Elongation of textile pelvic floor implants under load is related to complete loss of effective porosity, thereby favoring incorporation in scar plates

Abstract

Use of textile structures for reinforcement of pelvic floor structures has to consider mechanical forces to the implant, which are quite different to the tension free conditions of the abdominal wall. Thus, biomechanical analysis of textile devices has to include the impact of strain on stretchability and effective porosity. Prolift V R and Prolift 1 M V R , developed for tension free conditions, were tested by measuring stretchability and effective porosity applying mechanical strain. For comparison, we used Dynamesh-PR4 V R , which was designed for pelvic floor repair to withstand mechanical strain. Prolift V R at rest showed moderate porosity with little stretchability but complete loss of effective porosity at strain of 4.9 N/cm. Prolift 1 M V R revealed an increased porosity at rest, but at strain showed high stretchability, with subsequent loss of effective porosity at strain of 2.5 N/cm. Dynamesh PR4 V R preserved its high porosity even under strain, but as consequence of limited stretchability. Though in tension free conditions Prolift V R and Prolift 1 M V R can be considered as large pore class I meshes, application of mechanical strain rapidly lead to collapse of pores. The loss of porosity at mechanical stress can be prevented by constructions with high structural stability. Assessment of porosity under strain was found helpful to define requirements for pelvic floor devices. Clinical studies have to prove whether devices with high porosity as well as high structural stability can improve the patients' outcome.

Impact of prolapse meshes on the metabolism of vaginal extracellular matrix in rhesus macaque

“…The stiffness of mesh determined in ex vivo testing may dramatically change following implantation, tensioning and loading. For example, Gynemesh PS undergoes a complete loss of porosity and an increase of stiffness at strains of just 4.9 N/cm, demonstrating the instability of mesh properties in response to even small loads 24, 25 . When the stiffness of implanted material is high, stressshielding of the underlying and associated tissues may increase the activity of MMPs resulting in tissue degeneration and a loss of mechanical integrity 26-29 .…”

Impact of Prolapse Meshes on the Metabolism of Vaginal Extracellular Matrix in Rhesus Macaque

“…The stiffness of mesh determined in ex vivo testing may dramatically change following implantation, tensioning and loading. For example, Gynemesh PS undergoes a complete loss of porosity and an increase of stiffness at strains of just 4.9 N/cm, demonstrating the instability of mesh properties in response to even small loads 24,25 . When the stiffness of implanted material is high, stressshielding of the underlying and associated tissues may increase the activity of MMPs resulting in tissue degeneration and a loss of mechanical integrity [26][27][28][29] .…”

Stresses produced by different textile mesh implants in a tissue equivalent

“…The closer it is to the clamp, the earlier the region of the mesh will detach from the gelatin because the tensile loading leads to strongly deformed rhomboidal pores that cut through the tissue. The change of pore size and shape that we observed during loading in the debonded section has also been investigated for meshes before ingrowth in [10]. Obviously the porosity of the meshes influences the healing process and scarring and therefore it needs more attention.…”