Behaviour of orthotropic surgical implant in hernia repair due to the material orientation and abdomen surface deformation

Surgical implants used in hernia repair reveal isotropic as well as orthotropic properties. In particular, its orthotropy, in relation to the different range of typical deformations observed in different directions and zones of abdomen surface due to the patients' life activities, has a significant influence on the extreme junction forces in the mesh–tissue connections and hence the repair persistence. The finite element model of the orthotropic implant was developed, and the junction forces in the connections of tissue and mesh were studied. The kinematical extortions representing the abdomen surface deformations identified in specific zones of hernia placement were applied to the model. The sensitive analysis was applied to specify the influence of the orthotropy (implant orientation) direction to the repair persistence. Due to the anisotropy of the human abdomen and also the different range of deformations observed in different areas of abdomen surface, the behaviour of the implant differs significantly depending on the hernia placement and the implant orientation. Especially, it is observed in the values of the implant–tissue junction forces which determinate considerably the repair persistence. The provided results and conclusions may be useful in some clinical recommendations for implantation of orthotropic surgical mesh specifying the hernia placement as well as the orthotropic implant orientation. This can also be considered in the design of new synthetic implants with more physiologic tissue-like properties also taking into account the human abdomen anisotropy.