title: Biomechanical study on the bladder neck and urethral positions: simulation of impairment of the pelvic ligaments.
abstract: Excessive mobility of the bladder neck and urethra are common features in stress urinary incontinence. We aimed at assessing, through computational modelling, the bladder neck position taking into account progressive impairment of the pelvic ligaments. Magnetic resonance images of a young healthy female were used to build a computational model of the pelvic cavity. Appropriate material properties and constitutive models were defined. The impairment of the ligaments was simulated by mimicking a reduction in their stiffness. For healthy ligaments, valsalva maneuver led to an increase in the α angle (between the bladder neck-symphysis pubis and the main of the symphysis) from 91.8° (at rest) to 105.7°, and 5.7 mm of bladder neck dislocation, which was similar to dynamic imaging of the same woman (α angle from 80° to 103.3°, and 5mm of bladder neck movement). For 95% impairment, they enlarged to 124.28° and 12 mm. Impairment to the pubourethral ligaments had higher effect than that of vaginal support (115° vs. 108°, and 9.1 vs. 7.3mm). Numerical simulation could predict urethral motion during valsalva maneuver, for both healthy and impaired ligaments. Results were similar to those of continent women and women with stress urinary incontinence published in the literature. Biomechanical analysis of the pubourethral ligaments complements the biomechanical study of the pelvic cavity in urinary incontinence. It may be useful in young women presenting stress urinary incontinence without imaging evidence of urethral and muscle lesions or organ descend during valsalva, and for whom fascial damage are not expected.
authors.affiliation: Department of Radiology, Centro Hospitalar de São João-EPE, Faculty of Medicine, University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal. Electronic address: Sofia.brand@gmail.com.
authors.forename: Sofia
authors.initials: S
authors.lastname: Brandão
authors.affiliation: IDMEC, Faculty of Engineering, University of Porto, Rua Dr Roberto Frias, s/n, 4200-465 Porto, Portugal. Electronic address: mparente@fe.up.pt.
authors.forename: Marco
authors.initials: M
authors.lastname: Parente
authors.affiliation: Department of Gynecology and Obstetrics, Hospital de S. João, Faculty of Medicine, University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal.
authors.forename: Teresa
authors.initials: T
authors.lastname: Mascarenhas
authors.affiliation: Department of Gynecology and Obstetrics, Hospital de S. João, Faculty of Medicine, University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal. Electronic address: rita.mgs89@gmail.com.
authors.forename: Ana Rita Gomes
authors.initials: AR
authors.lastname: da Silva
authors.affiliation: Department of Radiology, Centro Hospitalar de São João-EPE, Faculty of Medicine, University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal. Electronic address: iramos@med.up.pt.
authors.forename: Isabel
authors.initials: I
authors.lastname: Ramos
authors.affiliation: Department of Gynecology and Obstetrics, Hospital de S. João, Faculty of Medicine, University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal. Electronic address: rnatal@fe.up.pt.
authors.forename: Renato Natal
authors.initials: RN
authors.lastname: Jorge
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008022:Ligaments / Q000033:anatomy & histology* / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D055595:Mechanical Phenomena; D009068:Movement; D010388:Pelvis; D014521:Urethra / Q000033:anatomy & histology* / Q000502:physiology; D001743:Urinary Bladder / Q000033:anatomy & histology* / Q000502:physiology; D014636:Valsalva Maneuver
keywords: Biomechanical simulation; Finite element method; Ligament impairment; Pelvic floor dysfunction; Soft tissue analysis