Bridging repair of the abdominal wall in a rat experimental model. Comparison between uncoated and polyethylene oxide-coated equine pericardium meshes

Abstract

Biological meshes improve the outcome of incisional hernia repairs in infected fields but often lead to recurrence after bridging techniques. Sixty male Wistar rats undergoing the excision of an abdominal wall portion and bridging mesh repair were randomised in two groups: Group A (n = 30) using the uncoated equine pericardium mesh; Group B (n = 30) using the polyethylene oxide (PEO)-coated one. No deaths were observed during treatment. Shrinkage was significantly less common in A than in B (3% vs 53%, P < 0.001). Adhesions were the most common complication and resulted significantly higher after 90 days in B than in A (90% vs 30%, P < 0.01). Microscopic examination revealed significantly (p < 0.05) higher mesh integrity, fibrosis and calcification in B compared to A. The enzymatic degradation, as assessed with Raman spectroscopy and enzyme stability test, affected A more than B. the peo-coated equine pericardium mesh showed higher resistance to biodegradation compared to the uncoated one. Understanding the changes of these prostheses in a surgical setting may help to optimize the peo-coating in designing new biomaterials for the bridging repair of the abdominal wall. Incisional hernia affects 10-20% of laparotomies and represents the most common long-term complication after abdominal surgery 1-3. Since their first description by Usher et al. in 1985 4 , synthetic prostheses significantly reduced recurrence rate after the first incisional hernia repair, from more than 20% to less than 10% 5,6. Nevertheless, they are commonly contraindicated in situations in which the exposure to any additional bacterial burden constitutes an excessive risk of surgical site infection 7,8. According to the Ventral Hernia Working Group (VHWG), incisional hernias which are at high risk of surgical site occurrences, because of comorbidities or contamination/infection of the operative field, should be treated using biological meshes; this should also be recommended in those cases in which the complete rectus closure is not possible and bridging technique is unavoidable 9. Although some controversies arose about the influence of technique in determining the surgical site occurrences 10 , and other authors designed and validated other scores 11,12 , VHWG recommendations appear to be still the most reliable guidelines available in the