Validating the mesh integration (MINT) index: a 3-month porcine study

Background: Poor mesh tissue integration is thought to be responsible for hernia mesh repair failures years after surgery. The Mesh Integration (MINT) Index was proposed as a solution to unify methods of evaluating in vivo mesh behaviour. The aim was to validate the Index over a 3-month period using a porcine model. Methods: Twelve brands of mesh were implanted into twelve Landrace-White pigs. Appropriate mesh was randomised to retrorectus and intraperitoneal space. Post-mortems were performed at 2, 3, 4, 8, and 12 weeks. All mesh tissue samples were subjected to standardised testing as predefined in the Index. Results: Mesh was successfully implanted into all pigs. One pig died from congenital cardiomyopathy, and another was euthanised earlier than intended due to complications of midline wound infection. There were no difficulties at post-mortem. Multilevel linear regression analysis with maximum likelihood was performed. A strong fit of models were achieved for all four domains of the Index, with minimal residues. Integration and fibrosis were predicted by time (p=0.025 and p=0.038, respectively). Although statistically not significant when cluster robust version 2 (CR2) standard errors were used, retrorectus mesh had a greater numerical integration over time than intraperitoneal, and numerical differences were present between mesh products. Degradation was predicted by intraperitoneal mesh (p=0.008). A reduction in adhesion score was observed after week 4. Conclusion: The MINT Index is a valid framework to objectively assess in vivo mesh behaviour. Substantial research is required before full clinical utility of the Index can be achieved.