In modern hernia surgery, there are two competing mesh concepts which often lead to controversial discussions, on the one hand the heavyweight small porous model and on the other, the lightweight large porous hypothesis. The present review illustrates the rationale of both mesh concepts and compares experimental data with the first clinical data available. In summary, the lightweight large porous mesh philosophy takes into consideration all of the recent data regarding physiology and mechanics of the abdominal wall and inguinal region. Furthermore, the new mesh concept reveals an optimized foreign body reaction based on reduced amounts of mesh material and, in particular, a significantly decreased surface area in contact with the recipient host tissues by the large porous model. Finally, recent data demonstrate that alterations in the extracellular matrix of hernia patients play a crucial role in the development of hernia recurrence. In particular, long-term recurrences months or years after surgery and implantation of mesh can be explained by the extracellular matrix hypothesis. However, if the altered extracellular matrix proves to be the weak area, the decisive question is whether the amount of material as well as mechanical and tensile strength of the surgical mesh are really of significant importance for the development of recurrent hernia. All experimental evidence and first clinical data indicate the superiority of the lightweight large porous mesh concept with regard to a reduced number of long-term complications and particularly, increased comfort and quality of life after hernia repair.

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Different meshes caused specific histological reactions with changes of their mechanical properties after implantation in rodents. A new mesh with a reduced amount of polypropylene showed both less inflammation and less restriction in the mobility of the abdominal wall though it exceeded the required tensile strength of 16 N/cm.

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Meshes that contain a lot of polypropylene shrink to about 30%-50% of their original size after 4 weeks, requiring an overlap of at least 3 cm if implanted subfascially. Reduction in the polypropylene content decreases both the inflammatory response and the shrinkage. Meshes with big pores are less likely to fold and improve compatibility.

Cyclooxygenase-2 (COX-2) is the rate-limiting enzyme in prostanoid biosynthesis and is involved in tumor progression. We investigated expression of COX-1 and COX-2 in cell lines and tumors from ovarian carcinomas. Expression of COX-2 mRNA and protein was detectable in three of five ovarian carcinoma cell lines and was inducible by interleukin-1␤ or phorbolester in a subset of cell lines. Prostaglandin E 2 (PGE 2 ) production could be inhibited by the selective COX-2 inhibitor NS-398. In malignant ascites of ovarian carcinomas significantly increased levels of PGE 2 were found compared to other carcinomas or nonmalignant ascites (P ‫؍‬ 0.03). We investigated expression of COX-2 by immunohistochemistry in 117 ovarian surface epithelial tumors. Expression of COX-2 was detected in 42% of 86 ovarian carcinomas and in 37% of 19 low malignant potential tumors, but not in 12 cystadenomas or 2 normal ovaries. Expression of COX-1 was detected by immunohistochemistry in 75% of 75 invasive ovarian carcinomas and in 75% of 16 low malignant potential tumors, whereas 2 samples from normal ovaries and 8 cystadenomas were positive for COX-1. In univariate survival analysis of invasive carcinomas, expression of COX-2 was associated with a significantly reduced median survival time (log rank test, P ‫؍‬ 0.04). For patients younger than 60 years of age, this association was even more significant (P < 0.004). In contrast, expression of COX-1 was no prognostic parameter (P ‫؍‬ 0.89). There was no significant correlation between COX-2 or COX-1 expression and other clinicopathological markers. In multivariate analysis expression of COX-2 was an independent prognostic factor for poor survival (relative risk, 2.74; 95% CI, 1.38 to 5.47). Our data indicate that COX-2 expression is an independent prognostic factor in ovarian carcinoma. Based on the results of this study, it would be interesting to

BackgroundEffective repair of hernia is a difficult task. There have been many advances in hernia repair techniques over the past 50 years, but new strategies must be considered to enhance the success of herniorrhaphy.DiscussionAt the 30th International Congress of the European Hernia Society, nine experts in hernia repair and experimental mesh evaluation participated in a roundtable discussion about today’s unmet needs in hernia repair, including what constitutes an “ideal” hernia repair and the portfolio of “ideal” mesh prostheses. Defining characteristics of lightweight mesh, mesh alternatives, the surgeon’s role in hernia repair, adverse events, the unmet requirements for today’s hernia repair, and optimized animal models were among the topics discussed.ConclusionThe ideal mesh’s construction is still in progress, but greater understanding of its critical characteristics was explored. It is hoped that these suggestions will lead to the development of improved hernia treatments and a maximally effective portfolio of hernia mesh prostheses.

BackgroundIt is an undisputable fact that meshes have become standard for repair of abdominal wall hernias. Whereas in the late eighties there were only a couple of different devices available, today we have to choose among some hundreds, with lots of minor and major variations in polymer and structure. As most of the minor variations may not lead to significant change in clinical outcome and may be regarded as less relevant, we should focus on major differences. Eventually, this is used to structure the world of mesh by forming groups of textile devices with distinct biological response. Many experimental and some clinical studies have underlined the outstanding importance of porosity, which fortunately, in contrast to other biomechanical quanlities, is widely unaffected by the anisotropy of meshes.MethodsIn accordance with the major manufacturers of meshes, a classification of meshes was derived from a huge pool of textile data based briefly on the following: (1) large pores, (2) small pores, (3) additional features, (4) no pores, (5) 3D structure and (6) biological origin. At 1,000 explanted meshes the value of this classification was evaluated by group-specific assessment of inflammatory and connective tissue reaction.ResultsApplication of this classification to common products has proved feasable, and each of the six different classes includes devices that in clinical trials failed to show relevant differences in patients’ outcome when comparing products within the same group. Furthermore, histological analysis confirmed significant differences in tissue reactions between but not within the different classes.ConclusionsClassifying implants according to a similar response enables grouping patients into comparable cohorts despite implantation of different devices. Furthermore, it enables the examination of the impact of mesh classes for the various indications even from heterogenous data of registries. Finally and not the least, any grouping supports the surgeon to select the best device to meet the individual need and to tailor patients therapy.Electronic supplementary materialThe online version of this article (doi:10.1007/s10029-012-0913-6) contains supplementary material, which is available to authorized users.