Modeling the Biomechanics of Stress Urinary Incontinence

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Modeling the Biomechanics of Stress Urinary
Incontinence

• Thomas Spirka Margot Damaser
• Cleveland Clinic
• Cleveland State University
• Cleveland OH

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Stress Urinary IncontinenceWhat is it?
The complaint of involuntary leakage of urine on
effort or exertion, or on sneezing or
coughing. Abrams, et al. Neurourol. Urodyn.
21167-178, 2002.
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Stress Urinary IncontinenceWhy should we care?

• Urinary Incontinence
• 20-50 of women
• Risk Factors
• Age
• Vaginal Childbirth

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Mechanics of Stress Urinary Incontinence

• Little known regarding mechanics of continence
  maintenance
• Limited to two conflicting theories
• Mechanics of have never been validated in either
  case

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Project Goals

• Gain insight into the mechanics by which
  continence is maintained when abdominal pressure
  is increased through finite element modeling.
• Use finite element modeling to test the mechanics
  behind the two theories of continence.

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Project Goals

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

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Finite Element Modeling of Biomechanics

• Goal is to gain insight and understanding that
  cannot be obtained experimentally
• Modeled situations are complex and not well
  characterized
• Require several assumptions to be made and tested
• Sensitivity Analysis and Parametric Testing
  frequently required to determine effects of
  assumptions and understand how model is
  performing

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Mechanics of Stress Urinary Incontinence

• Structures that must be incorporated into model
• Pelvic Bones
• Bladder
• Urethra
• Vagina
• Levator Ani (Pubococcygeus, Illiococcygeus,
  Puborectalis)
• Arcus Tendinius Fascia Pelvis
• Endopelvic Fascia
• Pubourethral Ligaments

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Modeled by Xiao Long Li
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Modeling

• Need to account for
• Mechanics of each structure
• How does each structure deform
• Material Properties (Non-Linear)
• Contact between structures
• How do the structures deform in relation to one
  another
• How much support do the various structures
  provide to one another

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Modeling

• Need to account for
• Fluid Structure Interactions
• Is urine entering the urethra as a result of the
  abdominal pressure loads
• Is urine traveling the length of the urethra and
  leaking out
• Transient Loads
• Sharp transient events do not lend themselves to
  quasi-steady state modeling
• Forces arising from muscle contractions

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Computational Needs

• Hardware
• Computational Power
• Simple simulations are taking days to complete on
  desktop equipment
• Ability to run multiple parametric simulations if
  not concurrently then in at least a timely
  fashion
• Software
• LS Dyna
• Dynamic Finite Element Solver
• Pre/Post Processing
• Mesh Generation
• Display Results