Double-layer prostheses for repair of abdominal wall defects in a rabbit model

The primary objective of this study was to compare the effectiveness of expanded polytetrafluoroethylene (e-PTFE) and polypropylene (PPM) in a rabbit abdominal wall defect model using a double-layer repair technique. Fifty-four New Zealand white rabbits had full thickness resection of a 5 x 5-cm segment of the mid portion of at the abdominal wall. The defect was repaired with two 6 x 6-cm layers of prosthesis in an underlay/overlay fashion incorporating a 1-cm edge of abdominal wall and grouped accordingly. Group I: inner and outer layer of PPM; Group II: inner layer e-PTFE, outer layer PPM; Group III: inner and outer layer e-PTFE. Animals from each group were sacrificed at 3, 6, and 12 months. The abdominal wall was assessed for herniations and bowel adhesions to the inner layer of the prosthesis. Adhesions were graded according to an adhesion scoring system (grade 0-3). No herniations were observed. Intestinal adhesions to PPM were quite dense at 3 months with a mean adhesion score of 2.5; at 12 months, adhesions were more dense and extensive, having a mean score of 3. Adhesions to e-PTFE were thin and filmy with a mean score of 0.4 at 3 months and 0.6 at 12 months (P < 0.001, 95% CI for each time period). Histologically, PPM fibers were consistently surrounded by dense fibrous connective tissue; foreign body giant cells were present. A thin connective tissue capsule covered the inner e-PTFE layer; its pores were progressively infiltrated by fibroblasts. The double-layer technique prevented hernias in all groups.(ABSTRACT TRUNCATED AT 250 WORDS)