Dynamic Mechanical Properties of Tissue after Long-Term Implantation of Collagen and Polypropylene Meshes in Animal Models

Michail G Christodoulou,Stefanos Zaoutsos,Theodoros Kouranos,Miltiadis Seferlis,Angelos Liapis,Charilaos Katsifotis,Apostolos Papalois,Dionysios Mouzakis

doi:10.4236/oju.2013.33029

Abstract

Purpose: Pelvic floor reconstructive surgery has grown significantly in recent years. A wide variety of available types of meshes exist but the safety and success has not been adequately proven. We sought to evaluate the effects on dynamic biomechanical properties of tissue after long-term implantation of synthetic and biological grafts. Methods: A total of 96 New Zealand white female rabbits (approximately 3 kg) were used, 72 of which were surgically implanted with acellular, collagen mesh (n = 36) or nonabsorbable monofilament polypropylene mesh (n = 36). There was a no mesh-rupture of fascia group (n = 12) and a second, no-mesh, no-fascia rupture control group (n = 12). In the 59 rabbits, of 72 (13 died) tissue was harvested 3 months (n = 24), 6 months (n = 23) and 9 months (n = 12) later, while in the fascia rupture group, tissue was harvested 6 months later. Tissue samples (2 × 2 cm) underwent dynamic mechanical analysis (DMA) testing during which the dynamic rigidity and tissue damping capacities were measured. The statistical analysis was performed with General Linear Model with Tukeys post hoc testing (sPss v.17.0). Results: With respect to mesh type, the rabbit tissue in which polypropylene mesh was used showed the greatest dynamic rigidity. Those with biological mesh delivered the lowest rigidity results, while the two other groups had almost similar behavior. The meshes exhibited their highest relative dynamic tissue stiffening effect at 9 months. Conclusions: Biological mesh causes lower tissue rigidity, resulting in inferior mechanical response and thus seems to be inferior to polypropylene.

Highlights

Disorders of the pelvic floor encompass a wide spectrum of interrelated clinical entities, including pelvic organ prolapse and incontinence
The goal of this study was the appraisal of the biomechanical properties of rabbit tissues after the implantation of biological and synthetic mesh and their long-term stay in the abdominal rectus muscle
The collagen mesh showed the least rigidity among the four groups

Summary

Introduction

Disorders of the pelvic floor encompass a wide spectrum of interrelated clinical entities, including pelvic organ prolapse and incontinence. Pelvic organ prolapse affects almost one third of premenopausal and approximately one half of postmenopausal women [2,3]. Approximately 135,000 women undergo surgery for urinary incontinence [4] and 225,000 for pelvic organ prolapse at a cost of greater than $1 billion per year in the United States [4,5]. Reconstructive procedures for the pelvic floor have increased exponentially in the past 20 years and the recent literature has shown increasing interest in the use of biological and synthetic mesh [8,9]. The principle behind using such grafts in reconstructive surgery is reinforcement of existing tissues with materials that are safe, biologically compatible and provide suitable anatomical and functional results.

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