In vitro study of the mechanical performance of hernia mesh under cyclic loading

The use of prostheses for hernia surgery, made from synthetic polymers may lead to development of postoperative complications. The reason for this can be the mismatch of the mechanical properties of meshes and the loads acting on them. The aim of this work was to investigate the behavior of 3 different hernia meshes under in vitro simulated physiological conditions followed by cyclic loadings. Meshes, Ultrapro (poliglecaprone and polypropylene), Dynamesh (polyvinylidenefluoride) and Surgipro (polypropylene) were selected. For in vitro degradation test, samples were kept in alkaline and acid mediums at 37 °C during 42 and 90 days and analyzed in terms of their weight loss and thickness changes. This was followed by cyclic loading in three increasing load stages. The greatest weight loss and thickness reduction were suffered by Ultrapro mesh. The mesh showed pH independent characteristics. Surgipro mesh had pH independent behavior due to the degradation process, with slight weight loss and thickness reduction. The degradation mechanism of Dynamesh is highly dependent on the pH, with acid surrounding medium acting as a degradation catalyst. Mechanical hysteresis was observed in all three meshes. The larger deformations occurred in Surgipro (25%); necking phenomenon was also observed. The deformation of Dynamesh was 22%, the mesh unweaves under applied load and was unable to withstand the third period of cyclic loads. Ultrapro mesh exhibits the lowest level of deformation (10%). Despite the different compositions and architectures of the meshes, all three underwent permanent plastic deformation, which will induce decreased mesh flexibility over time.