Assessing Mouse Uterosacral Ligament Physiological Range: Measurement of Static and Dynamic Properties

The uterosacral ligaments (USLs) play a crucial role in maintaining pelvic floor stability, linking the uterine cervix to the sacrum. Alterations in USL structure and function are central in pelvic floor disorders (PFDs), especially pelvic organ prolapse (POP), which significantly impacts women's health. To address existing knowledge gap, experimental analysis is essential to clarify USLs' biomechanical behaviour. This study investigates the mechanical properties of the USL, focusing on its passive behavior. We developed a standardized protocol to test USL's static and dynamic properties in its physiological range, including a procedure to isolate it from the surrounding tissues for mechanical testing. Static tests were aimed at measuring the Young's Modulus and the toe-to-linear transition stress and strain values, while dynamic testing provided insight into the ligament's frequency-dependent behavior of the viscoelastic components. Results showed that the USL exhibited a consistent transition strain (11%) with low variability. As for the dynamic tests, storage compliance predominated over loss compliance, emphasizing the ligament's resistance to deformation and energy absorption, while viscosity increased at higher frequencies, reflecting adaptive behavior. This work offers valuable insights into USL mechanical performance, devising a complete testing protocol for its accurate and repeatable characterization, therefore contributing to a deeper understanding of its role in pelvic health.