Chronic hernia repair in a rat model using small intestinal submucosa.

BACKGROUND. Small intestinal submucosa (SIS) body wall defect repair in preclinical studies results in host tissue that resembles original host tissue histologically and has adequate strength to maintain repair integrity. However, these studies have been performed using acute hernia models that may not represent healing in a naturally occurring hernia. METHODS. Fifty-four male Sprague-Dawley rats were divided into nine groups (n = 6) and fascia/muscle/peritoneal abdominal wall defects were created. One control group had no surgery. Four surgery groups had defects repaired immediately by (1) fascia suture apposition, (2) polypropylene mesh (PPM) peritoneal onlay, (3) SIS inlay, or (4) SIS peritoneal onlay. After defect creation, chronic hernias matured for 28 days, and then were similarly repaired. Follow-up after hernia repair for all groups was 28 days. Gross evaluation for hernia recurrence, infection, and adhesions was followed by histopathology and tensile testing of the repair. RESULTS. There were no recurrent hernias or infection. Adhesions covered all implants. Histopathologic findings of inflammation and fibrosis were similar between all groups. There were no significant differences in tensile strength between SIS and PPM healing/incorporation or between acute and chronic hernia groups. Normal body wall was stronger than all repairs. Fascia closure in chronic hernias was stronger than acute fascia closure (p < .01). CONCLUSIONS. We found no significant differences between SIS and PPM healing/incorporation as determined by gross and histopathology and tensile strength testing. The study suggests that preclinical testing of abdominal body wall reconstruction in the rat may be adequately performed in acute studies.