Curvature reduces bending strains in the quokka femur.
Curvature reduces bending strains in the quokka femur.
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作者：
McCabe K;Henderson K;Pantinople J;Richards HL;Milne N
本研究探讨了短尾矮袋鼠股骨的曲率如何有助于减少运动过程中的弯曲应变。短尾矮袋鼠是一种小袋鼠，但在站立阶段，股骨的弯曲度和肌肉的活动与大多数四足哺乳动物相似。我们的假设是，在站立阶段，髋伸肌和踝关节跖屈肌的作用取代了颅弯曲应变，从而减少了股骨的尾端弯曲。纵向跨越股骨的膝伸肌和双关节肌在尾端弯曲骨（尾端凹侧）产生尾端弯曲应变。这些相反的张力可以相互平衡，从而减少对骨骼的压力。我们通过比较正常弯曲的短尾矮袋鼠股骨的有限元模型和相同骨头的数字拉直版本的性能来验证这一想法。通常弯曲的模型确实比伸直的模型受力更小。为了进一步研究股骨模型中曲率和应变之间的关系，我们还测试了具有相同载荷的超弯曲和反向弯曲版本。模型所经历的曲率和应变之间似乎存在线性关系。这些结果表明，骨的纵向曲率可能是一种可操纵的机制，由此骨可以诱导应变梯度来对抗由习惯性加载引起的应变。
This study explores how curvature in the quokka femur may help to reduce bending strain during locomotion. The quokka is a small wallaby, but the curvature of the femur and the muscles active during stance phase are similar to most quadrupedal mammals. Our hypothesis is that the action of hip extensor and ankle plantarflexor muscles during stance phase place cranial bending strains that act to reduce the caudal curvature of the femur. Knee extensors and biarticular muscles that span the femur longitudinally create caudal bending strains in the caudally curved (concave caudal side) bone. These opposing strains can balance each other and result in less strain on the bone. We test this idea by comparing the performance of a normally curved finite element model of the quokka femur to a digitally straightened version of the same bone. The normally curved model is indeed less strained than the straightened version. To further examine the relationship between curvature and the strains in the femoral models, we also tested an extra-curved and a reverse-curved version with the same loads. There appears to be a linear relationship between the curvature and the strains experienced by the models. These results demonstrate that longitudinal curvature in bones may be a manipulable mechanism whereby bone can induce a strain gradient to oppose strains induced by habitual loading.