was measured using a lateral approach wi th a dual energy radiograph absorptiometer on 177 healthy Taiwanese adults including 65 men and 55 premenopausal and 57 postmenopausal women. Results. The proportion of bone mineral content in the vertebral body was s ignificantly lower in premenopausal women than in age-matched men (39.1 +/- 0.9% vs. 50.0 +/- 1.7%, P < 0.0001). Furthermore, whereas postmenopausal w omen showed a decreased proportion of bone mineral content in the vertebral body with increased age (about -0.0022 per year, P = 0.0001), premenopausa l women and men showed a sustained proportion. Conclusions. The proportion of bone mineral content distributed in the body of L3 vertebrae was lower in women than in men, The discrepancy of this pa rameter between the genders was even larger with increased ages.