Department of Mechanical Engineering, University of Manitoba, 75A Chancellor's Circle, Winnipeg, MB, R3T 2N2, Canada.
Department of Biomedical Engineering, University of Manitoba, 75A Chancellor's Circle, Winnipeg, MB, R3T 2N2, Canada.
Osteoporos Int. 2018 Jun;29(6):1419-1425. doi: 10.1007/s00198-018-4461-5. Epub 2018 Mar 5.
Femur expansion occurs during normal aging in both men and women. Average bone mineral density (BMD) over a region of interest (ROI) on the femur may considerably decrease with age even in healthy people, and therefore, it is inaccurate if used to monitor treatment-induced bone change.
Areal bone mineral density (BMD), averaged over a region of interest (ROI) on the femur, is widely used in the diagnosis of osteoporosis, assessment of fracture risk, and monitoring of treatment effectiveness. We studied the effect of age-related change in femur geometry on average BMD.
The effect of age-related bone geometric change on averaged BMD was investigated by a cross-sectional study. Total 83 healthy subjects were selected for this study. For each subject, QCT of left femur was scanned using clinical scanner. For each standard volume of interest (VOI), integral/cortical/trabecular bone volume, volumetric BMD (vBMD), and bone mass were measured using QCT Pro; the corresponding areal BMD (aBMD) was projected using CTXA-Hip. Both QCT Pro and CTXA-Hip are commercial software. Correlations between bone volume/density/mass and age were studied.
In the studied population, there was no association between body weight/BMI (body mass index) and age, correlation between normalized femoral neck width and age was 0.24 (p < 0.05). Both aBMD and integral vBMD decreased with age (after adjusted by BMI, for aBMD, r = - 0.21 to - 0.24, p ≤ 0.05 except at trochanter; for vBMD, r = - 0.20 to - 0.31, p < 0.05); cortical vBMD had no significant change; trabecular vBMD decreased at all VOIs except at trochanter (after adjusted by BMI, r = - 0.22 to 0.32, p ≤ 0.05). Integral volume showed slight increase but only significant at the trochanter after adjusted by body size, cortical volume showed insignificant decrease, and trabecular volume considerably increased with age in all VOIs (after adjusted by body size, r = 0.27-0.40, p < 0.05). Integral, cortical, and trabecular mass had no significant change in all VOIs, except that at the trochanter trabecular mass slightly increased with age (r = 0.31, p < 0.05).
Even though there is no change in bone mass, average BMD may considerably decrease with age due to bone expansion. Comparatively, aBMD is less affected than vBMD.
研究与年龄相关的股骨几何变化对平均骨密度（BMD）的影响。
采用横断面研究。共纳入 83 名健康受试者。对每位受试者的左股骨进行 QCT 扫描。使用 QCT Pro 测量每个标准感兴趣区（VOI）的整体/皮质/小梁骨体积、容积 BMD（vBMD）和骨量；使用 CTXA-Hip 投影相应的面积 BMD（aBMD）。QCT Pro 和 CTXA-Hip 均为商用软件。研究骨体积/密度/量与年龄的相关性。
在研究人群中，体重/体重指数（BMI）与年龄无关，股骨颈宽度与年龄的相关性为 0.24（p<0.05）。aBMD 和整体 vBMD 均随年龄下降（经 BMI 校正后，aBMD 的 r 值为-0.21 至-0.24，p≤0.05，除在转子间区外；vBMD 的 r 值为-0.20 至-0.31，p<0.05）；皮质 vBMD 无明显变化；除转子间区外，所有 VOI 的小梁 vBMD 均下降（经 BMI 校正后，r 值为-0.22 至 0.32，p≤0.05）。整体体积略有增加，但仅在经体型校正后在转子间区有统计学意义，皮质体积无明显减少，小梁体积在所有 VOI 中随年龄显著增加（经体型校正后，r 值为 0.27-0.40，p<0.05）。除转子间区的小梁骨量随年龄轻微增加（r=0.31，p<0.05）外，所有 VOI 的整体、皮质和小梁骨量均无明显变化。
尽管骨量没有变化，但由于骨扩张，平均 BMD 可能会随年龄显著下降。相比之下，aBMD 受影响小于 vBMD。
