Effects of reactive oxygen species on the physical properties of polypropylene surgical mesh at various concentrations: a model for inflammatory reaction as a cause for mesh embrittlement and failure.

BACKGROUND: Oxidative degradation by reactive oxygen species (ROS) from inflammation initiates cross-linking, depolymerization, and formation of a quasi-crystalline quality in polypropylene (PP) meshes that cause embrittlement (J Urol 188:1052, 2012). Embrittlement leads to change in tensile strength and is associated with post-operative complications that include pain, adhesion, dislodgment, and fragmentation.
METHODS: A laboratory environment was constructed to study the relationship between concentration of ROS and change in tensile strength. Samples of Ethicon Ultrapro© PP mesh were exposed to 1 mM, 0.1 M, or 1 M hydrogen peroxide solutions for 6 months and were subjected to load displacement tensile testing (LDTT) and compared to unexposed (0 M) meshes of the same brand.
RESULTS: Load at failure and elongation to failure after LDTT were determined with 95 % confidence interval. For unexposed (0 M) samples, tensile strength was 28.0 ± 2.4 lbf and elongation to failure was 2.0 ± 0.3 in. For samples exposed to 1 mM, tensile strength was 19.2 ± 1.1 lbf and the elongation to failure was 2.0 ± 0.1 in. For samples exposed to 0.1 M, tensile strength was 19.3 ± 1.6 lbf and elongation to failure was 1.9 ± 0.1 in. For samples exposed to 1 M, tensile strength was 20.7 ± 1.2 lbf and elongation to failure was 0.47 ± 0.02 in.
CONCLUSION: The results demonstrated that a 6-month exposure to a physiologic range of ROS (1 mM) decreased tensile strength of PP mesh by 31 %. 1 mM and 0.1 M samples behaved similarly demonstrating properties of a quasi-crystalline nature. 1 M samples displayed qualities of extreme embrittlement. Scanning electron microscopy (SEM) observed fiber changes. 1 M meshes had features of brittle materials. Knowledge of changes in physical properties of PP meshes is useful for considerations for the development of a more biocompatible surgical mesh.