Opening angle and residual strain in a three-layered model of pig oesophagus |
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| Authors: | Zhao Jingbo Chen Xudong Yang Jian Liao Donghua Gregersen Hans |
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| Affiliation: | 1. Center of Excellence in Visceral Biomechanics and Pain, Aalborg Hospital Science and Innovation Center (AHSIC), Room 404, Aalborg Hospital, Søndre Skovvej 15, DK 9000 Aalborg, Denmark;2. Department of Mechanical Engineering, ITT, Dublin, Ireland;1. Department of Biomedical Engineering, Tulane University, 6823 St. Charles Ave, New Orleans, LA 70118, USA;2. Department of Biomedical Engineering, University of Virginia, 415 Lane Road, Charlottesville, VA 22908, USA;3. Department of Pharmacology, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA;4. Department of Female Pelvic Medicine & Reconstructive Surgery, University of Queensland, Ochsner Clinical School, 1514 Jefferson Highway, New Orleans, LA 70121, USA;1. Giome Academia, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark;2. GIOME and the Key Laboratory for Biorheological Science and Technology of Ministry of Education, Bioengineering College of Chongqing University, Chongqing 400044, China;1. Institute of Biomechanics, Center of Biomedical Engineering, Graz University of Technology, Austria;2. Department of Pediatric- and Adolescent Surgery, Medical University of Graz, Austria;3. Department of Solid Mechanics, Royal Institute of Technology (KTH), Stockholm, Sweden;1. Vascular Surgery Group, 2nd Surgical Clinic, Department of Surgical, Oncological, and Gastroenterological Sciences at the University of Padua, School of Medicine, Padova, Italy;2. Department of Neurosciences at the University of Padua, School of Medicine, Padova, Italy;1. Department of Management and Manufacturing Engineering, Faculty of Engineering and Architecture, University of Zaragoza, Spain;2. Applied Mechanics and Bioengineering, Aragón Institute of Engineering Research (I3A), Mechanical Engineering Department, University of Zaragoza, Spain;3. CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Zaragoza, Spain |
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| Abstract: | 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. |
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