Tensile properties of the rectal and sigmoid colon: a comparative analysis of human and porcine tissue

Abstract

For many patients, rectal catheters are an effective means to manage bowel incontinence. Unfortunately, the incidence of catheter leakage in these patients remains troublingly high. Matching the mechanical properties of the catheter and the surrounding tissue may improve the catheter seal and reduce leakage. However, little data is available on the mechanical properties of colorectal tissue. Therefore, our group examined the mechanical properties of colorectal tissue obtained from both a common animal model and humans. Uniaxial tension tests were performed to determine the effects of location, orientation, and species (porcine and human) on bowel tissue tensile mechanical properties. Bowel tissue ultimate strength, elongation at failure, and elastic modulus were derived from these tests and statistically analyzed. Ultimate tensile strength (0.58 MPa, 0.87 MPa), elongation at failure (113.19%, 62.81%), and elastic modulus (1.83 MPa, 5.18 MPa) for porcine and human samples respectively exhibited significant differences based on species. Generally, human tissues were stronger and less compliant than their porcine counterparts. Furthermore, harvest site location and testing orientation significantly affected several mechanical properties in porcine derived tissues, but very few in human tissues. The data suggests that porcine colorectal tissue does not accurately model human colorectal tissue mechanical properties. Ultimately, the tensile properties reported herein may be used to help guide the design of next generation rectal catheters with tissue mimetic properties, as well as aid in the development of physical and computer based bowel models.

Hypertension-linked mechanical changes of rat gut

“…7). Previous methods to study the mechanical behavior of the colon have resulted in a wide range of values for modulus spanning 5–6000 kPa [7–12]. Our calculated values for steady-state moduli fall within this range, and our observation of stiffening with disease parallels findings from studies of colitis and Crohn’s Disease [9–11].…”

“…Uniaxial and biaxial test (dashed lines) results range from 850 to 6480 kPa (Christensen et al [7] and Bellini et al [8]), but tests using mesoscale compression/indentation methodology (solid line) showed a significantly lower modulus ranging from 0.3 to 58.5 kPa (Stidham et al [9], Kim et al [10], Johnson et al [11], and Stewart et al, this work and small intestine data unpublished). Despite differences that can occur between species, age of the animal, and ex-vivo conditions [12], the high variability of this data over three orders of magnitude warrants more consistent testing and reporting methods for the characterization of soft tissue.…”

Technical Aspects in Esophageal Lengthening: An Investigation of Traction Procedures and Suturing Techniques in Swine

“…20 The advantages of pigs in experimental pediatric esophageal surgery have been pointed out earlier, 21 but the tissue equivalence of porcine and human esophagi 11 make their use compelling, especially as it is a feature unique to the esophagus, but not to other organs, for example, the colon. 22 We found no difference between using a USP 4-0 or USP 5-0 suture concerning the breaking strength for a simple stitch with a distance of 8 mm from the cut surface. We used 8 mm as a suture bite because previous experiments suggested optimal strength.…”

A Continuous Suture Anastomosis Outperforms a Simple Interrupted Suture Anastomosis in Esophageal Elongation

“…[20][21][22] Moreover, tissue equivalence of porcine and human esophagi 31 supports using swine as an experimental model, in particular because tissue equivalence is a feature unique to the esophagus, but not to other organs, for example, the colon. 32 There has been an ongoing debate on the right anastomotic technique in adult esophageal surgery. The most common techniques have narrowed to stapled versus continuous hand-sewn anastomoses, 33 but recently also included robotic-assisted anastomoses.…”