Peritoneal regeneration after implant of a composite prosthesis in the abdominal wall

Prosthetic materials currently used to repair abdominal wall defects occasi onally must be placed in direct contact with the visceral peritoneum. The p rosthesis-peritoneum interface is the site of several possible problems, in cluding the formation of adhesions and erosion of the intestinal loops, whi ch mag lead to the formation of fistulas. This investigation was designed t o compare the behavior of two prosthetic biomaterials in composite form at the level of the peritoneum. Defects (7 x 5 cm) were created in the abdomin al wall of 18 white New Zealand rabbits weighing approximately 2500 g. The defects (involving aponeurotic and muscular planes and the parietal periton eum) were repaired with polypropylene (PL) + ePTFE (Preclude dura substitut e) or Parietex composite (PC) prostheses. Tile prostheses were secured to t he edges of the defect by continuous PL sutures interrupted at the corners of the implant. Three study groups were established according to the type o f implant: group I(n = 6) (controls)-PL; group II (n = 6)-PL + ePTFE; and g roup III (n = 6)-PC. The animals mere sacrificed 14 days after implant, and the prostheses were examined by light microscopy and scanning electron mic roscopy (SEM). The formation of adhesions at the prosthesis-visceral perito neum interface were quantified according to a protocol previously described by us. The biomechanical resistance of the implant was evaluated using str ips comprising prosthetic material and anchorage tissue. The Mann-Whitney U -test was used to compare data corresponding to each group. There was no po stimplant mortality. No infection or rejection of the prosthesis was observ ed in any of the animals. Firm adhesions were detected in the PL implants, whereas in the PL + ePTFE and PC implants the adhesions were loose. The mea n prosthetic surface areas covered by adhesions mere 7.67, 0.10 and 0.19 cm (2) for groups I, II, and iii, respectively, shelving a significant differe nce between values corresponding to groups I and II and to groups I and III (p < 0.05). Comparison of values recorded for groups II and III yielded no significant difference (p >0.05). In groups II and III, the neoperitoneum was homogeneous and composed of organized and vascularized connective tissu e covered by a mesoendothelium that was interrupted by accumulations of fib roblasts and white blood cells. In contrast, a disorganized neoperitoneum o f rough texture was observed in the group I specimens. At times, areas of h emorrhage and necrosis corresponding to the sites of adhesion formation cou ld be observed. Resistance to traction of composite implants (mean +/- SD: 15.72 +/- 1.32 and 15.89 +/- 2.73) was similar to that of the PL implants ( 15.03 +/- 2.92) (Mann-Whitney U-test, p < 0.05). It may be concluded that ( 1) composite prostheses show optimum behavior in terms of adhesion formatio n at the prosthesis-visceral peritoneum interface; (2) the neoperitoneum fo rmed after the implant of a composite prosthesis almost physically and func tionally replaces the normal peritoneum; (3) a significantly greater degree of peritoneal regeneration is achieved after implant of a PC prosthesis; a nd (4) there was no significant difference regarding biomechanical resistan ce between PL prostheses and PL + ePTFE and Parietex composites.