Objective: To examine the tensile properties (break load and maximum average load), after in vivo implantation in a rat animal model, of tension-free vaginal tape (TVT) and cadaveric fascia lata (CFL), as pubovaginal slings of these materials have become popular for treating stress urinary incontinence.
Materials and methods: Twenty Sprague-Dawley rats (300-400 g) had 1 x 2 cm strips of commercially available TVT and CFL implanted on the right and left anterior abdominal wall, respectively. Half of the animals were then killed at 6 weeks and the remainder at 12 weeks, after which the strips of TVT and CFL were removed and their tensile properties measured using a tensiometer. The tensile strength of TVT and CFL strips maintained only in normal saline served as controls.
Results: The TVT strips had a mean break load of 0.740 kg in the control and only 0.390 kg for CFL (P < 0.05). At 6 weeks the TVT material had a mean (sd) maximum average load of 0.634 (0.096) kg and a mean break load of 0.589 (0.249) kg, whereas the respective values for the CFL were 0.323 (0.198) and 0.167 (0.063) kg (P < 0.05). Similarly at 12 weeks, TVT had a greater mean maximum average and break load than CFL, at 0.742 (0.052) and 0.274 (0.126), and 0.737 (0.056) and 0.185 (0.128) kg, respectively.
Conclusion: This is the first study to assess the tensile properties of the currently used sling materials, TVT and CFL, in an in vivo model. TVT has a greater break load and maximum average load than CFL; the tensile strength of these materials does not decrease with time.