[Mechanical resistance of pelvic ligaments used for incontinence or prolapse surgery]

Underline the objective strength of the pelvic ligaments.

Twenty nine human female pelvis cadavers, whose storage conditions differed, were used in our study. In each cadaver we dissected all the ligaments used in pelvic surgery. A subjective clinical evaluation of the ligament properties was performed by visual observation as well as by finger palpation. Ligaments were classified into three groups in terms of thickness and apparent strength following finger palpation, high, doubtful and low apparent quality ligaments. Then a suture taking the entire ligament switched the ligaments and a force was applied on the vagina axis until tearing. The device used for strength measurement during traction was a Samson type force gauge, which was developed for the purpose of our study. Results were given in Newtons.

We found a great variability in the values obtained at tearing with maximal values at 200 newtons and minimal at 22. Individually measured, ligament strength varied between individuals, and for a same patient between the type of ligaments and the side. The pre-vertebral ligament was on average the strongest. For bilateral ligaments, there was no difference between the left and right side. The iliopectineal ligament was statistically significantly stronger than sacrospinous and arcus tendineus of pelvic fascia. There was a correlation between subjective evaluation and objective strength measurements.

We performed the only study of the strength of pelvic ligaments at tearing. These are, however, routinely used in the cure of prolapse and urinary incontinence. Our results show that there is a great variability in strength between individuals, and for a same patient between the types of ligaments and side. These observations could explain some of the surgical intervention failures and demonstrate the importance of per-operative strength evaluation. Per-operative subjective evaluation on strength is related to objective measurements and could be used to determine the type of ligaments to be used for surgical assembly suspension.