Dokument-ID Dokumenttyp Verfasser/Autoren Herausgeber Haupttitel Abstract Auflage Verlagsort Verlag Erscheinungsjahr Seitenzahl Schriftenreihe Titel Schriftenreihe Bandzahl ISBN Quelle der Hochschulschrift Konferenzname Bemerkung Quelle:Titel Quelle:Jahrgang Quelle:Heftnummer Quelle:Erste Seite Quelle:Letzte Seite URN DOI Zugriffsart Link Abteilungen OPUS4-6507 Konferenzveröffentlichung Bhattarai, Aroj, bhattarai@fh-aachen.de; Frotscher, Ralf, frotscher@fh-aachen.de; Sora, M.-C., ; Staat, Manfred, m.staat@fh-aachen.de Onate, E. A 3D finite element model of the female pelvic floor for the reconstruction of urinary incontinence 2014 11 11th World Congress on Computational Mechanics (WCCM XI) ; 5th European Conference on Computational Mechanics (ECCM V) ; 6th European Conference on Computational Fluid Dynamics (ECFD VI) ; July 20-25, 2014, Barcelona 1 12 Fachbereich Medizintechnik und Technomathematik OPUS4-7301 Konferenzveröffentlichung Bhattarai, Aroj, bhattarai@fh-aachen.de; Frotscher, Ralf, frotscher@fh-aachen.de; Staat, Manfred, m.staat@fh-aachen.de Biomechanical study of the female pelvic floor dysfunction using the finite element method Aachen RWTH Aachen University 2015 3 Conference proceedings of the YIC GACM 2015 : 3rd ECCOMAS Young Investigators Conference and 6th GACM Colloquium on Computational Mechanics , Aachen , Germany, 20.07.2015 - 23.07.2015 / ed.: Stefanie Elgeti ; Jaan-Willem Simon 1 4 weltweit http://nbn-resolving.de/urn:nbn:de:hbz:82-rwth-2015-039806 Fachbereich Medizintechnik und Technomathematik OPUS4-7733 Konferenzveröffentlichung Bhattarai, Aroj, bhattarai@fh-aachen.de; Staat, Manfred, m.staat@fh-aachen.de Erni, Daniel Female pelvic floor dysfunction: progress weakening of the support system The structure of the female pelvic floor (PF) is an inter-related system of bony pelvis,muscles, pelvic organs, fascias, ligaments, and nerves with multiple functions. Mechanically, thepelvic organ support system are of two types: (I) supporting system of the levator ani (LA) muscle,and (II) the suspension system of the endopelvic fascia condensation [1], [2]. Significantdenervation injury to the pelvic musculature, depolimerization of the collagen fibrils of the softvaginal hammock, cervical ring and ligaments during pregnancy and vaginal delivery weakens thenormal functions of the pelvic floor. Pelvic organ prolapse, incontinence, sexual dysfunction aresome of the dysfunctions which increases progressively with age and menopause due toweakened support system according to the Integral theory [3]. An improved 3D finite elementmodel of the female pelvic floor as shown in Fig. 1 is constructed that: (I) considers the realisticsupport of the organs to the pelvic side walls, (II) employs the improvement of our previous FEmodel [4], [5] along with the patient based geometries, (III) incorporates the realistic anatomy andboundary conditions of the endopelvic (pubocervical and rectovaginal) fascia, and (IV) considersvarying stiffness of the endopelvic fascia in the craniocaudal direction [3]. Several computationsare carried out on the presented computational model with healthy and damaged supportingtissues, and comparisons are made to understand the physiopathology of the female PF disorders. Duisburg Universität Duisburg-Essen 2016 1 1st YRA MedTech Symposium 2016 : April 8th / 2016 / University of Duisburg-Essen 11 12 10.17185/duepublico/40821 weltweit https://doi.org/10.17185/duepublico/40821 Fachbereich Medizintechnik und Technomathematik OPUS4-7841 Konferenzveröffentlichung Bhattarai, Aroj, bhattarai@fh-aachen.de; Frotscher, Ralf, Frotscher@fh-aachen.de; Staat, Manfred, m.staat@fh-aachen.de Natal Jorge, Renato Significance of fibre geometry on passive-active response of pelvic muscles to evaluate pelvic dysfunction Boca Raton CRC Press 2016 3 BioMedWomen: Proceedings of the international conference on clinical and bioengineering for women's health 978-1-138-02910-1 185 188 Fachbereich Medizintechnik und Technomathematik OPUS4-8076 Konferenzveröffentlichung Jabbari, Medisa, ; Bhattarai, Aroj, ; Anding, Ralf, ; Staat, Manfred, m.staat@fh-aachen.de Erni, Daniel; Fischerauer, Alice; Himmel, Jörg; Seeger, Thomas; Thelen, Klaus Biomechanical simulation of different prosthetic meshes for repairing uterine/vaginal vault prolapse Duisburg Universität Duisburg-Essen 2017 1 2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West 978-3-9814801-9-1 A young researchers track of the 7th IEEE Workshop & SENSORICA 2017 118 119 10.17185/duepublico/43984 weltweit https://doi.org/10.17185/duepublico/43984 Fachbereich Medizintechnik und Technomathematik OPUS4-8293 Wissenschaftlicher Artikel Bhattarai, Aroj, bhattarai@fh-aachen.de; Jabbari, Medisa, ; Anding, Ralf, ; Staat, Manfred, m.staat@fh-aachen.de Surgical treatment of vaginal vault prolapse using different prosthetic mesh implants: a finite element analysis Particularly multiparous elderly women may suffer from vaginal vault prolapse after hysterectomy due to weak support from lax apical ligaments. A decreased amount of estrogen and progesterone in older age is assumed to remodel the collagen thereby reducing tissue stiffness. Sacrocolpopexy is either performed as open or laparoscopic surgery using prosthetic mesh implants to substitute lax ligaments. Y-shaped mesh models (DynaMesh, Gynemesh, and Ultrapro) are implanted in a 3D female pelvic floor finite element model in the extraperitoneal space from the vaginal cuff to the first sacral (S1) bone below promontory. Numerical simulations are conducted during Valsalva maneuver with weakened tissues modeled by reduced tissue stiffness. Tissues are modeled as incompressible, isotropic hyperelastic materials whereas the meshes are modeled either as orthotropic linear elastic or as isotropic hyperlastic materials. The positions of the vaginal cuff and the bladder base are calculated from the pubococcygeal line for female pelvic floor at rest, for prolapse and after repair using the three meshes. Due to mesh mechanics and mesh pore deformation along the loaded direction, the DynaMesh with regular rectangular mesh pores is found to provide better mechanical support to the organs than the Gynemesh and the Ultrapro with irregular hexagonal mesh pores. Insbesondere ältere, mehrgebährende Frauen leiden häufiger an einem Scheidenvorfall nach einer Hysterektomie aufgrund der schwachen Unterstützung durch laxe apikale Bänder. Es wird angenommen, dass eine verringerte Menge an Östrogen und Progesteron im höheren Alter das Kollagen umformt, wodurch die Gewebesteifigkeit reduziert wird. Die Sakrokolpopexie ist eine offene oder laparoskopische Operation, die mit prothetischen Netzimplantaten durchgeführt wird, um laxe Bänder zu ersetzen. Y-förmige Netzmodelle (DynaMesh, Gynemesh und Ultrapro) werden in einem 3D-Modell des weiblichen Beckenbodens im extraperitonealen Raum vom Vaginalstumpf bis zum Promontorium implantiert. Numerische Simulationen werden während des Valsalva-Manövers mit geschwächtem Gewebe durchgeführt, das durch eine reduzierte Gewebesteifigkeit modelliert wird. Die Gewebe werden als inkompressible, isotrop hyperelastische Materialien modelliert, während die Netze entweder als orthotrope linear elastische oder als isotrope hyperlastische Materialien modelliert werden. Die Positionen des Vaginalstumpfs, der Blase und der Harnröhrenachse werden anhand der Pubococcygeallinie aus der Ruhelage, für den Prolaps und nach der Reparatur unter Verwendung der drei Netze berechnet. Aufgrund der Netzmechanik und der Netzporenverformung bietet das DynaMesh mit regelmäßigen rechteckigen Netzporen eine bessere mechanische Unterstützung und eine Neupositionierung des Scheidengewölbes, der Blase und der Urethraachse als Gynemesh und Ultrapro mit unregelmäßigen hexagonalen Netzporen. Berlin De Gruyter 2018 11 tm - Technisches Messen 85 5 331 342 10.1515/teme-2017-0115 campus https://doi.org/10.1515/teme-2017-0115 Fachbereich Medizintechnik und Technomathematik OPUS4-8255 Teil eines Buches Bhattarai, Aroj, bhattarai@fh-aachen.de; Frotscher, Ralf, frotscher@fh-aachen.de; Staat, Manfred, m.staat@fh-aachen.de Computational Analysis of Pelvic Floor Dysfunction Pelvic floor dysfunction (PFD) is characterized by the failure of the levator ani (LA) muscle to maintain the pelvic hiatus, resulting in the descent of the pelvic organs below the pubococcygeal line. This chapter adopts the modified Humphrey material model to consider the effect of the muscle fiber on passive stretching of the LA muscle. The deformation of the LA muscle subjected to intra-abdominal pressure during Valsalva maneuver is compared with the magnetic resonance imaging (MRI) examination of a nulliparous female. Numerical result shows that the fiber-based Humphrey model simulates the muscle behavior better than isotropic constitutive models. Greater posterior movement of the LA muscle widens the levator hiatus due to lack of support from the anococcygeal ligament and the perineal structure as a consequence of birth-related injury and aging. Old and multiparous females with uncontrolled urogenital and rectal hiatus tend to develop PFDs such as prolapse and incontinence. Cham Springer 2018 13 Women's Health and Biomechanics 978-3-319-71574-2 Lecture Notes in Computational Vision and Biomechanics, vol 29 217 230 10.1007/978-3-319-71574-2_17 campus http://doi.org/10.1007/978-3-319-71574-2_17 Fachbereich Medizintechnik und Technomathematik OPUS4-8257 Wissenschaftlicher Artikel Bhattarai, Aroj, bhattarai@fh-aachen.de; Staat, Manfred, m.staat@fh-aachen.de Modelling of Soft Connective Tissues to Investigate Female Pelvic Floor Dysfunctions 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. New York, NY Hindawi 2018 15 Computational and Mathematical Methods in Medicine 2018 Article ID 9518076 1 16 10.1155/2018/9518076 weltweit http://doi.org/10.1155/2018/9518076 Fachbereich Medizintechnik und Technomathematik OPUS4-8362 Teil eines Buches Bhattarai, Aroj, bhattarai@fh-aachen.de; Staat, Manfred, m.staat@fh-aachen.de Artmann, Gerhard; Temiz Artmann, Aysegül; Zhubanova, Azhar A.; Digel, Ilya Mechanics of soft tissue reactions to textile mesh implants For pelvic floor disorders that cannot be treated with non-surgical procedures, minimally invasive surgery has become a more frequent and safer repair procedure. More than 20 million prosthetic meshes are implanted each year worldwide. The simple selection of a single synthetic mesh construction for any level and type of pelvic floor dysfunctions without adopting the design to specific requirements increase the risks for mesh related complications. Adverse events are closely related to chronic foreign body reaction, with enhanced formation of scar tissue around the surgical meshes, manifested as pain, mesh erosion in adjacent structures (with organ tissue cut), mesh shrinkage, mesh rejection and eventually recurrence. Such events, especially scar formation depend on effective porosity of the mesh, which decreases discontinuously at a critical stretch when pore areas decrease making the surgical reconstruction ineffective that further augments the re-operation costs. The extent of fibrotic reaction is increased with higher amount of foreign body material, larger surface, small pore size or with inadequate textile elasticity. Standardized studies of different meshes are essential to evaluate influencing factors for the failure and success of the reconstruction. Measurements of elasticity and tensile strength have to consider the mesh anisotropy as result of the textile structure. An appropriate mesh then should show some integration with limited scar reaction and preserved pores that are filled with local fat tissue. This chapter reviews various tissue reactions to different monofilament mesh implants that are used for incontinence and hernia repairs and study their mechanical behavior. This helps to predict the functional and biological outcomes after tissue reinforcement with meshes and permits further optimization of the meshes for the specific indications to improve the success of the surgical treatment. Singapore Springer 2018 24 Biological, Physical and Technical Basics of Cell Engineering 978-981-10-7904-7 251 275 10.1007/978-981-10-7904-7_11 campus https://doi.org/10.1007/978-981-10-7904-7_11 Fachbereich Medizintechnik und Technomathematik OPUS4-8354 Konferenzveröffentlichung Bhattarai, Aroj, bhattarai@fh-aachen.de; Staat, Manfred, m.staat@fh-aachen.de Fernandes, P.R.; Tavares, J. M. Pectopexy to repair vaginal vault prolapse: a finite element approach The vaginal prolapse after hysterectomy (removal of the uterus) is often associated with the prolapse of the vaginal vault, rectum, bladder, urethra or small bowel. Minimally invasive surgery such as laparoscopic sacrocolpopexy and pectopexy are widely performed for the treatment of the vaginal prolapse with weakly supported vaginal vault after hysterectomy using prosthetic mesh implants to support (or strengthen) lax apical ligaments. Implants of different shape, size and polymers are selected depending on the patient's anatomy and the surgeon's preference. In this computational study on pectopexy, DynaMesh®-PRP soft, GYNECARE GYNEMESH® PS Nonabsorbable PROLENE® soft and Ultrapro® are tested in a 3D finite element model of the female pelvic floor. The mesh model is implanted into the extraperitoneal space and sutured to the vaginal stump with a bilateral fixation to the iliopectineal ligament at both sides. Numerical simulations are conducted at rest, after surgery and during Valsalva maneuver with weakened tissues modeled by reduced tissue stiffness. Tissues and prosthetic meshes are modeled as incompressible, isotropic hyperelastic materials. The positions of the organs are calculated with respect to the pubococcygeal line (PCL) for female pelvic floor at rest, after repair and during Valsalva maneuver using the three meshes. 2018 Proceedings CMBBE 2018 15th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering and 3rd Conference on Imaging and Visualization. CMBBE 2018. 26-29 March 2018, Lisbon, Portugal weltweit http://cmbbe2018.tecnico.ulisboa.pt/pen_cmbbe2018/pdf/WEB_PAPERS/CMBBE2018_paper_148.pdf Fachbereich Medizintechnik und Technomathematik OPUS4-8456 Wissenschaftlicher Artikel Bhattarai, Aroj, bhattarai@fh-aachen.de; Staat, Manfred, m.staat@fh-aachen.de Computational comparison of different textile implants to correct apical prolapse in females Prosthetic textile implants of different shapes, sizes and polymers are used to correct the apical prolapse after hysterectomy (removal of the uterus). The selection of the implant before or during minimally invasive surgery depends on the patient's anatomical defect, intended function after reconstruction and most importantly the surgeon's preference. Weakness or damage of the supporting tissues during childbirth, menopause or previous pelvic surgeries may put females in higher risk of prolapse. Numerical simulations of reconstructed pelvic floor with weakened tissues and organ supported by textile product models: DynaMesh®-PRS soft, DynaMesh®-PRP soft and DynaMesh®-CESA from FEG Textiletechnik mbH, Germany are compared. Berlin De Gruyter 2018 3 Current Directions in Biomedical Engineering 4 1 661 664 10.1515/cdbme-2018-0159 bezahl https://doi.org/10.1515/cdbme-2018-0159 Fachbereich Medizintechnik und Technomathematik OPUS4-8849 Bericht Bhattarai, Aroj, bhattarai@fh-aachen.de; Frotscher, Ralf, Frotscher@fh-aachen.de; Durong, Minh Tuán, ; Staat, Manfred, m.staat@fh-aachen.de Schlussbericht zu BINGO. Optimierung des Systems Netzimplantat-Beckenboden zur therapeutischen Gewebeverstärkung nach der Integraltheorie. Aachen 2016 34 Förderkennzeichen BMBF 03FH073PX2 weltweit https://edocs.tib.eu/files/e01fb17/881343862.pdf Fachbereich Medizintechnik und Technomathematik OPUS4-9077 Dissertation Bhattarai, Aroj, bhattarai@fh-aachen.de Constitutive modeling of female pelvic floor dysfunctions and reconstructive surgeries using prosthetic mesh implants 2018 192 S. 978-3-9818074-8-6 Duisburg-Essen, Univ., Diss., 2018 10.17185/duepublico/70340 weltweit https://doi.org/10.17185/duepublico/70340 Fachbereich Medizintechnik und Technomathematik OPUS4-9947 Wissenschaftlicher Artikel Bhattarai, Aroj, ; Horbach, Andreas, horbach@fh-aachen.de; Staat, Manfred, m.staat@fh-aachen.de; Kowalczyk, Wojciech, ; Tran, Thanh Ngoc, tran@fh-aachen.de Virgin passive colon biomechanics and a literature review of active contraction constitutive models The objective of this paper is to present our findings on the biomechanical aspects of the virgin passive anisotropic hyperelasticity of the porcine colon based on equibiaxial tensile experiments. Firstly, the characterization of the intestine tissues is discussed for a nearly incompressible hyperelastic fiber-reinforced Holzapfel-Gasser-Ogden constitutive model in virgin passive loading conditions. The stability of the evaluated material parameters is checked for the polyconvexity of the adopted strain energy function using positive eigenvalue constraints of the Hessian matrix with MATLAB. The constitutive material description of the intestine with two collagen fibers in the submucosal and muscular layer each has been implemented in the FORTRAN platform of the commercial finite element software LS-DYNA, and two equibiaxial tensile simulations are presented to validate the results with the optical strain images obtained from the experiments. Furthermore, this paper also reviews the existing models of the active smooth muscle cells, but these models have not been computationally studied here. The review part shows that the constitutive models originally developed for the active contraction of skeletal muscle based on Hill's three-element model, Murphy's four-state cross-bridge chemical kinetic model and Huxley's sliding-filament hypothesis, which are mainly used for arteries, are appropriate for numerical contraction numerical analysis of the large intestine. Basel MDPI 2022 19 Biomechanics 2 2 138 157 10.3390/biomechanics2020013 weltweit https://doi.org/10.3390/biomechanics2020013 Fachbereich Medizintechnik und Technomathematik OPUS4-9042 Wissenschaftlicher Artikel Bhattarai, Aroj, bhattarai@fh-aachen.de; Staat, Manfred, m.staat@fh-aachen.de A computational study of organ relocation after laparoscopic pectopexy to repair posthysterectomy vaginal vault prolapse London Taylor & Francis 2019 Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization 10.1080/21681163.2019.1670095 bezahl https://doi.org/10.1080/21681163.2019.1670095 Fachbereich Medizintechnik und Technomathematik OPUS4-10231 Wissenschaftlicher Artikel Bhattarai, Aroj, ; May, Charlotte Anabell, ; Staat, Manfred, m.staat@fh-aachen.de; Kowalczyk, Wojciech, ; Tran, Thanh Ngoc, Layer-specific damage modeling of porcine large intestine under biaxial tension The mechanical behavior of the large intestine beyond the ultimate stress has never been investigated. Stretching beyond the ultimate stress may drastically impair the tissue microstructure, which consequently weakens its healthy state functions of absorption, temporary storage, and transportation for defecation. Due to closely similar microstructure and function with humans, biaxial tensile experiments on the porcine large intestine have been performed in this study. In this paper, we report hyperelastic characterization of the large intestine based on experiments in 102 specimens. We also report the theoretical analysis of the experimental results, including an exponential damage evolution function. The fracture energies and the threshold stresses are set as damage material parameters for the longitudinal muscular, the circumferential muscular and the submucosal collagenous layers. A biaxial tensile simulation of a linear brick element has been performed to validate the applicability of the estimated material parameters. The model successfully simulates the biomechanical response of the large intestine under physiological and non-physiological loads. Basel MDPI 2022 16 Bioengineering 9 Der Artikel gehört zum Sonderheft "Computational Biomechanics" 10, Early Access 1 17 10.3390/bioengineering9100528 weltweit https://doi.org/10.3390/bioengineering9100528 Fachbereich Medizintechnik und Technomathematik