enced by the biomechanical properties of implant and
native tissue, respectively, and the biomechanical properties
of synthetic meshes is important in choosing appropriate
materials for a variety of urogynecologic procedures,
particularly sub-urethral slings. These authors conclude
that the lowest initial stiffness, i.e. low resistance to
deformation at forces below the elastic limit, may be at
least partly respon sible for the apparent clinical success of
the implants. This observation seems to be supported by
other authors. Feifer and Corcos [18] referred that tensile
strength of synthetic meshes is not a d ifferentiating factor
among products since it is one order of magnitude higher
than normal fibrous tissue. Neymeyer et al. [19] also
recommended that the most appropriate mesh properties
should be as close as possible to natural human tissue.
For the same material, stiffness is related with mesh
geometry, mesh manufacturing and mesh thickness. Alter-
natively, for the same mesh (same manufacturing and same
thickness), the stiffness can be changed by using different
materials. The sample’s stiffness is directly proportional
with thickness values obtained from the tensile test.
However, considering the tape ring compression t est,
stiffness varies in an inversely cubic manner with thickness
[20]. From solid mechanics considerations, we can assume
that polypropylene filament thickness has more influence
(mechanically) on the tape ring compression test than on
the uniaxial tensile test.
This study shows that there are significant differences on
the mechanical properties between urogynecology meshes.
The TVTO™ mesh as stated by the manufactur er is
approximately 50% more flexible than the standard poly-
propylene mesh, and the bi-directional elastic properties
allow adaptation to various stresses encountered in the body
[ 11]. The test results obtained in the present work
confirmed that the referred mesh has an inferior tensile
stiffness when compared to the other studied meshes.
Although the experimental values of tensile and flexural
stiffness are low, Auto Suture™ is currently not used in the
practical clinic for pelvic floor repair.
Cons idering the stress urinary incontinen ce meshes,
Aris™ presented a tensile stiffness signi ficantly higher than
Uretex™ and TVTO™; however, the flexural stiffness was
found to be significantly smaller. For these meshes, the
decrease in flexural stiffness is followed by a reduction in
monofilament diameter. All these meshes are made of
polypropylene monofilament fibres and present macropores
[5, 21]. The tested mesh used on pelvic floor repair of
vaginal wall prolapse (Avaulta™) shows high tensile and
flexural stiffness values. Additional clinical studies are
necessary to evaluate the real importance of the flexural
stiffness.
A compa rison of the present results with previous related
works is consistent with the behaviour of TVTO mesh
stiffness. In the current work as well as in Dietz et al. [13],
the TVT presents the lowest tensile stiffness values.
Conclusion
This study shows that there are significant differences on
the mechanical properties between urogynecology meshes.
Acknowledgments This work was supported by CAPES (Federal
Government of Brazil), and Ministério da Ciência, Tecnologia e
Ensino Superior (FCT, Portugal) under the grant PTDC/SAU-BEB/
71459/2006.
Conflict of interest statement The work reported has not been
supported by industry and the authors do not have conflict of interests.
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