Determination of the Uncertainties Associated With the Measurement of the Main Parameters Characterizing Mouse Uterosacral Ligament Quasi-Static Behavior

The uterosacral ligaments (USLs) are key suspensory structures essential for female pelvic organ stability, providing support to the uterus and upper vagina. Their laxity, often induced during childbirth, is strongly linked to pelvic floor disorders (PFDs). Despite advances in USL mechanics, variability remains high due to the lack of standardized protocols for tissue extraction and mechanical testing. To address these challenges, we developed tissue-specific dissection and uniaxial quasi-static mechanical testing procedures to investigate the mechanical properties along the principal direction of the ligament over its full length. This enabled reliable identification of the nonlinear stress-strain curve, expected for soft tissues. In this work, we improve USL mechanical testing by systematically analyzing sources of uncertainty, including tissue measurement, load–position recording, curve-fitting methods, and natural biological variability. Using offline data fitting, we identified the average values and combined associated uncertainty of toe-to-linear transition region related key parameters: transition stress (80.0 ± 16 kPa), transition strain (11.54 ± 0.43 %) and Youngs modulus (2.46 ± 0.34 MPa). Sensitivity analysis confirmed the reliability of the fitting process, with minimal impact on elasticity estimation. Biological variability was the primary source of uncertainty (0.33 MPa) for elasticity, while measurement system uncertainty (0.014 MPa) and fitting sensitivity uncertainty (0.34 %) mainly affected transition stress and transition strain values, respectively. By quantifying these uncertainties, this study provided a robust framework for biomechanical testing, advancing standardized research and supporting pelvic health applications.