Page 40 - Postoperative Intra-Abdominal Adhesions- New insights in prevention and consequences
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                                Chapter 2
Biological mesh
Biological meshes may be derived from human (allograft) or animal (xenograft: porcine or bovine) tissues [154]. These meshes constitute a theoretical advantage over synthetic and composite meshes as they are supposed to provide an extracellular scaffold necessary for healthy tissue regeneration and as a result allowing infiltration of native fibroblasts. [154]. It has been suggested that because of this characteristic the biological mesh is more suitable for contaminated wounds [155, 156]. Furthermore, some biologic grafts are chemically cross-linked to make them less prone to degradation in vivo [157]. This additional process resists the degradation of collagen scaffolds by either host or bacterial collagenases and is claimed to enhance mesh durability [156, 158].
In general biologic meshes are thought to induce fewer adhesions because of increased ‘‘biocompatibility’’ and less foreign body reaction [159-161]. However, in different animal studies the results concerning adhesion formation to biological meshes were disappointing. Many investigators have the opinion that an answer can be found in the process of crosslinking. Varying in vivo experiments demonstrate that crosslinked porcine dermis grafts are typically associated with heightened foreign body response and pronounced early inflammatory response, which ultimately may result in adhesion formation [157, 162-164].
Nevertheless, a low rate of adhesion formation is not the only characteristic a mesh should have. Incorporation, susceptibility to infection, shrinkage, handling properties, hernia recurrences and costs are all factors, which play a role in the assessment of the different meshes. Interestingly, despite all efforts made in the last decade, three recent reviews concluded that there is an insufficient level of high-quality evidence in the literature on the value of bioprosthetics for incisional hernia repair [156, 159, 165].
To summarize, biological meshes are currently not yet the answer to the problem of adhesion formation to the prosthesis in laparoscopic hernia repair. When contact with the viscera is inevitable for example in complex
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