Towards Mechanical Compatibility: Optimization of an Implant Used in Ventral Hernia Repair

Effective treatment of abdominal hernia with synthetic implants requires a prosthetic material biologically and mechanically compatible with the tissue. The mechanical compatibility is particularly important because the human abdominal wall is a complex multilayer structure and its properties may have individual characteristics that are not fully known. To address this issue, we propose a novel approach to optimal implant design for hernia repair by modifying locally the implant thickness to adapt it to the applied loads. Compatibility criteria are translated to an objective function that is to be minimized in the optimization procedure. The objective function is designed to equalize and minimize forces at the tissue-implant interface and minimize implant deflection. This reduces vulnerability to failure without hindering functionality. The input data are taken from in vivo tests on human subjects performed using digital image correlation and applied to a computational model of the implant defined by means of the Finite Element Method. The results show that the material distribution varies across models with different properties in two perpendicular directions (i.e., orthotropy) and across individuals, suggesting the potential for patient-specific design of the implant and a patient-specific approach to hernia repair. This approach takes into account abdominal wall heterogeneity and anisotropy, which in practice may help to reduce the ventral hernia recurrence rate.