Intraperitoneal mesh devices for small midline hernias: mesh behavior in a porcine model.

Purpose: Although clinical data on long-term efficacy are lacking, the use of self-expanding devices for intraperitoneal placement in the management of small midline hernias has been popularized. In the present experimental study, two different devices were investigated regarding tissue ingrowth, adhesion formation and solid mesh placement.

Methods: Two devices of 4.3 cm diameter, one ePTFE-containing small pore polypropylene mesh (PP/ePTFE) and a multi-layered large-pore polypropylene patch with an oxidized cellulose anti-adhesive barrier (PP/ORC), both containing a self-deployment system, were placed intraperitoneally at the linea alba of 24 female pigs. A first laparoscopy was performed to evaluate mesh positioning against the abdominal wall. 1 (n = 6), 2 (n = 6), 4 (n = 6) and 12 weeks (n = 6) later, mesh appearance was inspected and adhesion formation was assessed. All meshes were excised for histological evaluation.

Results: Folding of the patch was more frequently observed at PP/ePTFE, yet no excessive cupping was noticed. Adhesions predominantly presented at short-term evaluation. Overall adhesion formation at all samples was significantly more extensive for PP/ORC (p = 0.048). Massive shrinkage was observed for PP/ORC: after a 12-week period 22% residual surface was preserved, compared to 83% for PP/ePTFE (p < 0.001). While at short-term inflammatory reaction was comparable, at long-term PP/ORC induced a significant more pronounced inflammatory and foreign body reaction.

Conclusions: Although a strong deployment system provides adequate initial placement, shrinkage and excessive adhesion formation are much more prominent in the large-pore multi-layered restorbable devices compared to the ePTFE patch. This might influence long-term clinical outcome and caution seems warranted.