Influence of Age on the Characterization of Elasticity of Prolapsed Vaginal Tissue on a Postmenopausal Women Group

ABSTRACT

Introduction and Objective: The objective of the current study is to evaluate the influence of age on the Elasticity of prolapsed vaginal tissue. Despite the recent efforts of several researchers [1,2], the mechanical properties of vaginal tissue are not fully understood. This information is important, for example, as an aid to evaluate the adequacy of urogynecologic implant materials [3], or it can be a contribution to the improvement of numerical simulations related with the pelvic cavity on women with pathologies like pelvic organ prolapse or urinary incontinence.


Methods: For the current study 28 post-menopausal patients were considered. Patient‚s age ranged from 49 to 84 years old. All patients were assisted on São João Hospital, and live on the North of Portugal. The tissue samples were collected between April of 2006 and October of 2007. Sample removal was performed during prolapse correction surgeries, according to a procedure approved by the Ethics Committee of S. João Hospital. Uniaxial tension tests were performed. The maximum time until testing was 6 hours and most of the specimens were tested no more than 4 hours after surgery. It was measured an elasticity parameter E describing the linear elastic portion of the stress/stretch curves [3]. The software package MATLAB® version 7 for windows was the platform used for statistics, data interpolation and graphical presentation of the results. The R-square value (complete miss? 0 = R-square = 1? complete match) was as a statistical measurement for the accuracy of the curve fittings presented.

Results: The experimental (average ± SD) value obtained for the elasticity parameter E was E = 12.34 ± 4.71 MPa. The results of the current study are a close match to those reported in [1], considering that they were achieved with a different experimental protocol [2,3]. A linear approximation of E (E˘-0.017*age+13; R-square = 0.001) shows a slight decreasing tendency of this property with age. However, a very small R-square coefficient indicates that the fitting does not describe the experimental results with accuracy.

Conclusion: It is known that biomechanical properties of living tissues are influenced by a multitude of patient dependent factors [4]. For the particular case of vaginal tissue, there have been recent works [1,2] debating the influence of patient dependent characteristics (such as age or parity) on the biomechanical properties. The present study, in agreement with the consulted literature, indicates that patient age does not influence the biomechanical properties of prolapsed vaginal tissue in any special way [1], but nevertheless does have some influence.

REFERENCES

  1. Lei, L., Y. Song, et al. (2007). "Biomechanical properties of prolapsed vaginal tissue in pre- and postmenopausal women." Int Urogynecol J 18: 603-607
  2. Epstein, L., M. Heit, et al. (2006). "Systemic and vaginal elasticity in women with and without pelvic organ prolapse." Int Urogynecol J 17(S2): S57
  3. Afonso, J., P. Martins, et al. (2008). "Mechanical properties of polypropylene mesh used in pelvic floor repair." Int Urogynecol J 19: 375-380
  4. Fung, Y. C. (1993). Biomechanics: Mechanical properties of living tissues, 2nd ed. Springer-Verlag. 

 

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