FINITE ELEMENT MODELING OF ABDOMINAL WALL BIOMECHANICS AFTER HERNIA REPAIR: THE EFFECTS OF MUSCLE CONTRACTION

Understanding the biomechanics of the abdominal wall is fundamental to address nonphysiological conditions like hernias. For this purpose, a computational approach is frequently proposed to assess how the abdominal wall interacts with surgical meshes, to support surgeons in the pre-operative planning. In this paper, numerical models of the abdominal wall are developed to evaluate the effect of muscle contraction on abdominal biomechanics after hernia repair. The geometry of the model is based on medical images from a healthy male subject. Fasciae, linea alba, and aponeuroses are modeled with hyperelastic fiber-reinforced constitutive models, while the contractile behavior of muscles is represented by a Hill-type three-element model. The effect of Intra-Abdominal Pressure (IAP) is simulated through a filled cavity. An epigastric hernia is modeled and virtually repaired with a surgical mesh. Numerical analyses are carried out at increasing IAP in both passive and active muscle states. The results show that surgical meshes reduce the compliance of the abdominal wall and this stiffening effect is more pronounced when considering abdominal contraction. This suggests that muscular contraction should be included in the computational models to mimic the effective mesh-abdomen interaction.