title: Measuring the compressive viscoelastic mechanical properties of human cervical tissue using indentation.
abstract: The human cervix is an important mechanical barrier in pregnancy which must withstand the compressive and tensile forces generated from the growing fetus. Premature cervical shortening resulting from premature cervical remodeling and alterations of cervical material properties are known to increase a woman׳s risk of preterm birth (PTB). To understand the mechanical role of the cervix during pregnancy and to potentially develop indentation techniques for in vivo diagnostics to identify women who are at risk for premature cervical remodeling and thus preterm birth, we developed a spherical indentation technique to measure the time-dependent material properties of human cervical tissue taken from patients undergoing hysterectomy. In this study we present an inverse finite element analysis (IFEA) that optimizes material parameters of a viscoelastic material model to fit the stress-relaxation response of excised tissue slices to spherical indentation. Here we detail our IFEA methodology, report compressive viscoelastic material parameters for cervical tissue slices from nonpregnant (NP) and pregnant (PG) hysterectomy patients, and report slice-by-slice data for whole cervical tissue specimens. The material parameters reported here for human cervical tissue can be used to model the compressive time-dependent behavior of the tissue within a small strain regime of 25%.
authors.affiliation: Department of Mechanical Engineering, Columbia University, New York, NY, USA.
authors.forename: Wang
authors.initials: W
authors.lastname: Yao
authors.affiliation: Department of Mechanical Engineering, Columbia University, New York, NY, USA.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Yoshida
authors.affiliation: Department of Mechanical Engineering, Columbia University, New York, NY, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Fernandez
authors.affiliation: Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY, USA.
authors.forename: Joy
authors.initials: J
authors.lastname: Vink
authors.affiliation: Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY, USA.
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Wapner
authors.affiliation: Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY, USA; Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY, USA.
authors.forename: Cande V
authors.initials: CV
authors.lastname: Ananth
authors.affiliation: Department of Engineering, Cambridge University, Cambridge, UK.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Oyen
authors.affiliation: Department of Mechanical Engineering, Columbia University, New York, NY, USA. Electronic address: kmm2233@columbia.edu.
authors.forename: Kristin M
authors.initials: KM
authors.lastname: Myers
mesh_terms: D001696:Biomechanical Phenomena; D002584:Cervix Uteri; D019245:Compressive Strength; D004548:Elasticity; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008422:Materials Testing; D014783:Viscosity
keywords: Biomechanics; Cervix; Indentation; Viscoelastic