Tissue response to polypropylene meshes used in the repair of abdominal wall defects

The degree of integration of biomaterials used in the repair of abdominal wall defects seems to depend upon the structure of the prosthesis. Several polypropylene (PP) prostheses are currently available which differ in the number of PP filaments, the type of weave and the porosity. The aim of this study was to evaluate the integration, adhesion formation and resistance to traction of three types of PP prostheses (Marlex, Trelex and Prolene) used in the partial or total repair of abdominal wall defects. Abdominal wall defects (7 x 5 cm) were created in 54 New Zealand rabbits involving all the tissue layers (total substitutions (TS); n = 27) or all layers excluding the parietal peritoneum (partial substitutions (PS); n = 27). The defects were repaired with PP monofilament prostheses of different weave (1 mm porosity) (Marlex, n = 18; Trelex, n = 18) or bifilament (2 mm porosity) (Prolene; n = 18). They were placed in contact on one side with subcutaneous tissue and on the other with abdominal viscera or parietal peritoneum. Animals were killed at 30, 60 and 90 days and samples of prosthesis and scar tissue processed for light and scanning microscopy. The adhesion formation with viscera was evaluated. Resistance to traction was measured with a tensiometer using strips including the prosthesis and anchorage tissue. Adhesions were detected in all the TS and in four PS. Microscopic analysis revealed total integration of the TS samples by fibrous and disorganized tissue. Prostheses used for PS were integrated by white adipose tissue with the exception of the areas around the mesh nodes and anchorage zones. The foreign body reaction could be seen as a moderate accumulation of white blood cells. Tensiometric analysis showed an increase in resistance to traction with time (P < 0.001) in each type of prosthesis, but no differences were detected (P > 0.001) between them. We concluded that: (a) the formation of adhesions was almost inhibited when the parietal peritoneum was left intact; (b) in both TS and PS, polypropylene prostheses integrated completely although the composition of the scar tissue was seem to differ; and (c) resistance to traction was similar in both TS and PS.