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.

Keywords: Hernia; In-vivo; Mesh; Standardisation; Testing.

Fig. 1

A chart showing the distribution of how testing strips were formed amongst 42 studies in which uniaxial tensile strength testing was undertaken

Fig. 2

A graph showing the number of studies in which each structural factor was assessed. Blue represents studies which used quantitative methods, and orange qualitative methods (colour figure online)

Fig. 3

A graph showing the number of studies to assess collagen in terms of abundance or alignment. Assessment can be made purely qualitatively or quantitatively or with the use of a scoring system

Fig. 4

A graph showing the number of studies in which each inflammatory cell was assessed. Blue represents studies which used quantitative methods, and orange for qualitative methods (colour figure online)