On the defect tolerance of fetal membranes
On the defect tolerance of fetal membranes
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DOI：
10.1098/rsfs.2019.0010
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发表时间：
2019-10-06
期刊：
影响因子：
4.4
通讯作者：
Mazza, Edoardo
中科院分区：
文献类型：
--
作者：
Bircher, Kevin;Ehret, Alexander E.;Mazza, Edoardo
进行了一系列机械实验来量化人类羊膜和绒毛膜的强度和断裂韧性。这些实验通过使用“混合”模型的计算研究进行了补充，该模型包括羊膜胶原纤维网络的明确表示。尽管羊膜厚度小得多，但它比绒毛膜更硬、更坚固、更坚韧，因此可以确定胎膜在变形和断裂行为方面的机械反应。单轴拉伸和断裂测试的数据用于告知和验证计算模型，然后将其应用于合理化含有裂纹状缺陷的组织样品的抗撕裂性测量。实验和计算表明，小于1毫米的缺陷不会显着降低羊膜的强度，但胎儿手术中羊膜穿刺和胎膜缝合时穿孔引起的裂纹尺寸可能大于此值。与之前的实验观察结果一致，计算模型预测由于局部纤维排列和胶原压实，羊膜裂纹尖端的近场非常窄。这种机制可以保护组织免受缺陷的影响，并大大减少多个相邻裂纹的相互作用。这些发现通过相应的实验得到了证实，表明羊膜和绒毛膜的缝合距离分别大于 1 毫米和 3 毫米的多重缝合预计不会发生相互作用。本研究中应用的实验程序和数值模型可用于优化针和/或钉的尺寸和缝合距离，从而降低羊膜穿刺术、胎儿镜和开放性产前手术导致医源性早产胎膜早破的风险。
A series of mechanical experiments were performed to quantify the strength and fracture toughness of human amnion and chorion. The experiments were complemented with computational investigations using a 'hybrid' model that includes an explicit representation of the collagen fibre network of amnion. Despite its much smaller thickness, amnion is shown to be stiffer, stronger and tougher than chorion, and thus to determine the mechanical response of fetal membranes, with respect to both, deformation and fracture behaviour. Data from uniaxial tension and fracture tests were used to inform and validate the computational model, which was then applied to rationalize measurements of the tear resistance of tissue samples containing crack-like defects. Experiments and computations show that the strength of amnion is not significantly reduced by defects smaller than 1 mm, but the crack size induced by perforations for amniocentesis and fetal membrane suturing during fetal surgery might be larger than this value. In line with previous experimental observations, the computational model predicts a very narrow near field at the crack tip of amnion, due to localized fibre alignment and collagen compaction. This mechanism shields the tissue from the defect and strongly reduces the interaction of multiple adjacent cracks. These findings were confirmed through corresponding experiments, showing that no interaction is expected for multiple sutures for an intersuture distance larger than 1 mm and 3 mm for amnion and chorion, respectively. The experimental procedures and numerical models applied in the present study might be used to optimize needle and/or staple dimensions and inter-suture distance, and thus to reduce the risk of iatrogenic preterm premature rupture of the membranes from amniocentesis, fetoscopic and open prenatal surgery.