The biomechanics of being born: characterising ovine pelvic tissues for computational models

Up to 20-30% of women over 20 years old and up to 50% over 50 may suffer from pelvic floor disorders. Challenges with experimental investigation of the biomechanics of childbirth, such as ethical and clinical restrictions in physical testing and observation of this complex phenomenon, have led to a shift towards computational modelling, which is heavily dependent on accurate material properties to predict realistic and accurate biomechanics.

In particular, there is a lack of data on anisotropic and time-dependent mechanical properties of female LA and VA muscles.<br><br>Thus, this work set out to investigate both the elastic and time-dependant nature of the LA and VA muscles. These two muscles undergo large strains during delivery and are frequently injured, leading to the development of pelvic floor disorders in many women. This study began with the development of a novel radial tissue stretcher (RTS), selection of ovine LA and VA muscles as suitable analogues for the corresponding human pelvic floor muscles based on literature review, followed by uniaxial and multiaxial testing of the LA and VA muscles of the ovine pelvic floor, and finally fitting a fibre-reinforced visco-hyperelastic constitutive model to the experimental data.