Taddei Fulvia, Palmadori Ilaria, Taylor William R, Heller Markus O, Bordini Barbara, Toni Aldo, Schileo Enrico
Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Bologna, Italy.
Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Bologna, Italy.
J Biomech. 2014 Nov 7;47(14):3433-40. doi: 10.1016/j.jbiomech.2014.08.030. Epub 2014 Sep 18.
It has been suggested that the mechanical competence of the proximal femur is preserved with respect to physiological loading conditions rather than accidental overloading, but the consequences of this adaptation for fracture risk in the elderly remain unclear. The goal of the present study was to analyse the safety factor of the human femur in the two most frequent daily activities, level walking and stair climbing, and to understand the dependence, if any, of this safety factor on age, volumetric bone mineral density (vBMD), and gender. To this aim, a finite element study was performed on 200 subjects (116 women and 84 men), spanning a large range of age (23-84 years) and vBMD levels (T-score from 0 to -3.59). For the first time, finite element models that included a subject-specific description of the anatomy and mineral density distribution of each bone were coupled with a personalisation of the loads acting on the proximal femur during movement, including the action of the muscles and their variability across the population. The results demonstrate that the human proximal femur is characterised by a high safety factor (on average five, never reaching fracture threshold), even in the presence of advanced age and low mineral content. These results corroborate the hypothesis that the relationship between loading and mechanical competence is generally preserved in the elderly population for the most frequent motor activities, walking and stair climbing. Interestingly, a decrease of the safety factor was observed with increasing lifespan and reduced mineral content in women but not in men.
有人提出，相对于意外过载而言，股骨近端的力学性能在生理负荷条件下得以保留，但这种适应性变化对老年人骨折风险的影响仍不明确。本研究的目的是分析人体股骨在两种最常见的日常活动（平地行走和爬楼梯）中的安全系数，并了解该安全系数是否依赖于年龄、体积骨密度（vBMD）和性别。为此，对200名受试者（116名女性和84名男性）进行了有限元研究，这些受试者年龄范围较大（23 - 84岁），vBMD水平也各不相同（T值从0到 - 3.59）。首次将包含每块骨骼的个体解剖结构和矿物质密度分布描述的有限元模型与运动过程中作用于股骨近端的负荷（包括肌肉的作用及其在人群中的变异性）个性化相结合。结果表明，即使在高龄和矿物质含量较低的情况下，人体股骨近端的安全系数仍较高（平均为5，从未达到骨折阈值）。这些结果证实了这样一种假设，即在老年人中，对于最常见的运动活动（行走和爬楼梯），负荷与力学性能之间的关系通常得以保留。有趣的是，观察到女性的安全系数随着寿命延长和矿物质含量降低而下降，而男性则没有。
