The influence of mesh structure and strain level on the stress relaxation of warp-knitted surgical mesh for hernia repair

Abstract

Surgical meshes as a replacement for the abdominal wall in hernia reconstruction are subjected to constant strain in the body. Thus, considering their stress relaxation is vital to ensure no recurrence of the disease. The aim of this study is to survey the influence of mesh structure and strain level on the stress relaxation of warp-knitted polypropylene meshes. To evaluate the stress relaxation of the meshes, a novel index named stress relaxation index was introduced. This index is obtained by multiplication of initial stress by the porosity of the mesh divided to the mass per unit area of the mesh. It was observed that mesh structure has remarkable effect on the stress relaxation of the meshes, and by increasing the stress relaxation index, stress relaxation increases. Furthermore, in all mesh structures, higher stress relaxation occurs in the meshes under higher tensile strain. Besides, among investigated rheological models, three components Maxwell model in parallel with nonlinear spring demonstrated the best fit to the experimental stress relaxation data. Eventually, quasi-Marquisette mesh structure suggested as the preferable mesh, owing to its lighter weight, higher porosity, and lower stress relaxation.