Sievänen H, Uusi-Rasi K, Heinonen A, Oja P, Vuori I
UKK Institute, Tampere, Finland.
Osteoporos Int. 1999;10(4):295-302. doi: 10.1007/s001980050230.
The width of long bone diaphyses apparently increase with age, a phenomenon that is suggested to have some positive impact on bone strength. On the other hand, these changes in size that are site-specific may cause a deterioration in the local mechanical integrity of the whole bone. Physical activity and calcium intake are known to be able to modify bone mass and size. It is, however, not known whether these lifestyle habits can modify the postulated disproportionate changes in bone size. To address this question, bone mineral content (BMC)-derived estimates of cross-sectional areas (CSA) of femur and radius in 158 premenopausal (mean age 43, standard deviation 2 years) and 134 postmenopausal (63 (2) years), clinically healthy women with contrasting long-term histories in physical activity and calcium intake were determined from dual-energy X-ray absorptiometry (DXA) data. The DXA-obtained BMC correlated strongly with the actual CSA (r = 0.94) determined with peripheral quantitative computed tomography. The ratios between functionally interrelated CSA data (i.e., (radial shaft CSA/distal radius CSA), (trochanter CSA/femoral neck CSA), (femoral shaft CSA/trochanter CSA) and (femoral shaft CSA/femoral neck CSA)) were considered primary outcome variables. Neither physical activity nor calcium intake separately or interactively were associated with any CSA ratio. Age showed no interaction with physical activity or calcium intake but was independently associated with all CSA ratios, except the ratio of femoral shaft CSA to trochanteric CSA. This study indicated clearly that a preferential reduction in the cross-sectional area occupied by bone mineral occurs disproportionately at the long bone ends as compared with diaphyseal sites, and this apparently inherent, age-associated relative loss seems not to be prevented by physical activity or calcium intake. In particular, given the utmost clinical relevance of the proximal femur region, an observed loss in femoral neck CSA of about 10% in contrast to about a 5% loss in trochanteric CSA warrants further investigation regarding its potential role as a predictor for hip fracture. Not only the local differences in bone composition but also the biomechanical aspects are important factors underlying these apparent changes in CSA at the studied skeletal sites.
长骨干骺端的宽度显然会随着年龄增长而增加，这种现象被认为对骨强度有一些积极影响。另一方面，这些特定部位的尺寸变化可能会导致整个骨骼局部机械完整性的恶化。已知体育活动和钙摄入能够改变骨量和尺寸。然而，尚不清楚这些生活方式习惯是否能改变假定的骨尺寸不成比例变化。为了解决这个问题，我们根据双能X线吸收法（DXA）数据，测定了158名绝经前（平均年龄43岁，标准差2岁）和134名绝经后（63（2）岁）临床健康女性的股骨和桡骨骨矿物质含量（BMC）衍生的横截面积（CSA）估计值，这些女性在体育活动和钙摄入方面有不同的长期经历。通过DXA获得的BMC与外周定量计算机断层扫描测定的实际CSA密切相关（r = 0.94）。功能相关的CSA数据之间的比率（即（桡骨干CSA/桡骨远端CSA）、（转子CSA/股骨颈CSA）、（股骨干CSA/转子CSA）和（股骨干CSA/股骨颈CSA））被视为主要结局变量。体育活动和钙摄入单独或相互作用均与任何CSA比率无关。年龄与体育活动或钙摄入没有相互作用，但除股骨干CSA与转子CSA的比率外，年龄与所有CSA比率均独立相关。这项研究清楚地表明，与骨干部位相比，长骨末端骨矿物质所占横截面积的优先减少不成比例，而且这种明显的、与年龄相关的相对损失似乎无法通过体育活动或钙摄入来预防。特别是，考虑到股骨近端区域的极端临床相关性，观察到股骨颈CSA损失约10%，而转子CSA损失约5%，这一差异值得进一步研究其作为髋部骨折预测指标的潜在作用。在所研究的骨骼部位，不仅骨成分的局部差异，而且生物力学方面都是这些CSA明显变化的重要因素。
