Polymers in hernia repair - common polyester vs. polypropylene surgical meshes

Within the last years meshes have become essential for the repair of abdominal wall hernias. While the type of mesh obviously influences the clinical result, the selection of the best suitable mesh-modification should have favourable effects onto the rate of complications. Available surgical meshes mainly differ in the type and amount of the basic polymers. The most common meshes are made either out of monofilament polypropylene (PP) or multifilament polyester (PET). In the following contribution we studied the functional and histological results of standard and commercially available surgical meshes: a standard heavyweight, large pore-sized PP-mesh (Prolene (R)), a heavyweight, large pore-sized PET-mesh (Parietex (R), coated with bovine collagen) and a low weight small pore-sized PET-mesh (Mersilene (R)) in a standardised rat model. The meshes are studied by three dimensional stereography, tensiometry, light-(LM) and transmission electron microscopy (TEM), as well as morphometry over implantation intervals of 3, 7, 14, 21 and 90 days. The results proved marked differences between the tested meshes in regard to textile properties, the mechanical function (tensile strength, abdominal wall mobility), as well as the histologically proved tissue reaction. Both heavyweight meshes (PP and PET) revealed an enormous and most similar strength whereas the low weight PET-mesh primarily showed a considerable increase of flexibility. Despite their different structures and their diverse histological response all tested meshes led to a similar and significant reduction of the abdominal wall flexibility. However, the local tissue response of the interface mesh/recipient tissues revealed a significant reduction of the acute inflammatory activity and a significant decrease of connective tissue formation in the case of the low weight PET-mesh Mersilene (R) compared to both heavyweight mesh-modifications. Mersilene (R) showed an excellent and relatively inert tissue reaction of the interface compared to Prolene (R) and Parietex (R). Modifications of the mesh-structure (e.g. larger pores) should improve the functional results, in particular, abdominal wall flexibility. However, the use of PET in hernia surgery is at least questionable in respect to the obligate long-term degradation of this polymer. (C) 2000 Kluwer Academic Publishers.