A new test that has been developed for biomaterials could help to avoid a repeat of the vaginal mesh scandal, researchers have reported.
Researchers at the University of Sheffield, led by Dr Nicholas Farr from the Department of Materials Science and Engineering, say their oxidative stress test is an early-warning system to identify biomaterials that are not suitable for clinical use inside the human body.
Writing in RSC Advances, they say the test better simulates deployment environments, such as those inside the human body, and better identifies racks and surface degradation in biomaterials.
The researchers evaluated PP mesh, which was used to treat pelvic organ prolapse and stress urinary incontinence but caused life-changing complications in thousands of women and led to medical negligence lawsuits.
Although the PP mesh manufacturers said the material is inert and non-degradable, there is growing evidence that PP meshes suffer oxidative damage.
Dr Farr said: “The process starts with subjecting the material to conditions which mimic the natural processes of oxidation and mechanical stress experienced within the human body.
“This is followed by analysis using novel material characterisation techniques to evaluate the nanoscale surface of the material.
“It is envisioned that the process outlined has the potential to form the basis of an ‘early warning’ analysis system which possesses the ability to identify materials which are not suitable for clinical deployment within the human body.
“My hope is that this research can not only aid the development of new implantable materials but also help to update the regulatory standards which govern medical device production.”
Using their newly developed method, the research team found the stress loaded onto the PP mesh inside the body is likely to have caused polymer oxidation and chemical reactions in the materials.
These are likely to have changed the material’s molecular structure, causing the material to crack. The subsequent release of etched oxidised insoluble particles would have initiated an inflammatory response in the body.
Emeritus Professor Sheila MacNeil, who has worked with NHS consultant Professor Chris Chapple to develop alternative safer materials for use in the pelvic floor, added: “The polypropylene material used to provide support in the pelvic floor is very strong but has produced severe complications in many women. In this study we looked to see how the material performed under simulated stress conditions.
“We stretched the material repeatedly for three days, subjected it to mild oxidative stress and then we used the very sensitive test to reveal tiny fissures and cracks in the surface of the material. Our extensive study has shown this material does not cope well under pressure.”
Farr NTH, Roman S, Schäfer J et al. A novel characterisation approach to reveal the mechano–chemical effects of oxidation and dynamic distension on polypropylene surgical mesh. RSC Advances 27 October 2021
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