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Modeling the Modeling the Biomechanics of Stress Biomechanics of Stress Urinary Incontinence Urinary Incontinence Thomas Spirka Margot Damaser Thomas Spirka Margot Damaser Cleveland Clinic Cleveland Clinic Cleveland State University Cleveland State University Cleveland OH Cleveland OH

Modeling the Biomechanics of Stress Urinary Incontinence Thomas Spirka Margot Damaser Cleveland Clinic Cleveland State University Cleveland OH

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Page 1: Modeling the Biomechanics of Stress Urinary Incontinence Thomas Spirka Margot Damaser Cleveland Clinic Cleveland State University Cleveland OH

Modeling the Biomechanics of Modeling the Biomechanics of Stress Urinary IncontinenceStress Urinary Incontinence

Thomas Spirka Margot DamaserThomas Spirka Margot Damaser

Cleveland Clinic Cleveland Clinic Cleveland State UniversityCleveland State University

Cleveland OHCleveland OH

Page 2: Modeling the Biomechanics of Stress Urinary Incontinence Thomas Spirka Margot Damaser Cleveland Clinic Cleveland State University Cleveland OH

Stress Urinary IncontinenceStress Urinary IncontinenceWhat is it?What is it?

Increased Abdominal Pressure

Increases Bladder

Pressure

Urine Leakage

Cough

The complaint of involuntary leakage of urine on effort or exertion, or on sneezing or coughing.

Abrams, et al. Neurourol. & Urodyn. 21:167-178, 2002.

Page 3: Modeling the Biomechanics of Stress Urinary Incontinence Thomas Spirka Margot Damaser Cleveland Clinic Cleveland State University Cleveland OH

Stress Urinary IncontinenceStress Urinary IncontinenceWhy should we care?Why should we care?

Urinary IncontinenceUrinary Incontinence 20-50% of women20-50% of women

Risk FactorsRisk Factors– Age Age – Vaginal ChildbirthVaginal Childbirth

Page 4: Modeling the Biomechanics of Stress Urinary Incontinence Thomas Spirka Margot Damaser Cleveland Clinic Cleveland State University Cleveland OH

Mechanics of Stress Urinary Mechanics of Stress Urinary IncontinenceIncontinence

Little known regarding mechanics of Little known regarding mechanics of continence maintenancecontinence maintenance

Limited to two conflicting theoriesLimited to two conflicting theories– Mechanics of have never been validated in Mechanics of have never been validated in

either caseeither case

Page 5: Modeling the Biomechanics of Stress Urinary Incontinence Thomas Spirka Margot Damaser Cleveland Clinic Cleveland State University Cleveland OH

Project GoalsProject Goals

Gain insight into the mechanics by which Gain insight into the mechanics by which continence is maintained when abdominal continence is maintained when abdominal pressure is increased through finite element pressure is increased through finite element modeling.modeling.

Use finite element modeling to test the Use finite element modeling to test the mechanics behind the two theories of mechanics behind the two theories of continence.continence.

Page 6: Modeling the Biomechanics of Stress Urinary Incontinence Thomas Spirka Margot Damaser Cleveland Clinic Cleveland State University Cleveland OH

Project GoalsProject Goals

Key to understanding this continence Key to understanding this continence mechanism is understanding how structures mechanism is understanding how structures of the pelvic floor and lower urinary tract of the pelvic floor and lower urinary tract deform in relation to one another when deform in relation to one another when abdominal pressure is increasedabdominal pressure is increased

Page 7: Modeling the Biomechanics of Stress Urinary Incontinence Thomas Spirka Margot Damaser Cleveland Clinic Cleveland State University Cleveland OH

Finite Element Modeling of Finite Element Modeling of BiomechanicsBiomechanics

Goal is to gain insight and understanding that cannot be Goal is to gain insight and understanding that cannot be obtained experimentallyobtained experimentally

Modeled situations are complex and not well characterizedModeled situations are complex and not well characterized– Require several assumptions to be made and testedRequire several assumptions to be made and tested

Sensitivity Analysis and Parametric Testing frequently Sensitivity Analysis and Parametric Testing frequently required to determine effects of assumptions and required to determine effects of assumptions and understand how model is performingunderstand how model is performing

Page 8: Modeling the Biomechanics of Stress Urinary Incontinence Thomas Spirka Margot Damaser Cleveland Clinic Cleveland State University Cleveland OH

Mechanics of Stress Urinary Mechanics of Stress Urinary IncontinenceIncontinence

Structures that must be incorporated into modelStructures that must be incorporated into model– Pelvic BonesPelvic Bones– BladderBladder– UrethraUrethra– VaginaVagina– Levator Ani (Pubococcygeus, Illiococcygeus, Levator Ani (Pubococcygeus, Illiococcygeus,

Puborectalis)Puborectalis)– Arcus Tendinius Fascia PelvisArcus Tendinius Fascia Pelvis– Endopelvic FasciaEndopelvic Fascia– Pubourethral LigamentsPubourethral Ligaments

Page 9: Modeling the Biomechanics of Stress Urinary Incontinence Thomas Spirka Margot Damaser Cleveland Clinic Cleveland State University Cleveland OH

Modeled by Xiao Long Li

Page 10: Modeling the Biomechanics of Stress Urinary Incontinence Thomas Spirka Margot Damaser Cleveland Clinic Cleveland State University Cleveland OH

ModelingModeling

Need to account forNeed to account for– Mechanics of each structureMechanics of each structure

How does each structure deformHow does each structure deform Material Properties (Non-Linear)Material Properties (Non-Linear)

– Contact between structuresContact between structures How do the structures deform in relation to one How do the structures deform in relation to one

anotheranother How much support do the various structures provide How much support do the various structures provide

to one anotherto one another

Page 11: Modeling the Biomechanics of Stress Urinary Incontinence Thomas Spirka Margot Damaser Cleveland Clinic Cleveland State University Cleveland OH

ModelingModeling

Need to account forNeed to account for– Fluid Structure InteractionsFluid Structure Interactions

Is urine entering the urethra as a result of the Is urine entering the urethra as a result of the abdominal pressure loadsabdominal pressure loads

Is urine traveling the length of the urethra and leaking Is urine traveling the length of the urethra and leaking outout

– Transient LoadsTransient Loads Sharp transient events do not lend themselves to Sharp transient events do not lend themselves to

quasi-steady state modelingquasi-steady state modeling

– Forces arising from muscle contractionsForces arising from muscle contractions

Page 12: Modeling the Biomechanics of Stress Urinary Incontinence Thomas Spirka Margot Damaser Cleveland Clinic Cleveland State University Cleveland OH

Computational NeedsComputational Needs

HardwareHardware– Computational PowerComputational Power

Simple simulations are taking days to complete on desktop Simple simulations are taking days to complete on desktop equipmentequipment

Ability to run multiple parametric simulations if not concurrently Ability to run multiple parametric simulations if not concurrently then in at least a timely fashionthen in at least a timely fashion

SoftwareSoftware– LS DynaLS Dyna

Dynamic Finite Element SolverDynamic Finite Element Solver

– Pre/Post Processing Pre/Post Processing Mesh Generation Mesh Generation Display ResultsDisplay Results