膀胱颈位移验证有限元模型

… was to model, under … bladder neck mobility and the changes in the α angle for valsalva maneuver using live subject MRI and a computational model based on the Finite element method. …

… (FEA) was performed to determine the displacements of all nodes in the model. A static … finite element model to simulate the interaction between pelvic organs solely caused by bladder …

… Once the model construction was complete, finite element analysis (FEA) was performed to determine the displacement field in the response of the pressure load by solving partial …

Midurethral slings are used to correct urethral hypermobility in female stress urinary incontinence (SUI), defined as the complaint of involuntary urine leakage when the intra-abdominal pressure (IAP) is increased. Structural and thermal features influence their mechanical properties, which may explain postoperative complications, e.g., erosion and urethral obstruction. We studied the effect of the mesh stiffness on urethral mobility at Valsalva maneuver, under impairment of the supporting structures (levator ani and/or ligaments), by using a numerical model. For that purpose, we modeled a sling with “lower” versus “higher” stiffness and evaluated the mobility of the bladder and urethra, that of the urethrovesical junction (the α-angle), and the force exerted at the fixation of the sling. The effect of impaired levator ani or pubourethral ligaments (PUL) alone on the organs displacement and α-angle opening was similar, showing their important role together on urethral stabilization. When the levator ani and all the ligaments were simulated as impaired, the descent of the bladder and urethra went up to 25.02 mm, that of the bladder neck was 14.57 mm, and the α-angle was 129.7 deg, in the range of what was found in women with SUI. Both meshes allowed returning to normal positioning, although at the cost of higher force exerted by the mesh with higher stiffness (3.4 N against 2.3 N), which can relate to tissue erosion. This finite element analysis allowed mimicking the biomechanical response of the pelvic structures in response to changing a material property of the midurethral synthetic mesh.

To evaluate the role of soft tissue and ligaments damage and level of pelvic muscles activation versus intra‐abdominal pressure, on pelvic organ prolapse.

… finite element method and the material constants were determined for different constitutive models (… Muscle displacements obtained in the numerical simulations of Valsalva maneuver …

… A finite element (FE) model of the prostate, rectum and bladder motion has been developed, investigating more specifically the influence of the rectum and bladder … and the bladder, …

… a woman’s quality of life including increasing her risk for urinary or anal incontinence, perineal pain, … The distal displacement was 4.9 cm in both models (Table 2). The stress level in the …

The use of supportive underwear has been applied for preventing stress urinary incontinence (SUI) which is caused by descent of the bladder neck due to weakness in the pelvic floor muscles, because it is known that SUI can be improved by elevating the descended bladder neck. However, appropriate approaches to the underwear design are still being explored. In order to establish an appropriate first-order design strategy for supportive underwear, clarifying the relationship between the pressure from the underwear and the amount of elevation of the bladder neck is necessary. We constructed a finite element model of the pelvis based on magnetic resonance images of a subject in an upright position, experimentally explored Young’s modulus of the soft tissue and analyzed the amount of elevation of the bladder neck when changing the combination of applied pressures from the underwear. The position of the bladder neck relatively elevated when the pressure in the region from the abdomen to the pubis decreased and when the pressure in the region from the perineum to the coccyx increased, suggesting an appropriate design for the supportive underwear.

Graphical abstract Stress urinary incontinence often results from pelvic support structures’ weakening or damage. This dysfunction is related to direct injury of the pelvic organ’s muscular, ligamentous or connective tissue structures due to aging, vaginal delivery or increase of the intra-abdominal pressure, for example, defecation or due to obesity. Mechanical changes alter the soft tissues’ microstructural composition and therefore may affect their biomechanical properties. This study focuses on adapting an inverse finite element analysis to estimate the in vivo bladder’s biomechanical properties of two groups of women (continent group (G1) and incontinent group (G2)). These properties were estimated based on MRI, by comparing measurement of the bladder neck’s displacements during dynamic MRI acquired in Valsalva maneuver with the results from inverse analysis. For G2, the intra-abdominal pressure was adjusted after applying a 95% impairment to the supporting structures. The material parameters were estimated for the two groups using the Ogden hyperelastic constitutive model. Finite element analysis results showed that the bladder tissue of women with stress urinary incontinence have the highest stiffness (α1 = 0.202 MPa and µ1 = 7.720 MPa) approximately 47% higher when compared to continent women. According to the bladder neck’s supero-inferior displacement measured in the MRI, the intra-abdominal pressure values were adjusted for the G2, presenting a difference of 20% (4.0 kPa for G1 and 5.0 kPa for G2). The knowledge of the pelvic structures’ biomechanical properties, through this non-invasive methodology, can be crucial in the choice of the synthetic mesh to treat dysfunction when considering personalized options.

… Figure 3 shows a finite element model of a normal female … displacements that constrain the Z-directional displacements of … urine in the bladder to act as a transmitter, while our bladder …

… After the determination of the material constants, we compared the displacement of the pelvic … from women with thinner or disrupted muscles presenting urinary incontinence or pelvic …

… Furthermore, the vesical neck of the bladder would descent … deviation for cervix displacement corresponding to the … material model , we obtain a simulated cervix displacement of 11.49 …

… The urethra and bladder neck appear to have been opened out by the downward … displacement to the trigone of the bladder according to the displacement seen in Fig. 1b. We found the …

… using the finite element method on computational meshes based on live subject data. … cannot be measured, models can be validated only by comparing displacement and strain fields …

The problems of modeling the human bladder and its stress-strain state under external static influence were considered. A method for identification of the anisotropic biomechanical characteristics of bladder tissue was proposed. A FEM model was created, which accepts into regard that the bladder is surrounded by fiber and affected by surrounding organs, and partially protected by pelvic bones. The model considered the presence of constant hydrostatic pressure on the walls of the bladder when it is full. It has been shown that isotropic mechanical characteristics of biological tissue can be used for studying the deformed state of a filled bladder if the filled bladder 300 ml is considered as initial non-deformed stage. This was shown by modeling and verification the effect of the external static force on the bladder. Numerical experiments were conducted based on the constructed model. To validate the results obtained, a series of natural experiments on the effect of external pressure on the bladder under ultrasound control was conducted. In the future, it is planned to use the constructed model to study rupture deformations of the bladder under the influence of static and dynamic loads.

… The main outcome measure was a 3D biomechanical model of the female pelvic system. The various configurations of bladder displacement simulated mechanisms underlying medial, …

A new surgical procedure for the treatment of primary bladder neck obstruction with maintenance of anterograde ejaculation is proposed. In place of monolateral or bilateral bladder neck incision, associated with a loss of ejaculation rate of up to 30%, the new surgical procedure consists of laser drilling the bladder neck with a number of holes and without muscle fiber disruption. The effect of this novel procedure has been studied numerically, with a simplified two-dimensional numerical model of the internal urethral sphincter, varying the position and the number of holes in the fibrotic region of the urethral tissue. Results show an improvement of the urethral sphincter opening by increasing the number of holes, ranging from about 6% to 16% of recovery. Moreover, a non-aligned position of holes positively influences the opening recovery. The concentrations of maximum principal strain and stress have been registered in the proximity of the interface between the physiologic and diseased sphincter, and in those regions where the radial thickness is significantly thinner. The effects on the first five patients have been included in the study, showing improvement in micturition, lower urinary tract symptoms, sustained ejaculatory function, and quality of life.

To better understand the disorders in the pelvic cavity associated with the pelvic floor muscles (PFM) using computational models, it is fundamental to identify the biomechanical properties of these muscles. For this purpose, we implemented an optimization scheme, involving a genetic algorithm (GA) and an inverse finite element analysis (FEA), in order to estimate the material properties of the pubovisceralis muscle (PVM). The datasets of five women were included in this noninvasive analysis. The numerical models of the PVM were built from static axial magnetic resonance (MR) images, and the hyperplastic Mooney-Rivlin constitutive model was used. The material parameters obtained were compared with the ones established through a similar optimization scheme, using Powell's algorithm. To validate the values of the material parameters that characterize the passive behavior of the PVM, the displacements obtained via the numerical models with both methods were compared with dynamic MR images acquired during Valsalva maneuver. The material parameters (c1 and c2) were higher for the GA than for Powell's algorithm, but when comparing the magnitude of the displacements in millimeter of the PVM, there was only a 5% difference, and 4% for the principal logarithmic strain. The GA allowed estimating the in vivo biomechanical properties of the PVM of different subjects, requiring a lower number of simulations when compared to Powell's algorithm.

… by weakened bladder neck support and urine leakage. POP is … Figure 3 Biomechanical model of a female pelvic support … The data are based on validated pelvic floor distress inventory …

… We hypothesized that the presence of connective tissue supports at the bladder neck and at … Although this will require robust clinical and computational validation, we speculate that a …

This chapter presents an approach for the mechanical behavior of soft biological tissue using the finiteelements method (FEM) and a general constitutive model. Specifically, we analyze the mechanical behavior of a urinary bladder starting from a procedure for obtaining the mechanical characterization of the biological tissue. The difficulty in this study lies not only in modeling the mechanical behavior of the bladder subjected to inflation under the presence of an internal fluid, but also in the difficulty encountered in determining the biomechanical properties of the biological tissue that forms the bladder. Bladder tissue is modeled as a composite material formed by soft matrix reinforced with preferentially oriented fibers. In the first part of the chapter we present a procedure for identifying the mechanical properties of biological tissue’s main constituents by an inverse method. Then this information is used for the numerical simulation of the mechanical behavior of the bladder within the FEM. The formulation can be applied to various types of biological tissues, both in the field of material characterization and in the numerical simulation of the tissue’s biomechanical behavior. The approach presented in this chapter has been applied to the study of the arterial tissue behavior [1].

In this work, a 3D urinary bladder was subjected to various pressure loading conditions mimicking the bladder filling volume. The bladder layer consisting of adventitia, detrusor and mucosa layer having different mechanical properties produced different deformation and stresses when subjected to the varying loads. The volume of the bladder changed to 231.34[Formula: see text]ml which was 128.91% higher than the assumed initial volume of 50[Formula: see text]ml on application of 18[Formula: see text]kPa of pressure. The detrusor layer which is thickest of the bladder wall reduced to 1.312[Formula: see text]mm from 4.4[Formula: see text]mm, recording a 108% change in its thickness at 18[Formula: see text]kPa pressure. The maximum von-Mises stress obtained were significantly higher in case of the Mucosa layer when compared to the detrusor and adventia layer. The unique layup of the bladder wall having different properties plays a major role in sustaining adverse pressure gradients and absorbing high stresses.

Abstract Pathological conditions of a male urethra, including fibrosis, have a mechanical background along the entire length of the urethra. They may be caused by excessive deformation of the urethra locally or globally. The condition of prolonged overload causes abnormal tissue remodelling and, consequently, the formation of a thick layer of scar tissue differentiated from the connective tissue of the urethra. This tissue, which has higher mechanical properties, is not highly deformable and therefore, causes a decrease in the diameter of the urethra, which results in conditions that disturb the natural flow of urine. In this paper, it was decided to determine the deformation conditions in the proximal part of the urethra. The study was conducted in three main stages. Transverse sections of the animal urethral tissues were prepared in order to examine mechanical properties and perform histological examinations. On the basis of these examinations, material models which fitted best for the experimental results were sought. Material constants of the Mooney-Rivlin material model with the best fit ratio were determined for further research. On the basis of histological photographs, a geometrical and numerical model of the urethra was developed. The urethra was tested in a flat state of deformation. The strain and stress fields of the Caucha tensor were examined. The methodology of testing the dynamics of the urine flow in the highly deformable urethra was proposed. This is important for the analysis of the influence of at excessive pressure on pathological tissue remodelling leading to fibrosis.

… a cadaveric female lower urinary tract (©DeLancey). The yellow square represents the region of interest in the proximal urethra immediately inferior to the bladder neck. PB represents …

… ing, urethral function during micturition, pelvic floor muscles, and neural-control models of the urinary tract are reviewed in this paper in the context of their application to the …

… to the finite element model. Contemporarily, a finite element model of a typical AUS device was developed. Numerical analyses have been performed to analyze interaction phenomena …

… Considering the intimate relation between the symphysis pubis and the lower urinary tract, PRT can produce potentially severe trauma to the posterior urethra [1] and/or the bladder. The …

… sphincter dyssynergia on urodynamic parameters in the lower urinary tract. A geometric model of male lower urinary tract tissue was constructed from collodion slices, accounting for the …

Background: Nowadays, a challenging task concerns the biomechanical study of the human lower urinary tract (LUT) due to the variety of its tissues and the low availability of samples. Methods: This work attempted to further extend the knowledge through a comprehensive mechanical characterization of the male LUT by considering numerous tissues harvested from the same cadaver, including some never studied before. Samples of the bladder, urethra, prostate, Buck’s fascia and tunica albuginea related to corpora cavernosa were considered and distinguished according to testing direction, specimen conformation and anatomical region. Uniaxial tensile and indentation tests were performed and ad hoc protocols were developed. Results: The tissues showed a non-linear and viscoelastic response but different mechanical properties due to their specific functionality and microstructural configuration. Tunica albuginea longitudinally displayed the highest stiffness (12.77 MPa), while the prostate transversally had the lowest one (0.66 MPa). The minimum stress relaxation degree (65.74%) was reached by the tunica albuginea and the maximum (88.55%) by the bladder. The prostate elastic modulus was shown to vary according to the presence of pathological changes at the microstructure. Conclusions: This is the first experimental work that considers the mechanical evaluation of the LUT tissues in relation to the same subject, setting the basis for future developments by expanding the sample population and for the development of effective in silico models to improve the solutions for most LUT pathologies.

Male urinary incontinence is a widespread healthcare problem, leading to a miserable quality of life. Artificial urinary sphincter (AUS) is a device inserted mostly around the urethra in adult males, which mimics the urinary sphincter by providing a closure during urinary storage and a subsequent open to permit voiding. The interaction phenomena occurring between AUS cuff and urethral duct represent a fundamental problem in the investigation of AUS reliability and durability. In this work, computational methods are exploited to deeply investigate the mechanics of interaction phenomena occurring between urethral duct and AUS device. Experimental studies are performed on urethral tissues, and structural tests are carried out on the overall urethral duct to obtain a large set of information required for mechanical properties definition. The mechanical behavior of AUS cuff is investigated using mechanical and physicochemical procedures. The cuff conformation is acquired by computed tomography techniques for the definition of the numerical model. Numerical analyses are developed to evaluate the mechanical response of urethral duct in interaction with AUS cuff, considering the lumen occlusion process for maintaining urinary continence. Finally, the investigation of the compressive stress and strain fields within urethral tissues allows the identification of device performance and reliability in correlation with surgical practice.

BACKGROUND The purpose of this study was to use the finite element analysis method to simulate sling surgeries for arcus tendineus fascia pelvis damage-induced stress urinary incontinence: tension-free vaginal tape and tension-free vaginal tape - obturator, to evaluate their therapeutic effects at different positions of the urethra, and to judge the occurrence of complications through the sling-urethra interaction force which is difficult to obtain clinically. METHODS Pelvic geometric model was constructed based on the MRI of a woman without pelvic floor diseases. The constraints between arcus tendineus fascia pelvis and the lateral wall of the vagina were removed to simulate arcus tendineus fascia pelvis rupture. Gradient abdominal pressure was applied to the incontinence model, and tension-free vaginal tape and tension-free vaginal tape - obturator were placed at the proximal (30 %), mid-distal (60 %), and distal ends (80 %) of the urethra, respectively. FINDINGS All three types of slings were able to return the parameters of the urethra and bladder to normal levels. High urethral pressure was observed with proximal placement. Distal placement led to a "knot" effect and sudden pressure spikes as abdominal pressure increased. Mid-distal placement resulted in the lowest urethral pressure. The pressure between tension-free vaginal tape and the urethra was generally greater than that between tension-free vaginal tape - obturator. INTERPRETATION Placing slings at various positions within the urethra can all treat arcus tendineus fascia pelvis damage-induced stress urinary incontinence; the mid-distal tension-free vaginal tape - obturator should be considered the preferred treatment option.

The motivation behind this study is to understand how ureterovesical junction (UVJ) deformation during urine storage in the bladder affects vesicoureteral reflux (VUR), when urine flows backward from the bladder toward the kidneys. Using nonlinear, large deformation finite element simulations, the deformation of the bladder wall during urine storage is modeled in this study. The bladder wall is assumed to be a homogeneous, isotropic, hyperelastic spherical shell with a finite thickness. The UVJ is defined as a straight elliptical cylindrical hole through the bladder wall at the reference configuration before inflation. Broad parametric studies on different UVJ configurations are performed as the bladder inner surface stretches by a factor of 2.2 from an initial radius corresponding to bladder volumes of 10% to slightly over physiologic capacity. For each considered UVJ configuration, a simple fluid analysis of the tunnel flow resistance compares different bladder inner surface stretch ratios. Our model shows that the deformation of the UVJ depends on its orientation with respect to the bladder wall radial and circumferential directions. We show that as the UVJ insertion angle increases, the UVJ cross section decreases and its tunnel length increases during urine storage causing the closure of the UVJ and a rise in its flow resistance. The modeling results indicate that UVJ closure could be explained by bladder wall deformation rather than the local differential pressure. Our findings are consistent with the accepted primary anti-reflux mechanism of the UVJ being dependent on the tunnel length-to-diameter ratio and consequently the UVJ insertion angle.

… The pubourethral angle, that is, the angle between the bladder neck and the midline of the pubic symphysis, was quantified for all models using lines of best fit and used as a …

… simulated loading as occurs in vivo. In the present study, we determined bladder wall deformations of whole bladders … during controlled filling of the bladders in two states, passive and …

PURPOSE Computational fluid dynamics have paradigm shifting potential in understanding the physiological flow of fluids in the human body. This translational branch of engineering has already made an important clinical impact on the study of cardiovascular disease. We evaluated the feasibility and applicability of computational fluid dynamics to model urine flow. MATERIALS AND METHODS We prepared a computational fluid dynamics model using an idealized male genitourinary system. We created 16 hypothetical urethral stricture scenarios as a test bed. Standard parameters of urine such as pressure, temperature and viscosity were applied as well as typical assumptions germane to fluid dynamic modeling. We used ABAQUS/CAE 6.14 (Dassault Systèmes®) with a direct unsymmetrical solver with standard (FC3D8) 3D brick 8Node elements for model generation. RESULTS The average flow rate in urethral stricture disease as measured by our model was 5.97 ml per second (IQR 2.2-10.9). The model predicted a flow rate of 2.88 ml per second for a single 5Fr stricture in the mid bulbar urethra when assuming all other variables constant. The model demonstrated that increasing stricture diameter and bladder pressure strongly impacted urine flow while stricture location and length, and the sequence of multiple strictures had a weaker impact. CONCLUSIONS We successfully created a computational fluid dynamics model of an idealized male urethra with varied types of urethral strictures. The resultant flow rates were consistent with the literature. The accuracy of modeling increasing bladder pressure should be improved by future iterations. This technology has vast research and clinical potential.

BackgroundNumerous studies indicated that Intravesical prostatic protrusion is relevant to prognosis of LUTS, however, the confounding effect that is brought about by prostate volume, urethra anterior curvature angle and other factors makes it hard to evaluate the role of intravesical prostatic protrusion in clinical observation.MethodsWe proposed a fluid structural interaction analysis approach. 3D models were constructed based on MRI images, and prostatic urethra diameters were calibrated with urodynamic data. Comparisons of urine flow dynamics were made between models with various degree of intravesical prostatic protrusion, while the intravesical pressure, anterior urethra curvature angle and diameter of prostatic urethra were same among all models to rule out their confounding effects.ResultsSimulation result showed that the decrement of diameter and increment of variation in cross-sectional area for prostatic urethra were related to the degree of intravesical prostatic protrusion. Such deformation would lead to deterioration of flow efficiency and could compromise the effect of bladder outlet obstruction alleviation treatment.ConclusionsThese results provided further evidence for intravesical prostatic protrusion being an independent risk factor for bladder outlet obstruction severity and demonstrated that intravesical prostatic protrusion would be a promising marker in clinical decision making.

… The results demonstrated that the vesical pressure simulated … The urethra retropubic bladder neck and the bladder neck-… Table 2 Comparison of bladder neck mobility parameters in …

… The first fifth is surrounded by the bladder neck, the next two fifths are encircled by the … addresses the fluid–structure interaction associated with the urethral resistance and urinary flow. …

… bladder neck, urethral angle, bladder-urethra posterior angle and position of vaginal vault by urinary bladder … equations which are suitable for problems with fluid-solid interaction (FSI). …

Lower urinary track symptoms (LUTS) affect many older adults. Multi-channel urodynamic studies provide information about bladder pressure and urinary flow but offer little insight into changes in bladder anatomy and detrusor muscle function. Here we present a novel method for real time MRI during bladder voiding. This was performed in a small cohort of healthy men and men with benign prostatic hyperplasia and lower urinary tract symptoms (BPH/LUTS) to demonstrate proof of principle; The MRI urodynamic protocol was successfully implemented, and bladder wall displacement and urine flow dynamics were calculated. Displacement analysis on healthy controls showed the greatest bladder wall displacement in the dome of the bladder while men with BPH/LUTS exhibited decreased and asymmetric bladder wall motion. Computational fluid dynamics of voiding showed men with BPH/LUTS had larger recirculation regions in the bladder. This study demonstrates the feasibility of performing MRI voiding studies and their potential to provide new insight into lower urinary tract function in health and disease.

… In the present study, a fluid–structure interaction analysis was … pelvis to investigate the urine leakage in females during … the bladder neck, and a remarkable amount of urine flowed …

Abstract:  This article describes research involving finite element simulations of women's pelvic floor, undertaken in the engineering schools of Lisbon and Oporto, in collaboration with the medical school of Oporto. These studies are motivated by the pelvic floor dysfunctions that lead namely to urinary incontinence and pelvic organ prolapse. This research ultimately aims at: (i) contributing to clarify the primary mechanism behind such disorders; (ii) providing tools to simulate the pelvic floor function and the effects of its dysfunctions; (iii) contributing to planning and performing surgeries in a more controlled and reliable way. The finite element meshes of the levator ani are based on a publicly available geometric data set, and use triangular thin shell or special brick elements. Muscle and soft tissues are assumed as (quasi‐)incompressible hyperelastic materials. Skeletal muscles are transversely isotropic with a single fiber direction, embedded in an isotropic matrix. The fibers considered in this work may be purely passive, or active with input of neuronal excitation and consideration of the muscle activation process. The first assumption may be adequate to simulate passive deformations of the pelvic muscles and tissues (namely, under the extreme loading conditions of childbirth). The latter may be adequate to model faster contractions that occur in time intervals of the same order as those of muscle activation and deactivation (as in preventing urinary incontinence in coughing or sneezing). Numerical simulations are presented for the active deformation of the levator ani muscle under constant pressure and neural excitation, and for the deformation induced by a vaginal childbirth.

… one of the most important parts of the pelvic floor, the levator ani, using … Pelvic floor dysfunction is an extensive problem for women. The main disorders are: urinary incontinence, pelvic …

PURPOSE The main purpose of this study is to obtain a finite element biomechanical model that accurately mimics pelvic organ prolapse in women, to study pelvic floor supporting structures' biomechanical properties and function. We used thin-sectional high-resolution anatomical images (Chinese Visible Human, CVH) to reconstruct a detailed three-dimensional (3D) biomechanical finite element model of the female pelvic floor supporting structure including cardinal ligament, uterosacral ligament, levator ani muscle (LAM) and perianal body. The Valsalva maneuver was simulated by loading the uterus and bladder with a pressure increasing from 0 to 10 kPa. The stress, strain and displacement of supporting structures were calculated. The cardinal ligament, the uterosacral ligament and the LAM were stressed greatly when the uterus moved downward, and the maximum stress could reach 0.267 MPa, 1.51 MPa and 0.065 MPa respectively, and the maximum strain could reach 0.154, 0.16, 0.265, and the maximum displacement could reach 1.786 cm, 1.946 cm and 0.567 cm. Displacement of the perineal body also occurred, and its stress, strain and displacement were 0.092 MPa, 0.381, 0.73 cm. The stress, strain and displacement of the supporting structure around the urethra were 0.339 MPa, 0.169, 1.491 cm. Our model based on CVH has more detailed anatomical structures, which is superior to that based on MRI. Our simulation results were consistent with previous findings, which verified the unbalance of abdominal pressure and pelvic floor supporting structures will lead to POP, which provide a theoretical basis for pelvic floor anatomy and function as well as obstetrical surgery.

… ligaments on the uterus, vagina, bladder, and bladder neck, preventing their excessive anterior … variations of the female anatomy and their contribution to pelvic floor dysfunction due to a …

After menopause, decreased levels of estrogen and progesterone remodel the collagen of the soft tissues thereby reducing their stiffness. Stress urinary incontinence is associated with involuntary urine leakage due to pathological movement of the pelvic organs resulting from lax suspension system, fasciae, and ligaments. This study compares the changes in the orientation and position of the female pelvic organs due to weakened fasciae, ligaments, and their combined laxity. A mixture theory weighted by respective volume fraction of elastin-collagen fibre compound (5%), adipose tissue (85%), and smooth muscle (5%) is adopted to characterize the mechanical behaviour of the fascia. The load carrying response (other than the functional response to the pelvic organs) of each fascia component, pelvic organs, muscles, and ligaments are assumed to be isotropic, hyperelastic, and incompressible. Finite element simulations are conducted during Valsalva manoeuvre with weakened tissues modelled by reduced tissue stiffness. A significant dislocation of the urethrovesical junction is observed due to weakness of the fascia (13.89 mm) compared to the ligaments (5.47 mm). The dynamics of the pelvic floor observed in this study during Valsalva manoeuvre is associated with urethral-bladder hypermobility, greater levator plate angulation, and positive Q-tip test which are observed in incontinent females.

… women using finite element analysis methods: tension-free vaginal tape (TVT) and tension-… Results The sling at the proximal part of urethra would lead to the α-angle and bladder neck …

… Computer modeling using MR images and simulation using the finite element method (FEM… substantial ground for the application of the urethral mobility index, which could be obtained …

… model of the male pelvis to characterize the urethral mobility … METHODS: A comprehensive subject specific pelvic model … for biomechanical analysis with the finite element method. The …

Background: Stress urinary incontinence (SUI) is one of the top five chronic diseases globally. The traditional theory of SUI does not adequately explain certain subgroups of patients. This study aims to investigate the risk factors and potential mechanisms underlying female SUI. Materials and methods: A dual tertiary-center, cross-sectional study was conducted. A finite element model (FEM) was developed using data from a female volunteer. A total of 42 rats were utilized as animal models. Female participants presenting with lower urinary tract symptoms were recruited and categorized into four groups based on their SUI and Levator ani avulsion (LAA) status: SUI+/LAA+, SUI+/LAA−, SUI−/LAA+, and SUI−/LAA−. Data were collected from the FEM, animal models, and clinical participants. Results: The FEM demonstrated that in simulations of unilateral LAA, the ipsilateral urethra exhibited deviation and displacement toward the site of avulsion, accompanied by distortion. Rats with LAA showed a significantly higher incidence of SUI (P = 0.031), particularly those with unilateral LAA (P = 0.011). A total of 1629 women were ultimately included in the study. Statistical significance was observed specifically in patients with unilateral LAA (odds ratio = 1.87 [95% confidence interval, 1.389–2.481], P < 0.001). Measurements of the levator-urethral gap indicated that the closer the avulsion site was to the urethral opening, the higher the likelihood of SUI occurrence, which aligns with the urethral deviation patterns observed in the FEM analysis. Conclusion: Unilateral LAA is a significant risk factor for SUI. The urethral deviation induced by unilateral LAA may represent an additional etiological mechanism of SUI, beyond the traditional fascial hammock theory.

Dynamic behaviors of the single-incision sling (SIS) to correct urethral hypermobility are investigated via dynamic biomechanical analysis using a computational model of the female pelvis, developed from a female subject's high-resolution magnetic resonance (MR) images. The urethral hypermobility is simulated by weakening the levator ani muscle in the pelvic model. Four positions along the posterior urethra (proximal, midproximal, middle, and mid-distal) were considered for sling implantation. The α-angle, urethral excursion angle, and sling–urethra interaction force generated during Valsalva maneuver were quantitatively characterized to evaluate the effect of the sling implantation position on treatment outcomes and potential complications. Results show concern for overcorrection with a sling implanted at the bladder neck, based on a relatively larger sling–urethra interaction force of 1.77 N at the proximal implantation position (compared with 0.25 N at mid-distal implantation position). A sling implanted at the mid-distal urethral location provided sufficient correction (urethral excursion angle of 23.8 deg after mid-distal sling implantation versus 24.4 deg in the intact case) with minimal risk of overtightening and represents the optimal choice for sling surgery. This study represents the first effort utilizing a comprehensive pelvic model to investigate the performance of an implanted sling to correct urethral hypermobility. The computational modeling approach presented in the study can also be used to advance presurgery planning, sling product design, and to enhance our understanding of various surgical risk factors which are difficult to obtain in clinical practice.

Abstract The mobility of pelvic organs is the result of an equilibrium called Pelvic Static characterizing the balance between the properties and geometries of organs, suspensions and support system. Any imbalance in this complex system can cause of pelvic static disorder. Genital prolapse is a common hypermobility pathology which is complex, multi factorial and its surgical management has high rate of complications. The use of 3 D numerical models and simulation enables the role of the various suspension structures to be objectively studied and quantified. Fascias are connective tissues located between organs. Although their role are described as important in various descriptions of pelvic statics, their influence and role has never been quantitatively objectified. This article presents a refine Finite Element (FE) model for a better understanding of biomechanical contribution of inter-organ fascia. The model is built from MRI images of a young volunteer, the mechanical properties derived from literature data to take into account the age of the patient and new experimental results have enabled an order of magnitude of the mechanical properties of the fascias to be defined. The FE results allows to quantify the biomechanical role of the fascia on pelvic mobility quantified by an analysis of dynamic MRI images and a local mapping of the gap between calculated and measured displacements. This improved numerical model integrating the fascias makes it possible to describe pelvic mobilities with a gap of 1 mm between numerical simulations and measurements, whereas without taking them into account this gap locally reaches 20 mm.

… models of the bladder and urethra during stress events. The measured pressures can be utilized in these models to … of the pelvic floor for finite element modeling purposes. J. Biomech. …

Objective This study aims to utilize finite element analysis (FEA) to explore the effects of different rehabilitation training methods on the ability of elderly women to maintain urinary and fecal control. It also seeks to determine the muscle prioritization during pelvic rehabilitation training, providing a scientific basis for personalized rehabilitation nursing. Methods A 3D pelvic-thigh modeling was constructed based on CT and MRI images from a 70-year-old Chinese elderly female volunteer. Model validity was verified by assessing relative changes in waist circumference, RVA, and ARA against imaging measurements, with geometric deviations controlled within 10%. The material properties of the muscles were altered to simulate the effects of five different physical rehabilitation methods. By comparing changes in the retrovesical angle (RVA) and anorectal angulation (ARA) under different muscle material properties settings, the relationship between rehabilitation training methods and urinary and fecal control was quantified. Results The constructed model demonstrated high geometric consistency with pelvic floor anatomy, showing less than 8.28% deviation from imaging-based measurements. As muscle material properties improved, the RVA gradually decreased, and the ARA gradually increased, approaching normal ranges. The results highlight the critical roles of the levator ani, pelvic floor, rectus abdominis, erector spinae, and hip muscles. Conclusion The findings from this simulation indicate the potential efficacy of rehabilitation training in supporting urinary and fecal control. The study emphasizes the importance of personalized pelvic floor rehabilitation programs based on gender differences, muscle status, and dysfunction types, offering new perspectives and possibilities for using FEA in elderly populations. Nevertheless, the findings are derived from a single-subject model and computational simulations without direct clinical validation, which may limit generalizability. Clinical Trial Registration identifier (ChiCTR2400080749) (20240206).

… The urethral mobility was only slightly influenced by the alterations of the levator ani muscle stiffness. Implications for risk factors and treatment strategies were also discussed. …

Objective To re-evaluate the anatomy and biomechanics of the female pelvic floor using a novel “dynamic interaction–overall mechanical balance” framework, aiming to improve the …

… between the mobile and immobile portion of the urethra has … In this study, we carried out a statistical shape modeling … A finite element simulation of the urethra during Valsalva at (a…