Time dependent variations in biomechanical properties of cadaveric fascia, porcine dermis, porcine small intestine submucosa, polypropylene mesh and autologous fascia in the rabbit model: implications for sling surgery.

PURPOSE: We investigated time dependent variations in tensile strength, stiffness, shrinkage and distortion in 6 materials commonly used for transvaginal anti-incontinence surgery.
MATERIALS AND METHODS: A total of 15 rabbits were randomized into 3 survival groups (2, 6 and 12 weeks, respectively). Each rabbit had human cadaveric fascia, porcine dermis, porcine small intestine submucosa, polypropylene mesh and autologous fascia implanted on the anterior rectus fascia. At harvest tensiometry and image analysis were performed on each sling. Results were compared to baseline for each sling type and the percent decrease from baseline was compared among sling types.
RESULTS: Each type of human cadaveric fascia and porcine allografts showed a marked decrease (60% to 89%) in tensile strength and stiffness from baseline. Polypropylene mesh and autologous fascia did not differ in tensile strength from baseline. Polypropylene mesh increased in stiffness from baseline. Autologous fascia and small intestinal submucosa demonstrated a 41% and 50% decrease in surface area, respectively, at 12 weeks.
CONCLUSIONS: To our knowledge the relative contribution of biomechanical properties of sling material to the success of anti-incontinence surgery is unknown. However, rapid loss of tensile strength and stiffness in porcine and cadaveric materials may contribute to the early re-emergence of symptoms following successful sling surgery. The results of this study add scientific validity to the increasing use of synthetics in anti-incontinence surgery. Urologists selecting a sling material should be aware of its time dependent biomechanical fate relative to other sling materials.