Absorbable versus nonabsorbable mesh repair of congenital diaphragmatic hernias in a growing animal model

Introduction: The repair of large congenital diaphragmatic hernia frequently results in patch disruption and recurrence as patients grow in size. Absorbable meshes allow for ingrowth of endogenous tissue as they are degraded, providing a more natural and durable repair. The aim of this study was to compare the characteristics of the new diaphragmatic tissue between an absorbable biologic mesh and a nonabsorbable mesh for repairing diaphragmatic hernia in a growing animal model. Methods: The left hemi-diaphragm of twenty 2-month-old Yucatan pigs was nearly completely resected. Small intestinal submucosa (SIS; Cook Biotech, Lafayette, IN) and expanded polytetrafluoroethylene (ePTFE; W.L. Gore & Associates, Flagstaff, AZ) were randomly assigned to cover the defect in 10 animals each, and were survived for 6 months. During necropsy, newly formed diaphragmatic tissue was evaluated and compared between the two groups. Results: At necropsy, the animals had tripled their weight. Patch disruption and herniation occurred in 3 animals in the ePTFE group and none in the SIS group. The SIS mesh had better integration to the chest wall (2.8±0.2 versus 1.3±0.3), more muscle growth within the newly formed diaphragmatic tissue (1.9±0.2 versus 0.4±0.2), and less fibrotic tissue (2.1±0.5 versus 3.4±0.4) than ePTFE. There was no difference between SIS and ePTFE in terms of adhesion scores to the lung (2±0.4 versus 2.4±0.4) and liver (1.8±0.3 versus 2.2±0.5). Conclusion: SIS allows for tissue ingrowth from surrounding tissue as it degrades, providing a more durable repair with 30% less incidence of herniation in a porcine model. As the diaphragm grows, SIS resulted in a more natural repair of the defect with more tissue growth, better tissue integration, and a comparable adhesion formation to ePTFE.