College of Medicine, Mayo Clinic, Rochester, MN 55905, USA.
J Bone Miner Res. 2012 Mar;27(3):637-44. doi: 10.1002/jbmr.1468.
Previous studies using dual-energy X-ray absorptiometry (DXA) have demonstrated that age is a major predictor of bone fragility and fracture risk independent of areal bone mineral density (aBMD). Although this aBMD-independent effect of age has been attributed to poor bone "quality," the structural basis for this remains unclear. Because high-resolution peripheral quantitative computed tomography (HRpQCT) can assess bone microarchitecture, we matched younger and older subjects for aBMD at the ultradistal radius and assessed for possible differences in trabecular or cortical microstructure by HRpQCT. From an age-stratified, random sample of community adults, 44 women aged <50 years (mean age 41.0 years) were matched to 44 women aged ≥50 years (mean age 62.7 years) by ultradistal radius aBMD (mean ± SEM, younger and older aBMD 0.475 ± 0.011 and 0.472 ± 0.011 g/cm², respectively), and 57 men aged <50 years (mean age 41.3 years) were matched to 57 men aged ≥50 years (mean age 68.1 years; younger and older aBMD both 0.571 ± 0.008 g/cm²). In these matched subjects, there were no sex-specific differences in trabecular microstructural parameters. However, significant differences were noted in cortical microstructure (all p < 0.05): Older women and men had increased cortical porosity (by 91% and 56%, respectively), total cortical pore volume (by 77% and 61%, respectively), and mean cortical pore diameter (by 9% and 8%, respectively) compared with younger subjects. These findings indicate that younger and older women and men matched for DXA aBMD have similar trabecular microarchitecture but clearly different cortical microstructure, at least at an appendicular site represented by the radius. Further studies are needed to define the extent to which this deterioration in cortical microstructure contributes to the aBMD-independent effect of age on bone fragility and fracture risk at the distal radius and other sites of osteoporotic fractures.
先前使用双能 X 射线吸收法 (DXA) 的研究表明，年龄是独立于面积骨密度 (aBMD) 的骨骼脆弱性和骨折风险的主要预测因素。尽管这种年龄对骨密度的独立影响归因于骨“质量”差，但这种结构基础尚不清楚。由于高分辨率外周定量计算机断层扫描 (HRpQCT) 可以评估骨微结构，我们根据桡骨远端的 aBMD 将年轻和老年受试者相匹配，并通过 HRpQCT 评估小梁或皮质微观结构的可能差异。从年龄分层的社区成年人随机样本中，44 名年龄<50 岁（平均年龄 41.0 岁）的女性与 44 名年龄≥50 岁（平均年龄 62.7 岁）的女性按桡骨远端 aBMD 匹配（平均±SEM，年轻和老年 aBMD 分别为 0.475±0.011 和 0.472±0.011 g/cm²），57 名年龄<50 岁（平均年龄 41.3 岁）的男性与 57 名年龄≥50 岁（平均年龄 68.1 岁；年轻和老年 aBMD 均为 0.571±0.008 g/cm²）的男性相匹配。在这些匹配的受试者中，小梁微观结构参数没有性别差异。然而，在皮质微观结构方面存在显著差异（均 p<0.05）：与年轻受试者相比，老年女性和男性的皮质孔隙率增加（分别增加 91%和 56%）、总皮质孔体积增加（分别增加 77%和 61%）和平均皮质孔直径增加（分别增加 9%和 8%）。这些发现表明，在桡骨等四肢部位的 DXA aBMD 匹配的年轻和老年女性和男性具有相似的小梁微观结构，但皮质微观结构明显不同。需要进一步研究以确定这种皮质微观结构恶化在多大程度上导致桡骨远端和其他骨质疏松性骨折部位的年龄对骨密度的独立影响对骨骼脆弱性和骨折风险的影响。
