A Viscoelastic Model For Human Prolapsed Vaginal Wall Tissue

Abstract

Pelvic organ prolapse (POP) affects thousands of elderly women each year. Improvements in surgical repair could benefit from the understanding of the biomechanical properties of the vaginal wall (VW) tissues to better tailor the needed repair. VW tissue property has been measured by uniaxial tensile test on excised fresh human anterior VW tissues. Data available, however, are limited to elastic modulus obtained in vitro. Recently, in vivo biomechanical data of VW from POP patients have been obtained by adapting a cutometer-like device, the BTC-2000TM (SRLI). The Voigt and Standard Linear models in conjunction with the framework of quasi-linear viscoelasticity theory have been developed to account for the creep response of the VW tissues. Using these models, we are able to reproduce the time course of the measurements of VW tissue uplift in response to the suction pressure increase from POP patients as recorded using the BTC-2000TM. For the majority of the patient sets, the model revealed lower tissue damping and higher elastic response during tissue uplift in the VW tissue as a result of a predominant spring with a miniscule dashpot featured in both viscoelastic models.