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Wang R, Liu G, Jing L, Zhang J, Ye Y, Zhu H. Quantifying the effects of five rehabilitation training methods on the ability of elderly men to control bowel movements: a finite element analysis study. Front Bioeng Biotechnol 2024; 12:1392448. [PMID: 38988865 PMCID: PMC11233532 DOI: 10.3389/fbioe.2024.1392448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Accepted: 06/04/2024] [Indexed: 07/12/2024] Open
Abstract
Purpose The study aims to develop a finite element model of the pelvic floor and thighs of elderly men to quantitatively assess the impact of different pelvic floor muscle trainings and the urinary and defecation control ability. Methods A finite element model of the pelvic floor and thighs of elderly men was constructed based on MRI and CT. Material properties of pelvic floor tissues were assigned through literature review, and the relative changes in waistline, retrovesical angle (RVA) and anorectad angulation (ARA) to quantitatively verify the effectiveness of the model. By changing the material properties of muscles, the study analyzed the muscle strengthening or impairment effects of the five types of rehabilitation training for four types of urination and defecation dysfunction. The changes in four outcome indicators, including the retrovesical angle, anorectad angulation, stress, and strain, were compared. Results This study indicates that ARA and RVA approached their normal ranges as material properties changed, indicating an enhancement in the urinary and defecation control ability, particularly through targeted exercises for the levator ani muscle, external anal sphincter, and pelvic floor muscles. This study also emphasizes the effectiveness of personalized rehabilitation programs including biofeedback, exercise training, electrical stimulation, magnetic stimulation, and vibration training and advocates for providing optimized rehabilitation training methods for elderly patients. Discussion Based on the results of computational biomechanics, this study provides foundational scientific insights and practical recommendations for rehabilitation training of the elderly's urinary and defecation control ability, thereby improving their quality of life. In addition, this study also provides new perspectives and potential applications of finite element analysis in elderly men, particularly in evaluating and designing targeted rehabilitation training.
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Affiliation(s)
- Rui Wang
- School of Nursing, Capital Medical University, Beijing, China
| | - Guangtian Liu
- College of Nursing and Rehabilitation, North China University of Science and Technology, Hebei, China
| | - Liwei Jing
- School of Nursing, Capital Medical University, Beijing, China
| | - Jing Zhang
- School of Nursing, Capital Medical University, Beijing, China
| | - Yan Ye
- School of Nursing, Capital Medical University, Beijing, China
| | - Haoran Zhu
- School of Nursing, Capital Medical University, Beijing, China
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Yang M, Chen C, Wang Z, Long J, Huang R, Qi W, Shi R. Finite element analysis of female pelvic organ prolapse mechanism: current landscape and future opportunities. Front Med (Lausanne) 2024; 11:1342645. [PMID: 38323034 PMCID: PMC10844411 DOI: 10.3389/fmed.2024.1342645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 01/05/2024] [Indexed: 02/08/2024] Open
Abstract
The prevalence of pelvic organ prolapse (POP) has been steadily increasing over the years, rendering it a pressing global health concern that significantly impacts women's physical and mental wellbeing as well as their overall quality of life. With the advancement of three-dimensional reconstruction and computer simulation techniques for pelvic floor structures, research on POP has progressively shifted toward a biomechanical focus. Finite element (FE) analysis is an established tool to analyze the biomechanics of complex systems. With the advancement of computer technology, an increasing number of researchers are now employing FE analysis to investigate the pathogenesis of POP in women. There is a considerable number of research on the female pelvic FE analysis and to date there has been less review of this technique. In this review article, we summarized the current research status of FE analysis in various types of POP diseases and provided a detailed explanation of the issues and future development in pelvic floor disorders. Currently, the application of FE analysis in POP is still in its exploratory stage and has inherent limitations. Through continuous development and optimization of various technologies, this technique can be employed with greater accuracy to depict the true functional state of the pelvic floor, thereby enhancing the supplementation of the POP mechanism from the perspective of computer biomechanics.
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Affiliation(s)
- Miyang Yang
- The First Clinical Medical College, The Affiliated People's Hospital of Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, China
| | - Chujie Chen
- The First Clinical Medical College, The Affiliated People's Hospital of Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, China
| | - Zhaochu Wang
- Department of Anorectal, The Affiliated People's Hospital of Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, China
| | - Jiaye Long
- Department of Interventional Radiology, Inner Mongolia Forestry General Hospital, The Second Clinical Medical School of Inner Mongolia University for The Nationalities, Yakeshi, China
| | - Runyu Huang
- The First Clinical Medical College, The Affiliated People's Hospital of Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, China
| | - Wan Qi
- Department of Radiology, The Affiliated People's Hospital of Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, China
| | - Rong Shi
- Department of Anorectal, The Affiliated People's Hospital of Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, China
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Xue X, Zheng Q, Gao Z, Shen J, Yao T. The influence of the combined impairments and apical mesh surgery on the biomechanical behavior of the pelvic floor system. Front Bioeng Biotechnol 2024; 11:1292407. [PMID: 38260732 PMCID: PMC10800848 DOI: 10.3389/fbioe.2023.1292407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 12/08/2023] [Indexed: 01/24/2024] Open
Abstract
Objective: The prolapse mechanism of multifactorial impairment of the female pelvic floor system and the mechanics of the pelvic floor after apical suspension surgery are not yet understood, so we developed biomechanical models of the pelvic floor for the normal physiological state (0°) and 90° pathological state. Methods: Under different types and levels of the impairments and uterosacral suspensions, the possible changes in the morphometric characteristics and the mechanical characteristics of suspension and support functions were simulated based on the biomechanical models of the pelvic floor. Results: After the combined impairments, the descending displacement of the pelvic floor cervix and the stress and displacement of the perineal body reached maximum values. After surgical mesh implantation, the stresses of the normal pelvic floor were concentrated on the uterine fundus, cervix, and top of the bladder and the stresses of the 90° pathological state pelvic floor were concentrated on the uterine fundus, uterine body, cervix, middle of the posterior vaginal wall, and bottom of the perineal body. Conclusion: After the combined impairments, the biomechanical support of the bladder and sacrococcyx in the anterior (0°) and 90° pathological state pelvic floor system is diminished, the anterior vaginal wall dislodges from the external vaginal opening, and the posterior vaginal wall forms "kneeling" profiles. The pelvic floor system may evolve with a tendency toward the cervical prolapse with anterior and posterior vaginal wall prolapse and eventually prolapse. After surgical mesh implantation, the cervical position can be better restored; however, the load of combined impairment of the pelvic floor is mainly borne by the surgical mesh suspension, the biomechanical support function of pelvic floor organs and sacrococcyx was not repaired by the physiological structure, and the results of uterosacral suspension alone may be poor.
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Affiliation(s)
- Xianglu Xue
- Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming, China
| | - Qiuyu Zheng
- Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming, China
| | - Zhenhua Gao
- The First Department of Urology, The First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Jihong Shen
- The First Department of Urology, The First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Tingqiang Yao
- Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming, China
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Roshanfar M, Fatehi E, Torkaman T, Ashouri N, Lalani I, Khademi S, Aghili M, Saboukhi A, Gangal M. Toward Patient-specific Pessary to Manage Pelvic Organ Prolapse: Design and Simulation. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023; 2023:1-4. [PMID: 38083613 DOI: 10.1109/embc40787.2023.10340082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
This study proposed a novel design and personalized approach to developing an intra-vaginal device, also known as a pessary, for the treatment of Pelvic Organ Prolapse (POP). Although POP is likely to have a more diverse dynamic than other health conditions in women, it is currently treated as a "one-shape-fits-all" problem in all cases. Pessaries are conservative devices inserted into the vagina to support its internal structure and predominantly come in a ring shape design. Failure rates as high as 50% within the first year of use have been attributed to the poor design of these pessaries; with symptoms such as irritation, bleeding, and lacerations felt by most users. To address this problem, a new base shape design was proposed and its deformation was examined using Finite Element Analysis (FEA). Based on the anatomical measurements of each patient, the base design can be adjusted accordingly. To demonstrate the effectiveness of the proposed design, a comparative study was conducted with the most commonly used support pessary, also known as the ring pessary. In order to model the large deformation of the pessaries, the hyperelastic constitutive law (Yeoh model) was fitted to the available stress-strain data of SIL 30 (a silicone urethane resin supplied by Carbon Inc.). The results showed that re-directing the reaction forces of the pessary towards the lateral walls, supported by the pelvic bones, could decrease the overall displacement of the pessaries, and provide effective symptomatic relief thereby, delaying or preventing surgical procedures.Clinical relevance- There is a clear clinical need to develop a more effective conservative therapy for managing POP. The personalized pessaries proposed in this paper can be an effective method for providing symptomatic relief and avoiding displacement, compared to the currently available devices on the market. Made-to-measure for each patient, the devices are anatomically suited and can be adjusted throughout a patient's treatment plan to allow for higher compliance and overall success rate.
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Xue X, Wang H, Xie J, Gao Z, Shen J, Yao T. Two-dimensional biomechanical finite element modeling of the pelvic floor and prolapse. Biomech Model Mechanobiol 2023:10.1007/s10237-023-01729-y. [PMID: 37294482 DOI: 10.1007/s10237-023-01729-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Accepted: 05/20/2023] [Indexed: 06/10/2023]
Abstract
We developed the pelvic floor model in physiological and pathological states to understand the changes of biomechanical axis and support that may occur from the normal physiological state to the prolapse pathological state of the pelvic floor. Based on the physiological state model of the pelvic floor, we model the uterus to the pathological state position by balancing intra-abdominal pressure (IAP) and uterine pathological position load. Under combined impairments, we compared the patterns of changes in pelvic floor biomechanics that may be induced by different uterine morphological characteristic positions under different IAP. The orientation of the uterine orifice gradually changes from the sacrococcygeal direction to the vertical downward of vaginal orifice, and a large downward prolapse displacement occurs, and the posterior vaginal wall shows "kneeling" profile with posterior wall bulging prolapse. When the abdominal pressure value was 148.1 cmH2O, the descent displacement of the cervix in the normal and pathological pelvic floor system was 11.94, 20, 21.83 and 19.06 mm in the healthy state, and 13.63, 21.67, 22.94 and 19.38 mm in the combined impairment, respectively. The above suggests a maximum cervical descent displacement of the uterus in the anomalous 90° position, with possible cervical-uterine prolapse as well as prolapse of the posterior vaginal wall. The combined forces of the pelvic floor point in the direction of vertical downward prolapse of the vaginal orifice, and the biomechanical support of the bladder and sacrococcygeal bone gradually diminishes, which may exacerbate the soft tissue impairments and biomechanical imbalances of the pelvic floor to occur of POP disease.
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Affiliation(s)
- Xianglu Xue
- Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, No.727, Jingming South Road, Chenggong District, Kunming, 650500, China
| | - Haifeng Wang
- The First Department of Urology, The First Affiliated Hospital of Kunming Medical University, 295 Xichang Road, Kunming, 650032, China
| | - Jiachen Xie
- Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, No.727, Jingming South Road, Chenggong District, Kunming, 650500, China
| | - Zhenhua Gao
- The First Department of Urology, The First Affiliated Hospital of Kunming Medical University, 295 Xichang Road, Kunming, 650032, China
| | - Jihong Shen
- The First Department of Urology, The First Affiliated Hospital of Kunming Medical University, 295 Xichang Road, Kunming, 650032, China
| | - Tingqiang Yao
- Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, No.727, Jingming South Road, Chenggong District, Kunming, 650500, China.
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Ogier AC, Rapacchi S, Bellemare ME. Four-dimensional reconstruction and characterization of bladder deformations. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2023; 237:107569. [PMID: 37186971 DOI: 10.1016/j.cmpb.2023.107569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 03/31/2023] [Accepted: 04/24/2023] [Indexed: 05/17/2023]
Abstract
BACKGROUND AND OBJECTIVE Pelvic floor disorders are prevalent diseases and patient care remains difficult as the dynamics of the pelvic floor remains poorly understood. So far, only 2D dynamic observations of straining exercises at excretion are available in the clinics and 3D mechanical defects of pelvic organs are not well studied. In this context, we propose a complete methodology for the 3D representation of non-reversible bladder deformations during exercises, combined with a 3D representation of the location of the highest strain areas on the organ surface. METHODS Novel image segmentation and registration approaches have been combined with three geometrical configurations of up-to-date rapid dynamic multi-slice MRI acquisitions for the reconstruction of real-time dynamic bladder volumes. RESULTS For the first time, we proposed real-time 3D deformation fields of the bladder under strain from in-bore forced breathing exercises. The potential of our method was assessed on eight control subjects undergoing forced breathing exercises. We obtained average volume deviations of the reconstructed dynamic volume of bladders around 2.5% and high registration accuracy with mean distance values of 0.4 ± 0.3 mm and Hausdorff distance values of 2.2 ± 1.1 mm. CONCLUSIONS The proposed framework provides proper 3D+t spatial tracking of non-reversible bladder deformations. This has immediate applicability in clinical settings for a better understanding of pelvic organ prolapse pathophysiology. This work can be extended to patients with cavity filling or excretion problems to better characterize the severity of pelvic floor pathologies or to be used for preoperative surgical planning.
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Affiliation(s)
- Augustin C Ogier
- Aix Marseille Univ, Universite de Toulon, CNRS, LIS, Marseille, France.
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Zarrinchang P, Ashrafizaadeh M, Jamshidi N. Simulation of the female pelvic mobility and vesical pressure changes employing fluid-structure interaction method. Int Urogynecol J 2023; 34:571-580. [PMID: 36169682 DOI: 10.1007/s00192-022-05362-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 09/05/2022] [Indexed: 01/26/2023]
Abstract
INTRODUCTION AND HYPOTHESIS This study aims to develop a fluid-structural interaction (FSI) method to pinpoint the effects of pressure changes inside the bladder and their impact on the supporting structure and the urethra mobility. METHODS A physiological model of the nulliparous female pelvis, including the organs, supportive structures, and urine, was developed based on magnetic resonance images. Soft tissues with nonlinear hyperelastic material characteristics were modeled. The Navier-Stokes equations governing the fluid flow within the computational domain (urine) were solved. The urine and soft tissue interactions were simulated by the FSI method. The vesical pressure and its impact on the urethral mobility and supportive structures were investigated during the Valsalva maneuver. Moreover, the simulation results were validated by comparing with a urodynamic test and other research. RESULTS The results demonstrated that the vesical pressure simulated by the FSI method could predict the nonlinear behavior of the urodynamic test pressure. The urethra retropubic bladder neck and the bladder neck-pubic bone angle changed 58.92% and -55.76%, respectively. The retropubic urethral length distance changed by -48.74%. The error compared to the statistical results of other research is < 5%. CONCLUSIONS The total deformation and mobility of the urethra predicted by the FSI model were consistent with clinical observations in a subject. The urethra supports dependence on the tissues' mechanical properties, interaction between the tissues, and effect of urine fluid inside the bladder. This simulation effectively depicts the patterns of urethra mobility, which provides a better understanding of the behavior of the pelvic floor.
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Affiliation(s)
- Pouya Zarrinchang
- Mechanical Engineering group, Pardis College, Isfahan University of Technology, Isfahan, 84156-83111, Iran
| | - Mahmud Ashrafizaadeh
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, 84156-83111, Iran.
| | - Nima Jamshidi
- Department of Biomedical Engineering, Faculty of Engineering, University of Isfahan, Isfahan, Iran
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Biomechanics of Hollow Organs: Experimental Testing and Computational Modeling. Bioengineering (Basel) 2023; 10:bioengineering10020175. [PMID: 36829669 PMCID: PMC9952441 DOI: 10.3390/bioengineering10020175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 01/24/2023] [Indexed: 01/31/2023] Open
Abstract
Hollow organs are visceral organs that are hollow tubes or pouches (such as the intestine or the stomach, respectively) or that include a cavity (such as the heart) and which subserve a vital function [...].
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Xie J, Li S, Yao T, Shen J. A 2D equivalent mechanical model of the whole pelvic floor and impairment simulation. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2023; 39:e3659. [PMID: 36305715 DOI: 10.1002/cnm.3659] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 08/28/2022] [Accepted: 10/23/2022] [Indexed: 06/16/2023]
Abstract
We developed a complete 2D equivalent mechanical model of the pelvic floor based on magnetic resonance imaging (MRI) images of a 35-year-old healthy woman. This model can simulate anterior vaginal prolapse (AVP) due to soft tissue impairment. Thus, we can study the mechanism of prolapse formation from a mechanical perspective and improve the assessment and treatment of the condition in clinical practice. Based on 2D MRI image parameter measurements and computer-aided design methods, the 2D equivalent mechanical model of the whole pelvic floor in the sagittal plane was accurately reconstructed, which includes all necessary tissues of the pelvic floor system. Material parameters were mainly from the literature. We simulated the impairment by reducing the tissue's mechanical properties, and numerical simulations predicted the mechanical response and morphological changes of the healthy and impaired pelvic floor in different states. In six intra-abdominal pressure (IAP) states (8.4-208.9 cmH2 O), the maximum cervical descent in the impaired pelvic floor was 0.3-18.521 mm, which was much greater than that in the healthy pelvic floor (0.14-6.55 mm). Once the impairment occurred (0%-25%), there was a significant increase in maximum displacement, stress, and cervical descent (30.9-36.5 mm, 0.56-1.12 MPa, 4.6-12.1 mm), and a clinically similar prolapse shape occurred. Simple supine and standing will not cause prolapse. The formation of prolapse is closely related to vaginal tissue impairment. In the standing position, the main forces on the healthy pelvic floor system are distributed horizontally posteriorly and inferiorly, reducing the burden in the vertically downward direction.
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Affiliation(s)
- Jiachen Xie
- Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming, China
| | - Song Li
- Department of Urology, First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Tingqiang Yao
- Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming, China
| | - Jihong Shen
- Department of Urology, First Affiliated Hospital of Kunming Medical University, Kunming, China
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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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Makki K, Bohi A, Ogier AC, Bellemare ME. Characterization of surface motion patterns in highly deformable soft tissue organs from dynamic MRI: An application to assess 4D bladder motion. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 218:106708. [PMID: 35245782 DOI: 10.1016/j.cmpb.2022.106708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 10/17/2021] [Accepted: 02/21/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND AND OBJECTIVES Dynamic Magnetic Resonance Imaging (MRI) may capture temporal anatomical changes in soft tissue organs with high-contrast but the obtained sequences usually suffer from limited volume coverage which makes the high-resolution reconstruction of organ shape trajectories a major challenge in temporal studies. Because of the variability of abdominal organ shapes across time and subjects, the objective of the present study is to go towards 3D dense velocity measurements to fully cover the entire surface and to extract meaningful features characterizing the observed organ deformations and enabling clinical action or decision. METHODS We present a pipeline for characterization of bladder surface dynamics during deep respiratory movements. For a compact shape representation, the reconstructed temporal volumes were first used to establish subject-specific dynamical 4D mesh sequences using the large deformation diffeomorphic metric mapping (LDDMM) framework. Then, we performed a statistical characterization of organ dynamics from mechanical parameters such as mesh elongations and distortions. Since we refer to organs as non-flat surfaces, we have also used the mean curvature change as metric to quantify surface evolution. However, the numerical computation of curvature is strongly dependant on the surface parameterization (i.e. the mesh resolution). To cope with this dependency, we employed a non-parametric method for surface deformation analysis. Independent of parameterization and minimizing the length of the geodesic curves, it stretches smoothly the surface curves towards a sphere by minimizing a Dirichlet energy. An Eulerian PDE approach is used to derive a shape descriptor from the curve-shortening flow. Intercorrelations between individuals' motion patterns are computed using the Laplace-Beltrami Operator (LBO) eigenfunctions for spherical mapping. RESULTS Application to extracting characterization correlation curves for locally-controlled simulated shape trajectories demonstrates the stability of the proposed shape descriptor. Its usability was shown on MRI acquired for seven healthy participants for which the bladder was highly deformed by maximum of inspiration. As expected, the study showed that deformations occured essentially on the top lateral regions. CONCLUSION Promising results were obtained, showing the organ in its 3D complexity during deformation due to strain conditions. Smooth genus-0 manifold reconstruction from sparse dynamic MRI data is employed to perform a statistical shape analysis for the determination of bladder deformation.
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Affiliation(s)
- Karim Makki
- Aix Marseille Univ, Université de Toulon, CNRS, LIS, Marseille, France
| | - Amine Bohi
- Aix Marseille Univ, Université de Toulon, CNRS, LIS, Marseille, France
| | - Augustin C Ogier
- Aix Marseille Univ, Université de Toulon, CNRS, LIS, Marseille, France
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Diallo MN, Mayeur O, Lecomte-Grosbras P, Patrouix L, Witz JF, Lesaffre F, Rubod C, Cosson M, Brieu M. Simulation of the mobility of the pelvic system: influence of fascia between organs. Comput Methods Biomech Biomed Engin 2021; 25:1073-1087. [PMID: 34783611 DOI: 10.1080/10255842.2021.2001460] [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] [Indexed: 10/19/2022]
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.
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Affiliation(s)
- Mouhamadou Nassirou Diallo
- CNRS, Centrale Lille, UMR 9013 - LaMcube - Laboratoire de Mécanique, Multiphysique, Multiéchelle, University of Lille, Lille, France
| | - Olivier Mayeur
- CNRS, Centrale Lille, UMR 9013 - LaMcube - Laboratoire de Mécanique, Multiphysique, Multiéchelle, University of Lille, Lille, France
| | - Pauline Lecomte-Grosbras
- CNRS, Centrale Lille, UMR 9013 - LaMcube - Laboratoire de Mécanique, Multiphysique, Multiéchelle, University of Lille, Lille, France
| | - Laurent Patrouix
- CNRS, Centrale Lille, UMR 9013 - LaMcube - Laboratoire de Mécanique, Multiphysique, Multiéchelle, University of Lille, Lille, France
| | - Jean François Witz
- CNRS, Centrale Lille, UMR 9013 - LaMcube - Laboratoire de Mécanique, Multiphysique, Multiéchelle, University of Lille, Lille, France
| | - François Lesaffre
- CNRS, Centrale Lille, UMR 9013 - LaMcube - Laboratoire de Mécanique, Multiphysique, Multiéchelle, University of Lille, Lille, France
| | - Chrystle Rubod
- CNRS, Centrale Lille, UMR 9013 - LaMcube - Laboratoire de Mécanique, Multiphysique, Multiéchelle, University of Lille, Lille, France.,Service de chirurgie gynécologique - CHU Lille, Lille, France
| | - Michel Cosson
- CNRS, Centrale Lille, UMR 9013 - LaMcube - Laboratoire de Mécanique, Multiphysique, Multiéchelle, University of Lille, Lille, France.,Service de chirurgie gynécologique - CHU Lille, Lille, France
| | - Mathias Brieu
- CNRS, Centrale Lille, UMR 9013 - LaMcube - Laboratoire de Mécanique, Multiphysique, Multiéchelle, University of Lille, Lille, France.,Department of Mechanical Engineering, College Engineering, Computer Science and Technology, California State University, Los Angeles, Long Angeles, CA, USA
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13
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Autocuidado domiciliar após cirurgias ginecológicas: elaboração e validação de material educativo. ACTA PAUL ENFERM 2021. [DOI: 10.37689/acta-ape/2021ao03154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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14
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Singh G, Chanda A. Mechanical properties of whole-body soft human tissues: a review. Biomed Mater 2021; 16. [PMID: 34587593 DOI: 10.1088/1748-605x/ac2b7a] [Citation(s) in RCA: 95] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 09/29/2021] [Indexed: 11/11/2022]
Abstract
The mechanical properties of soft tissues play a key role in studying human injuries and their mitigation strategies. While such properties are indispensable for computational modelling of biological systems, they serve as important references in loading and failure experiments, and also for the development of tissue simulants. To date, experimental studies have measured the mechanical properties of peripheral tissues (e.g. skin)in-vivoand limited internal tissuesex-vivoin cadavers (e.g. brain and the heart). The lack of knowledge on a majority of human tissues inhibit their study for applications ranging from surgical planning, ballistic testing, implantable medical device development, and the assessment of traumatic injuries. The purpose of this work is to overcome such challenges through an extensive review of the literature reporting the mechanical properties of whole-body soft tissues from head to toe. Specifically, the available linear mechanical properties of all human tissues were compiled. Non-linear biomechanical models were also introduced, and the soft human tissues characterized using such models were summarized. The literature gaps identified from this work will help future biomechanical studies on soft human tissue characterization and the development of accurate medical models for the study and mitigation of injuries.
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Affiliation(s)
- Gurpreet Singh
- Centre for Biomedical Engineering, Indian Institute of Technology (IIT), Delhi, India
| | - Arnab Chanda
- Centre for Biomedical Engineering, Indian Institute of Technology (IIT), Delhi, India.,Department of Biomedical Engineering, All India Institute of Medical Sciences (AIIMS), Delhi, India
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15
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Bhattarai A, Kowalczyk W, Tran TN. A literature review on large intestinal hyperelastic constitutive modeling. Clin Biomech (Bristol, Avon) 2021; 88:105445. [PMID: 34416632 DOI: 10.1016/j.clinbiomech.2021.105445] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 06/29/2021] [Accepted: 07/29/2021] [Indexed: 02/07/2023]
Abstract
Impacts, traumas and strokes are spontaneously life-threatening, but chronic symptoms strangle patient every day. Colorectal tissue mechanics in such chronic situations not only regulates the physio-psychological well-being of the patient, but also confirms the level of comfort and post-operative clinical outcomes. Numerous uniaxial and multiaxial tensile experiments on healthy and affected samples have evidenced significant differences in tissue mechanical behavior and strong colorectal anisotropy across each layer in thickness direction and along the length. Furthermore, this study reviewed various forms of passive constitutive models for the highly fibrous colorectal tissue ranging from the simplest linearly elastic and the conventional isotropic hyperelastic to the most sophisticated second harmonic generation image based anisotropic mathematical formulation. Under large deformation, the isotropic description of tissue mechanics is unequivocally ineffective which demands a microstructural based tissue definition. Therefore, the information collected in this review paper would present the current state-of-the-art in colorectal biomechanics and profoundly serve as updated computational resources to develop a sophisticated characterization of colorectal tissues.
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Affiliation(s)
- Aroj Bhattarai
- Department of Orthopaedic Surgery, University of Saarland, Germany
| | | | - Thanh Ngoc Tran
- Department of Orthopaedic Surgery, University of Saarland, Germany.
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16
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Xu Y, Liu H, Hao D, Taggart M, Zheng D. Uterus Modeling from Cell to Organ Level: towards Better Understanding of Physiological Basis of Uterine Activity. IEEE Rev Biomed Eng 2020; 15:341-353. [PMID: 32915747 DOI: 10.1109/rbme.2020.3023535] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The relatively limited understanding of the physiology of uterine activation prevents us from achieving optimal clinical outcomes for managing serious pregnancy disorders such as preterm birth or uterine dystocia. There is increasing awareness that multi-scale computational modeling of the uterus is a promising approach for providing a qualitative and quantitative description of uterine physiology. The overarching objective of such approach is to coalesce previously fragmentary information into a predictive and testable model of uterine activity that, in turn, informs the development of new diagnostic and therapeutic approaches to these pressing clinical problems. This article assesses current progress towards this goal. We summarize the electrophysiological basis of uterine activation as presently understood and review recent research approaches to uterine modeling at different scales from single cell to tissue, whole organ and organism with particular focus on transformative data in the last decade. We describe the positives and limitations of these approaches, thereby identifying key gaps in our knowledge on which to focus, in parallel, future computational and biological research efforts.
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The histological microstructure and in vitro mechanical properties of pregnant and postmenopausal ewe perineal body. ACTA ACUST UNITED AC 2020; 26:1289-1301. [PMID: 31513089 DOI: 10.1097/gme.0000000000001395] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
OBJECTIVE The mechanical properties and microstructure of the perineal body are important for the improvement of numerical models of pelvic organs. We determined the mechanical parameters and volume fractions of the ewe perineal body as an animal model. METHODS The 39 specimens of 13 pregnant swifter ewes delivering by cesarean section (aged 2 years, weight 61.2 ± 6.2 kg (mean ± standard deviation) and 24 specimens of 8 postmenopausal swifter ewes 150 days after surgical ovariectomy (aged 7 years, 58.6 ± 4.6 kg)) were loaded uniaxially to determine Young's moduli of elasticity in the small (E0) and large (E1) deformation regions, and ultimate stresses and strains. The 63 adjacent tissue samples were processed histologically to assess volume fractions of smooth and skeletal muscle, adipose cells, elastin, and type I collagen using a stereological point testing grid. We compared the structural and mechanical differences along the ewe perineal body, and between pregnant and postmenopausal groups. RESULTS The pregnant/postmenopausal perineal body was composed of smooth muscle (12/14%; median), skeletal muscle (12/16%), collagen (10/23%), elastin (8/7%), and adipose cells (6/6%). The E0 was 37/11 kPa (median), E1 was 0.97/1.04 MPa, ultimate stress was 0.55/0.59 MPa, and ultimate strain was 0.90/0.87 for pregnant/postmenopausal perineal body. The perineal body showed a structural and mechanical stability across the sites. The pregnant ewes had a higher amount of skeletal muscle, higher E0, and a less amount of collagen when compared with postmenopausal ewes. CONCLUSIONS The data can be used as input for models simulating vaginal delivery, pelvic floor prolapsed, or dysfunction.
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18
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The histological microstructure and in vitro mechanical properties of the human female postmenopausal perineal body. Menopause 2020; 26:66-77. [PMID: 29994970 DOI: 10.1097/gme.0000000000001166] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The perineal body connects muscles from the pelvic floor and is critical for support of the lower part of the vagina and proper function of the anal canal. We determined mechanical parameters and volume fractions of main components of the human female postmenopausal perineal body. METHODS The specimens were taken from 15 fresh female cadavers (age 74 ± 10, mean ± standard deviation). Seventy-five specimens from five regions of the perineal body were processed histologically to assess volume fractions of tissue components using stereological point testing grid. Fifteen specimens taken from the midline region were loaded uniaxially with 6 mm/min velocity until tissue rupture to determine Young's modulus of elasticity, ultimate stresses, and strains. RESULTS The perineal body was composed of collagen (29%), adipose cells (27%), elastin (7%), smooth muscle (11%), and skeletal muscle (3%). The residual tissue (19%) constituted mostly peripheral nerves, lumina of blood vessels, fibroblasts, and fibrocytes. Young's modulus of elasticity at midline region was 18 kPa (median) at small and 232 kPa at large deformations, respectively. The ultimate stress was 172 kPa and the ultimate strain was 1.4. CONCLUSIONS We determined the structural and mechanical parameters of the perineal body. The resultant data could be used as input for models simulating pelvic floor prolapse or dysfunction.
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Guachi R, Bini F, Bici M, Campana F, Marinozzi F, Guachi L. Finite element analysis in colorectal surgery: non-linear effects induced by material model and geometry. COMPUTER METHODS IN BIOMECHANICS AND BIOMEDICAL ENGINEERING: IMAGING & VISUALIZATION 2019. [DOI: 10.1080/21681163.2019.1679669] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Robinson Guachi
- Department of Mechatronics, Universidad Internacional del Ecuador, Quito, Ecuador
- Dipartimento di ingegneria Meccanica e Aerospaziale, Universita degli Studi di Roma La Sapienza, Roma, Italy
| | - Fabiano Bini
- Dipartimento di ingegneria Meccanica e Aerospaziale, Universita degli Studi di Roma La Sapienza, Roma, Italy
| | - Michele Bici
- Dipartimento di ingegneria Meccanica e Aerospaziale, Universita degli Studi di Roma La Sapienza, Roma, Italy
| | - Francesca Campana
- Dipartimento di ingegneria Meccanica e Aerospaziale, Universita degli Studi di Roma La Sapienza, Roma, Italy
| | - Franco Marinozzi
- Dipartimento di ingegneria Meccanica e Aerospaziale, Universita degli Studi di Roma La Sapienza, Roma, Italy
| | - Lorena Guachi
- Mathematical and Computational Sciences, Yachay University, Urcuquí, Ecuador
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20
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Mancuso E, Downey C, Doxford‐Hook E, Bryant MG, Culmer P. The use of polymeric meshes for pelvic organ prolapse: Current concepts, challenges, and future perspectives. J Biomed Mater Res B Appl Biomater 2019; 108:771-789. [DOI: 10.1002/jbm.b.34432] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 05/07/2019] [Accepted: 05/31/2019] [Indexed: 12/18/2022]
Affiliation(s)
- Elena Mancuso
- Ulster UniversityNanotechnology and Integrated Bio‐Engineering Centre (NIBEC) Jordanstown campus ‐ Newtownabbey UK
| | - Candice Downey
- Leeds Institute of Medical Research at St James'sUniversity of Leeds Leeds UK
| | | | | | - Peter Culmer
- School of Mechanical EngineeringUniversity of Leeds Leeds UK
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21
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Babayi M, Azghani MR, Hajebrahimi S, Berghmans B. Three-dimensional finite element analysis of the pelvic organ prolapse: A parametric biomechanical modeling. Neurourol Urodyn 2018; 38:591-598. [PMID: 30499117 DOI: 10.1002/nau.23885] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Accepted: 10/17/2018] [Indexed: 11/12/2022]
Abstract
AIMS To evaluate the role of soft tissue and ligaments damage and level of pelvic muscles activation versus intra-abdominal pressure, on pelvic organ prolapse. METHODS This was a computational modeling based on the finite element analysis. Three pelvic muscles, four pelvic ligaments, and three organs (urethra, vagina, and rectum) were simulated. The model was subjected to total 41 472 analysis cases including three intra-abdominal pressures, two damaging levels for the ligaments, three damaging levels for the muscles, and four intentional levels of activation for muscles. RESULTS Increased intra-abdominal pressures caused significant statistical increase of the pelvic organ prolapse (P = 0.000) up to 10 mm downward. Ligaments' defect had no statistically-significant effect on prolapse of the organs (P = 0.981 for rectum, P = 0.423 for urethra, and P = 0.752 for vagina). Damage in the pelvic floor muscles and low intentional level of activation also deteriorated the prolapse (P = 0.000). CONCLUSION Increase of the intra-abdominal pressure (IAP) as may be existed during pregnancy or physical activity increased the organ prolapse. Damages of the ligaments caused less effects on the prolapse. Loss of the passive properties of the muscles which is probable after delivery or aging moderately deteriorated the prolapse disorder. However, activation of the pelvic floor muscles prevented the prolapse. Different recruitments of the muscles, specifically the pubococcygeus (PCM), could compensate the possible defects in other tissues. Targeted pelvic floor muscle training (PFMT) could also be effective in older adults due to considerable role of the pelvic muscles' intentional activation.
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Affiliation(s)
- Masumeh Babayi
- Department of Biomechanics, Faculty of Biomedical Engineering, Sahand University of Technology, Tabriz, Iran
| | - Mahmood-Reza Azghani
- Department of Biomechanics, Faculty of Biomedical Engineering, Sahand University of Technology, Tabriz, Iran
| | - Sakineh Hajebrahimi
- Research Center for Evidence-Based Medicine, Urology department, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Bary Berghmans
- School for Public Health and Primary Care, Maastricht University, Maastricht, The Netherlands
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22
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Nekooeimehr I, Lai-Yuen S, Bao P, Weitzenfeld A, Hart S. Automated contour tracking and trajectory classification of pelvic organs on dynamic MRI. J Med Imaging (Bellingham) 2018; 5:014008. [PMID: 29651450 DOI: 10.1117/1.jmi.5.1.014008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 03/12/2018] [Indexed: 11/14/2022] Open
Abstract
A method is presented to automatically track and segment pelvic organs on dynamic magnetic resonance imaging (MRI) followed by multiple-object trajectory classification to improve understanding of pelvic organ prolapse (POP). POP is a major health problem in women where pelvic floor organs fall from their normal position and bulge into the vagina. Dynamic MRI is presently used to analyze the organs' movements, providing complementary support for clinical examination. However, there is currently no automated or quantitative approach to measure the movement of the pelvic organs and their correlation with the severity of prolapse. In the proposed method, organs are first tracked and segmented using particle filters and [Formula: see text]-means clustering with prior information. Then, the trajectories of the pelvic organs are modeled using a coupled switched hidden Markov model to classify the severity of POP. Results demonstrate that the presented method can automatically track and segment pelvic organs with a Dice similarity index above 78% and Hausdorff distance of [Formula: see text] for 94 tested cases while demonstrating correlation between organ movement and POP. This work aims to enable automatic tracking and analysis of multiple deformable structures from images to improve understanding of medical disorders.
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Affiliation(s)
| | - Susana Lai-Yuen
- University of South Florida, Department of Industrial and Management Systems Engineering, Tampa, Florida, United States
| | - Paul Bao
- University of South Florida, Department of Computer Science and Engineering, Tampa, Florida, United States
| | - Alfredo Weitzenfeld
- University of South Florida, Department of Computer Science and Engineering, Tampa, Florida, United States
| | - Stuart Hart
- University of South Florida, Department of Obstetrics and Gynecology, Tampa, Florida, United States.,Medtronic, Tampa, Florida, United States
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Modelling of Soft Connective Tissues to Investigate Female Pelvic Floor Dysfunctions. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2018; 2018:9518076. [PMID: 29568322 PMCID: PMC5820624 DOI: 10.1155/2018/9518076] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 12/04/2017] [Accepted: 12/11/2017] [Indexed: 01/04/2023]
Abstract
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.
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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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25
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Abstract
PURPOSE OF REVIEW Provide an evidence-based review of pelvic floor functional anatomy related to pelvic organ prolapse. RECENT FINDINGS Pelvic organ support depends on interactions between the levator ani muscle and pelvic connective tissues. Muscle failure exposes the vaginal wall to a pressure differential producing abnormal tension on the attachments of the pelvic organs to the pelvic sidewall. Birth-induced injury to the pubococcygeal portion of the levator ani muscle is seen in 55% of women with prolapse and 16% of women with normal support. Failure of the lateral connective tissue attachments between the uterus and vagina to the pelvic wall (cardinal, uterosacral, and paravaginal) are strongly related with prolapse (effect sizes ∼2.5) and are also highly correlated with one another (r ∼ 0.85). Small differences exist with prolapse in factors involving the vaginal wall length and width (effect sizes ∼1). The primary difference in ligament properties between women with and without prolapse is found in ligament length. Only minor differences in ligament stiffness are seen. SUMMARY Pelvic organ prolapse occurs because of injury to the levator ani muscles and failure of the lateral connections between the pelvic organs to the pelvic sidewall. Abnormalities of the vaginal wall fascial tissues may play a minor role.
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Guachi R, Bini F, Bici M, Campana F, Marinozzi F. Finite Element Model Set-up of Colorectal Tissue for Analyzing Surgical Scenarios. VIPIMAGE 2017 2018. [DOI: 10.1007/978-3-319-68195-5_65] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Chanda A, Meyer I, Richter HE, Lockhart ME, Moraes FRD, Unnikrishnan V. Vaginal Changes Due to Varying Degrees of Rectocele Prolapse: A Computational Study. J Biomech Eng 2017; 139:2644119. [PMID: 28696484 DOI: 10.1115/1.4037222] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Indexed: 12/25/2022]
Abstract
Pelvic organ prolapse (POP), downward descent of the pelvic organs resulting in a protrusion of the vagina, is a highly prevalent condition, responsible for 300,000 surgeries in the U.S. annually. Rectocele, a posterior vaginal wall (PVW) prolapse of the rectum, is the second most common type of POP after cystocele. A rectocele usually manifests itself along with other types of prolapse with multicompartment pelvic floor defects. To date, the specific mechanics of rectocele formation are poorly understood, which does not allow its early stage detection and progression prediction over time. Recently, with the advancement of imaging and computational modeling techniques, a plethora of finite element (FE) models have been developed to study vaginal prolapse from different perspectives and allow a better understanding of dynamic interactions of pelvic organs and their supporting structures. So far, most studies have focused on anterior vaginal prolapse (AVP) (or cystocele) and limited data exist on the role of pelvic muscles and ligaments on the development and progression of rectocele. In this work, a full-scale magnetic resonance imaging (MRI) based three-dimensional (3D) computational model of the female pelvic anatomy, comprising the vaginal canal, uterus, and rectum, was developed to study the effect of varying degrees (or sizes) of rectocele prolapse on the vaginal canal for the first time. Vaginal wall displacements and stresses generated due to the varying rectocele size and average abdominal pressures were estimated. Considering the direction pointing from anterior to posterior side of the pelvic system as the positive Y-direction, it was found that rectocele leads to negative Y-direction displacements, causing the vaginal cross section to shrink significantly at the lower half of the vaginal canal. Besides the negative Y displacements, the rectocele bulging was observed to push the PVW downward toward the vaginal hiatus, exhibiting the well-known "kneeling effect." Also, the stress field on the PVW was found to localize at the upper half of the vaginal canal and shift eventually to the lower half with increase in rectocele size. Additionally, clinical relevance and implications of the results were discussed.
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Affiliation(s)
- Arnab Chanda
- Department of Aerospace Engineering and Mechanics, University of Alabama, Tuscaloosa, AL 35487 e-mail:
| | - Isuzu Meyer
- Department of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, AL 35233 e-mail:
| | - Holly E Richter
- J Marion Sims Professor of Obstetrics and Gynecology, Urology and Geriatrics Division of Urogynecology and Pelvic Reconstructive Surgery, Department of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, AL 35233 e-mail:
| | - Mark E Lockhart
- Professor Diagnostic Radiology, Department of Radiology, University of Alabama at Birmingham, Birmingham, AL 35233 e-mail:
| | - Fabia R D Moraes
- Department of Mechanical Engineering, Sao Paulo State University, Sao Paulo 01049, Brazil e-mail:
| | - Vinu Unnikrishnan
- Department of Aerospace Engineering and Mechanics, University of Alabama, Tuscaloosa, AL 35487 e-mail:
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28
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Dias N, Peng Y, Khavari R, Nakib NA, Sweet RM, Timm GW, Erdman AG, Boone TB, Zhang Y. Pelvic floor dynamics during high-impact athletic activities: A computational modeling study. Clin Biomech (Bristol, Avon) 2017; 41:20-27. [PMID: 27886590 PMCID: PMC5519824 DOI: 10.1016/j.clinbiomech.2016.11.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 11/09/2016] [Accepted: 11/15/2016] [Indexed: 02/07/2023]
Abstract
BACKGROUND Stress urinary incontinence is a significant problem in young female athletes, but the pathophysiology remains unclear because of the limited knowledge of the pelvic floor support function and limited capability of currently available assessment tools. The aim of our study is to develop an advanced computer modeling tool to better understand the dynamics of the internal pelvic floor during highly transient athletic activities. METHODS Apelvic model was developed based on high-resolution MRI scans of a healthy nulliparous young female. A jump-landing process was simulated using realistic boundary conditions captured from jumping experiments. Hypothesized alterations of the function of pelvic floor muscles were simulated by weakening or strengthening the levator ani muscle stiffness at different levels. Intra-abdominal pressures and corresponding deformations of pelvic floor structures were monitored at different levels of weakness or enhancement. FINDINGS Results show that pelvic floor deformations generated during a jump-landing process differed greatly from those seen in a Valsalva maneuver which is commonly used for diagnosis in clinic. 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. INTERPRETATION Results suggest that clinical diagnosis should make allowances for observed differences in pelvic floor deformations between a Valsalva maneuver and a jump-landing process to ensure accuracy. Urethral hypermobility may be a less contributing factor than the intrinsic sphincteric closure system to the incontinence of young female athletes.
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Affiliation(s)
- Nicholas Dias
- Department of Biomedical Engineering, University of Houston, 360 HBS Building, 4811 Calhoun Rd., Houston, TX 77004, USA.
| | - Yun Peng
- Department of Biomedical Engineering, University of Houston, 360 HBS Building, 4811 Calhoun Rd., Houston, TX 77004, USA.
| | - Rose Khavari
- Department of Urology, Houston Methodist Hospital and Research Institute, 6565 Fannin St, Suite 2100, Houston, TX 77030-2703, USA.
| | - Nissrine A Nakib
- Department of Urology, University of Minnesota, 420 Delaware St. SE MMC 394, Minneapolis, MN 55455-0341, USA.
| | - Robert M Sweet
- Department of Urology, University of Minnesota, 420 Delaware St. SE MMC 394, Minneapolis, MN 55455-0341, USA.
| | - Gerald W Timm
- Department of Urology, University of Minnesota, 420 Delaware St. SE MMC 394, Minneapolis, MN 55455-0341, USA.
| | - Arthur G Erdman
- Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE, Minneapolis, MN 55455-0341, USA.
| | - Timothy B Boone
- Department of Urology, Houston Methodist Hospital and Research Institute, 6565 Fannin St, Suite 2100, Houston, TX 77030-2703, USA.
| | - Yingchun Zhang
- Department of Biomedical Engineering, University of Houston, 360 HBS Building, 4811 Calhoun Rd., Houston, TX 77004, USA.
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Chanda A, Unnikrishnan V, Richter HE, Lockhart ME. A biofidelic computational model of the female pelvic system to understand effect of bladder fill and progressive vaginal tissue stiffening due to prolapse on anterior vaginal wall. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2016; 32:e02767. [PMID: 26732347 DOI: 10.1002/cnm.2767] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 12/23/2015] [Accepted: 12/27/2015] [Indexed: 06/05/2023]
Abstract
Treatment of anterior vaginal prolapse (AVP), suffered by over 500,000 women in the USA, is a challenge in urogynecology because of the poorly understood mechanics of AVP. Recently, computational modeling combined with finite element method has been used to model AVP through the study of pelvic floor muscle and connective tissue impairments on the anterior vaginal wall (AVW). Also, the effects of pelvic organ displacements on the AVW were studied numerically. In our current work, an MRI-based full-scale biofidelic computational model of the female pelvic system composed of the urinary bladder, vaginal canal, and the uterus was developed, and a novel finite element method framework was employed to simulate vaginal tissue stiffening and also bladder filling due to expansion for the first time. A mesh convergence study was conducted to choose a computationally efficient mesh, and a non-linear hyperelastic Yeoh's material model was adopted for the study. The AVW displacements, mechanical stresses, and strains were estimated at varying degrees of bladder fills and vaginal tissue stiffening. Both bladder filling and vaginal stiffening were found to increase the stress concentration on the AVW with varying trends, which have been discussed in detail in the paper. To our knowledge, this study is the first to estimate the individual and combined effects of bladder filling and vaginal tissue stiffening due to prolapse on the AVW. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Arnab Chanda
- Department of Aerospace Engineering and Mechanics, University of Alabama, Tuscaloosa, 35487, AL, USA
| | - Vinu Unnikrishnan
- Department of Aerospace Engineering and Mechanics, University of Alabama, Tuscaloosa, 35487, AL, USA.
| | - Holly E Richter
- Division of Urogynecology and Pelvic Reconstructive Surgery, Department of Obstetrics and Gynecology, University of Alabama at Birmingham, 1720 2nd Ave S, Birmingham, AL, 35233, USA
| | - Mark E Lockhart
- Department of Radiology, University of Alabama at Birmingham, 1720 2nd Ave S, Birmingham, AL, 35233, USA
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Peng Y, Khavari R, Nakib NA, Boone TB, Zhang Y. Assessment of urethral support using MRI-derived computational modeling of the female pelvis. Int Urogynecol J 2016; 27:205-12. [PMID: 26224383 PMCID: PMC5519823 DOI: 10.1007/s00192-015-2804-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2015] [Accepted: 07/13/2015] [Indexed: 01/03/2023]
Abstract
INTRODUCTION AND HYPOTHESIS This study aimed to assess the role of individual anatomical structures and their combinations to urethral support function. METHODS A realistic pelvic model was developed from an asymptomatic female patient's magnetic resonance (MR) images for dynamic biomechanical analysis using the finite element method. Validation was performed by comparing simulation results with dynamic MR imaging observations. Weaknesses of anatomical support structures were simulated by reducing their material stiffness. Urethral mobility was quantified by examining urethral axis excursion from rest to the final state (intra-abdominal pressure = 100 cmH2O). Seven individual support structures and five of their combinations were studied. RESULT Among seven urethral support structures, we found that weakening the vaginal walls, puborectalis muscle, and pubococcygeus muscle generated the top three largest urethral excursion angles. A linear relationship was found between urethral axis excursions and intra-abdominal pressure. Weakening all three levator ani components together caused a larger weakening effect than the sum of each individually weakened component, indicating a nonlinearly additive pattern. The pelvic floor responded to different weakening conditions distinctly: weakening the vaginal wall developed urethral mobility through the collapsed vaginal canal, while weakening the levator ani showed a more uniform pelvic floor deformation. CONCLUSIONS The computational modeling and dynamic biomechanical analysis provides a powerful tool to better understand the dynamics of the female pelvis under pressure events. The vaginal walls, puborectalis, and pubococcygeus are the most important individual structures in providing urethral support. The levator ani muscle group provides urethral support in a well-coordinated way with a nonlinearly additive pattern.
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Affiliation(s)
- Yun Peng
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, 2027 SERC Building, 3605 Cullen Blvd, Houston, TX, 77024, USA
| | - Rose Khavari
- Department of Urology, Houston Methodist Hospital and Research Institute, Houston, TX, 77030, USA
| | - Nissrine A Nakib
- Department of Urology, University of Minnesota, Minneapolis, MN, USA
| | - Timothy B Boone
- Department of Urology, Houston Methodist Hospital and Research Institute, Houston, TX, 77030, USA
| | - Yingchun Zhang
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, 2027 SERC Building, 3605 Cullen Blvd, Houston, TX, 77024, USA.
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Peng Y, Khavari R, Nakib NA, Stewart JN, Boone TB, Zhang Y. The Single-Incision Sling to Treat Female Stress Urinary Incontinence: A Dynamic Computational Study of Outcomes and Risk Factors. J Biomech Eng 2015; 137:2389888. [PMID: 26142123 DOI: 10.1115/1.4030978] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Indexed: 12/16/2022]
Abstract
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.
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Boubaker MB, Haboussi M, Ganghoffer JF, Aletti P. Predictive model of the prostate motion in the context of radiotherapy: A biomechanical approach relying on urodynamic data and mechanical testing. J Mech Behav Biomed Mater 2015; 49:30-42. [PMID: 25974099 DOI: 10.1016/j.jmbbm.2015.04.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Revised: 04/13/2015] [Accepted: 04/16/2015] [Indexed: 11/16/2022]
Abstract
In this paper, a biomechanical approach relying on urodynamic data and mechanical tests is proposed for an accurate prediction of the motion of the pelvic organs in the context of the prostate radiotherapy. As a first step, an experimental protocol is elaborated to characterize the mechanical properties of the bladder and rectum wall tissues; uniaxial tensile tests are performed on porcine substrates. In a second step, the parameters of Ogden-type hyperelastic constitutive models are identified; their relevance in the context of the implementation of a human biomechanical model is verified by means of preliminary Finite Elements (FE) simulations against human urodynamic data. In a third step, the identified constitutive equations are employed for the simulations of the motion and interactions of the pelvic organs due to concomitant changes of the distension volumes of the urinary bladder and rectum. The effectiveness of the developed biomechanical model is demonstrated in investigating the motion of the bladder, rectum and prostate organs; the results in terms of displacements are shown to be in good agreement with measurements inherent to a deceased person, with a relative error close to 6%.
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Affiliation(s)
| | - Mohamed Haboussi
- L.S.P.M., U.P.R., C.N.R.S. 3407 Université Paris 13, 99, av. J-B. Clément, 93430 Villetaneuse, France
| | - Jean-François Ganghoffer
- L.E.M.T.A., Université de Lorraine, C.N.R.S., 2 avenue de la forêt de Haye, TSA 60604, 54518 Vandoeuvre CEDEX, France.
| | - Pierre Aletti
- Centre Alexis Vautrin, C.R.A.N., I.N.P.L., C.N.R.S. 54500 Vandoeuvre Cedex, France
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