@inproceedings{BhattaraiFrotscherSoraetal.2014, author = {Bhattarai, Aroj and Frotscher, Ralf and Sora, M.-C. and Staat, Manfred}, title = {A 3D finite element model of the female pelvic floor for the reconstruction of urinary incontinence}, series = {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}, booktitle = {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}, editor = {Onate, E.}, organization = {World Congress on Computational Mechanics <11, 2014, Barcelona>}, pages = {1 -- 12}, year = {2014}, language = {en} } @article{BhattaraiStaat2019, author = {Bhattarai, Aroj and Staat, Manfred}, title = {A computational study of organ relocation after laparoscopic pectopexy to repair posthysterectomy vaginal vault prolapse}, series = {Computer Methods in Biomechanics and Biomedical Engineering: Imaging \& Visualization}, journal = {Computer Methods in Biomechanics and Biomedical Engineering: Imaging \& Visualization}, publisher = {Taylor \& Francis}, address = {London}, issn = {2168-1171}, doi = {10.1080/21681163.2019.1670095}, year = {2019}, language = {en} } @inproceedings{JabbariBhattaraiAndingetal.2017, author = {Jabbari, Medisa and Bhattarai, Aroj and Anding, Ralf and Staat, Manfred}, title = {Biomechanical simulation of different prosthetic meshes for repairing uterine/vaginal vault prolapse}, series = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West}, booktitle = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West}, editor = {Erni, Daniel and Fischerauer, Alice and Himmel, J{\"o}rg and Seeger, Thomas and Thelen, Klaus}, publisher = {Universit{\"a}t Duisburg-Essen}, address = {Duisburg}, organization = {MedTech Symposium}, isbn = {978-3-9814801-9-1}, doi = {10.17185/duepublico/43984}, pages = {118 -- 119}, year = {2017}, language = {en} } @inproceedings{BhattaraiFrotscherStaat2015, author = {Bhattarai, Aroj and Frotscher, Ralf and Staat, Manfred}, title = {Biomechanical study of the female pelvic floor dysfunction using the finite element method}, series = {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}, booktitle = {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}, publisher = {RWTH Aachen University}, address = {Aachen}, organization = {ECCOMAS Young Investigators Conference <3, 2015, Aachen>}, pages = {1 -- 4}, year = {2015}, language = {en} } @incollection{BhattaraiFrotscherStaat2018, author = {Bhattarai, Aroj and Frotscher, Ralf and Staat, Manfred}, title = {Computational Analysis of Pelvic Floor Dysfunction}, series = {Women's Health and Biomechanics}, booktitle = {Women's Health and Biomechanics}, publisher = {Springer}, address = {Cham}, isbn = {978-3-319-71574-2}, doi = {10.1007/978-3-319-71574-2_17}, pages = {217 -- 230}, year = {2018}, abstract = {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.}, language = {en} } @article{BhattaraiStaat2018, author = {Bhattarai, Aroj and Staat, Manfred}, title = {Computational comparison of different textile implants to correct apical prolapse in females}, series = {Current Directions in Biomedical Engineering}, volume = {4}, journal = {Current Directions in Biomedical Engineering}, number = {1}, publisher = {De Gruyter}, address = {Berlin}, doi = {10.1515/cdbme-2018-0159}, pages = {661 -- 664}, year = {2018}, abstract = {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.}, language = {en} } @phdthesis{Bhattarai2018, author = {Bhattarai, Aroj}, title = {Constitutive modeling of female pelvic floor dysfunctions and reconstructive surgeries using prosthetic mesh implants}, isbn = {978-3-9818074-8-6}, doi = {10.17185/duepublico/70340}, pages = {192 S.}, year = {2018}, language = {en} } @inproceedings{BhattaraiStaat2016, author = {Bhattarai, Aroj and Staat, Manfred}, title = {Female pelvic floor dysfunction: progress weakening of the support system}, series = {1st YRA MedTech Symposium 2016 : April 8th / 2016 / University of Duisburg-Essen}, booktitle = {1st YRA MedTech Symposium 2016 : April 8th / 2016 / University of Duisburg-Essen}, editor = {Erni, Daniel}, publisher = {Universit{\"a}t Duisburg-Essen}, address = {Duisburg}, organization = {MedTech Symposium}, doi = {10.17185/duepublico/40821}, pages = {11 -- 12}, year = {2016}, abstract = {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.}, language = {en} } @article{BhattaraiMayStaatetal.2022, author = {Bhattarai, Aroj and May, Charlotte Anabell and Staat, Manfred and Kowalczyk, Wojciech and Tran, Thanh Ngoc}, title = {Layer-specific damage modeling of porcine large intestine under biaxial tension}, series = {Bioengineering}, volume = {9}, journal = {Bioengineering}, number = {10, Early Access}, publisher = {MDPI}, address = {Basel}, issn = {2306-5354}, doi = {10.3390/bioengineering9100528}, pages = {1 -- 17}, year = {2022}, abstract = {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.}, language = {en} } @incollection{BhattaraiStaat2018, author = {Bhattarai, Aroj and Staat, Manfred}, title = {Mechanics of soft tissue reactions to textile mesh implants}, series = {Biological, Physical and Technical Basics of Cell Engineering}, booktitle = {Biological, Physical and Technical Basics of Cell Engineering}, editor = {Artmann, Gerhard and Temiz Artmann, Ayseg{\"u}l and Zhubanova, Azhar A. and Digel, Ilya}, publisher = {Springer}, address = {Singapore}, isbn = {978-981-10-7904-7}, doi = {10.1007/978-981-10-7904-7_11}, pages = {251 -- 275}, year = {2018}, abstract = {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.}, language = {en} }