Purpose: We evaluated tissue reactions to 5 sling materials used in tension-free vaginal tape (TVT), intravaginal slingplasty (IVS), polypropylene mesh hernia repair, the suprapubic approach to suburethral polypropylene tape (SPARC) and cadaveric fascia lata procedures. We also compared the mesh-to-tissue attachment strength of 4 sling mesh materials (TVT, IVS, surgical polypropylene mesh and SPARC) at on days 2, 7, 15 and 30 after implantation.
Materials and methods: A total of 20 female New Zealand White rabbits were randomized to group 1-2 days, group 2-7 days, group 3-15 days and group 4-30 days. After the rabbits were anesthetized an 8 cm midline incision was made for rectus muscle access, and 0.5 x 1 cm pieces of TVT, IVS, SPARC, surgical polypropylene mesh and cadaveric fascia lata were sewn to the rectus muscle with direct contact. At the same time 4 subfascial tunnels in the medial surface of the upper extremities were prepared, and 1.0 x 0.5 cm strips of TVT, IVS, SPARC and polypropylene mesh were implanted in each tunnel. On days 2, 7, 15 and 30 after implantation mechanical testing was performed to define tissue detachment strength. The strips of 5 sling materials were then harvested with the surrounding tissue. Specimens were studied by light microscopy.
Results: Mean detachment strength, that is the minimum weight needed to move the mesh, of the synthetic meshes from days 2 to 30 were 291.6 to 2,390.0 gm for TVT, 178.4 to 2,160.0 gm for SPARC, 188.4 to 1,850.0 gm for hernia mesh and 92.8 to 1,510.0 gm for IVS (at all data points TVT vs IVS p < 0.05). Light microscopy revealed a quite uniform tissue reaction with a sign of marked acute inflammation in and around the mesh fibers on days 2 and 7 after implantation. All meshes showed stable fibrosis and muscle infiltration on day 30.
Conclusions: All 5 synthetic sling materials produce similar tissue reactions beginning soon after implantation. Cadaveric fascia lata persisted in tissue with remarkable perifascial fibrosis at day 30. When comparing the 4 polypropylene mesh materials; the attachment capacity of TVT was superior and that of IVS was the least of the 4. TVT was statistically better than IVS at all data points. SPARC and hernia mesh provided results similar to those of TVT.