[Biomechanics of stress distribution and resistance of biological tissues: why use prostheses for the treatment of genital prolapse?]

Abstract

Background: Solidity and elasticity are the two main biomechanical properties of pelvic tissues involved in surgical cure of genital prolapse-prevertebral, pectinate, and sacrospinal ligaments, tendinous arcs of the pelvic fascia, vaginal tissue. We report data in the literature and personal studies concerning these autologous biological tissues.

Material and methods: The resistance of pelvic tissues was tested on 29 cadavers. Measurements were also made on two 2-cm samples of vaginal tissue obtained during vaginal route surgery for prolapse cure in 20 menopaused women. Stress tests were conducted to determine resistance and level of rupture.

Results: There was a wide variability in ligament resistance, ranging from a minimum of 22 Newtons to a maximum to the order of 200 Newtons. Results varied greatly from one woman to another and also between the two sides in the same woman. The prevertebral ligament exhibited the greatest resistance. The pectinate ligament was significantly more resistant than the sacrospinal ligaments and the tendinous arcs of the pelvic fascia. There was a significant relationship between the subjective assessment of ligament quality and objective measurements of resistance. For vaginal tissues, resistance varied greatly from 12 Newtons to a maximum to the order of 76 Newtons. Flexion values ranged from 14 to 130 Newtons.

Conclusion: Our findings illustrate pelvic tissue failure observed in patients with genital prolapse. Individual maximal resistance of the pelvic ligaments is vary variable, between ligaments and between subjects, and even between sides in a given subject. Pelvic ligaments used for cure of genital prolapse are moderately resistant with wide interindividual variability. The mechanical properties of vaginal tissue are also very variable, illustrating why these tissues may exhibit a certain resistance against dissociation when exposed to loading but much less resistance when exposed to traction by a surgical suture. These findings suggest a revision of classical surgical procedures.