1
|
Durcan C, Hossain M, Chagnon G, Perić D, Girard E. Mechanical experimentation of the gastrointestinal tract: a systematic review. Biomech Model Mechanobiol 2024; 23:23-59. [PMID: 37935880 PMCID: PMC10901955 DOI: 10.1007/s10237-023-01773-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 09/10/2023] [Indexed: 11/09/2023]
Abstract
The gastrointestinal (GI) organs of the human body are responsible for transporting and extracting nutrients from food and drink, as well as excreting solid waste. Biomechanical experimentation of the GI organs provides insight into the mechanisms involved in their normal physiological functions, as well as understanding of how diseases can cause disruption to these. Additionally, experimental findings form the basis of all finite element (FE) modelling of these organs, which have a wide array of applications within medicine and engineering. This systematic review summarises the experimental studies that are currently in the literature (n = 247) and outlines the areas in which experimentation is lacking, highlighting what is still required in order to more fully understand the mechanical behaviour of the GI organs. These include (i) more human data, allowing for more accurate modelling for applications within medicine, (ii) an increase in time-dependent studies, and (iii) more sophisticated in vivo testing methods which allow for both the layer- and direction-dependent characterisation of the GI organs. The findings of this review can also be used to identify experimental data for the readers' own constitutive or FE modelling as the experimental studies have been grouped in terms of organ (oesophagus, stomach, small intestine, large intestine or rectum), test condition (ex vivo or in vivo), number of directions studied (isotropic or anisotropic), species family (human, porcine, feline etc.), tissue condition (intact wall or layer-dependent) and the type of test performed (biaxial tension, inflation-extension, distension (pressure-diameter), etc.). Furthermore, the studies that investigated the time-dependent (viscoelastic) behaviour of the tissues have been presented.
Collapse
Affiliation(s)
- Ciara Durcan
- Zienkiewicz Centre for Modelling, Data and AI, Faculty of Science and Engineering, Swansea University, Swansea, SA1 8EN, UK
- Université Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France
| | - Mokarram Hossain
- Zienkiewicz Centre for Modelling, Data and AI, Faculty of Science and Engineering, Swansea University, Swansea, SA1 8EN, UK.
| | - Grégory Chagnon
- Université Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France
| | - Djordje Perić
- Zienkiewicz Centre for Modelling, Data and AI, Faculty of Science and Engineering, Swansea University, Swansea, SA1 8EN, UK
| | - Edouard Girard
- Université Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France
- Laboratoire d'Anatomie des Alpes Françaises, Université Grenoble Alpes, Grenoble, France
| |
Collapse
|
2
|
Caulk AW, Chatterjee M, Barr SJ, Contini EM. Mechanobiological considerations in colorectal stapling: Implications for technology development. Surg Open Sci 2023; 13:54-65. [PMID: 37159635 PMCID: PMC10163679 DOI: 10.1016/j.sopen.2023.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/07/2023] [Accepted: 04/08/2023] [Indexed: 05/11/2023] Open
Abstract
Technological advancements in minimally invasive surgery have led to significant improvements in patient outcomes. One such technology is surgical stapling, which has evolved into a key component of many operating rooms by facilitating ease and efficacy in resection and repair of diseased or otherwise compromised tissue. Despite such advancements, adverse post-operative outcomes such as anastomotic leak remain a persistent problem in surgical stapling and its correlates (i.e., hand-sewing), most notably in low colorectal or coloanal procedures. Many factors may drive anastomotic leaks, including tissue perfusion, microbiome composition, and patient factors such as pre-existing disease. Surgical intervention induces complex acute and chronic changes to the mechanical environment of the tissue; however, roles of mechanical forces in post-operative healing remain poorly characterized. It is well known that cells sense and respond to their local mechanical environment and that dysfunction of this "mechanosensing" phenomenon contributes to a myriad of diseases. Mechanosensing has been investigated in wound healing contexts such as dermal incisional and excisional wounds and development of pressure ulcers; however, reports investigating roles of mechanical forces in adverse post-operative gastrointestinal wound healing are lacking. To understand this relationship well, it is critical to understand: 1) the intraoperative material responses of tissue to surgical intervention, and 2) the post-operative mechanobiological response of the tissue to surgically imposed forces. In this review, we summarize the state of the field in each of these contexts while highlighting areas of opportunity for discovery and innovation which can positively impact patient outcomes in minimally invasive surgery.
Collapse
Affiliation(s)
- Alexander W. Caulk
- Corresponding author at: 60 Middletown Ave., North Haven, CT 06473, USA.
| | | | | | | |
Collapse
|
3
|
Zhao Y, Siri S, Feng B, Pierce DM. Computational Modeling of Mouse Colorectum Capturing Longitudinal and Through-thickness Biomechanical Heterogeneity. J Mech Behav Biomed Mater 2021; 113:104127. [PMID: 33125950 PMCID: PMC8053306 DOI: 10.1016/j.jmbbm.2020.104127] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 09/03/2020] [Accepted: 10/01/2020] [Indexed: 12/19/2022]
Abstract
Mechanotransduction, the encoding of local mechanical stresses and strains at sensory endings into neural action potentials at the viscera, plays a critical role in evoking visceral pain, e.g., in the distal colon and rectum (colorectum). The wall of the colorectum is structurally heterogeneous, including two major composites: the inner consists of muscular and submucosal layers, and the outer consists of circular muscular, intermuscular, longitudinal muscular, and serosal layers. In fact the colorectum presents biomechanical heterogenity across both the longitudinal and through-thickness directions thus highlighting the differential roles of sensory nerve endings within different regions of the colorectum in visceral mechanotransduction. We determined constitutive models and model parameters for individual layers of the colorectum from three longitudinal locations (colonic, intermediate, and distal) using nonlinear optimization to fit our experimental results from biaxial extension tests on layer-separated colorectal tissues (mouse model, 7×7 mm2, Siri et al., Am. J. Physiol. Gastrointest. Liver Physiol. 316, G473-G481 and 317, G349-G358), and quantified the thicknesses of the layers. In this study we also quantified the residual stretches stemming from separating colorectal specimens into inner and outer composites and we completed new pressure-diameter mechanical testing to provide an additional validation case. We implemented the constitutive equations and created two-layered, 3-D finite element models using FEBio (University of Utah), and incorporated the residual stretches. We validated the modeling framework by comparing FE-predicted results for both biaxial extension testing of bulk specimens of colorectum and pressure-diameter testing of bulk segments against corresponding experimental results independent of those used in our model fitting. We present the first theoretical framework to simulate the biomechanics of distal colorectum, including both longitudinal and through-thickness heterogeneity, based on constitutive modeling of biaxial extension tests of colon tissues from mice. Our constitutive models and modeling framework facilitate analyses of both fundamental questions (e.g., the impact of organ/tissue biomechanics on mechanotransduction of the sensory nerve endings, structure-function relationships, and growth and remodeling in health and disease) and specific applications (e.g., device design, minimally invasive surgery, and biomedical research).
Collapse
Affiliation(s)
- Y Zhao
- Department of Mechanical Engineering, University of Connecticut, Storrs, CT, USA; Department of Biomedical Engineering, University of Connecticut, Storrs, CT, USA
| | - S Siri
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, USA
| | - B Feng
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, USA
| | - D M Pierce
- Department of Mechanical Engineering, University of Connecticut, Storrs, CT, USA; Department of Biomedical Engineering, University of Connecticut, Storrs, CT, USA.
| |
Collapse
|
4
|
Silva CHS, Amarante MSM, Cordero-Schmidt E, Vargas-Mena JC, Barros MAS, Sartori SSR, Morais DB. Comparative Study on the Small and Large Intestines of the Bats Artibeus planirostris and Diphylla ecaudata: Influence of Food Habits on Morphological Parameters. ACTA CHIROPTEROLOGICA 2020. [DOI: 10.3161/15081109acc2020.22.2.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Carlos H. S. Silva
- Departament of Morphology, Center of Biosciences, Federal University of Rio Grande do Norte, Natal-RN, 59078-970, Brazil
| | - Maria S. M. Amarante
- Departament of Morphology, Center of Biosciences, Federal University of Rio Grande do Norte, Natal-RN, 59078-970, Brazil
| | - Eugenia Cordero-Schmidt
- Departament of Ecology, Center of Biosciences, Federal University of Rio Grande do Norte, Natal-RN, 59078-970, Brazil
| | - Juan C. Vargas-Mena
- Departament of Ecology, Center of Biosciences, Federal University of Rio Grande do Norte, Natal-RN, 59078-970, Brazil
| | - Marília A. S. Barros
- Departament of Zoology, Center of Biological Sciences, Federal University of Pernambuco, Recife-PE, 50670-901, Brazil
| | - Sirlene S. R. Sartori
- Departament of Animal Biology, Center of Biological Sciences and Health, Federal University of Viçosa, Viçosa-MG, 36570-900, Brazil
| | - Danielle B. Morais
- Departament of Morphology, Center of Biosciences, Federal University of Rio Grande do Norte, Natal-RN, 59078-970, Brazil
| |
Collapse
|
5
|
The Macro- and Micro-Mechanics of the Colon and Rectum I: Experimental Evidence. Bioengineering (Basel) 2020; 7:bioengineering7040130. [PMID: 33086503 PMCID: PMC7712174 DOI: 10.3390/bioengineering7040130] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/12/2020] [Accepted: 10/15/2020] [Indexed: 12/14/2022] Open
Abstract
Many lower gastrointestinal diseases are associated with altered mechanical movement and deformation of the large intestine, i.e., the colon and rectum. The leading reason for patients' visits to gastrointestinal clinics is visceral pain, which is reliably evoked by mechanical distension rather than non-mechanical stimuli such as inflammation or heating. The macroscopic biomechanics of the large intestine were characterized by mechanical tests and the microscopic by imaging the load-bearing constituents, i.e., intestinal collagen and muscle fibers. Regions with high mechanical stresses in the large intestine (submucosa and muscularis propria) coincide with locations of submucosal and myenteric neural plexuses, indicating a functional interaction between intestinal structural biomechanics and enteric neurons. In this review, we systematically summarized experimental evidence on the macro- and micro-scale biomechanics of the colon and rectum in both health and disease. We reviewed the heterogeneous mechanical properties of the colon and rectum and surveyed the imaging methods applied to characterize collagen fibers in the intestinal wall. We also discussed the presence of extrinsic and intrinsic neural tissues within different layers of the colon and rectum. This review provides a foundation for further advancements in intestinal biomechanics by synergistically studying the interplay between tissue biomechanics and enteric neurons.
Collapse
|
6
|
ZHANG PEISEN, LI JING, HAO YANG, CIUTI GASTONE, ARAI TATSUO, HUANG QIANG, DARIO PAOLO. EXPERIMENTAL ASSESSMENT OF INTACT COLON DEFORMATION UNDER LOCAL FORCES APPLIED BY MAGNETIC CAPSULE ENDOSCOPES. J MECH MED BIOL 2020. [DOI: 10.1142/s0219519420500414] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Magnetically guided capsule endoscopy is a promising technology for clinical application. A platform that simulates the magnetic capsule endoscope system is built to study the deformation process of the colon when its lumen suffers local forces. Force-displacement curves of the porcine large intestine under various experiment conditions, including different loading positions (haustra or taeniae coli), loading directions, colon inner pressures and specimen lengths, were measured to analyze the mechanical behavior of the intact large intestine during interactions with magnetic capsule endoscopes. In the practical application of the magnetic capsule endoscope, these data are imperative to optimize the control scheme and reduce operation risks. Based on our experiments, the taeniae coli of the intact large intestine show higher linear stiffness than the haustra, and inflation reduces the linear stiffness of the colon. Magnetic capsule with small edge radii can more easily damage or even perforate the colon. Based on our test results, we suggest that the force applied to the colon should be limited to below 17[Formula: see text]N when the capsule is actuated forward along the colon and limited to below 10[Formula: see text]N when the capsule is vertical to the colon during lesion screening.
Collapse
Affiliation(s)
- PEISEN ZHANG
- Intelligent Robotics Institute, School of Mechatronical Engineering, Beijing Institute of Technology, Beijing, P. R. China
| | - JING LI
- Beijing Advanced Innovation Center for Intelligent Robots and Systems, Beijing Institute of Technology, Beijing, P. R. China
| | - YANG HAO
- Intelligent Robotics Institute, School of Mechatronical Engineering, Beijing Institute of Technology, Beijing, P. R. China
| | - GASTONE CIUTI
- Beijing Advanced Innovation Center for Intelligent Robots and Systems, Beijing Institute of Technology, Beijing, P. R. China
- The Biorobotics Institute, Scuola Superiore Sant’Anna, 56025, Pontedera, Pisa, Italy
| | - TATSUO ARAI
- Beijing Advanced Innovation Center for Intelligent Robots and Systems, Beijing Institute of Technology, Beijing, P. R. China
| | - QIANG HUANG
- Intelligent Robotics Institute, School of Mechatronical Engineering, Beijing Institute of Technology, Beijing, P. R. China
- Beijing Advanced Innovation Center for Intelligent Robots and Systems, Beijing Institute of Technology, Beijing, P. R. China
| | - PAOLO DARIO
- Beijing Advanced Innovation Center for Intelligent Robots and Systems, Beijing Institute of Technology, Beijing, P. R. China
- The Biorobotics Institute, Scuola Superiore Sant’Anna, 56025, Pontedera, Pisa, Italy
| |
Collapse
|
7
|
Puértolas S, Peña E, Herrera A, Ibarz E, Gracia L. A comparative study of hyperelastic constitutive models for colonic tissue fitted to multiaxial experimental testing. J Mech Behav Biomed Mater 2020; 102:103507. [DOI: 10.1016/j.jmbbm.2019.103507] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 10/04/2019] [Accepted: 10/23/2019] [Indexed: 01/16/2023]
|
8
|
Tobella J, Pons-Beltrán V, Santonja A, Sánchez C, Campillo-Fernández AJ, Vidaurre A. Analysis of the ‘Endoworm’ prototype’s ability to grip the bowel in in vitro and ex vivo models. Proc Inst Mech Eng H 2020; 234:468-477. [DOI: 10.1177/0954411920901414] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Access to the small bowel by means of an enteroscope is difficult, even using current devices such as single-balloon or double-balloon enteroscopes. Exploration time and patient discomfort are the main drawbacks. The prototype ‘Endoworm’ analysed in this paper is based on a pneumatic translation system that, gripping the bowel, enables the endoscope to move forward while the bowel slides back over its most proximal part. The grip capacity is related to the pressure inside the balloon, which depends on the insufflate volume of air. Different materials were used as in vitro and ex vivo models: rigid polymethyl methacrylate, flexible silicone, polyester urethane and ex vivo pig small bowel. On measuring the pressure–volume relationship, we found that it depended on the elastic properties of the lumen and that the frictional force depended on the air pressure inside the balloons and the lumen’s elastic properties. In the presence of a lubricant, the grip on the simulated intestinal lumens was drastically reduced, as was the influence of the lumen’s properties. This paper focuses on the Endoworm’s ability to grip the bowel, which is crucial to achieving effective endoscope forward advance and bowel folding.
Collapse
Affiliation(s)
- Javier Tobella
- Centre for Biomaterials and Tissue Engineering (CBIT), Universitat Politècnica de València, Valencia, Spain
| | - Vicente Pons-Beltrán
- Digestive Endoscopy Unit, Digestive Diseases Department, La Fe Polytechnic University Hospital, Valencia, Spain
- Gastrointestinal Endoscopy Research Group, IIS Hospital La Fe, Valencia, Spain
| | | | - Carlos Sánchez
- Department of Electronic Engineering, Universitat Politècnica de València, Valencia, Spain
| | | | - Ana Vidaurre
- Centre for Biomaterials and Tissue Engineering (CBIT), Universitat Politècnica de València, Valencia, Spain
- Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid, Spain
| |
Collapse
|
9
|
An Experimental Study of Intraluminal Hyperpressure Reproducing a Gastric Leak Following a Sleeve Gastrectomy. Obes Surg 2019; 29:2773-2780. [DOI: 10.1007/s11695-019-03924-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
10
|
Mechanical effects of load speed on the human colon. J Biomech 2019; 91:102-108. [PMID: 31133391 DOI: 10.1016/j.jbiomech.2019.05.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 05/04/2019] [Accepted: 05/11/2019] [Indexed: 12/15/2022]
Abstract
The aim of this study was to examine the mechanical behavior of the colon using tensile tests under different loading speeds. Specimens were taken from different locations of the colonic frame from refrigerated cadavers. The specimens were submitted to uniaxial tensile tests after preconditioning using a dynamic load (1 m/s), intermediate load (10 cm/s), and quasi-static load (1 cm/s). A total of 336 specimens taken from 28 colons were tested. The stress-strain analysis for longitudinal specimens indicated a Young's modulus of 3.17 ± 2.05 MPa under dynamic loading (1 m/s), 1.74 ± 1.15 MPa under intermediate loading (10 cm/s), and 1.76 ± 1.21 MPa under quasi-static loading (1 cm/s) with p < 0.001. For the circumferential specimen, the stress-strain curves indicated a Young's modulus of 3.15 ± 1.73 MPa under dynamic loading (1 m/s), 2.14 ± 1.3 MPa under intermediate loading (10 cm/s), and 0.63 ± 1.25 MPa under quasi-static loading (1 cm/s) with p < 0.001. The curves reveal two types of behaviors of the colon: fast break behavior at high speed traction (1 m/s) and a lower break behavior for lower speeds (10 cm/s and 1 cm/s). The circumferential orientation required greater levels of stress and strain to obtain lesions than the longitudinal orientation. The presence of taeniae coli changed the mechanical response during low-speed loading. Colonic mechanical behavior varies with loading speeds with two different types of mechanical behavior: more fragile behavior under dynamic load and more elastic behavior for quasi-static load.
Collapse
|
11
|
Massalou D, Masson C, Afquir S, Baqué P, Arnoux PJ, Bège T. Influence of gender, age, shelf-life, and conservation method on the biomechanical behavior of colon tissue under dynamic solicitation. Clin Biomech (Bristol, Avon) 2019; 65:34-40. [PMID: 30954683 DOI: 10.1016/j.clinbiomech.2019.03.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Revised: 03/19/2019] [Accepted: 03/27/2019] [Indexed: 02/07/2023]
Abstract
BACKGROUND Data from biomechanical tissue sample studies of the human digestive tract are highly variable. The aim of this study was to investigate 4 factors which could modify the mechanical response of human colonic specimens placed under dynamic solicitation until tissue rupture: gender, age, shelf-life and conservation method. METHODS We performed uniaxial dynamic tests of human colonic specimens. Specimens were taken according to three different protocols: refrigerated cadavers without embalming, embalmed cadavers and fresh colonic tissue. A total of 143 specimens were subjected to tensile tests, at a speed of 1 m s-1. FINDINGS Young's modulus of the different conservation protocols are as follows: embalmed, 3.08 ± 1.99; fresh, 2.97 ± 2.59; and refrigerated 3.17 ± 2.05. The type of conservation does not modify the stiffness of the tissue (p = 0.26) but does modify the stress necessary for rupture (p < 0.001) and the strain required to obtain lesions of the outer layer and the inner layer (p < 0.001 and p < 0.05, respectively). Gender is also a factor responsible for a change in the mechanical response of the colon. The age of the subjects and the shelf-life of the bodies did not represent factors influencing the mechanical behavior of the colon (p > 0.05). INTERPRETATION The mechanical response of the colon tissue showed a biphasic injury process depending on gender and method of preservation. The age and shelf-life of anatomical subjects do not alter the mechanical response of the colon.
Collapse
Affiliation(s)
- D Massalou
- Emergency Surgery Unit, University Hospital of Nice, CHU de Nice Hôpital Pasteur 2, Université de Nice Sophia-Antipolis, France; Biomechanical Applied Laboratory, UMRT24, IFSTTAR, Aix-Marseille University, France.
| | - C Masson
- Biomechanical Applied Laboratory, UMRT24, IFSTTAR, Aix-Marseille University, France.
| | - S Afquir
- Biomechanical Applied Laboratory, UMRT24, IFSTTAR, Aix-Marseille University, France
| | - P Baqué
- Emergency Surgery Unit, University Hospital of Nice, CHU de Nice Hôpital Pasteur 2, Université de Nice Sophia-Antipolis, France.
| | - P-J Arnoux
- Biomechanical Applied Laboratory, UMRT24, IFSTTAR, Aix-Marseille University, France.
| | - T Bège
- Department of Visceral Surgery, AP-HM Hôpital Nord, Aix-Marseille University, France; Biomechanical Applied Laboratory, UMRT24, IFSTTAR, Aix-Marseille University, France.
| |
Collapse
|
12
|
Johnson S, Schultz M, Scholze M, Smith T, Woodfield J, Hammer N. How much force is required to perforate a colon during colonoscopy? An experimental study. J Mech Behav Biomed Mater 2018; 91:139-148. [PMID: 30579111 DOI: 10.1016/j.jmbbm.2018.11.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 11/08/2018] [Accepted: 11/23/2018] [Indexed: 01/16/2023]
Abstract
INTRODUCTION Colonoscopy is a commonly-performed procedure to diagnose pathology of the large intestine. Perforation of the colon is a rare but feared complication. It is currently unclear how much force is actually required to cause such injury nor how this is altered in certain diseases. Our aim was to analyze the forces required to perforate the colon in experiments using porcine tissues. METHODS Using 3D printing technology, models of two commercially available colonoscope heads were printed under three configurations: straight (I), 90°- bent (L) and fully bent (U). Samples of porcine colon were assessed with the models and configurations under perpendicular and angular load application and these data compared to the maximum force typically exerted by experienced colonoscopists. RESULTS The force required for perforation was significantly lower for the I compared to the L of the larger colonoscope head configuration under angular loading (14.1 vs. 46.5 N). Similar differences were found for linear stiffness when loaded (I vs. L small when loaded perpendicular: 0.8 vs. 2.4 N/mm, I vs. L large when loaded angled 0.7 vs. 2.1 N/mm). The mode and site of failure varied significantly between the scopes, with delamination of the mucosa/submucosa below the sample (96%) for the I, blunt mucosa/submucosa/muscularis failure adjacent to the loading site (77%) for the L, and failure of all colon layers lateral to the loading site (59%) for the U configuration, respectively. Perpendicular and angulated loading resulted in similar load-deformation values. Maximum forces typically exerted by colonoscopists averaged 13.9-27.9 N, depending on the colonoscope model and head configuration. DISCUSSION The force required for colon perforation varies depending on the type mode of loading and is likely lower than the force an experienced colonoscopist would exert in daily practice. There is a real risk of perforation, especially when the end of the scope is advancing directly into the colonic wall. The given experimental setup allowed to obtain reliable data of the colon in a standardized scenario, forming the basis for further experiments.
Collapse
Affiliation(s)
- Steve Johnson
- Department of Medicine, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand; Gastroenterology Unit, Southern District Health Board, Dunedin Hospital, Dunedin, New Zealand
| | - Michael Schultz
- Department of Medicine, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand; Gastroenterology Unit, Southern District Health Board, Dunedin Hospital, Dunedin, New Zealand
| | - Mario Scholze
- Department of Anatomy, University of Otago, Dunedin, New Zealand Department of Anatomy, Dunedin, New Zealand; Institute of Materials Science and Engineering, Chemnitz University of Technology, Chemnitz, Germany
| | - Troy Smith
- Department of Anatomy, University of Otago, Dunedin, New Zealand Department of Anatomy, Dunedin, New Zealand
| | - John Woodfield
- Department of Surgical Sciences, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Niels Hammer
- Department of Anatomy, University of Otago, Dunedin, New Zealand Department of Anatomy, Dunedin, New Zealand; Department of Orthopedic and Trauma Surgery, University of Leipzig, Germany; Fraunhofer Institute for Machine Tools and Forming Technology IWU, Dresden, Germany.
| |
Collapse
|