Variation of Passive Biomechanical Properties of the Small Intestine along Its Length: Microstructure-Based...

Area of Science:

• Biomechanics
• Biomaterials Science
• Gastroenterology

Background:

• Multiaxial testing of the small intestinal wall is vital for understanding its biomechanical properties and developing material models.
• Limited data and existing material models hinder comprehensive analysis of small intestine biomechanics.

Purpose of the Study:

• To develop a microstructure-based material model for the small intestine.
• To investigate variations in passive biomechanical properties along the length of the small intestine.

Main Methods:

• Rat small intestinal tissue was divided into eight segments for inflation/extension testing.
• A fiber-reinforced, hyper-elastic, and anisotropic material model was employed to characterize tissue response.
• Parametric analysis was performed to refine the model and assess the contribution of different tissue components.

Main Results:

• A reduced neo-Hookean model incorporating axial and diagonal fiber families provided accurate fitting without over-parameterization.
• The primary direction of anisotropy was approximately 35° to the axial direction, aligning with collagen fiber orientation.
• Estimated model parameters showed significant variations across the duodenum, jejunum, and ileum, correlating with histological differences.

Conclusions:

• The developed microstructure-based model effectively captures the passive biomechanical behavior of the small intestine.
• Significant regional variations in biomechanical properties exist along the small intestine's length.
• These findings provide a foundation for more accurate computational modeling of gastrointestinal function.