Investigation of colorectal stapled anastomosis by means of experimental and numerical approaches

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Diseases of the colon, the lower part of the digestive tract, are very common and according to the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) more than 600,000 surgical procedures are performed in the United States every year to treat them. Colorectal surgery is performed to repair damage to the colon, rectum, and anus, caused by diseases such as cancer, diverticulitis, intestinal polyps and inflammatory bowel. Note that colorectal cancer is the fourth most common cancer in men and the third most common cancer in women worldwide. During a colon resection, the diseased part of the bowel is removed and the two healthy sections of the colon are reattached which is called a colorectal anastomosis. Anastomotic technique has traditionally been influenced by surgeons’ preference to use either suturing or stapling. Although the later technique is more standardized, quicker and easier than the former one with benefits such as excellent blood control, reduced tissue manipulation and uniformity of tissue adaptation, there remain complications like leakage, stricture and postoperative bleeding. Anastomotic leak is the most serious complication and is a significant cause of morbidity and mortality. Postoperative rates of leak and mortality up to 16% and 3.2% have been reported. Scientific literature shows that technical errors can play a significant role, potentially increasing the risk of postoperative complications.The integrity of the staple lines, which depends on adequate tissue compression, is the primary factor in making a stable anastomosis. Understanding how tissues interact with stapler and staples is the key to improving patient outcomes. The purpose of this research is to study the overall mechanical performance of the end-to-end stapled colorectal anastomosis by means of experimental measurement and finite element simulation in order to initially fill the existing knowledge gap in anastomotic technique. This would help manufacturers to develop optimal stapler configurations and surgeons to handle these instruments correctly, and subsequently to improve patient outcomes. To do this, biomechanical tests will be done to characterize colon tissues. Computational models based on two current circular staplers that are frequently used in colorectal surgery will be developed and simulated. The effect of initial tissue thickness and properties, staple height, number of staple rows and number of staples per row will be investigated through a parametric study. Optimal design of circular stapler for use in minimally invasive surgery will be ascertained. Best-fitted staple heights as a function of the tissue thickness will also be evaluated and discussed for clinical decision making.