Page 312 - Prevention and Treatment of Incisional Hernia- New Techniques and Materials

Chapter 15
The aim of biological mesh implantation is to create a functional abdominal wall by deposition of native collagen during mesh degradation (‘remodelling’). In our current study incorporation of the mesh was highest in Permacol however with only 20.7% incorporation (20.7%, 5.7-24.5), followed by Strattice (13.7%, 10.3-22.4). The steps in this dynamic process include in ammatory response, cellular penetration and neovascularisation of the mesh, broblast in ltration and collagen deposition(17). It appears that all meshes induce varying levels of foreign body reaction and brosis. Multiple characteristics of the mesh in uence this response: mesh material, weight, pore size, crosslinking and sterilisation technique. More data is becoming available on histopathologic responses to speci c synthetic and biological meshes in animal models(16, 18, 19). Novitsky et al observed that crosslinked meshes caused extensive foreign body reaction with brous encapsulation and no evidence of integration or remodelling of the mesh(16). Dissimilarities have been found between crosslinked and non-crosslinked meshes suggesting that improved integration into host tissue in non-crosslinked matrix is due to a moderate mononucleair cell reaction(20). Possible cause of this foreign body reaction is due to presence of nucleair material in the mesh or exposure of antigentic epitopes following implantation(21-25). It is suggested that some crosslinking processes damage the extracellular matrix and negatively in uence the host response leading to encapsulation, decreased broblast penetration in the matrix and little collagen synthesis(20, 23, 26-28). Similar results have been found in patients who underwent removal of porcine biologic mesh where no to little evidence of neovascularisation or neocellularisation was detected in crosslinked meshes(17). Non-crosslinked Strattice mesh showed highest degree of new collagen deposition and organization in the study by Novitsky et al. which is comparable to the results in our current study(28).
Clinical studies like the multicentre RICH study showed similar results with a recurrence hernia rate of 19% after 1 year and 28% after 2 years(11). Likewise, Rosen et al recorded a recurrence rate of 31.3% with a follow-up of 21.7 months after implantation of biological mesh(29). These results can hardly be called sustainable hernia repairs and are not that dissimilar to synthetic meshes(6, 30). Increasingly synthetic meshes are being implanted in clean-contaminated and contaminated surgical eld with quite favorable results(31-34) . Recent studies in grade II contaminated wounds showed lower recurrence rate after implantation of synthetic meshes compared to biological meshes with similar adverse event(35).
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