Study On The Adhesion Characteristics And Anti-infection Safety Of The Patch Applied In Abdominal Wall Hernia Repair

BackgroundPosterior component separation has become a common approach to complex abdominal wall reconstructions.This technique includes creation of an extraperitoneal retromuscular space for subsequent large synthetic mesh reinforcement.In certain cases,when complete restoration of posterior layer is precluded by significant tissue loss/damage,one proposed strategy is to replace the posterior fascia with an absorbable synthetic polyglactin(Vicryl)mesh.However,the safety of this strategy to prevent mesh related visceral complication is unknown.Herein,we aimed to characterize mesh-viscera adhesion profiles and host tissue response of synthetic mesh either exposed directly to the viscera,or protected with Vicryl mesh.MethodsUsing adult Yorkshire pigs,5x5 cm pieces of mesh were secured to the intact peritoneum in each of the four quadrants(n = 6 pigs,24 mesh samples).The study groups were Vicryl(V),Marlex(M),Softmesh(S),Marlex + Vicryl construct(MV),Softmesh+Vicryl construct(SV).The self-made composite meshes were then implanted with the Vicryl side facing the exposed viscera.The pigs were survived for 60 days.At necropsy,grossly,the extent and tenacity of visceral adhesions were evaluated using established scales.Histologically,all specimens for fibrous encapsulation on the visceral surface of the mesh were reviewed by an experienced pathologist blind to meshes used.ResultsAt necropsy,all Vicryl meshes were completely resorbed.The mean adhesion and tenacity scores for M and MV were 1.8 and 1.1(P>0.05),2.0 and 1.5(P>0.05),respectively;while the mean adhesion extent scores and tenacity scores for S and SV were 2.0 and 1.2(P>0.05),2.0 and 1.7(P>0.05).No significant difference in adhesion extent and tenacity was observed between Synthetic and Vicryl composite mesh groups.Histologically,Marlex+Vicryl mesh and Softmesh+Vicryl mesh constructs had thicker fibrous capsules than the corresponding unprotected Marlex and Soft mesh implants.Furthermore,visceral adhesions in the composite groups were noted to be to the fibrous capsule and not synthetic mesh itself.ConclusionUtilization of the absorbable polyglactin(Vicryl)mesh as a separating layer between a synthetic mesh and intestines,did not reduce adhesions across various mesh types and composites.Histologically,however,a thick fibrous capsule replaced the Vicryl mesh and may be an important layer to prevent intestinal erosion into retromuscular synthetic meshes.BackgroundIndications regarding hernia repair after removal of previously infected prostheses remain unclear.Patients may receive staged primary repair or single-stage reconstructions,neither of which may be ideal.Although animal models have simulated contamination by direct inoculation of implants with bacteria,there remains a paucity of literature,which simulates a field following mesh infection and removal.We aimed to develop a murine model to mimic this complex scenario to allow for further testing of various implants.MethodsThirty-six female CL57BL/6J mice underwent implantation of a 0.7×4.7 cm polyester mesh in the dorsal subcutaneous position.Wounds were closed and inoculated with 100 uL containing 1 × 104 CFU of GFP labeled MSS A.After 2 weeks,the infected mesh was removed and the cavity was copiously irrigated with saline.Mice were split into four groups:with three groups receiving new polyester,polypropylene,and porcine mesh and remaining as non-mesh controls.Mice were survived for another 2 weeks and underwent necropsy.Gross infection was evaluated at 2 and 4 weeks.Tissue homogenization and direct plating to recover GFP MSS A was completed at 4 weeks.ResultsAt 2 weeks,all mice were noted to have gross mesh infection.One animal died due to overwhelming infection and wound breakdown.At 4 weeks,5/6(83%)control mice who did not have a second mesh implantation had full clearance of their wounds.In contrast,9/10(90%)mice with re-implantation of polypropylene were noted to have pus and recovery of GFP MSSA on plating.This was also observed in 100%of mice with polyester and porcine mesh.Conclusion Our novel murine model demonstrates that mesh re-implantation after infected mesh removal results in infection of the newly placed prosthesis,regardless of the material characteristic or type.This model lays foundation for development and investigation of implants for treatment strategies following infected mesh removal.