Influence of altered geometry and material properties on tissue stress distribution under load in tendinopathic Achilles tendons - A subject-specific finite element analysis.
Influence of altered geometry and material properties on tissue stress distribution under load in tendinopathic Achilles tendons - A subject-specific finite element analysis.
复制标题
改变几何形状和材料特性对肌腱病变跟腱负载下组织应力分布的影响 - 特定主题的有限元分析。
DOI：
10.1016/j.jbiomech.2018.10.027
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发表时间：
2019
影响因子：
2.4
通讯作者：
R. Barrett
中科院分区：
文献类型：
--
作者：
V. Shim;Wencke Hansen;R. Newsham;Leila Nuri;S. Obst;C. Pizzolato;D. Lloyd;R. Barrett
跟腱材料特性和几何形状在跟腱病中改变。本研究的目的是确定相对于健康肌腱，肌腱病患者在次最大收缩期间，材料特性和几何形状改变对游离跟腱应力分布的相对贡献。肌腱病（n = 8）和健康肌腱（n = 8）在休息和次最大自愿等长收缩期间使用三维徒手超声成像。手动分割图像并用于创建受试者特定的有限元模型。与健康肌腱相比，肌腱病患者的游离肌腱的静息横截面积平均大31%。使用数值参数优化方法确定每个肌腱的材料特性，该方法最大限度地减少了实验测量的纵向应变和有限元模型预测的每个肌腱在次最大载荷条件下的应变之间的差异。肌腱病变肌腱的平均杨氏模量比相应的对照值低53%。有限元分析表明，肌腱病变肌腱经历24%的压力下，相同的次最大外部负荷条件相比，健康肌腱。肌腱病变中较低的肌腱应力是由于肌腱横截面积的影响更大，单独减少肌腱应力30%，相比之下，较低的杨氏模量，单独增加肌腱应力8%。这些发现表明，肌腱病变中观察到的更大的肌腱横截面积补偿了显著较低的杨氏模量，从而保护病理肌腱免受过度应力。
Achilles tendon material properties and geometry are altered in Achilles tendinopathy. The purpose of this study was to determine the relative contributions of altered material properties and geometry to free Achilles tendon stress distribution during a sub-maximal contraction in tendinopathic relative to healthy tendons. Tendinopathic (n = 8) and healthy tendons (n = 8) were imaged at rest and during a sub-maximal voluntary isometric contraction using three-dimensional freehand ultrasound. Images were manually segmented and used to create subject-specific finite element models. The resting cross-sectional area of the free tendon was on average 31% greater for the tendinopathic compared to healthy tendons. Material properties for each tendon were determined using a numerical parameter optimisation approach that minimised the difference in experimentally measured longitudinal strain and the strain predicted by the finite element model under submaximal loading conditions for each tendon. The mean Young’s modulus for tendinopathic tendons was 53% lower than the corresponding control value. Finite element analyses revealed that tendinopathic tendons experience 24% less stress under the same submaximal external loading conditions compared to healthy tendons. The lower tendon stress in tendinopathy was due to a greater influence of tendon cross-sectional area, which alone reduced tendon stress by 30%, compared to a lower Young’s modulus, which alone increased tendon stress by 8%. These findings suggest that the greater tendon cross-sectional area observed in tendinopathy compensates for the substantially lower Young’s modulus, thereby protecting pathological tendon against excessive stress.