Department of Orthopaedics, University of British Columbia, Vancouver, Canada.
J Bone Miner Res. 2013 Sep;28(9):2035-42. doi: 10.1002/jbmr.1939.
Paradoxically, Asians have lower areal bone mineral density (aBMD), but their rates of hip and wrist fractures are lower than whites. Therefore, we used high-resolution pQCT (HR-pQCT) to determine whether differences in bone macrostructure and microstructure, BMD, and bone strength at the distal radius were apparent in Asian (n = 91, 53 males, 38 females, [mean ± SD] 17.3 ± 1.5 years) and white (n = 89, 46 males, 43 females, 18.1 ± 1.8 years) adolescents and young adults. HR-pQCT outcomes included total BMD (Tt.BMD), trabecular bone volume fraction (BV/TV), and trabecular number (Tb.N), thickness (Tb.Th), and separation (Tb.Sp). We used an automated segmentation algorithm to determine total bone area (Tt.Ar), and cortical BMD (Ct.BMD), porosity (Ct.Po), and thickness (Ct.Th), and we applied finite element (FE) analysis to HR-pQCT scans to estimate bone strength. We fit sex-specific multivariable regression models to compare bone outcomes between Asians and whites, adjusting for age, age at menarche (girls), lean mass, ulnar length, dietary calcium intake, and physical activity. In males, after adjusting for covariates, Asians had 11% greater Tt.BMD, 8% greater Ct.BMD, and 25% lower Ct.Po than whites (p < 0.05). Also, Asians had 9% smaller Tt.Ar and 27% greater Ct.Th (p < 0.01). In females, Asians had smaller Tt.Ar than whites (16%, p < 0.001), but this difference was not significant after adjusting for covariates. Asian females had 5% greater Ct.BMD, 12% greater Ct.Th, and 11% lower Tb.Sp than whites after adjusting for covariates (p < 0.05). Estimated bone strength did not differ between Asian and white males or females. Our study supports the notion of compensatory elements of bone structure that sustain bone strength; smaller bones as observed between those of Asian origin compared with white origin have, on average, more dense, less porous, and thicker cortices. Longitudinal studies are needed to determine whether ethnic differences in bone structure exist in childhood, persist into old age, and whether they influence fracture risk.
具有讽刺意味的是，亚洲人的骨矿物质密度（aBMD）较低，但髋部和腕部骨折率却低于白人。因此，我们使用高分辨率 pQCT（HR-pQCT）来确定亚洲人（n=91，53 名男性，38 名女性，[均值±标准差]17.3±1.5 岁）和白人（n=89，46 名男性，43 名女性，18.1±1.8 岁）青少年和年轻人的桡骨远端骨宏观结构和微观结构、BMD 和骨强度是否存在差异。HR-pQCT 结果包括总 BMD（Tt.BMD）、骨小梁体积分数（BV/TV）和骨小梁数量（Tb.N）、厚度（Tb.Th）和分离度（Tb.Sp）。我们使用自动分割算法来确定总骨面积（Tt.Ar）、皮质 BMD（Ct.BMD）、孔隙率（Ct.Po）和厚度（Ct.Th），并应用有限元（FE）分析对 HR-pQCT 扫描进行估计骨强度。我们拟合了性别特异性多变量回归模型，以比较亚洲人和白人之间的骨骼结果，调整了年龄、初潮年龄（女孩）、瘦体重、尺骨长度、膳食钙摄入量和身体活动。在男性中，在调整了协变量后，亚洲人的 Tt.BMD 增加了 11%，Ct.BMD 增加了 8%，Ct.Po 降低了 25%（p<0.05）。此外，亚洲人的 Tt.Ar 减少了 9%，Ct.Th 增加了 27%（p<0.01）。在女性中，亚洲人的 Tt.Ar 比白人小（16%，p<0.001），但在调整了协变量后，这一差异并不显著。调整协变量后，亚洲女性的 Ct.BMD 增加了 5%，Ct.Th 增加了 12%，Tb.Sp 降低了 11%（p<0.05）。亚洲男性和女性的估计骨强度没有差异。我们的研究支持这样一种观点，即骨骼结构的补偿元素可以维持骨骼强度；与白人相比，亚洲人骨骼较小，皮质密度更高、孔隙率更低、厚度更大。需要进行纵向研究来确定骨骼结构在儿童时期是否存在种族差异，是否持续到老年，以及它们是否会影响骨折风险。
