Zhao Jingbo, Chen Xudong, Yang Jian, Liao Donghua, Gregersen Hans
Center of Excellence in Visceral Biomechanics and Pain, Aalborg Hospital Science and Innovation Center, Room 404, Aalborg Hospital, Søndre Skovvej 15, DK 9000 Aalborg, Denmark.
J Biomech. 2007;40(14):3187-92. doi: 10.1016/j.jbiomech.2007.04.002. Epub 2007 May 22.
Studies of various biological tissues have shown that residual strains are important for tissue function. Since a force balance exists in whole wall thickness specimens cut radially, it is evident that layer separation is an important procedure in the understanding of the meaning of residual stresses and strains. The present study investigated the zero-stress state and residual strain distribution in a three-layer model of the pig oesophagus. The middle part of the oesophagus was obtained from six slaughterhouse pigs. Four 3-mm-wide rings were serially cut from each oesophagus. Two of them were used for separating the wall into mucosa-submucosa, inner and outer muscle layers. The remaining two rings were kept as intact rings. The inner and outer circumferences and wall thickness of different layers in intact and separated rings were measured from the digital images in the no-load state and zero-stress state. The opening angle was measured and the residual strain at the inner and outer surface of different layers and the intact wall were computed. Compared with intact sectors (62.8+/-9.8 degrees ), the opening angles were smaller in the inner muscle sectors (37.2+/-11.4 degrees , P<0.01), whereas the opening angles of mucosa-submucosa (63.9+/-6.8 degrees ) and outer muscle sectors (63.9+/-6.8 degrees ) did not differ (P>0.1). Referenced to the zero-stress state of the intact sectors, the inner and outer residual strains of the intact rings was -0.128+/-0.043 and outer residual strain was 0.308+/-0.032. Referenced to the "true" zero-stress state of separated three-layered sectors, the inner residual strain of intact rings were -0.223+/-0.021 (P<0.01) and 0.071+/-0.022 (P<0.01). Referenced to the "true" zero-stress state, the residual strain distribution of different layers in intact rings was shown that the inner surface residual strain was negative at mucosa-submucosa and inner muscle layers and was positive at outer muscle layer, whereas the outer surface residual strain was negative at the mucosa-submucosa layer and positive at the inner and outer muscle layers. For the separated different layered rings, the inner residual strain was negative and outer residual strain was positive; however, the absolute values did not differ (P>0.1). In conclusion, it is possible to microsurgically separate the oesophagus into three layers, i.e., mucosa-submucosa, inner muscle and outer muscle layers, the residual strain differ between the layers, and the residual strain distribution was more uniform after the layers were separated.
对各种生物组织的研究表明，残余应变对组织功能很重要。由于在径向切割的全壁厚标本中存在力平衡，显然层分离是理解残余应力和应变意义的重要步骤。本研究调查了猪食管三层模型中的零应力状态和残余应变分布。食管中部取自六头屠宰场的猪。从每个食管上依次切下四个3毫米宽的环。其中两个用于将管壁分离为黏膜 - 黏膜下层、内层和外层肌肉层。其余两个环保持完整。在无负载状态和零应力状态下，从数字图像中测量完整环和分离环中不同层的内外周长和壁厚。测量开口角度，并计算不同层和完整管壁内外表面的残余应变。与完整扇形（62.8±9.8度）相比，内层肌肉扇形的开口角度较小（37.2±11.4度，P<0.01），而黏膜 - 黏膜下层（63.9±6.8度）和外层肌肉扇形（63.9±6.8度）的开口角度无差异（P>0.1）。以完整扇形的零应力状态为参考，完整环的内外残余应变分别为-０.128±0.043，外层残余应变为0.308±0.032。以分离的三层扇形区域的“真实”零应力状态为参考，完整环的内层残余应变分别为-0.223±0.021（P<0.01）和0.071±0.022（P<0.01）。以“真实 ”零应力状态为参考，完整环中不同层的残余应变分布表明，黏膜 - 黏膜下层和内层肌肉层的内表面残余应变呈负，外层肌肉层呈正，而黏膜 - 黏膜下层的外表面残余应变呈负，内层和外层肌肉层呈正。对于分离的不同层环，内层残余应变呈负，外层残余应变呈正；然而，绝对值无差异（P>0.1）。总之，通过显微手术将食管分离为三层，即黏膜 - 黏膜下层、内层肌肉和外层肌肉层是可行的，各层之间的残余应变不同，且层分离后残余应变分布更均匀。
