A biomechanical approach relying on urodynamic data and mechanical tests is proposed for an accurate modelling of the lower urinary tract dysfunction. The goal of the study is to obtain a model that mimics the urethra and bladder with dysfunction, to identify which mechanical changes have led to the problem, proposing treatments to repair disorders effectively.

Based on MRI data of a nulliparous 24-years female without pelvic floor dysfunction complaints, a computer model of the lower urinary tract was obtained (Fig. 1).
To characterize the bladder tissue biomechanical behavior, experimental tests from the literature will be reproduced by computer models [1,2]. The typical features of the tissue mechanical response will be described by a visco-hyperelastic constitutive formulation.
Computational analysis will be performed to simulate the filling, storage and voiding phases of a dysfunctional bladder (stress urinary incontinence).
To calibrate and validate the obtained computational model, data from urodynamics will be used.
 
Fig. 1 - Computational model of the lower urinary tract and pelvic bones.

The anisotropic, non-linear and time-dependent stress–strain behavior showed by experimental results was fully described by the constitutive model adopted.
The developed biomechanical model can predict the pressure-flow curves, and receiving as input the reproduced patient’s symptoms, it can identify the underlying pathophysiological mechanisms.

Precise characterization of the mechanical properties of the bladder wall tissues are mandatory to describe different urinary tract dysfunction. 
Computational models are an important tool to mimics a dysfunctional system, helping to plan the best strategy to solve the problem. Such models can help to understand, from a mechanical point of view, different maximum flow rate (Qmax), variations in detrusor and vesical pressures, and other important parameters. Furthermore, different geometries of the bladder can also be analysed.

Using both a 3D geometrical model of the bladder and urethra and data from urodynamics, it was possible to establish proper material properties regarding the behaviour of the bladder wall tissues, contribute to deepen the understanding of lower urinary tract biomechanics.

Natali et al (2015) Bladder tissue biomechanical behavior: Experimental tests and constitutive formulation. Journal of Biomechanics, 48:3088–3096.
Jokandan et al (2018) Bladder wall biomechanics: A comprehensive study on fresh porcine urinary bladder. Journal of the Mechanical Behavior of Biomedical Materials, 79:92–103.