The experimental methodology and comparators used for in vivo hernia mesh testing: a 10-year scoping review

Abstract

Purpose Before being marketed, hernia mesh must undergo in vivo testing, which often includes biomechanical and histological assessment. Currently, there are no universal standards for this testing and methods vary greatly within the literature. A scoping review of relevant studies was undertaken to analyse the methodologies used for in vivo mesh testing. Methods Medline and Embase databases were searched for relevant studies. 513 articles were identified and 231 duplicates excluded. 126 papers were included after abstract and full text review. The data extraction was undertaken using standardised forms. Results Mesh is most commonly tested in rats (53%). 78% of studies involve the formation of a defect; in 52% of which the fascia is not opposed. The most common hernia models use mesh to bridge an acute defect (50%). Tensile strength testing is the commonest form of mechanical testing (63%). Testing strip widths and test speeds vary greatly (4–30 mm and 1.625–240 mm/min, respectively). There is little consensus on which units to use for tensile strength testing. Collagen is assessed for its abundance (54 studies) more than its alignment (18 studies). Alignment is not measured quantitatively. At least 21 histological scoring systems are used for in vivo mesh testing. Conclusions The current practice of in vivo mesh testing lacks standardisation. There is significant inconsistency in every category of testing, both in methodology and comparators. We would call upon hernia organisations and materials testing institutions to discuss the need for a standardised approach to this field.

A Systematic Review Examining the Experimental Methodology Behind In Vivo Testing of Hiatus Hernia and Diaphragmatic Hernia Mesh

“…Unlike previous work, 9 the comparators used for uniaxial tensile testing were mostly consistent. One hundred percent of mechanical testing studies measured tissue modulus and 80% measured the stress or strain at point of rupture.…”

“…Over the 20 years reviewed, 18 in vivo DH or HH mesh testing studies were conducted. Unlike previous studies that reviewed in vivo models of ventral hernia repair, 9,19 porcine models were used most frequently (39% of studies) and rat models were least frequent (6% of studies). This finding is reassuring given that porcine models should provide a more accurate representation of human physiology.…”

“…Before data extraction began, a meeting was held between the four authors responsible for data extraction (T.W.C., V.B., J.B., R.K.) to standardise the process. The same four authors from our group had previously collaborated on a similar project, 9 which created a good understanding of the process. Data collection forms were adapted during the process to reflect the results being collected.…”

“…Given these potential complications behind mesh materials, pre-clinical in vivo testing represents an essential tool in optimising performance and is a legal requirement across the world. Following our group's recently published review of hernia mesh testing, which revealed a significant variation in studies, 9 we have conducted a new systematic review of in vivo studies assessing meshes for HH and DH repair.…”

In vitro characterisation of low-cost synthetic meshes intended for hernia repair in the UK

“…Although animal models are an essential step in the pathway to clinical applications, performing in vitro experiments prior to in vivo studies, would provide useful information about the materials and help to better predict mesh response, which for CM is currently lacking [21]. This approach would help optimise the design of further in vivo experiments, enabling a reduction in animal testing.…”