Foreign Body Reaction to Meshes Used for the Repair of Abdominal Wall Hernias

OBJECTIVE: To investigate the local tissue reactions to meshes that had been removed from humans. DESIGN: Open study SETTING: Surgical department of the technical University, Aachen, Germany. MATERIAL: Samples of 17 non-absorbable meshes (1 polyester, 10 polypropylene, 2 reduced polypropylene, and 4 polytetrafluorethylene, PTFE) and 1 absorbable mesh (polyglactin 910) that had been implanted for repair of abdominal wall defects. INTERVENTIONS: Light and transmission electron microscopy, immunohistochemistry, and histological examination. MAIN OUTCOME MEASURES: Signs of inflammatory response. RESULTS: Light microscopy showed chronic inflammatory tissue reaction, even after years, with pronounced differences among materials. Partial volume of inflammatory cells (%) varied from 32 in polypropylene, to 12 in expanded PTFE, 8 in polyester, and 7 in reduced polypropylene. Formation of connective tissue correlated significantly with the extent of the inflammatory reaction (p<0.01). In meshes implanted for long periods there were still numerous macrophages at the interface between tissue and polypropylene (45%), polyester (45%), expanded PTFE (25%), and reduced polypropylene (22%). There was no difference in time dependent tissue reactions (p = 0.19). CONCLUSION: Inflammation around alloplastic materials used to repair defects in the abdominal wall persists for many years. There was evidence of long term wound complications as a result of persistent foreign body reactions. Further studies are required to evaluate the long term tissue response to these materials.