A novel technique to measure in vivo uterine suspensory ligament stiffness

Smith, Tovia M.; Luo, Jiajia; Hsu, Yvonne; Ashton‐Miller, James A.; DeLancey, John O.L.

doi:10.1016/j.ajog.2013.06.003

Cited by 29 publications

(26 citation statements)

References 22 publications

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“…Results from our physiologic testing suggest that apical ligament stiffness is not the primary factor contributing to uterine support. In a study by Smith et al, in vivo ligament stiffness only explained 19 % of the variation in POP-Q point C [4]. Therefore, when thinking about the etiology of apical support loss, we may presently have a tendency to overestimate the role of apical ligament stiffness and underestimate other important factors, such as ligament length.…”

Section: Discussionmentioning

confidence: 99%

“…The technique for making measurements of cervix location in the OR using a computer-controlled servoactuator device has been previously described [4] and is shown in Fig. 3.…”

Section: Methodsmentioning

confidence: 99%

“…For example, it is common to perform in vitro uniaxial tension tests on small excised pieces of the uterosacral ligaments and then calculate the tissue stress–strain curves [2, 3]. More recently, in vivo tests performed using cervical traction in the operating room (OR) resulted in force-displacement curves from which the stiffness of the cardinal and uterosacral ligament complexes were calculated [4, 5]. Whether either of these are physiologically relevant measures is unclear.…”

Section: Introductionmentioning

confidence: 99%

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Traction force needed to reproduce physiologically observed uterine movement: technique development, feasibility assessment, and preliminary findings

et al. 2016

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Introduction and hypothesis This study aimed to describe a novel strategy to determine the traction forces needed to reproduce physiologic uterine displacement in women with and without prolapse. Methods Participants underwent dynamic stress magnetic resonance imaging (MRI) testing as part of a study examining apical uterine support. Physiologic uterine displacement was determined by analyzing uterine location in images taken at rest and at maximal Valsalva. Force-displacement curves were calculated based on intraoperative cervical traction testing. The intraoperative force required to achieve the uterine displacement measured during MRI was then estimated from these curves. Women were categorized into three groups based on pelvic organ support: group 1 (normal apical and vaginal support), group 2 (normal apical support but vaginal prolapse present), and group 3 (apical prolapse). Results Data from 19 women were analyzed: five in group 1, five in group 2, and nine in group 3. Groups were similar in terms of age, body mass index (BMI), and parity. Median operating room (OR) force required for uterine displacement measured during MRI was 0.8 N [interquartile range (IQR) 0.62–3.22], and apical ligament stiffness determined using MRI uterine displacement was 0.04 N/mm (IQR 0.02–0.08); differences between groups were nonsignificant. Uterine locations determined at rest and during maximal traction were lower in the OR compared with MRI in all groups. Conclusions Using this investigative strategy, we determined that only 0.8 N of traction force in the OR was required to achieve maximal physiologic uterine displacement seen during dynamic (maximal Valsalva) MRI testing, regardless of the presence or absence of prolapse.

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Section: Discussionmentioning

confidence: 99%

“…The technique for making measurements of cervix location in the OR using a computer-controlled servoactuator device has been previously described [4] and is shown in Fig. 3.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Traction force needed to reproduce physiologically observed uterine movement: technique development, feasibility assessment, and preliminary findings

et al. 2016

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“…While ex vivo studies have provided very valuable information with regards to the elastic and viscoelastic properties of the USL, in vivo mechanical tests of the USL, whenever possible, are ideal. 36,43 However, these tests can be conducted in humans only over a very short period of time due to ethical concerns associated with subjecting patients to mechanical testing for extended periods of time.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Analysis of the Uterosacral Ligament: Swine vs. Human

et al. 2018

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The uterosacral ligament (USL) is a major suspensory structure of the female pelvic floor, providing support to the cervix and/or upper vagina. it plays a pivotal role in surgical procedures for pelvic organ prolapse (PoP) aimed at restoring apical support. Despite its important mechanical function, little is known about the mechanical properties of the USL due to the constraints associated with in vivo testing of human USL and the lack of validated large animal models that enable such investigations. in this study, we provide the first comparison of the mechanical properties of swine and human USLs. Preconditioning and pre-creep data up to a 2 N load and creep data under a 2 N load over 1200 s were obtained on swine (n = 9) and human (n = 9) USL specimens by performing planar equi-biaxial tensile tests and using the digital image correlation method. No differences in the peak strain during preconditioning tests, secant modulus of the pre-creep response, and strain at the end of creep tests were detected in the USLs from the two species along both axial loading directions (the main in vivo loading direction and the direction that is perpendicular to it). These findings suggest that the swine holds promise as large animal model for studying the mechanical role of the USL in apical vaginal support and treatment of PoP.

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“…The constitutive model was evaluated in Abaqus and the evaluation result showed that it was stable. The material properties values for the apical supports and uterine support tissues, which include a cardinal ligament (CL) and uterosacral ligament (USL) on each side of the vagina, were taken from our recent in vivo tissue tests (Luo et al, 2014b; Smith et al, 2013) on healthy women. In those studies we used a computer-controlled linear servo actuator to apply a continuous force and simultaneously recorded cervical displacement.…”

Section: Methodsmentioning

confidence: 99%

A multi-compartment 3-D finite element model of rectocele and its interaction with cystocele

Luo

Chen

Fenner

et al. 2015

Journal of Biomechanics

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We developed a subject-specific 3-D finite element model to understand the mechanics underlying formation of female pelvic organ prolapse, specifically a rectocele and its interaction with a cystocele. The model was created from MRI 3-D geometry of a healthy 45 year-old multiparous woman. It included anterior and posterior vaginal walls, levator ani muscle, cardinal and uterosacral ligaments, anterior and posterior arcus tendineus fascia pelvis, arcus tendineus levator ani, perineal body, perineal membrane and anal sphincter. Material properties were mostly from the literature. Tissue impairment was modeled as decreased tissue stiffness based on previous clinical studies. Model equations were solved using Abaqus v 6.11. The sensitivity of anterior and posterior vaginal wall geometry was calculated for different combinations tissue impairments under increasing intraabdominal pressure. Prolapse size was reported as POP-Q point at point Bp for rectocele and point Ba for cystocele. Results show that a rectocele resulted from impairments of the levator ani and posterior compartment support. For 20% levator and 85% posterior support impairments, simulated rectocele size (at POP-Q point: Bp) increased 0.29 mm/cm H2O without apical impairment and 0.36 mm/cm H2O with 60% apical impairment, as intraabdominal pressures increased from 0 to 150 cm H2O. Apical support impairment could result in the development of either a cystocele or rectocele. Simulated repair of posterior compartment support decreased rectocele but increased a preexisting cystocele. We conclude that development of rectocele and cystocele depend on the presence of anterior, posterior, levator and/or or apical support impairments, as well as the interaction of the prolapse with the opposing compartment.

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A novel technique to measure in vivo uterine suspensory ligament stiffness

Cited by 29 publications

References 22 publications

Traction force needed to reproduce physiologically observed uterine movement: technique development, feasibility assessment, and preliminary findings

Traction force needed to reproduce physiologically observed uterine movement: technique development, feasibility assessment, and preliminary findings

Mechanical Analysis of the Uterosacral Ligament: Swine vs. Human

A multi-compartment 3-D finite element model of rectocele and its interaction with cystocele

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