In vivo polypropylene mesh degradation is hardly a myth

http://crossmark.crossref.org/dialog/?doi=10.1007/s00192-016-3233-z&domain=pdf

Web End = Int Urogynecol J (2017) 28:333335 DOI 10.1007/s00192-016-3233-z

http://crossmark.crossref.org/dialog/?doi=10.1007/s00192-016-3233-z&domain=pdf

Web End = LETTER TO THE EDITOR

In vivo polypropylene mesh degradation is hardly a myth

Margaret Thompson1 & Scott Guelcher2 & Robert Bendavid3 & Vladimir Iakovlev4 &

Donald R. Ostergard5

http://orcid.org/0000-0001-7720-9871

Web End = Received: 4 November 2016 /Accepted: 5 December 2016 /Published online: 29 December 2016 # The International Urogynecological Association 2016

Dear Editor,We read with interest the article by Thames et al. entitled, The myth: in vivo degradation of polypropylene-based meshes [1]. The authors dispute the occurrence of degradation (the process of breaking down or deteriorating) of polypropylene (PP) mesh in vivo, reporting a novel cleaning method using multiple cycles of prolonged ultrasonication, shaking, and bleach (NaOCl) treatments of explanted mesh samples. Assessing the exposed surface and not analyzing the material removed, they conclude that the cracked layerthe typical feature of degraded polymerseen on explanted meshes is an adsorbed protein-formaldehyde complex, rather than degraded PP as reported in numerous other publications. Of note, the authors are affiliated with Exponent, a business consulting firm retained by defendants in the mesh litigation. Furthermore, according to their disclosure, their findings were based on work paid for by Ethicon, Inc. [1].

In drawing their conclusions, the authors ignore the vast body of peer-reviewed literature describing PP degradation and fail to address the histological findings reported by other researchers [25]. Furthermore, their investigations utilize an unproven and unvalidated methodology, apparently designed specifically to remove all detachable material nonselectively (including protein and degraded PP) from the surface of the mesh fibers.

Polypropylene is a thermoplastic polymer, well known in the ex vivo setting to undergo oxidative degradation. All forms of polypropylene are susceptible to oxidative attack at the tertiary hydrogencarbon bond, resulting in the breaking of the PP molecular chain. This process continues until no more PP can be oxidized. Degradation appears on the external surface as cracks and fissures and results in hardening and shrinkage of the material. Anti-oxidants are normally added to PP to prevent polymer degradation, as is the case with all PP mesh used in surgical applications.

There is a large body of published literature, estimated to be well over 100 peer-reviewed articles, accepting or describing the degradation of PP in...