Trinity Centre for Bioengineering, Department of Mechanical and Manufacturing Engineering, Parsons Building, Trinity College, College Green, Dublin 2, Ireland.
Academic Medical Centre, Department of Radiology, Meibergdreef 9, 1100 DD Amsterdam, The Netherlands.
J Mech Behav Biomed Mater. 2015 Jan;41:68-82. doi: 10.1016/j.jmbbm.2014.09.026. Epub 2014 Oct 7.
Incisional hernia is a severe complication post-laparoscopic/laparotomy surgery that is commonly associated with the linea alba. However, the few studies on the mechanical properties of the linea alba in the literature appear contradictory, possible due to challenges with the physical dimensions of samples and variations in protocol. This study focuses on the tensile mechanical characterisation of the porcine linea alba, as determined by uniaxial and equi-load biaxial testing using image-based strain measurement methods. Results show that the linea alba demonstrated a non-linear elastic, anisotropic behaviour which is often observed in biological soft tissues. The transverse direction (parallel to fibres) was found to be approximately eight times stiffer than the longitudinal (cross-fibre) direction under both uniaxial and equi-load biaxial loading. The equi-load biaxial tensile tests revealed that contraction could occur in the transverse direction despite increasing load, probably due to the anisotropy of the tissue. Optical surface marker tracking and digital image correlation methods were found to greatly improve the accuracy of stretch measurement, resulting in a 75% change in the apparent stiffness compared to using strain derived from machine cross-head displacement. Additionally, a finite element model of the experiments using a combination of an Ogden and fibre exponential power law model for the linea alba was implemented to quantify the effect of clamping and tissue dimensions (which are suboptimal for tensile testing) on the results. The preliminary model results were used to apply a correction factor to the uniaxial experimental data prior to inverse optimisation to derive best fit material parameters for the fibre reinforced Ogden model. Application of the model to the equi-load biaxial case showed some differences compared to the experimental data, suggesting a more complex anisotropic model may be necessary to capture biaxial behaviour. These results provide an improved assessment of the mechanical properties of the porcine linea alba for wound closure and other studies.
切口疝是腹腔镜/剖腹手术后的一种严重并发症,通常与白线有关。然而,文献中关于白线力学性能的少数研究似乎存在矛盾,这可能是由于样本的物理尺寸和方案的变化带来的挑战。本研究专注于使用基于图像的应变测量方法,通过单轴和等负荷双轴测试来确定猪白线的拉伸力学特性。结果表明,白线表现出非线性弹性各向异性行为,这在生物软组织中经常观察到。在单轴和等负荷双轴加载下,横向(与纤维平行)方向的刚度约为纵向(跨纤维)方向的 8 倍。等负荷双轴拉伸试验表明,尽管负荷增加,横向仍可能发生收缩,这可能是由于组织的各向异性所致。光学表面标记跟踪和数字图像相关方法被发现极大地提高了拉伸测量的准确性,与使用机器十字头位移得出的应变相比,表观刚度的变化高达 75%。此外,使用 Ogden 和纤维指数幂律模型的组合对实验进行有限元建模,以量化夹持和组织尺寸(不适合拉伸测试)对结果的影响。初步模型结果用于在逆优化之前对单轴实验数据应用校正因子,以得出纤维增强 Ogden 模型的最佳拟合材料参数。将模型应用于等负荷双轴情况与实验数据存在一些差异,这表明可能需要更复杂的各向异性模型来捕捉双轴行为。这些结果为伤口闭合和其他研究提供了对猪白线力学性能的更好评估。
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