Department of Engineering Mechanics, Jilin University, Changchun, 130022, People's Republic of China.
School of Civil Engineering, Jilin Jianzhu University, Changchun, 130118, People's Republic of China.
Biomed Eng Online. 2019 Mar 22;18(1):33. doi: 10.1186/s12938-019-0654-1.
Bone tissue displays a hierarchical organization. Mechanical environments influence bone mass and structure. This study aimed to explore the effects of different mechanical stimuli on growing bone properties at macro-micro-nano scales.
Sixty five-week-old female Wistar rats were treadmill exercised at moderate intensity with the speed of 12 m/min, and then randomly divided into five groups according to weight-bearing level. After 8 weeks of experiment, femurs were harvested to perform multiscale tests.
Bone formation was significantly increased by weight-bearing exercise, whereas bone resorption was not significantly inhibited. Trabecular and cortical bone mineral densities showed no significant increase by weight-bearing exercise. The microstructure of trabecular bone was significantly improved by 12% weight-bearing exercise. However, similar positive effects were not observed with further increase in weight-bearing levels. The nanomechanical properties of trabecular bone were not significantly changed by weight-bearing exercise. The macrostrength of whole femur and the nanomechanical properties of cortical bone significantly decreased in the 19% and 26% weight-bearing exercise groups.
When rats ran on the treadmill at moderate intensity during growth period, additional 12% weight-bearing level could significantly increase bone formation, improve microstructure of trabecular bone, as well as maintain the structure and mechanical properties of cortical bone. Excessive weight-bearing level caused no positive effects on the trabecular bone microstructure and properties of cortical bone at all scales. In addition, increased weight-bearing level exerted no significant influence on trabecular and cortical bone mineral densities.
骨骼组织具有层次结构。力学环境会影响骨量和结构。本研究旨在探讨不同力学刺激对宏观-微观-纳米尺度生长骨特性的影响。
65 周龄雌性 Wistar 大鼠以 12m/min 的速度在中等强度下进行跑步机运动，然后根据体重水平随机分为五组。实验 8 周后，取出股骨进行多尺度测试。
负重运动显著增加了骨形成，而骨吸收并未受到显著抑制。负重运动并未显著增加骨小梁和皮质骨的骨密度。12%负重运动显著改善了骨小梁的微观结构。然而，进一步增加负重水平并没有观察到类似的积极效果。负重运动对骨小梁的纳米力学性能没有显著影响。19%和 26%负重运动组的全股骨宏观强度和皮质骨纳米力学性能显著降低。
在生长期，当大鼠在跑步机上以中等强度跑步时，额外的 12%负重水平可以显著增加骨形成，改善骨小梁的微观结构，并维持皮质骨的结构和力学性能。过高的负重水平对骨小梁的微观结构和皮质骨的所有尺度的性能都没有积极影响。此外，增加的负重水平对骨小梁和皮质骨的骨密度没有显著影响。
