title: Biomechanical properties of the pelvic floor muscles of continent and incontinent women using an inverse finite element analysis.
abstract: Pelvic disorders can be associated with changes in the biomechanical properties in the muscle, ligaments and/or connective tissue form fascia and ligaments. In this sense, the study of their mechanical behavior is important to understand the structure and function of these biological soft tissues. The aim of this study was to establish the biomechanical properties of the pelvic floor muscles of continent and incontinent women, using an inverse finite element analysis (FEA). The numerical models, including the pubovisceral muscle and pelvic bones were built from magnetic resonance (MR) images acquired at rest. The numerical simulation of Valsalva maneuver was based on the finite element method and the material constants were determined for different constitutive models (Neo-Hookean, Mooney-Rivlin and Yeoh) using an iterative process. The material constants (MPa) for Neo-Hookean (c1) were 0.039 ± 0.022 and 0.024 ± 0.004 for continent vs. incontinent women. For Mooney-Rivlin (c1) the values obtained were 0.026 ± 0.010 vs. 0.016 ± 0.003, and for Yeoh (c1) the values obtained were 0.031 ± 0.023 vs. 0.016 ± 0.002, (p < 0.05). Muscle displacements obtained in the numerical simulations of Valsalva maneuver were compared with the muscle displacements obtained through additional dynamic MRI. Incontinent women presented a higher antero-posterior displacement than the continent women. The results were also similar between MRI and numerical simulations (40.27% vs. 42.17% for Neo-Hookean, 39.87% for Mooney-Rivlin and 41.61% for Yeoh). Using an inverse FEA coupled with MR images allowed to obtain the in vivo biomechanical properties of the pelvic floor muscles, leading to a relationship between them for the continent and incontinent women in a non-invasive manner.
authors.affiliation: a LAETA, INEGI, Faculty of Engineering , University of Porto , Porto , Portugal.
authors.forename: M E T
authors.initials: MET
authors.lastname: Silva
authors.affiliation: a LAETA, INEGI, Faculty of Engineering , University of Porto , Porto , Portugal.|b Faculty of Medicine, Department of Radiology, Centro Hospitalar de São João-EPE , University of Porto , Porto , Portugal.
authors.forename: S
authors.initials: S
authors.lastname: Brandão
authors.affiliation: a LAETA, INEGI, Faculty of Engineering , University of Porto , Porto , Portugal.
authors.forename: M P L
authors.initials: MPL
authors.lastname: Parente
authors.affiliation: c Faculty of Medicine, Department of Gynecology and Obstetrics, Centro Hospitalar de São João-EPE , University of Porto , Porto , Portugal.
authors.forename: T
authors.initials: T
authors.lastname: Mascarenhas
authors.affiliation: a LAETA, INEGI, Faculty of Engineering , University of Porto , Porto , Portugal.
authors.forename: R M
authors.initials: RM
authors.lastname: Natal Jorge
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D003710:Demography; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008279:Magnetic Resonance Imaging; D009132:Muscles / Q000503:physiopathology*; D009716:Numerical Analysis, Computer-Assisted; D017773:Pelvic Floor / Q000503:physiopathology*; D013314:Stress, Mechanical; D014549:Urinary Incontinence / Q000503:physiopathology*
keywords: Pelvic floor muscles; inverse finite element analysis; material constants; stress urinary incontinence