Numerical modelling of abdominal wall mechanics: The role of muscular contraction and intra-abdominal pressure.

Abstract

The biomechanics of the abdominal wall depends on muscular activation, tissue mechanical behavior and Intra-Abdominal Pressure (IAP). In this work, a numerical model of a human abdomen is presented, based on abdominal wall geometry from medical images. Specific constitutive formulations describe tissues mechanical behavior. Connective tissues are modelled as hyperelastic fiber-reinforced materials, while muscular tissues are described by means of a three-element Hill's model. The abdominal cavity is represented by a volume region interacting with the abdominal wall. Numerical analyses are developed by applying a muscular contraction, inducing a volume reduction of the abdominal cavity and a simultaneous IAP increase. Numerical results of abdomen displacement at IAP corresponding to an abdominal crunch are compared with experimental results acquired via 3D laser scanning on a healthy subject. Numerical and experimental results are mutually consistent and show that muscular activation induces a raising in the region adjacent to linea alba along the posterior-anterior direction and a lowering along lateral-medial direction of the abdominal wall sides. The numerical model developed in this work allows a coherent representation of the abdominal wall mechanics.