Heaney R P, Barger-Lux M J, Davies K M, Ryan R A, Johnson M L, Gong G
Osteoporosis Research Center, Creighton University, Omaha, Nebraska 68131, USA.
Osteoporos Int. 1997;7(5):426-31. doi: 10.1007/pl00004150.
Changes in bony dimensions with age were assessed longitudinally from standardized X-ray films in 170 middle-aged Caucasian women, starting at age 40 years and with a median duration of observation of 21.125 years. Consistent with earlier work, cortical area of the metacarpals and radial shaft declined with age at rates ranging from 0.57 to 0.86%/year. As predicted, estrogen replacement therapy decreased this loss in a dose-dependent manner. Not previously reported is the fact that weight gain over the period of observation reduced upper extremity bone loss. Moreover, this protection was independent of the estrogen effect. In contrast with bone loss in the upper extremity, both femur shaft diameter and femur shaft cortical area increased significantly with age (0.23 and 0.26%/year, respectively). Estrogen replacement therapy inhibited femur shaft expansion but had no effect on femur cortical area. Weight change, however, strongly influenced gain (or loss) of femur cortical area: those in the highest weight change tertile gained 4 times as much cortical area as those in the lowest weight change tertile. VDR genotype also significantly influenced femoral shaft changes: women with the bb genotype had both greater shaft expansion and a greater increase in cortical area. The VDR effects were independent of the effects of weight change and estrogen. Femoral shaft expansion was of sufficient magnitude to suggest that the mechanical properties of the entire femur may change appreciably with age. Finally, contrary to widespread belief, there was significant, if modest, expansion at the femoral neck with age.
对170名中年白人女性的标准化X光片进行纵向评估，以观察随着年龄增长骨骼尺寸的变化。这些女性从40岁开始参与研究，观察期中位数为21.125年。与早期研究结果一致，掌骨和桡骨干的皮质面积随年龄下降，每年下降速率在0.57%至0.86%之间。正如预期的那样，雌激素替代疗法以剂量依赖的方式减少了这种骨质流失。此前未报道的是，在观察期内体重增加减少了上肢骨质流失。此外，这种保护作用独立于雌激素效应。与上肢骨质流失情况相反，股骨干直径和股骨干皮质面积均随年龄显著增加（分别为每年0.23%和0.26%）。雌激素替代疗法抑制了股骨干增粗，但对股骨皮质面积没有影响。然而，体重变化对股骨皮质面积的增加（或减少）有很大影响：体重变化处于最高三分位数的人群获得的皮质面积是最低三分位数人群的4倍。维生素D受体（VDR）基因型也显著影响股骨干的变化：bb基因型的女性股骨干增粗更明显，皮质面积增加也更多。VDR的作用独立于体重变化和雌激素的作用。股骨干增粗幅度足以表明，整个股骨的力学性能可能会随着年龄的增长而发生显著变化。最后，与普遍看法相反的是，股骨颈虽然变化幅度不大，但随着年龄增长也有显著增粗。
