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Liu X, Rong Q, Liu Y, Wang J, Xie B, Ren S. Relationship between high intra-abdominal pressure and compliance of the pelvic floor support system in women without pelvic organ prolapse: A finite element analysis. Front Med (Lausanne) 2022; 9:820016. [PMID: 36004379 PMCID: PMC9393536 DOI: 10.3389/fmed.2022.820016] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 07/14/2022] [Indexed: 11/13/2022] Open
Abstract
Previous studies mainly focused on the relationship between the size of the prolapse and injury to the supporting tissues, but the strain and stress distributions of the supporting tissues as well as high-risk areas of injury are still unknown. To further investigate the effect of supporting tissues on organs and the interactions between organs, this study focused on the relationship between high intra-abdominal pressure and the compliance of the pelvic floor support system in a normal woman without pelvic organ prolapse (POP), using a finite element model of the whole pelvic support system. A healthy female volunteer (55 years old) was scanned using magnetic resonance imaging (MRI) during rest and Valsalva maneuver. According to the pelvic structure contours traced by a gynecologist and anatomic details measured from dynamic MRI, a finite element model of the whole pelvic support system was established, including the uterus, vagina with cavity, cardinal and uterosacral ligaments, levator ani muscle, rectum, bladder, perineal body, pelvis, and obturator internus and coccygeal muscles. This model was imported into ANSYS software, and an implicit iterative method was employed to simulate the biomechanical response with increasing intra-abdominal pressure. Stress and strain distributions of the vaginal wall showed that the posterior wall was more stable than the anterior wall under high intra-abdominal pressure. Displacement at the top of the vagina was larger than that at the bottom, especially in the anterior–posterior direction. These results imply potential injury areas with high intra-abdominal pressure in non-prolapsed women, and provide insight into clinical managements for the prevention and surgical repair plans of POP.
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Affiliation(s)
- Xiaode Liu
- X Lab, The Second Academy of China Aerospace Science and Industry Corporation, Beijing, China
- Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing, China
| | - Qiguo Rong
- Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing, China
| | - Yanan Liu
- Department of Obstetrics and Gynecology, Dongping County People’s Hospital, Taian, China
| | - Jianliu Wang
- Department of Obstetrics and Gynecology, Peking University People’s Hospital, Peking University, Beijing, China
- Beijing Key Laboratory of Female Pelvic Floor Disorders, The Research Center of Female Pelvic Floor Disorder Disease of Peking University, Beijing, China
- Joint International Research Center of Translational and Clinical Research, Beijing, China
| | - Bing Xie
- Department of Obstetrics and Gynecology, Peking University People’s Hospital, Peking University, Beijing, China
- Beijing Key Laboratory of Female Pelvic Floor Disorders, The Research Center of Female Pelvic Floor Disorder Disease of Peking University, Beijing, China
- Joint International Research Center of Translational and Clinical Research, Beijing, China
- Bing Xie,
| | - Shuang Ren
- Beijing Key Laboratory of Sports Injuries, Department of Sports Medicine, Institute of Sports Medicine of Peking University, Peking University Third Hospital, Beijing, China
- *Correspondence: Shuang Ren,
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Silva MET, Bessa JNM, Parente MPL, Mascarenhas T, Natal Jorge RM, Fernandes AA. Effect of mesh anchoring technique in uterine prolapse repair surgery: A finite element analysis. J Biomech 2021; 127:110649. [PMID: 34375905 DOI: 10.1016/j.jbiomech.2021.110649] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 05/28/2021] [Accepted: 07/25/2021] [Indexed: 11/17/2022]
Abstract
The female pelvic cavity involves muscles, ligaments, endopelvic fasciae and multiple organs where different pathologies may occur, namely the pelvic organ prolapse (POP). The synthetic implants are used for the reconstructive surgery of POP, but severe complications associated with their use have been reported, mainly related to their mechanical properties (e.g., implant stiffness) and microstructure. In this study, we mimicked a transvaginal reconstructive surgery to repair the apical ligaments (uterosacral ligaments (USLs) and cardinal ligaments (CLs)), by modeling, their impairment (90% and 50%) and/or total rupture. The implants to reinforce/replace these ligaments were built based on literature specifications and their mechanical properties were obtained through uniaxial tensile tests. The main aim of this study was to simulate the effect of mesh anchoring technique (simple stich and continuous stitch), and compare the displacement magnitude of the pelvic tissues, during Valsalva maneuver. The absence/presence of the synthetic implant was simulated when total rupture of the CLs and USLs occurs, causing a variation of the vaginal displacement (9% for the CLs and 27% for the USLs). Additionally, the simulations showed that there was a variation of the supero-inferior displacement of the vaginal wall between different anchoring techniques (simple stich and continuous stitch) being approximately of 10% for the simulation USLs and CLs implant. The computational simulation was able to mimic the biomechanical behavior of the USLs and CLs, in response to different anchoring techniques, which can be help improving the outcomes of the prolapse surgery.
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Affiliation(s)
- M E T Silva
- LAETA, INEGI, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias s/n, Porto 4200 - 465, Portugal.
| | - J N M Bessa
- Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias s/n, Porto 4200 - 465, Portugal.
| | - M P L Parente
- LAETA, INEGI, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias s/n, Porto 4200 - 465, Portugal.
| | - T Mascarenhas
- Dep. of Obstetrics and Gynecology, CHSJ-EPE / Faculty of Medicine, University of Porto, Alameda Professor Hernâni Monteiro, Porto 4200 - 319, Portugal.
| | - R M Natal Jorge
- LAETA, INEGI, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias s/n, Porto 4200 - 465, Portugal.
| | - A A Fernandes
- LAETA, INEGI, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias s/n, Porto 4200 - 465, Portugal.
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On Structure-Function Relationships in the Female Human Urethra: A Finite Element Model Approach. Ann Biomed Eng 2021; 49:1848-1860. [PMID: 33782810 DOI: 10.1007/s10439-021-02765-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 03/02/2021] [Indexed: 10/21/2022]
Abstract
Remarkably little is known about urethral striated and smooth muscle and vascular plexus contributions to maintaining continence or initiating micturition. We therefore developed a 3-D, multiphysics, finite element model, based on sequential MR images from a 23-year-old nulliparous heathy woman, to examine the effect of contracting one or more individual muscle layers on the urethral closure pressure (UCP). The lofted urethra turned out to be both curved and asymmetric. The model results led us to reject the current hypothesis that the striated and smooth muscles contribute equally to UCP. While a simulated contraction of the outer (circular) striated muscle increased closure pressure, a similar contraction of the large inner longitudinal smooth muscle both reduced closure pressure and shortened urethral length, suggesting a role in initiating micturition. When age-related atrophy of the posterior striated muscle was simulated, a reduced and asymmetric UCP distribution developed in the transverse plane. Lastly, a simple 2D axisymmetric model of the vascular plexus and lumen suggests arteriovenous pressure plays and important role in helping to maintain luminal closure in the proximal urethra and thereby functional urethral length. More work is needed to examine interindividual differences and validate such models in vivo.
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Routzong MR, Cook MS, Barone W, Abramowitch SD, Alperin M. Novel Application of Photogrammetry to Quantify Fascicle Orientations of Female Cadaveric Pelvic Floor Muscles. Ann Biomed Eng 2021; 49:1888-1899. [PMID: 33638030 DOI: 10.1007/s10439-021-02747-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 02/04/2021] [Indexed: 11/28/2022]
Abstract
Although critical for understanding and simulating pelvic floor muscle function and pathophysiology, the fascicle arrangements of the coccygeus and levator ani remain mostly undetermined. We performed close-range photogrammetry on cadaveric pelvic floor muscles to robustly quantify surface fascicle orientations. The pelvic floor muscles of 5 female cadavers were exposed through anatomic dissections, removed en bloc, and photographed from every required angle. Overlapping images were mapped onto in silico geometries and muscle fascicles were traced manually. Tangent vectors were calculated along each trace; interpolated to define continuous, 3D vector fields; and projected onto axial and sagittal planes to calculate angles with respect to the pubococcygeal line. Contralateral and ipsilateral pelvic floor muscles were compared within each donor (Kuiper's tests) and using mean values from all donors (William-Watsons tests). Contralateral muscles and all but one ipsilateral muscle pair differed significantly within each donor (p < 0.001). When mean values were considered collectively, no contralateral or ipsilateral statistical differences were found but all muscles compared differed by more than 10° on average. Close-range photogrammetry and subsequent analyses robustly quantified surface fascicle orientations of the pelvic floor muscles. The continuous, 3D vector fields provide data necessary for improving simulations of the female pelvic floor muscles.
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Affiliation(s)
- Megan R Routzong
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Mark S Cook
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - William Barone
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | | | - Marianna Alperin
- Department of Obstetrics, Gynecology & Reproductive Sciences, Division of Female Medicine and Reconstructive Surgery, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0863, USA.
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Bilston LE, Bolsterlee B, Nordez A, Sinha S. Contemporary image-based methods for measuring passive mechanical properties of skeletal muscles in vivo. J Appl Physiol (1985) 2019; 126:1454-1464. [PMID: 30236053 DOI: 10.1152/japplphysiol.00672.2018] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Skeletal muscles' primary function in the body is mechanical: to move and stabilize the skeleton. As such, their mechanical behavior is a key aspect of their physiology. Recent developments in medical imaging technology have enabled quantitative studies of passive muscle mechanics, ranging from measurements of intrinsic muscle mechanical properties, such as elasticity and viscosity, to three-dimensional muscle architecture and dynamic muscle deformation and kinematics. In this review we summarize the principles and applications of contemporary imaging methods that have been used to study the passive mechanical behavior of skeletal muscles. Elastography measurements can provide in vivo maps of passive muscle mechanical parameters, and both MRI and ultrasound methods are available (magnetic resonance elastography and ultrasound shear wave elastography, respectively). Both have been shown to differentiate between healthy muscle and muscles affected by a broad range of clinical conditions. Detailed muscle architecture can now be depicted using diffusion tensor imaging, which not only is particularly useful for computational modeling of muscle but also has potential in assessing architectural changes in muscle disorders. More dynamic information about muscle mechanics can be obtained using a range of dynamic MRI methods, which characterize the detailed internal muscle deformations during motion. There are several MRI techniques available (e.g., phase-contrast MRI, displacement-encoded MRI, and "tagged" MRI), each of which can be collected in synchrony with muscle motion and postprocessed to quantify muscle deformation. Together, these modern imaging techniques can characterize muscle motion, deformation, mechanical properties, and architecture, providing complementary insights into skeletal muscle function.
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Affiliation(s)
- Lynne E Bilston
- Neuroscience Research Australia, Randwick, New South Wales , Australia.,Prince of Wales Clinical School, University of New South Wales, Randwick, New South Wales , Australia
| | - Bart Bolsterlee
- Neuroscience Research Australia, Randwick, New South Wales , Australia.,Graduate School of Biomedical Engineering, University of New South Wales , Kensington, New South Wales , Australia
| | - Antoine Nordez
- Health and Rehabilitation Research Institute, Auckland University of Technology , Auckland , New Zealand.,Movement, Interactions, Performance Laboratory (EA 4334), Faculty of Sport Sciences, University of Nantes , Nantes , France
| | - Shantanu Sinha
- Muscle Imaging and Modeling Laboratory, Department of Radiology, University of California , San Diego, California
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Zifan A, Reisert M, Sinha S, Ledgerwood-Lee M, Cory E, Sah R, Mittal RK. Connectivity of the Superficial Muscles of the Human Perineum: A Diffusion Tensor Imaging-Based Global Tractography Study. Sci Rep 2018; 8:17867. [PMID: 30552351 PMCID: PMC6294750 DOI: 10.1038/s41598-018-36099-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 11/09/2018] [Indexed: 12/02/2022] Open
Abstract
Despite the importance of pelvic floor muscles, significant controversy still exists about the true structural details of these muscles. We provide an objective analysis of the architecture and orientation of the superficial muscles of the perineum using a novel approach. Magnetic Resonance Diffusion Tensor Images (MR-DTI) were acquired in 10 healthy asymptomatic nulliparous women, and 4 healthy males. Global tractography was then used to generate the architecture of the muscles. Micro-CT imaging of a male cadaver was performed for validation of the fiber tracking results. Results show that muscles fibers of the external anal sphincter, from the right and left side, cross midline in the region of the perineal body to continue as transverse perinea and bulbospongiosus muscles of the opposite side. The morphology of the external anal sphincter resembles that of the number '8' or a "purse string". The crossing of muscle fascicles in the perineal body was supported by micro-CT imaging in the male subject. The superficial muscles of the perineum, and external anal sphincter are frequently damaged during child birth related injuries to the pelvic floor; we propose the use of MR-DTI based global tractography as a non-invasive imaging technique to assess damage to these muscles.
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Affiliation(s)
- Ali Zifan
- Department of Bioengineering, Medicine & Radiology, University of California, San Diego, CA, USA
| | - Marco Reisert
- Department of Radiology, Medical Physics, Faculty of Medicine, University Hospital Freiburg, Freiburg, Germany
| | - Shantanu Sinha
- Department of Bioengineering, Medicine & Radiology, University of California, San Diego, CA, USA
| | - Melissa Ledgerwood-Lee
- Department of Bioengineering, Medicine & Radiology, University of California, San Diego, CA, USA
| | - Esther Cory
- Department of Bioengineering, Medicine & Radiology, University of California, San Diego, CA, USA
| | - Robert Sah
- Department of Bioengineering, Medicine & Radiology, University of California, San Diego, CA, USA
| | - Ravinder K Mittal
- Department of Bioengineering, Medicine & Radiology, University of California, San Diego, CA, USA.
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A Systematic Review of Continuum Modeling of Skeletal Muscles: Current Trends, Limitations, and Recommendations. Appl Bionics Biomech 2018; 2018:7631818. [PMID: 30627216 PMCID: PMC6305050 DOI: 10.1155/2018/7631818] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 11/06/2018] [Accepted: 11/13/2018] [Indexed: 12/21/2022] Open
Abstract
Finite elasticity theory has been commonly used to model skeletal muscle. A very large range of heterogeneous constitutive laws has been proposed. In this review, the most widely used continuum models of skeletal muscles were synthetized and discussed. Trends and limitations of these laws were highlighted to propose new recommendations for future researches. A systematic review process was performed using two reliable search engines as PubMed and ScienceDirect. 40 representative studies (13 passive muscle materials and 27 active muscle materials) were included into this review. Note that exclusion criteria include tendon models, analytical models, 1D geometrical models, supplement papers, and indexed conference papers. Trends of current skeletal muscle modeling relate to 3D accurate muscle representation, parameter identification in passive muscle modeling, and the integration of coupled biophysical phenomena. Parameter identification for active materials, assumed fiber distribution, data assumption, and model validation are current drawbacks. New recommendations deal with the incorporation of multimodal data derived from medical imaging, the integration of more biophysical phenomena, and model reproducibility. Accounting for data uncertainty in skeletal muscle modeling will be also a challenging issue. This review provides, for the first time, a holistic view of current continuum models of skeletal muscles to identify potential gaps of current models according to the physiology of skeletal muscle. This opens new avenues for improving skeletal muscle modeling in the framework of in silico medicine.
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Silva M, Parente M, Brandão S, Mascarenhas T, Natal Jorge R. Characterization of the passive and active material parameters of the pubovisceralis muscle using an inverse numerical method. J Biomech 2018; 71:100-110. [DOI: 10.1016/j.jbiomech.2018.01.033] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 12/11/2017] [Accepted: 01/28/2018] [Indexed: 12/28/2022]
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Peng Y, Miller BD, Boone TB, Zhang Y. Modern Theories of Pelvic Floor Support : A Topical Review of Modern Studies on Structural and Functional Pelvic Floor Support from Medical Imaging, Computational Modeling, and Electromyographic Perspectives. Curr Urol Rep 2018; 19:9. [PMID: 29435856 DOI: 10.1007/s11934-018-0752-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PURPOSE OF REVIEW Weakened pelvic floor support is believed to be the main cause of various pelvic floor disorders. Modern theories of pelvic floor support stress on the structural and functional integrity of multiple structures and their interplay to maintain normal pelvic floor functions. Connective tissues provide passive pelvic floor support while pelvic floor muscles provide active support through voluntary contraction. Advanced modern medical technologies allow us to comprehensively and thoroughly evaluate the interaction of supporting structures and assess both active and passive support functions. The pathophysiology of various pelvic floor disorders associated with pelvic floor weakness is now under scrutiny from the combination of (1) morphological, (2) dynamic (through computational modeling), and (3) neurophysiological perspectives. This topical review aims to update newly emerged studies assessing pelvic floor support function among these three categories. RECENT FINDINGS A literature search was performed with emphasis on (1) medical imaging studies that assess pelvic floor muscle architecture, (2) subject-specific computational modeling studies that address new topics such as modeling muscle contractions, and (3) pelvic floor neurophysiology studies that report novel devices or findings such as high-density surface electromyography techniques. We found that recent computational modeling studies are featured with more realistic soft tissue constitutive models (e.g., active muscle contraction) as well as an increasing interest in simulating surgical interventions (e.g., artificial sphincter). Diffusion tensor imaging provides a useful non-invasive tool to characterize pelvic floor muscles at the microstructural level, which can be potentially used to improve the accuracy of the simulation of muscle contraction. Studies using high-density surface electromyography anal and vaginal probes on large patient cohorts have been recently reported. Influences of vaginal delivery on the distribution of innervation zones of pelvic floor muscles are clarified, providing useful guidance for a better protection of women during delivery. We are now in a period of transition to advanced diagnostic and predictive pelvic floor medicine. Our findings highlight the application of diffusion tensor imaging, computational models with consideration of active pelvic floor muscle contraction, high-density surface electromyography, and their potential integration, as tools to push the boundary of our knowledge in pelvic floor support and better shape current clinical practice.
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Affiliation(s)
- Yun Peng
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, 360 HBS Building, 4811 Calhoun Rd., Houston, TX, 77004, USA
| | - Brandi D Miller
- Department of Urology, Houston Methodist Hospital, Houston, TX, 77030, USA
| | - Timothy B Boone
- Department of Urology, Houston Methodist Hospital, Houston, TX, 77030, USA
| | - Yingchun Zhang
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, 360 HBS Building, 4811 Calhoun Rd., Houston, TX, 77004, USA.
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