Mesh Materials Used for Hernia Repair: Why Do They Shrink?

Abstract

Eleven hernia repair meshes implanted for up to 4 years were harvested at reoperation: 9 recurrences, 1 infection, and 1 infection associated with a fistula. They were made of polypropylene (PP) fabric and/or expanded polytetrafluoroethylene (ePTFE). The devices shrank considerably from 12 to 53% with heavy fibrotic embedding. This shrinkage occurred due to the contraction of the fibrotic tissues that penetrated through the materials and encroached all the polymer structures. The level of inflammation was aggravated in the case of oxidation of the external surface of the PP fibers. Multiple flaking led to detachment of PP particles. In addition, the collagen bundles in the scar tissue did not show any waviness, and thus could be considered as responsible for the lack of elasticity of the encapsulating tissues. Furthermore, particles from the ePTFE structures were occasionally identified dispersed in peri-implant tissues. Despite the plethora of devices commercially available, there is still no consensus about the most appropriate one. Future hernia mesh devices should reduce fibrotic encapsulation and encourage the formation of wavy collagen fibers and thus the elasticity of the encapsulation, which would prevent mesh shrinkage and lead to the lifelong rehabilitation of the patient. The search for smart materials and novel designs must be undertaken. Future devices should demonstrate adequate long-term biostability without ignoring the importance of biocompatibility.