Bhatia Varun A, Edwards W Brent, Johnson Joshua E, Troy Karen L
J Biomech Eng. 2015 Jan;137(1):0110011-5. doi: 10.1115/1.4028847.
Bone adaptation is understood to be driven by mechanical strains acting on the bone as a result of some mechanical stimuli. Although the strain/adaptation relation has been extensively researched using in vivo animal loading models, it has not been studied in humans,likely due to difficulties in quantifying bone strains and adaptation in living humans. Our purpose was to examine the relationship between bone strain and changes in bone mineral parameters at the local level. Serial computed tomography (CT) scans were used to calculate 14 week changes in bone mineral parameters at the distal radius for 23 women participating in a cyclic in vivo loading protocol (leaning onto the palm of the hand), and 12 women acting as controls. Strains were calculated at the distal radius during the task using validated finite element (FE) modeling techniques. Twelve subregions of interest were selected and analyzed to test the strain/adaptation relation at the local level. A positive relationship between mean energy equivalent strain and percent change in bone mineral density (BMD) (slope=0.96%/1000 le, p<0.05) was observed within experimental,but not control subjects. When subregion strains were grouped by quartile, significant slopes for quartile versus bone mineral content (BMC) (0.24%/quartile) and BMD(0.28%/quartile) were observed. Increases in BMC and BMD were greatest in the highest-strain quartile (energy equivalent strain>539 le). The data demonstrate preliminary prospective evidence of a local strain/adaptation relationship within human bone.These methods are a first step toward facilitating the development of personalized exercise prescriptions for maintaining and improving bone health.
骨骼适应性被认为是由某些机械刺激作用于骨骼所产生的机械应变驱动的。尽管应变/适应性关系已通过体内动物加载模型进行了广泛研究，但尚未在人类中进行研究，这可能是由于难以量化活体人类的骨应变和适应性。我们的目的是在局部水平上研究骨应变与骨矿物质参数变化之间的关系。对23名参与循环体内加载方案（靠在手掌上）的女性以及12名作为对照的女性，使用串行计算机断层扫描（CT）来计算桡骨远端骨矿物质参数在14周内的变化。在任务期间，使用经过验证的有限元（FE）建模技术计算桡骨远端的应变。选择并分析了12个感兴趣的子区域，以测试局部水平上的应变/适应性关系。在实验对象而非对照对象中，观察到平均能量等效应变与骨矿物质密度（BMD）百分比变化之间存在正相关关系（斜率=0.96%/1000με，p<0.05）。当按四分位数对亚区域应变进行分组时，观察到四分位数与骨矿物质含量（BMC）（0.24%/四分位数）和BMD（0.28%/四分位数）之间存在显著斜率。BMC和BMD的增加在最高应变四分位数（能量等效应变>539με）中最大。这些数据证明了人类骨骼内局部应变/适应性关系的初步前瞻性证据。这些方法是朝着制定个性化运动处方以维持和改善骨骼健康迈出的第一步。
