Yao Wang, Yoshida Kyoko, Fernandez Michael, Vink Joy, Wapner Ronald J, Ananth Cande V, Oyen Michelle L, Myers Kristin M
Department of Mechanical Engineering, Columbia University, New York, NY, USA.
Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY, USA.
J Mech Behav Biomed Mater. 2014 Jun;34:18-26. doi: 10.1016/j.jmbbm.2014.01.016. Epub 2014 Jan 29.
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%.
人类子宫颈是孕期重要的机械屏障，必须承受胎儿生长产生的压缩力和拉伸力。已知宫颈过早重塑和宫颈材料特性改变导致的宫颈过早缩短会增加女性早产（PTB）的风险。为了解孕期子宫颈的机械作用，并有可能开发用于体内诊断的压痕技术，以识别有宫颈过早重塑风险进而早产的女性，我们开发了一种球形压痕技术，用于测量接受子宫切除术患者的人宫颈组织随时间变化的材料特性。在本研究中，我们提出了一种逆有限元分析（IFEA），该分析优化了粘弹性材料模型的材料参数，以拟合切除的组织切片对球形压痕的应力松弛响应。在此，我们详细介绍我们的IFEA方法，报告非妊娠（NP）和妊娠（PG）子宫切除术患者宫颈组织切片的压缩粘弹性材料参数，并报告整个宫颈组织标本的逐片数据。这里报告的人宫颈组织的材料参数可用于模拟在25%的小应变范围内组织的压缩时间依赖性行为。
