Critical evaluation of prosthetic materials in repair of abdominal wall hernias: new criteria of tolerance and resistance.

Six different materials (3 mesh and 3 cloth) commonly used for the repair of abdominal wall hernias were evaluated in 180 rats after implantation through musculature and peritoneum. Serial macroscopic and bacteriologic investigations were done, and bursting strength of the wound was determined in all groups at intervals with an original device. Histologic criteria were used to characterize the resistance of the wound and the tolerance of the host to the foreign material. Statistical analysis of the results demonstrated: (1) after postoperative day 15, the resistance of the wound was similar for each material tested; (2) during this early period mesh materials exhibited more resistance to bursting pressures than cloth materials; (3) the incorporation of mesh material was constant, whereas encystment or extrusion was always observed after implantation of cloth material; (4) no infection occurred with mesh material, but significant bacteria were found in 18 per cent of cloth material implantations; (5) the extent of the cellular reaction, the enumeration of giant, inflammatory, and fibroblastic cells showed the superiority of mesh materials; and (6) the ratio of fibroblasts to inflammatory cells reflected closely the mechanical resistance and tolerance of the foreign material.