Textile Analysis of Heavy Weight, Mid-Weight, and Light Weight Polypropylene Mesh in a Porcine Ventral Hernia Model

Abstract

The purpose of this study was to assess the burst strength and stiffness of heavy weight (HW), mid-weight (MW), and light weight (LW) polypropylene mesh pre-implantation and 5 months post-implantation in a porcine ventral hernia model. HW (95 g/cm2), MW (45 g/cm2), and LW (28 g/cm2) polypropylene were tested as dry samples (n = 8/mesh) before implantation using a stamp strain machine. Three weeks after creating four hernia defects in each mini-pig (n = 18), the polypropylene meshes (8 x 10 cm; 24/mesh type) were implanted in the preperitoneal space, ensuring 2 cm overlap circumferentially. At 5 months, the mesh was harvested en bloc with the abdominal wall. Testing of burst strength and stiffness was repeated on the ex vivo specimens. After implantation in the pig for 5 months, the mean burst strength and stiffness of HW and MW meshes remains the same. LW mesh with an absorbable monofilament in its weave has significant reductions in mean burst strength (P = 0.01) and mean stiffness (P < 0.0001). The burst strength for all meshes tested was much higher than measured for the abdominal wall fascia alone. The degree of shrinkage of the various weight meshes did not differ. A reduction in mean burst strength and stiffness occurs after 5 months implantation of LW polypropylene mesh with an absorbable monofilament. All meshes exhibited burst strengths that were much greater than the burst strength of the abdominal wall fascia alone. After tissue incorporation, the LW polypropylene mesh maintains mean burst strength comparable to MW polypropylene mesh, while becoming less stiff than HW mesh. Long-term, this may contribute to more physiological abdominal wall compliance after LW polypropylene mesh implantation.