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Biomechanical Force Prediction for Lengthening of Small Intestine during Distraction Enterogenesis - PubMed

  • ️Wed Jan 01 2020

Biomechanical Force Prediction for Lengthening of Small Intestine during Distraction Enterogenesis

Hadi S Hosseini et al. Bioengineering (Basel). 2020.

Abstract

Distraction enterogenesis has been extensively studied as a potential treatment for short bowel syndrome, which is the most common form of intestinal failure. Different strategies including parenteral nutrition and surgical lengthening to manage patients with short bowel syndrome are associated with high complication rates. More recently, self-expanding springs have been used to lengthen the small intestine using an intraluminal axial mechanical force, where this biomechanical force stimulates the growth and elongation of the small intestine. Differences in physical characteristics of patients with short bowel syndrome would require a different mechanical force-this is crucial in order to achieve an efficient and safe lengthening outcome. In this study, we aimed to predict the required mechanical force for each potential intestinal size. Based on our previous experimental observations and computational findings, we integrated our experimental measurements of patient biometrics along with mechanical characterization of the soft tissue into our numerical simulations to develop a series of computational models. These computational models can predict the required mechanical force for any potential patient where this can be advantageous in predicting an individual's tissue response to spring-mediated distraction enterogenesis and can be used toward a safe delivery of the mechanical force.

Keywords: computational modeling; distraction enterogenesis; short bowel syndrome; small intestine biomechanics.

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Conflict of interest statement

J.C.Y.D. is the founder of Eclipse Regenesis.

Figures

Figure 1
Figure 1

Representative images for distraction enterogenesis experimental setup using intraluminal spring. (A) Relaxed spring. (B) Intra-operative image demonstrating compressed encapsulated spring within a segment of small intestine held in place with two plication sutures. (C) Distracted segment of small intestine with expanded intraluminal spring at time of tissue retrieval.

Figure 2
Figure 2

Representative cross-sectional light micrographs of H&E stained jejunum under normal (zero force) conditions. Black arrows indicate major layers of intestinal wall as mucosa (m), submucosa (sm) and muscularis propria (mp).

Figure 3
Figure 3

Geometrical metrics measurement of small intestine of a wide range of human subjects. Total number of human subjects was n = 61 for the full age range.

Figure 4
Figure 4

Mechanical characterization of pig and human small intestinal tissue. (A) Schematic diagram represents how rectangular specimens were prepared from cylindrical small intestinal tract. (B) Tensile test performed using an Instron type 5565 with anti-slip grips. (C) Representative force-displacement plot of a specimen. (D) Average Young’s modulus for pig and human. Sample numbers are n = 36, 27, 39, 31 for P-intact, P-(mu+sm), P-sm and H-intact, respectively, while subject (pig and human) numbers are n = 7, 5, 6, 7 for P-intact, P-(mu+sm), P-sm and H-intact, respectively.

Figure 5
Figure 5

Finite element model for distraction enterogenesis. (A,B) Frontal and cross-sectional view of the model with mucosa, submucosa and muscularis layers shown in red, yellow/green and red, respectively, in the distracted segment. Model also includes mesentery layer attached to the distracted segment on the mesentery side. Fixed boundary conditions were used for bottom end of mesentery layer. BC and F in (A) are abbreviations for boundary condition and force.

Figure 6
Figure 6

Computational model results after lengthening of distracted segment due to applied mechanical forces at both ends. (A) Representative frontal view of model. (B,C) Stress representation of computational model in R, θ, Z directions.

Figure 7
Figure 7

Dispacement, strain and stress in different directions across the thickness of intestinal wall calculated from computataional model results.

Figure 8
Figure 8

Predicted required mechanical force for different geometrical metrics (radius and thickness) of small intestine for human subjects. (A) Heat map and (B) Regular 3D plot.

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