Mechanical Analysis of the Uterosacral Ligament: Swine vs. Human

Abstract

The uterosacral ligament (USL) is a major suspensory structure of the female pelvic floor, providing support to the cervix and/or upper vagina. it plays a pivotal role in surgical procedures for pelvic organ prolapse (PoP) aimed at restoring apical support. Despite its important mechanical function, little is known about the mechanical properties of the USL due to the constraints associated with in vivo testing of human USL and the lack of validated large animal models that enable such investigations. in this study, we provide the first comparison of the mechanical properties of swine and human USLs. Preconditioning and pre-creep data up to a 2 N load and creep data under a 2 N load over 1200 s were obtained on swine (n = 9) and human (n = 9) USL specimens by performing planar equi-biaxial tensile tests and using the digital image correlation method. No differences in the peak strain during preconditioning tests, secant modulus of the pre-creep response, and strain at the end of creep tests were detected in the USLs from the two species along both axial loading directions (the main in vivo loading direction and the direction that is perpendicular to it). These findings suggest that the swine holds promise as large animal model for studying the mechanical role of the USL in apical vaginal support and treatment of PoP.

Comparison of Biaxial Biomechanical Properties of Post-menopausal Human Prolapsed and Non-prolapsed Uterosacral Ligament

“…This may be a limitation of the use of PicroSirius Red to quantify collagen content versus specified immunohistochemistry. However, collagen and smooth muscle content measured in this study were similar to those previously quantified using similar methods 25 . These discrepancies may be due, in part, to limitations in histology and immunohistochemistry which analyse small, arbitrary sections of the bulk tissue.…”

“…While the etiology of POP is multifactorial and not fully understood, the observed alterations in the USL suggest that changes in pelvic support tissue mechanical properties may contribute to POP progression. Further, the increased extensibility observed in the POP III/IV group may suggest changes in USL length occur with POP progression due to decreased ability to resist in vivo loads, which may have implications for reconstructive surgical planning 25 . While the correlations identified in this study may suggest that increased extensibility is due to decreased collagen content, no significant differences in collagen content were identified between POP groups.…”

“…Four fish hooks were used to mount each sample side (Fig. 1C) into a custom planar biaxial test device equipped with load cells (22 N) in both axes, and a camera 25,27 . The device permits independent control of displacement in the two orthogonal axes.…”

“…The samples were fully submerged in Hank's balance saline solution (HBSS) at room temperature throughout the experiment. To prevent movement of HBSS around the mounted sample, an acrylic glass table was placed over the bath, making a complete contact with the HBSS solution as described previously 25 .…”

Special Issue on the Advances in Engineering for Women’s Health

“…The diversity in engineering applications and techniques being developed to uniquely address health issues affecting women over their lifespan is increasing at a fast pace. Building upon recent publications in the Annals of Biomedical Engineering related to women's health, 3,4,7,9,13,16,17 this special issue will expand on the biomechanics of reproductive organs and their supporting structures, structural organization of pelvic organs and tissues and their functional alterations with aging and prolapse, and female-related cancers.…”