@article{WegmannHacklStaatetal.2016, author = {Wegmann, Kilian and Hackl, Michael and Staat, Manfred and Mayer, Katharina and M{\"u}ller, Lars-Peter}, title = {Double plate osteosynthesis of proximal ulna fractures: biomechanical and clinical results}, series = {Knee surgery, sports traumatology, arthroscopy}, volume = {Volume 24}, journal = {Knee surgery, sports traumatology, arthroscopy}, number = {Supplement 1}, publisher = {Springer}, address = {Berlin}, issn = {0942-2056}, doi = {10.1007/s00167-016-4079-0}, pages = {58 -- 59}, year = {2016}, abstract = {While plate fixation of proximal ulna fractures might lead to superior clinical results compared to tension band wiring, regular plates represent an established risk factor for wound complications. The olecranon double plates (Medartis, Basel, CH) might decrease complications related to the osteosynthesis because of their low profile and better anatomical fit. This study aimed to evaluate the biomechanical performance and clinical results of the olecranon double plates.}, language = {en} } @article{HacklLeschingerStaatetal.2016, author = {Hackl, Michael and Leschinger, T. and Staat, Manfred and M{\"u}ller, Lars-Peter and Wegmann, Kilian}, title = {Reconstruction of the interosseous membrane in the Essex Lopresti lesion — a biomechanical evaluation}, series = {Knee surgery, sports traumatology, arthroscopy}, volume = {Volume 24}, journal = {Knee surgery, sports traumatology, arthroscopy}, number = {Supplement 1}, publisher = {Springer}, address = {Berlin}, issn = {0942-2056}, doi = {10.1007/s00167-016-4080-7}, pages = {130 -- 131}, year = {2016}, abstract = {Surgical reconstruction of the interosseous membrane (IOM) could restore longitudinal forearm stability to avoid persisting disability due to capituloradial and ulnocarpal impingement in Essex Lopresti lesions. This biomechanical study aimed to assess longitudinal forearm stability of intact specimens, after sectioning of the IOM and after reconstruction with a TightRope construct using either a single or double bundle technique.}, language = {en} } @article{HacklKahmannWegmannetal.2016, author = {Hackl, Michael and Kahmann, Stephanie Lucina and Wegmann, Kilian and Ries, Christian and Staat, Manfred and M{\"u}ller, Lars-Peter}, title = {Shortening osteotomy of the proximal radius — a treatment option for isolated osteoarthritis of the lateral column of the elbow joint?}, series = {Knee surgery, sports traumatology, arthroscopy}, volume = {Volume 24}, journal = {Knee surgery, sports traumatology, arthroscopy}, number = {Supplement 1}, publisher = {Springer}, address = {Berlin}, issn = {0942-2056}, doi = {10.1007/s00167-016-4080-7}, pages = {128 -- 129}, year = {2016}, abstract = {Treatment of posttraumatic osteoarthritis of the radial column of the elbow joint remains a challenging yet common issue. While partial joint replacement leads to high revision rates, radial head excision has shown to severely increase joint instability. Shortening osteotomy of the radius could be an option to decrease the contact pressure of the radiohumeral joint and thereby pain levels without causing valgus instability. Hence, the aim of this biomechanical study was to evaluate the effects of radial shortening on axial load distribution and valgus stability of the elbow joint.}, language = {en} } @article{HacklMuellerStaatetal.2016, author = {Hackl, Michael and M{\"u}ller, Lars-Peter and Staat, Manfred and Kahmann, Stephanie Lucina and Wegmann, Kilian}, title = {Proximal phalangeal neck fractures of the hand — a biomechanical comparison of three fixation techniques}, series = {Knee surgery, sports traumatology, arthroscopy}, volume = {Volume 24}, journal = {Knee surgery, sports traumatology, arthroscopy}, number = {Supplement 1}, publisher = {Springer}, address = {Berlin}, issn = {0942-2056}, doi = {10.1007/s00167-016-4080-7}, pages = {148 -- 149}, year = {2016}, abstract = {Plate osteosynthesis of displaced proximal phalangeal neck fractures of the hand allows early mobilization due to a stable internal fixation. Nevertheless, joint stiffness—because of soft tissue irritation—represents a common complication leading to high complication rates. Del Pinal et al. recently reported promising clinical results for a new, minimally invasive fixation technique with a cannulated headless intramedullary compression screw. Hence, the aim of this study was to compare plate fixation of proximal phalangeal neck fractures to less two less invasive techniques: Crossed k-wire fixation and intramedullary screw fixation. We hypothesized that these fixation techniques provide inferior stability when compared to plate osteosynthesis.}, language = {en} } @article{FrotscherMuanghongDursunetal.2016, author = {Frotscher, Ralf and Muanghong, Danita and Dursun, G{\"o}zde and Goßmann, Matthias and Temiz Artmann, Ayseg{\"u}l and Staat, Manfred}, title = {Sample-specific adaption of an improved electro-mechanical model of in vitro cardiac tissue}, series = {Journal of Biomechanics}, volume = {49}, journal = {Journal of Biomechanics}, number = {12}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0021-9290 (Print)}, doi = {10.1016/j.jbiomech.2016.01.039}, pages = {2428 -- 2435}, year = {2016}, abstract = {We present an electromechanically coupled computational model for the investigation of a thin cardiac tissue construct consisting of human-induced pluripotent stem cell-derived atrial, ventricular and sinoatrial cardiomyocytes. The mechanical and electrophysiological parts of the finite element model, as well as their coupling are explained in detail. The model is implemented in the open source finite element code Code_Aster and is employed for the simulation of a thin circular membrane deflected by a monolayer of autonomously beating, circular, thin cardiac tissue. Two cardio-active drugs, S-Bay K8644 and veratridine, are applied in experiments and simulations and are investigated with respect to their chronotropic effects on the tissue. These results demonstrate the potential of coupled micro- and macroscopic electromechanical models of cardiac tissue to be adapted to experimental results at the cellular level. Further model improvements are discussed taking into account experimentally measurable quantities that can easily be extracted from the obtained experimental results. The goal is to estimate the potential to adapt the presented model to sample specific cell cultures.}, language = {en} } @article{GossmannFrotscherLinderetal.2016, author = {Goßmann, Matthias and Frotscher, Ralf and Linder, Peter and Bayer, Robin and Epple, U. and Staat, Manfred and Temiz Artmann, Ayseg{\"u}l and Artmann, Gerhard}, title = {Mechano-pharmacological characterization of cardiomyocytes derived from human induced pluripotent stem cells}, series = {Cellular physiology and biochemistry}, volume = {38}, journal = {Cellular physiology and biochemistry}, number = {3}, publisher = {Karger}, address = {Basel}, issn = {1421-9778 (Online)}, doi = {10.1159/000443124}, pages = {1182 -- 1198}, year = {2016}, abstract = {Background/Aims: Common systems for the quantification of cellular contraction rely on animal-based models, complex experimental setups or indirect approaches. The herein presented CellDrum technology for testing mechanical tension of cellular monolayers and thin tissue constructs has the potential to scale-up mechanical testing towards medium-throughput analyses. Using hiPS-Cardiac Myocytes (hiPS-CMs) it represents a new perspective of drug testing and brings us closer to personalized drug medication. Methods: In the present study, monolayers of self-beating hiPS-CMs were grown on ultra-thin circular silicone membranes and deflect under the weight of the culture medium. Rhythmic contractions of the hiPS-CMs induced variations of the membrane deflection. The recorded contraction-relaxation-cycles were analyzed with respect to their amplitudes, durations, time integrals and frequencies. Besides unstimulated force and tensile stress, we investigated the effects of agonists and antagonists acting on Ca²⁺ channels (S-Bay K8644/verapamil) and Na⁺ channels (veratridine/lidocaine). Results: The measured data and simulations for pharmacologically unstimulated contraction resembled findings in native human heart tissue, while the pharmacological dose-response curves were highly accurate and consistent with reference data. Conclusion: We conclude that the combination of the CellDrum with hiPS-CMs offers a fast, facile and precise system for pharmacological, toxicological studies and offers new preclinical basic research potential.}, language = {en} } @article{DuongNguyenStaat2015, author = {Duong, Minh Tuan and Nguyen, Nhu Huynh and Staat, Manfred}, title = {Physical response of hyperelastic models for composite materials and soft tissues}, series = {Asia pacific journal on computational engineering}, volume = {2}, journal = {Asia pacific journal on computational engineering}, number = {3 (December 2015)}, issn = {2196-1166}, doi = {10.1186/s40540-015-0015-x}, pages = {1 -- 18}, year = {2015}, language = {en} } @article{DuongNguyenTranetal.2015, author = {Duong, Minh Tuan and Nguyen, Nhu Huynh and Tran, Thanh Ngoc and Tolba, R. H. and Staat, Manfred}, title = {Influence of refrigerated storage on tensile mechanical properties of porcine liver and spleen}, series = {International biomechanics}, volume = {Vol. 2}, journal = {International biomechanics}, number = {Iss. 1}, publisher = {Taylor \& Francis}, address = {London}, issn = {2333-5432}, doi = {10.1080/23335432.2015.1049295}, pages = {79 -- 88}, year = {2015}, language = {en} } @article{FrotscherKochStaat2015, author = {Frotscher, Ralf and Koch, Jan-Peter and Staat, Manfred}, title = {Computational investigation of drug action on human-induced stem cell derived cardiomyocytes}, series = {Journal of biomechanical engineering}, volume = {Vol. 137}, journal = {Journal of biomechanical engineering}, number = {iss. 7}, publisher = {ASME}, address = {New York}, issn = {1528-8951 (E-Journal); 0148-0731 (Print)}, doi = {10.1115/1.4030173}, pages = {071002-1 -- 071002-7}, year = {2015}, language = {en} } @article{FrotscherStaat2014, author = {Frotscher, Ralf and Staat, Manfred}, title = {Stresses produced by different textile mesh implants in a tissue equivalent}, series = {BioNanoMaterials}, volume = {15}, journal = {BioNanoMaterials}, number = {1-2}, publisher = {De Gruyter}, address = {Berlin}, issn = {2191-4672 (E-Journal); 2193-066X (E-Journal); 0011-8656 (Print); 1616-0177 (Print); 2193-0651 (Print)}, doi = {10.1515/bnm-2014-0003}, pages = {25 -- 30}, year = {2014}, abstract = {Two single-incision mini-slings used for treating urinary incontinence in women are compared with respect to the stresses they produce in their surrounding tissue. In an earlier paper we experimentally observed that these implants produce considerably different stress distributions in a muscle tissue equivalent. Here we perform 2D finite element analyses to compare the shear stresses and normal stresses in the tissue equivalent for the two meshes and to investigate their failure behavior. The results clearly show that the Gynecare TVT fails for increasing loads in a zipper-like manner because it gradually debonds from the surrounding tissue. Contrary to that, the tissue at the ends of the DynaMesh-SIS direct may rupture but only at higher loads. The simulation results are in good agreement with the experimental observations thus the computational model helps to interpret the experimental results and provides a tool for qualitative evaluation of mesh implants.}, language = {en} } @article{CiobanuStaatRahimi2008, author = {Ciobanu, Octavian and Staat, Manfred and Rahimi, Alireza}, title = {The use of open source software in biomechanical finite element analysis}, series = {Buletinul Institutului Politehnic din Ia{\c{s}}i / Universitatea Tehnică Gh. Asachi, Ia{\c{s}}i Secţia 5, Construcţii de ma{\c{s}}ini = Machine construction = Bulletin of the Polytechnic Institute of Jassy = Izvestija Jasskogo Politechničeskogo Instituta}, volume = {54}, journal = {Buletinul Institutului Politehnic din Ia{\c{s}}i / Universitatea Tehnică Gh. Asachi, Ia{\c{s}}i Secţia 5, Construcţii de ma{\c{s}}ini = Machine construction = Bulletin of the Polytechnic Institute of Jassy = Izvestija Jasskogo Politechničeskogo Instituta}, number = {7/8}, issn = {1011-2855}, pages = {213 -- 220}, year = {2008}, language = {en} } @article{PhamStaat2014, author = {Pham, Phu Tinh and Staat, Manfred}, title = {FEM-based shakedown analysis of hardening structures}, series = {Asia Pacific journal on computational engineering}, journal = {Asia Pacific journal on computational engineering}, number = {1}, publisher = {SpringerOpen}, address = {Berlin}, issn = {2196-1166 (E-Journal)}, doi = {10.1186/2196-1166-1-4}, pages = {Article No. 4}, year = {2014}, abstract = {This paper develops a new finite element method (FEM)-based upper bound algorithm for limit and shakedown analysis of hardening structures by a direct plasticity method. The hardening model is a simple two-surface model of plasticity with a fixed bounding surface. The initial yield surface can translate inside the bounding surface, and it is bounded by one of the two equivalent conditions: (1) it always stays inside the bounding surface or (2) its centre cannot move outside the back-stress surface. The algorithm gives an effective tool to analyze the problems with a very high number of degree of freedom. Our numerical results are very close to the analytical solutions and numerical solutions in literature.}, language = {en} } @article{AndingTabazaStaatetal.2013, author = {Anding, Ralf and Tabaza, Ruth and Staat, Manfred and Trenz, Eva and Lohmann, Philipp and Klinge, Uwe and Kirschner-Hermanns, Ruth}, title = {Introducing a method of in vitro testing of different anchoring systems used for female incontinence and prolapse surgery}, series = {BioMed research international}, volume = {Vol. 2013}, journal = {BioMed research international}, issn = {1110-7251 (E-Journal); 2314-6141 (E-Journal); 1110-7243 (Print); 2314-6133 (Print)}, pages = {Article ID 401417}, year = {2013}, language = {en} } @article{JungStaatMueller2013, author = {Jung, Alexander and Staat, Manfred and M{\"u}ller, Wolfram}, title = {Flight style optimization in ski jumping on normal, large, and ski flying hills}, series = {Journal of biomechanics}, volume = {Vol. 47}, journal = {Journal of biomechanics}, number = {Iss. 3}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1873-2380 (E-Journal); 0021-9290 (Print)}, pages = {716 -- 722}, year = {2013}, language = {en} } @article{Staat2013, author = {Staat, Manfred}, title = {Limit and shakedown analysis under uncertainty}, series = {International journal of computational methods : IJCM}, journal = {International journal of computational methods : IJCM}, publisher = {World Scientific Publishing}, address = {Singapore}, issn = {0219-8762}, pages = {Publ. online}, year = {2013}, language = {en} } @article{HasanKeilStaatetal.2012, author = {Hasan, Istabrak and Keil, Ludger and Staat, Manfred and Wahl, Gerhard and Bourauel, Christoph}, title = {Determination of the frictional coefficient of the implant-antler interface : experimental approach}, series = {Biomedical Engineering / Biomedizinische Technik}, volume = {57}, journal = {Biomedical Engineering / Biomedizinische Technik}, number = {5}, publisher = {De Gruyter}, address = {Berlin}, issn = {1862-278X}, pages = {359 -- 363}, year = {2012}, abstract = {The similar bone structure of reindeer antler to human bone permits studying the osseointegration of dental implants in the jawbone. As the friction is one of the major factors that have a significant influence on the initial stability of immediately loaded dental implants, it is essential to define the frictional coefficient of the implant-antler interface. In this study, the kinetic frictional forces at the implant-antler interface were measured experimentally using an optomechanical setup and a stepping motor controller under different axial loads and sliding velocities. The corresponding mean values of the static and kinetic frictional coefficients were within the range of 0.5-0.7 and 0.3-0.5, respectively. An increase in the frictional forces with increasing applied axial loads was registered. The measurements showed an evidence of a decrease in the magnitude of the frictional coefficient with increasing sliding velocity. The results of this study provide a considerable assessment to clarify the suitable frictional coefficient to be used in the finite element contact analysis of antler specimens.}, language = {en} } @article{TranStaat2013, author = {Tran, Thanh Ngoc and Staat, Manfred}, title = {An Edge-Based Smoothed Finite Element Method for Primal-Dual Shakedown Analysis of Structures Under Uncertainties}, series = {Limit State of Materials and Structures : Direct Methods 2. Saxc{\´e}, G{\´e}ry de (Hrsg.)}, journal = {Limit State of Materials and Structures : Direct Methods 2. Saxc{\´e}, G{\´e}ry de (Hrsg.)}, publisher = {Springer}, address = {Dordrecht}, isbn = {978-94-007-5424-9}, pages = {89 -- 102}, year = {2013}, language = {en} } @article{PhamStaat2013, author = {Pham, Phu Tinh and Staat, Manfred}, title = {An Upper Bound Algorithm for Limit and Shakedown Analysis of Bounded Linearly Kinematic Hardening Structures}, series = {Limit State of Materials and Structures : Direct Methods 2. Saxc{\´e}, G{\´e}ry de (Hrsg.)}, journal = {Limit State of Materials and Structures : Direct Methods 2. Saxc{\´e}, G{\´e}ry de (Hrsg.)}, publisher = {Springer}, address = {Dordrecht}, isbn = {978-94-007-5424-9}, pages = {71 -- 87}, year = {2013}, language = {en} } @article{NovacekTranKlingeetal.2012, author = {Novacek, V. and Tran, Thanh Ngoc and Klinge, U. and Tolba, R. H. and Staat, Manfred and Bronson, D. G. and Miesse, A. M. and Whiffen, J. and Turquier, F.}, title = {Finite element modelling of stapled colorectal end-to-end anastomosis : Advantages of variable height stapler design}, series = {Journal of Biomechanics}, volume = {45}, journal = {Journal of Biomechanics}, number = {115}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1873-2380}, doi = {10.1016/j.jbiomech.2012.07.021}, pages = {2693 -- 2697}, year = {2012}, abstract = {The impact of surgical staplers on tissues has been studied mostly in an empirical manner. In this paper, finite element method was used to clarify the mechanics of tissue stapling and associated phenomena. Various stapling modalities and several designs of circular staplers were investigated to evaluate the impact of the device on tissues and mechanical performance of the end-to-end colorectal anastomosis. Numerical simulations demonstrated that a single row of staples is not adequate to resist leakage due to non-linear buckling and opening of the tissue layers between two adjacent staples. Compared to the single staple row configuration, significant increase in stress experienced by the tissue at the inner staple rows was observed in two and three rows designs. On the other hand, adding second and/or third staple row had no effect on strain in the tissue inside the staples. Variable height design with higher staples in outer rows significantly reduced the stresses and strains in outer rows when compared to the same configuration with flat cartridge.}, language = {en} } @article{NguyenDuongTranetal.2012, author = {Nguyen, Nhu Huynh and Duong, Minh Tuan and Tran, Thanh Ngoc and Pham, Phu Tinh and Grottke, O. and Tolba, R. and Staat, Manfred}, title = {Influence of a freeze-thaw cycle on the stress-stretch curves of tissues of porcine abdominal organs}, series = {Journal of Biomechanics}, volume = {45}, journal = {Journal of Biomechanics}, number = {14}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1873-2380}, doi = {10.1016/j.jbiomech.2012.07.008}, pages = {2382 -- 2386}, year = {2012}, abstract = {The paper investigates both fresh porcine spleen and liver and the possible decomposition of these organs under a freeze-thaw cycle. The effect of tissue preservation condition is an important factor which should be taken into account for protracted biomechanical tests. In this work, tension tests were conducted for a large number of tissue specimens from twenty pigs divided into two groups of 10. Concretely, the first group was tested in fresh state; the other one was tested after a freeze-thaw cycle which simulates the conservation conditions before biomechanical experiments. A modified Fung model for isotropic behavior was adopted for the curve fitting of each kind of tissues. Experimental results show strong effects of the realistic freeze-thaw cycle on the capsule of elastin-rich spleen but negligible effects on the liver which virtually contains no elastin. This different behavior could be explained by the autolysis of elastin by elastolytic enzymes during the warmer period after thawing. Realistic biomechanical properties of elastin-rich organs can only be expected if really fresh tissue is tested. The observations are supported by tests of intestines.}, language = {en} }