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J Biomech. 2015 Jun 25;48(9):1533-40. doi: 10.1016/j.jbiomech.2015.02.060. Epub 2015 Mar 14.

A continuous fiber distribution material model for human cervical tissue.

Author information

1
Department of Mechanical Engineering, Columbia University School of Engineering and Applied Science, 500 W. 120th Street, Mudd 220, New York, NY 10027, USA. Electronic address: kmm2233@columbia.edu.
2
Department of Electrical Engineering, Columbia University School of Engineering and Applied Science, New York, NY, USA.
3
Department of Mechanical Engineering, Columbia University School of Engineering and Applied Science, 500 W. 120th Street, Mudd 220, New York, NY 10027, USA.
4
Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY, USA.

Abstract

The uterine cervix during pregnancy is the vital mechanical barrier which resists compressive and tensile loads generated from a growing fetus. Premature cervical remodeling and softening is hypothesized to result in the shortening of the cervix, which is known to increase a woman׳s risk of preterm birth. To understand the role of cervical material properties in preventing preterm birth, we derive a cervical material model based on previous mechanical, biochemical and histological experiments conducted on nonpregnant and pregnant human hysterectomy cervical tissue samples. In this study we present a three-dimensional fiber composite model that captures the equilibrium material behavior of the tissue in tension and compression. Cervical tissue is modeled as a fibrous composite material, where a single family of preferentially aligned and continuously distributed collagen fibers are embedded in a compressible neo-Hookean ground substance. The total stress in the collagen solid network is calculated by integrating the fiber stresses. The shape of the fiber distribution is described by an ellipsoid where semi-principal axis lengths are fit to optical coherence tomography measurements. The composite material model is fit to averaged mechanical testing data from uni-axial compression and tension experiments, and averaged material parameters are reported for nonpregnant and term pregnant human cervical tissue. The model is then evaluated by investigating the stress and strain state of a uniform thick-walled cylinder under a compressive stress with collagen fibers preferentially aligned in the circumferential direction. This material modeling framework for the equilibrium behavior of human cervical tissue serves as a basis to determine the role of preferentially-aligned cervical collagen fibers in preventing cervical deformation during pregnancy.

KEYWORDS:

Cervix; Collagen fibers; Constitutive modeling; Pregnancy

PMID:
25817474
PMCID:
PMC6167934
DOI:
10.1016/j.jbiomech.2015.02.060
[Indexed for MEDLINE]
Free PMC Article

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