Identification of biomechanical properties in vivo in human uterine cervix

The mechanical role of the cervix in pregnancy

“…Insight into the physiologic loads experienced during pregnancy and the load-carrying capability of the cervix have been derived from finite element models (Fernandez et al, 2015; House et al, 2012, 2013; Mahmoud et al, 2013; Paskaleva, 2007), mechanical and biochemical studies of ex vivo tissue specimens (Conrad et al, 1980; Conrad and Ueland, 1976, 1979; Fernandez et al, 2013; Gan et al, 2014; Myers et al, 2008, 2010; Oxlund et al, 2010a,b; Petersen et al, 1991; Rechberger et al, 1988; Yao et al, 2014), in vivo mechanical and biochemical interrogations of the cervix (Badir et al, 2013a; Bauer et al, 2007; Feltovich et al, 2010, 2012; Feltovich and Hall, 2013; Hee et al, 2014; House et al, 2005, 2009; Hricak et al, 1990; Maldjian et al, 1999; Mazza et al, 2006, 2013; Parra-Saavedra et al, 2011), and theoretical mechanics (Liao et al, 2014; Myers and Ateshian, 2014; Paskaleva, 2007). At the present time, there is no single set of correlating geometric and material property data from a single pregnant patient throughout gestation.…”

“…Because of the positioning of the device in the inner canal, it was able to capture the deformation behavior from the internal to the external os. The pressure-displacement results are interpreted based on a fiber composite material model that assumes three preferentially aligned fiber families homogeneously distributed throughout a thick-walled cylinder (Liao et al, 2014). Fiber directionality is informed by a separate set of x-ray diffraction data, which elucidates the fiber directionality of the collagen in nonpregnant cervix (Aspden, 1988).…”

“…Different equilibrium constitutive material models have been used to describe cervical ex vivo tension and compression uni-axial material behavior (Myers et al, 2008, 2010, 2015), the in vivo pressure-displacement inner canal response recorded with the EndoFlip balloon inflation device (Liao et al, 2014; Hee et al, 2014), and the in vivo aspiration response of the external os of the cervix (Badir et al, 2013a,b). The two proposed fiber composite models, a continuously distributed fiber model (Myers et al, 2015) and a 3-fiber family model (Liao et al, 2014), are similar in that they attempt to account for the cervical collagen ultrastructure using early reports of fiber directionality (Aspden, 1988; Gan et al, 2014).…”

“…The two proposed fiber composite models, a continuously distributed fiber model (Myers et al, 2015) and a 3-fiber family model (Liao et al, 2014), are similar in that they attempt to account for the cervical collagen ultrastructure using early reports of fiber directionality (Aspden, 1988; Gan et al, 2014). They differ such that the material model based on the optical coherence tomography data and ex vivo mechanical tests uses a continuously distributed elliptical fiber distribution (EFD) (Gan et al, 2014; Myers et al, 2015), where fibers can only sustain tensile stresses, and the 3-fiber family model based on nonpregnant x-ray diffraction and EndoFlip data uses a fiber network with no fiber dispersion and the fiber strain energy density can sustain both tension and compression (Aspden, 1988; Hee et al, 2014; Liao et al, 2014). The third model, fit to the aspiration data, is a neo-Hookean material, where the tissue is assumed to be incompressible (Badir et al, 2013a).…”

Functional lumen imaging of the gastrointestinal tract

“…FLIP measurement provides a comprehensive evaluation of sphincter resistance to mechanical distension. However, to reveal the individual mechanical contributions from each part and component of the sphincter, studies introducing a real constitutive equation with mechanical parameters from different muscle layers and collagen fibers should be considered in future FLIP-based analysis of GI sphincters [70,71].…”