TY - CHAP A1 - Weber, Tim A1 - Renkawitz, Tobias A1 - Bulstra, Sjoerd K. A1 - Grifka, Joachim A1 - Verkerke, Gijsbertus Jacob A1 - Dendorfer, Sebastian T1 - Biomechanics of computer-assisted vs. conventional THR after one year follow up T2 - XXV Congress of the International Society of Biomechanics, Glasgow, UK, 12th-16th July 2015 Y1 - 2015 ER - TY - CHAP A1 - Ignasiak, Dominika A1 - Dendorfer, Sebastian A1 - Ferguson, Stephen J. T1 - Thoracolumbar spine model with articulated rigcage for the prediction of dynamic spinal loading T2 - International Workshop on Spine Loading and Deformation: From Loading to Recovery, 2-4 July 2015, Julius Wolff Institute, Charité-Universitatsmedizin Berlin, Germany Y1 - 2015 ER - TY - CHAP A1 - Weber, Tim A1 - Dendorfer, Sebastian A1 - Bulstra, Sjoerd K. A1 - Grifka, Joachim A1 - Verkerke, Gijsbertus Jacob A1 - Renkawitz, Tim T1 - Navigated Femur First Total Hip Arthroplasty leads to improved Biomechanical Outcome after surgery T2 - ORS annual meeting, Las Vegas, USA, 2015 Y1 - 2015 ER - TY - CHAP A1 - Billing, A. A1 - Götz, J. A1 - Weber, Tim A1 - Dendorfer, Sebastian T1 - Positionsanalyse von winkelstabilen Plattenosteosynthesesystemen zur Versorgung von Metatarsalfrakturen mit Hilfe von patientenspezifischen biomechanischen Modellen T2 - Vereinigung Süddeutscher Orthopäden und Unfallchirurgen Jahrestagung 2015, Baden-Baden, Germany Y1 - 2015 ER - TY - CHAP A1 - Weber, Tim A1 - Stezowski, P. A1 - Dullien, Silvia A1 - Putzer, Michael A1 - Dendorfer, Sebastian T1 - Eine biomechanische Bewertung verschiedener Belastungsszenarien nach Implantierung einer Hüft-Totalendoprothese T2 - GAMMA Workshop, Hannover, 2012 Y1 - 2012 ER - TY - CHAP A1 - Süß, Franz A1 - Kubowitsch, Simone A1 - Verkerke, Gijsbertus Jacob A1 - Dendorfer, Sebastian T1 - Investigation of cognitive stress induced changes in spinal disc forces due to altered kinematics and muscle activity T2 - World Congress Biomechanics, Dublin, 2018 Y1 - 2018 ER - TY - CHAP A1 - Spreiter, G. A1 - Galibarov, Pavel E. A1 - Dendorfer, Sebastian A1 - Ferguson, Stephen J. T1 - Influence of kyphosis on spinal loading T2 - 10th International Symposium Computer Methods in Biomechanics and Biomedical Engineering (CMBBE) Meeting, 11. - 14. April 2012, Berlin Y1 - 2012 ER - TY - CHAP A1 - Putzer, Michael A1 - Dendorfer, Sebastian T1 - Sensitivity of lumbar spine loading to anatomical parameters T2 - International Workshop on Spine Loading and Deformation: From Loading to Recovery, 2-4 July 2015, Julius Wolff Institute, Charité-Universitatsmedizin Berlin, Germany Y1 - 2015 ER - TY - CHAP A1 - Kubowitsch, Simone A1 - Dendorfer, Sebastian T1 - Psychologie und Biomechanik – Integrierte Betrachtung von Muskelrekrutierung BT - Erkenntnisse und Ableitungen für Biofeedback T2 - Jahrestagung der Deutschen Gesellschaft für Biofeedback e. V., Regensburg, 2018 Y1 - 2018 ER - TY - GEN A1 - Auer, Simon A1 - Reinker, Lukas A1 - Dendorfer, Sebastian T1 - Evaluation of muscle recruitment and muscle models in musculoskeletal simulation of dynamic motion T2 - 26th Congress of the European Society of Biomechanics, July 11-14, 2021, Milan, Italy N2 - Musculoskeletal simulation plays an increasingly important role in sports biomechanics. In the last years, the field of application widened from orthopaedics and ergonomics to sports [1]. A muscle recruitment algorithm with a quadratic objective function is usually used to calculate muscle activity in dynamic movements. The agreement of calculated and measured thigh muscle activity has already been investigated [2]. They found a strong agreement for sprinting and running, while the correlation decreased for side-cutting manoeuvres. Nevertheless, the influence of different muscle recruitment criteria on muscle activity in dynamic musculoskeletal simulations is currently unknown. Hence, this study aimed to analyse the effect of different muscle recruitment criteria and muscle models on the correlation of numerical and measured muscle activity in highly dynamic movements. KW - esb KW - biomechanics KW - muscle recruitment Y1 - 2021 UR - https://esbiomech.org/conference/archive/2021milan/Contribution_1719.pdf CY - Milan ER - TY - JOUR A1 - Visscher, Rosa A1 - Wyss, C. A1 - Singh, Navrag B. A1 - Taylor, William R. A1 - Dendorfer, Sebastian A1 - Rutz, E. A1 - Brunner, Reinald T1 - Influence of TAL-TATS surgery on energy production of Tricepts Surae - A musculoskeletal modeling evaluation JF - Gait & Posture Y1 - 2020 U6 - https://doi.org/10.1016/j.gaitpost.2020.08.090 VL - 81 IS - Suppl. 1 SP - 381 EP - 382 PB - Elsevier ER - TY - CHAP A1 - Penzkofer, Rainer A1 - Grechenig, S. A1 - Kujat, Richard A1 - Angele, Peter A1 - Dendorfer, Sebastian T1 - Biomechanical comparison of the dorsal femur condyles and the iliac crest in terms of failure behavior T2 - XXV Congress of the International Society of Biomechanics, Glasgow, UK, 12th-16th July 2015 Y1 - 2015 ER - TY - CHAP A1 - Striegl, B. A1 - Kujat, Richard A1 - Dendorfer, Sebastian T1 - Quantitative analysis of cartilage surface by confocal laser scanning microscopy T2 - Biomedizinische Technik Y1 - 2014 U6 - https://doi.org/10.1515/bmt-2014-4012 VL - 59 IS - s1-A SP - 24 ER - TY - CHAP A1 - Weber, Tim A1 - Dendorfer, Sebastian A1 - Bulstra, Sjoerd K. A1 - Verkerke, Gijsbertus Jacob A1 - Renkawitz, Tobias T1 - Musculoskeletal modeling for orthopedic surgery – Applications and chances T2 - Orthopedics meets Engineering, Regensburg, 2015 Y1 - 2015 ER - TY - CHAP A1 - Putzer, Michael A1 - Weber, Tim A1 - Dendorfer, Sebastian T1 - Design studies on hip prosthesis using patient specific data T2 - Simpleware Users meeting, November 9th 2011, Bristol, UK Y1 - 2011 ER - TY - CHAP A1 - Süß, Franz A1 - Putzer, Michael A1 - Dendorfer, Sebastian T1 - Numerische und experimentelle Untersuchungen an der Wirbelsäule T2 - Forschungssymposium Bad Abbach, Germany, 2015 Y1 - 2015 ER - TY - CHAP A1 - Dendorfer, Sebastian T1 - Mechanobiology – Impact on regeneration and degradation T2 - Translations in Regenerative Medicine, TIRM and FIFA Symposium, Regensburg, 2015 Y1 - 2015 ER - TY - CHAP A1 - Englert, Carsten A1 - Müller, F. A1 - Dendorfer, Sebastian T1 - Einfluss der Muskelkräfte, des Bewegungsausmaßes und der Bruchform auf die Kraftübertragung des Implantat-Knochenverbundes am Beispiel der Claviculafraktur im mittleren Drittel T2 - 17. Jahreskongress der Deutschen Vereinigung für Schulter- und Ellenbogenchirurgie (DVSE), Rosenheim 2010 N2 - Fragestellung Es soll in dieser Computersimulationsstudie untersucht werden, wie der Osteosyntheseverbund Platte mit Schrauben im Verbund mit einer im mittleren Drittel gebrochenen Clavicula durch das Bewegungsausmaß in vivo belastet ist. Was sind die grundlegenden Kräfte die auf Clavicula und Implantat wirken und welchen Einfl uss hat die Bruchform. Methodik Die Muskel- und Gelenkkräfte sowie die Belastung des Implantatverbundes wurden mit einer muskuloskelletalen Simulationssoftware (AnyBody Technology, V.4) berechnet. Hierfür wurden mit einem komplexen Model des menschlichen Körpers folgende Bewegungen analysiert: eine Flexion von 160° und Abduktion 160° mit einem Gewicht von 2 kg in der Hand. Aus CT-Patientendaten wurden zwei dreidimensionale Modelle des Clavicula-Implantat Verbundes gebildet, die sich in der Frakturform unterscheiden (Querfraktur und vertikale Fraktur). In beiden Modellen wurde eine Claviculaosteosynthese in superiorer Position mit einer 6 Loch LCP mit 2 Schrauben pro Hauptfragment verwendet. Die Materialeigenschaften wurden aus der Dichte des Materials sowie aus Literaturdaten verwendet. Die Muskel- und Gelenkkräfte aus der muskuloskelletalen Berechnung wurden auf das Finite Elemente Modell übertragen und die Spannungen und Dehnungen des Implantat-Knochenverbundes wurden berechnet. Ergebnisse Es zeigte sich, dass die simulierte in vivo Belastung stark abhängig vom Flexionswinkel ist. Das Implantat ist in der superioren Lage auf Biegung belastet, welche maximale Werte im Überschulterniveau erreicht. Die Bruchform mit anatomischer Reposition und Kontakt der Hauptfragmente zueinander führt zu einer deutlichen Entlastung des Osteosyntheseverbundes im Vergleich zu einer Bruchform mit vertikaler Fraktur. Schlussfolgerung Aus den Analysen ist eine Positionierung der Plattenosteosynthese für die im mittleren Drittel frakturierte Clavicula in anterior-superiorer Lage wünschenswert. Die anatomische Reposition entlastet den Osteosyntheseverbund und sollte möglichst erreicht werden. Die Nachbehandlung sollte ein Bewegungsausmaß für den Arm für 4 Wochen für einfache Bruchformen auf 70° Flexion und Abduktion limitieren und für komplexe Bruchformen diese Limitierung ausgedehnt werden. Y1 - 2010 ER - TY - JOUR A1 - Auer, Simon A1 - Krutsch, Werner A1 - Renkawitz, Tobias A1 - Kubowitsch, Simone A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Kognitiver Stress führt zu unphysiologisch erhöhten Kniebelastungen im Profifußball JF - Sports Orthopaedics and Traumatology Y1 - 2020 U6 - https://doi.org/10.1016/j.orthtr.2020.04.122 VL - 36 IS - 2 SP - 202 EP - 203 PB - Elsevier ER - TY - CHAP A1 - Andersen, Michael Skipper A1 - de Zee, Mark A1 - Dendorfer, Sebastian A1 - MacWilliams, Bruce A1 - Rasmussen, John T1 - Validation of a detailed lower extremity model based on the Klein Horsman data set T2 - Proceedings of the 12th International Symposium on Computer Simulation in Biomechanics (ISB 2009), July 2nd - 4th 2009, Cape Town, South Africa Y1 - 2009 SP - 27 EP - 28 ER - TY - CHAP A1 - Dendorfer, Sebastian A1 - Rasmussen, John A1 - Christensen, Soeren Toerholm A1 - Robie, Bruce T1 - The Effect of Spinal Disc Herniation on Multifidus Muscles T2 - 56th Orthopaedic Research Society Meeting, New Orleans, USA, 2010 Y1 - 2010 UR - https://www.ors.org/Transactions/56/1487.pdf ER - TY - GEN A1 - Suess, Franz A1 - Melzner, Maximilian A1 - Dendorfer, Sebastian T1 - Towards Ergonomic working - machine learning algorithms and musculoskeletal modeling T2 - RIM 2021, 13th International Scientific Conference on Manufacturing Engineering, 29 Sept. - 1 Oct 2021, Sarajevo, Bosnia and Herzegovina Y1 - 2021 ER - TY - CHAP A1 - Hammer, Joachim A1 - Dendorfer, Sebastian T1 - Cyclic loading and microstructure of cancellous bone T2 - Journal of Biomechanics Y1 - 2008 U6 - https://doi.org/10.1016/S0021-9290(08)70409-3 VL - 41 IS - Suppl. 1, July 2008 SP - S410 ER - TY - CHAP A1 - Robie, Bruce A1 - Rasmussen, John A1 - Christensen, Soeren Toerholm A1 - Dendorfer, Sebastian T1 - Herniation Induces 55% Increase in Load of Key Stabilizing Muscle – Impact on Herniation Treatment Devices? T2 - Spine Arthoplasty Society Meeting, New Orleans, 2010 Y1 - 2010 ER - TY - CHAP A1 - Dendorfer, Sebastian T1 - How much iron to pump? The determination of muscle forces for activities of daily living T2 - DGU, Berlin, 2008 Y1 - 2008 ER - TY - CHAP A1 - Dendorfer, Sebastian T1 - Biomechanical evaluation and optimisation of countermeasure exercises T2 - ESA/ESTEC Bedrest Strategy Workshop, Noordwijk, NL, 2009 Y1 - 2009 ER - TY - CHAP A1 - Dendorfer, Sebastian A1 - Carbes, S. A1 - Rasmussen, John T1 - The influence of muscle forces on biomechanical fracture fixation simulations – from in-vivo forces to tissue strains T2 - World Congress on Medical Physics and Biomedical Engineering, 7 - 12, 2009, Munich Y1 - 2009 ER - TY - CHAP A1 - Dendorfer, Sebastian A1 - Rasmussen, John T1 - The influence of in-vivo muscle forces on the stress distribution in a vertebral body during activities of daily living T2 - Eurospine Warsaw, Poland 2009 Y1 - 2009 ER - TY - CHAP A1 - Dendorfer, Sebastian A1 - Englert, Carsten T1 - Forces on a clavicles midshaft fracture and influence of fracture type T2 - AO Symposium, Regensburg, 2009 Y1 - 2009 ER - TY - JOUR A1 - Wiesent, Lisa A1 - Schultheiß, Ulrich A1 - Lulla, Philipp A1 - Noster, Ulf A1 - Schratzenstaller, Thomas A1 - Schmid, Christof A1 - Nonn, Aida A1 - Spear, Ashley T1 - Computational analysis of the effects of geometric irregularities and post-processing steps on the mechanical behavior of additively manufactured 316L stainless steel stents JF - PLoS ONE N2 - Advances in additive manufacturing enable the production of tailored lattice structures and thus, in principle, coronary stents. This study investigates the effects of process-related irregularities, heat and surface treatment on the morphology, mechanical response, and expansion behavior of 316L stainless steel stents produced by laser powder bed fusion and provides a methodological approach for their numerical evaluation. A combined experimental and computational framework is used, based on both actual and computationally reconstructed laser powder bed fused stents. Process-related morphological deviations between the as-designed and actual laser powder bed fused stents were observed, resulting in a diameter increase by a factor of 2-2.6 for the stents without surface treatment and 1.3-2 for the electropolished stent compared to the as-designed stent. Thus, due to the increased geometrically induced stiffness, the laser powder bed fused stents in the as-built (7.11 ± 0.63 N) or the heat treated condition (5.87 ± 0.49 N) showed increased radial forces when compressed between two plates. After electropolishing, the heat treated stents exhibited radial forces (2.38 ± 0.23 N) comparable to conventional metallic stents. The laser powder bed fused stents were further affected by the size effect, resulting in a reduced yield strength by 41% in the as-built and by 59% in the heat treated condition compared to the bulk material obtained from tensile tests. The presented numerical approach was successful in predicting the macroscopic mechanical response of the stents under compression. During deformation, increased stiffness and local stress concentration were observed within the laser powder bed fused stents. Subsequent numerical expansion analysis of the derived stent models within a previously verified numerical model of stent expansion showed that electropolished and heat treated laser powder bed fused stents can exhibit comparable expansion behavior to conventional stents. The findings from this work motivate future experimental/numerical studies to quantify threshold values of critical geometric irregularities, which could be used to establish design guidelines for laser powder bed fused stents/lattice structures. KW - Heat treatment KW - Lasers KW - Surface treatments KW - Specimen preparation and treatment KW - Material properties KW - Stiffness KW - Deformation KW - Powders KW - Koronarendoprothese KW - Rapid prototyping KW - Numerische Methode Y1 - 2020 U6 - https://doi.org/10.1371/journal.pone.0244463 N1 - Corresponding author: Lisa Wiesent VL - 15 IS - 12 SP - 1 EP - 30 PB - PLOS ER - TY - JOUR A1 - Wessely, Rainer A1 - Hausleiter, Jörg A1 - Michaelis, Cornelia A1 - Jaschke, Birgit A1 - Vogeser, Michael A1 - Milz, Stefan A1 - Behnisch, Boris A1 - Schratzenstaller, Thomas A1 - Renke-Gluszko, Magdalena A1 - Stöver, Michael A1 - Wintermantel, Erich A1 - Kastrati, Adnan A1 - Schömig, Albert T1 - Inhibition of neointima formation by a novel drug-eluting stent system that allows for dose-adjustable, multiple, and on-site stent coating JF - Arteriosclerosis, Thrombosis, and Vascular Biology N2 - Objective The risk of in-stent restenosis can be considerably reduced by stents eluting cytostatic compounds. We created a novel drug-eluting stent system that includes several new features in the rapidly evolving field of stent-based drug delivery. Methods and Results The aim of the present study was the preclinical evaluation of a stent-coating system permitting individual, on-site coating of stents with a unique microporous surface allowing for individualizable, dose-adjustable, and multiple coatings with identical or various compounds, designated ISAR (individualizable drug-eluting stent system to abrogate restenosis). Stents were coated with 0.75% rapamycin solution, and high-performance liquid chromatography (HPLC)-based determination of drug release profile indicated drug release for >21 days. Rapamycin-eluting microporous (REMP) stents implanted in porcine coronary arteries were safe. To determine the efficacy of REMP stents, this novel drug-eluting stent platform was compared with the standard sirolimus-eluting stent. At 30 days, in-stent neointima formation in porcine coronary arteries was similar in both groups, yielding a significant decrease of neointimal area and injury-dependent neointimal thickness compared with bare-metal stents. Conclusion The ISAR drug-eluting stent platform as a novel concept for stent coating allows for a safe, effective, on-site stent coating process, thus justifying further clinical evaluation to decrease in-stent restenosis in humans. In-stent neointima formation can be successfully attenuated by drug-eluting stents. We introduce a novel conceptual approach for stent-coating that allows for dose-adjustable, on-site stent coating process if desired with multiple compounds. Microporous stents coated with rapamycin proved safe and effective for the limitation of neointima formation in a porcine coronary stent model. KW - drug-eluting stent KW - stent platform KW - sirolimus KW - rapamycin Y1 - 2005 U6 - https://doi.org/10.1161/01.ATV.0000157579.52566.ee SN - 1524-4636 VL - 25 IS - 4 SP - 748 EP - 753 ER - TY - JOUR A1 - Wiesent, Lisa A1 - Schultheiss, Ulrich A1 - Schmid, Christof A1 - Schratzenstaller, Thomas A1 - Nonn, Aida T1 - Experimentally validated simulation of coronary stents considering different dogboning ratios and asymmetric stent positioning JF - PlOS One N2 - In-stent restenosis remains a major problem of arteriosclerosis treatment by stenting. Expansion-optimized stents could reduce this problem. With numerical simulations, stent designs/ expansion behaviours can be effectively analyzed. For reasons of efficiency, simplified models of balloon-expandable stents are often used, but their accuracy must be challenged due to insufficient experimental validation. In this work, a realistic stent life-cycle simulation has been performed including balloon folding, stent crimping and free expansion of the balloon-stent-system. The successful simulation and validation of two stent designs with homogenous and heterogeneous stent stiffness and an asymmetrically positioned stent on the balloon catheter confirm the universal applicability of the simulation approach. Dogboning ratio, as well as the final dimensions of the folded balloon, the crimped and expanded stent, correspond well to the experimental dimensions with only slight deviations. In contrast to the detailed stent life-cycle simulation, a displacement-controlled simulation can not predict the transient stent expansion, but is suitable to reproduce the final expanded stent shape and the associated stress states. The detailed stent life-cycle simulation is thus essential for stent expansion analysis/optimization, whereas for reasons of computational efficiency, the displacement-controlled approach can be considered in the context of pure stress analysis. KW - Catheters KW - Coronary stenting KW - Deformation KW - Stent implantation KW - Stiffness KW - Stent KW - Ballondilatation KW - Numerische Strömungssimulation Y1 - 2019 U6 - https://doi.org/10.1371/journal.pone.0224026 VL - 14 IS - 10 SP - 1 EP - 25 PB - PLOS ER - TY - GEN A1 - Kögler, Michael A1 - Ismail, Khaled M. A1 - Rusavy, Zdenek A1 - Kalis, Vladimir A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Influence of bed height and stance on accoucheurs lower back and glenohumeral load during simulated childbirth T2 - 31st meeting of Czech Urogynaecological Society, Prague, 2022 Y1 - 2022 ER - TY - JOUR A1 - Manaranche, Claire A1 - Hornberger, Helga T1 - A proposal for the classification of dental alloys according to their resistance to corrosion JF - Dental Materials N2 - Objectives The purpose of this study was to establish a method to compare and classify dental alloys in relation to their resistance to corrosion. Methods Alloy samples and pure metal samples were prepared and tested in chemical and electrochemical corrosion according to ISO 10271. For electrochemical test, the rest potential versus time and a potentiodynamic scan were recorded. After chemical corrosion test, the ions released were analyzed by ICP (induced coupled plasma) spectroscopy. Results High gold alloys had a similar polarization curve than gold. The same effect was observed for Pd–base alloys, their curves were similar to the one of palladium. The ions released during chemical corrosion were non-precious metallic ions. Thereby Ni–Cr alloys were found to release the most ions. Au–Pt alloys showed the highest release of ions compared with other precious alloys but low compared with Ni–Cr. Electrochemical corrosion was more aggressive than chemical corrosion and every type of elements was etched, the higher the precious metal content, the higher the resistance to corrosion of the alloy. Discussion Using the recorded data, a classification system for electrochemical corrosion was developed and discussed to judge the results. Hereby were gold and zinc used as reference materials. The applied classification system defines five classes and it is proposed that alloys of class V are not acceptable. For chemical corrosion resistance, three classes were distinguished according to the quantity of metallic ions released and it is proposed that class III (100–1000 μg/cm2 week) is not acceptable. Palladium and Pd–base alloys showed a higher electrochemical and chemical corrosion resistance than gold. KW - Dental alloys KW - Precious alloys KW - Corrosion test KW - Resistance to corrosion KW - Classification KW - Ion release Y1 - 2007 U6 - https://doi.org/10.1016/j.dental.2006.11.030 VL - 23 IS - 11 SP - 1428 EP - 1437 ER - TY - JOUR A1 - Dendorfer, Sebastian A1 - Melzner, Maximilian T1 - Rückenschmerzen bei Geburtshelfer:innen. Die Haltung macht's. JF - Deutsche Hebammen-Zeitschrift N2 - Für Mutter und Kind konnte das Risiko der Geburt durch die Weiterentwicklung der Medizin drastisch reduziert werden. Doch wie ist es um das Wohl derer bestellt, die die Gebärende unterstützen? Eine Studie der Ostbayerischen Technischen Hochschule Regensburg hat sich mit den muskuloskelettalen Beschwerden von Geburtshelfer:innen auseinandergesetzt Y1 - 2022 UR - https://ip.staudeverlag.de/de/profiles/c3962f735915-elwin-staude-verlag-kiosk-bc/editions/dhz-11-2022/pages/page/32 SN - 0012-026X VL - 74 IS - 11 SP - 60 EP - 62 PB - Staude CY - Hannover ER - TY - JOUR A1 - Kheiroddin, Parastoo A1 - Schöberl, Patricia A1 - Althammer, Michael A1 - Cibali, Ezgi A1 - Würfel, Thea A1 - Wein, Hannah A1 - Kulawik, Birgit A1 - Buntrock-Döpke, Heike A1 - Weigl, Eva A1 - Gran, Silvia A1 - Gründl, Magdalena A1 - Langguth, Jana A1 - Lampl, Benedikt A1 - Judex, Guido A1 - Niggel, Jakob A1 - Pagel, Philipp A1 - Schratzenstaller, Thomas A1 - Schneider-Brachert, Wulf A1 - Gastiger, Susanne A1 - Bodenschatz, Mona A1 - Konrad, Maike A1 - Levchuk, Artem A1 - Roth, Cornelius A1 - Schöner, David A1 - Schneebauer, Florian A1 - Rohrmanstorfer, René A1 - Burkovski, Andreas A1 - Ambrosch, Andreas A1 - Wagner, Thomas A1 - Kabesch, Michael ED - Buonsenso, Danilo T1 - Results of WICOVIR Gargle Pool PCR Testing in German Schools Based on the First 100,000 Tests JF - Frontiers in Pediatrics N2 - Background: Opening schools and keeping children safe from SARS-CoV-2 infections at the same time is urgently needed to protect children from direct and indirect consequences of the COVID-19 pandemic. To achieve this goal, a safe, efficient, and cost-effective SARS-CoV-2 testing system for schools in addition to standard hygiene measures is necessary. Methods: We implemented the screening WICOVIR concept for schools in the southeast of Germany, which is based on gargling at home, pooling of samples in schools, and assessment of SARS-CoV-2 by pool rRT-PCR, performed decentralized in numerous participating laboratories. Depooling was performed if pools were positive, and results were transmitted with software specifically developed for the project within a day. Here, we report the results after the first 13 weeks in the project. Findings: We developed and implemented the proof-of-concept test system within a pilot phase of 7 weeks based on almost 17,000 participants. After 6 weeks in the main phase of the project, we performed >100,000 tests in total, analyzed in 7,896 pools, identifying 19 cases in >100 participating schools. On average, positive children showed an individual CT value of 31 when identified in the pools. Up to 30 samples were pooled (mean 13) in general, based on school classes and attached school staff. All three participating laboratories detected positive samples reliably with their previously established rRT-PCR standard protocols. When self-administered antigen tests were performed concomitantly in positive cases, only one of these eight tests was positive, and when antigen tests performed after positive pool rRT-PCR results were already known were included, 3 out of 11 truly positive tests were also identified by antigen testing. After 3 weeks of repetitive WICOVIR testing twice weekly, the detection rate of positive children in that cohort decreased significantly from 0.042 to 0.012 (p = 0.008). Interpretation: Repeated gargle pool rRT-PCR testing can be implemented quickly in schools. It is an effective, valid, and well-received test system for schools, superior to antigen tests in sensitivity, acceptance, and costs. KW - children KW - COVID-19 KW - Germany KW - PCR KW - pooling KW - gargle KW - schools KW - pandemic KW - Covid-19 KW - Polymerase-Kettenreaktion KW - Nachweis KW - Schulkind KW - Deutschland Y1 - 2021 U6 - https://doi.org/10.3389/fped.2021.721518 SN - 2296-2360 VL - 9 PB - frontiers ER - TY - JOUR A1 - Geith, Markus A. A1 - Nothdurfter, Laurenz A1 - Heiml, Manuel A1 - Agrafiotis, Emmanouil A1 - Gruber, Markus A1 - Sommer, Gerhard A1 - Schratzenstaller, Thomas A1 - Holzapfel, Gerhard A. T1 - Quantifying stent-induced damage in coronary arteries by investigating mechanical and structural alterations JF - Acta Biomaterialia N2 - Vascular damage develops with diverging severity during and after percutaneous coronary intervention with stent placement and is the prevailing stimulus for in-stent restenosis. Previous work has failed to link mechanical data obtained in a realistic in vivo or in vitro environment with data collected during imaging processes. We investigated whether specimens of porcine right coronary arteries soften when indented with a stent strut shaped structure, and if the softening results from damage mechanisms inside the fibrillar collagen structure. To simulate the multiaxial loading scenario of a stented coronary artery, we developed the testing device ‘LAESIO’ that can measure differences in the stress-stretch behavior of the arterial wall before and after the indentation of a strut-like stamp. The testing protocol was optimized according to preliminary experiments, more specifically equilibrium and relaxation tests. After chemical fixation of the specimens and subsequent tissue clearing, we performed three-dimensional surface and second-harmonic generation scans on the deformed specimens. We analyzed and correlated the mechanical response with structural parameters of high-affected tissue located next to the stamp indentation and low-affected tissue beyond the injured area. The results reveal that damage mechanisms, like tissue compression as well as softening, fiber dispersion, and the lesion extent, are direction-dependent, and the severity of them is linked to the strut orientation, indentation pressure, and position. The findings highlight the need for further investigations by applying the proposed methods to human coronary arteries. Additional data and insights might help to incorporate the observed damage mechanisms into material models for finite element analyses to perform more accurate simulations of stent-implantations. KW - Percutaneous coronary intervention KW - Stent KW - Mechanical properties KW - Damage mechanism KW - Vascular injury KW - Coronary artery KW - Indentation test KW - Softening KW - Second-harmonic generation imaging KW - Micro-structure Y1 - 2020 U6 - https://doi.org/10.1016/j.actbio.2020.08.016 VL - 116 IS - October SP - 285 EP - 301 PB - Elsevier ER - TY - CHAP A1 - Wiesent, Lisa A1 - Geith, Markus A. A1 - Wagner, Marcus T1 - Simulation of Fluid-Structure Interaction between injection medium and balloon catheter using ICFD T2 - 11th European LS-DYNA Conference 2017, 9 - 11 May, Salzburg, Austria N2 - Arteriosclerosis is a major health issue worldwide. While it is commonly treated by the implantation of an balloon-expandable stent, micro injuries may occur during stent deployment, and induce in-stent restenosis, whose consequence can be fatal. Studying this undesirable phenomenon is usually limited as experimental data is hard to obtain on ethical ground. Numerical simulation are performed to better understand this problem. To construct a more realistic simulation of a balloon-expandable stent, a partitioned strongly-coupled FSI simulation of the balloon deployment was set up using the ICFD solver of LS-DYNA, - a quite innovative approach. The complex balloon configuration as well as the interaction of the injection medium and the balloon structure was considered. The balloon structure consisting of shell elements was obtained from preliminary balloon folding and pleating simulations. The balloon consists of a flexible thin walled polyamide. The injection fluid is implemented using volume elements. Balloon deployment was initiated by a pressure boundary condition inducing a volume flow into the balloon. The initial feasibility analysis showed promising result including a continuous balloon deployment and a reasonable development of the fluid pressure and velocity field. However, applying this FSI approach to a more complex balloon structure led to a non convergent solution. The non-convergence could be mainly reduced to mechanical factors including the low wall thickness of the balloon (< 0.05 mm) and the flexibility of the polyamide. Further, the ICFD solver shows less accuracy concerning the FSI conditions when dealing with thin flexible structures as well as enclosed volumes. A shell thickness of 0.06 mm is believed to result in a convergent solution. KW - Koronare Herzkrankheit KW - Stent KW - Ballondilatation KW - Numerische Strömungssimulation Y1 - 2017 UR - https://www.dynalook.com/conferences/11th-european-ls-dyna-conference/icfd-solver-and-fsi/simulation-of-fluid-structure-interaction-between-injection-medium-and-balloon-catheter-using-icfd SN - 978-3981621549 ER - TY - GEN A1 - Wiesent, Lisa A1 - Hupke, Constantin A1 - Balk, Christian A1 - Schultheiss, Ulrich A1 - Schratzenstaller, Thomas T1 - Optimization of the cardiovascular stent design towards improved expansion behaviour and radial stiffness properties T2 - Biomedizinische Technik N2 - - Development of a FEA Tool for a realistic stent simulation - investigation on minor modification on the stent design on the expansion behaviour - analysis of three stent designs: classical stent design with pronounced dogbone effect, two modified stent design (non-dogbone-design) KW - Kardiovaskuläres System KW - Stent Y1 - 2018 U6 - https://doi.org/10.1515/bmt-2018-6031 VL - 63 IS - s1 ER - TY - GEN A1 - Geith, Markus A. A1 - Swidergal, Krzysztof A1 - Schratzenstaller, Thomas A1 - Holzapfel, Gerhard A. A1 - Wagner, Marcus T1 - Numerical analysis of stent delivery systems during pre- and intraoperative processes T2 - 15. Deutsches LS-DYNA Forum, 15.-17.10.2018, Bamberg Y1 - 2018 UR - https://www.researchgate.net/publication/335260823_Numerical_analysis_of_stent_delivery_systems_during_pre-_and_intraoperative_processes ER - TY - JOUR A1 - Geith, Markus A. A1 - Sommer, Gerhard A1 - Schratzenstaller, Thomas A1 - Holzapfel, Gerhard A. T1 - Biomechanical and structural quantification of vascular damage: A unique investigation of stent implantation JF - Artery Research Y1 - 2017 U6 - https://doi.org/10.1016/j.artres.2017.10.025 VL - 20 IS - Issue C SP - 50 ER - TY - JOUR A1 - Wiesent, Lisa A1 - Spear, Ashley A1 - Nonn, Aida T1 - Computational analysis of the effects of geometric irregularities on the interaction of an additively manufactured 316L stainless steel stent and a coronary artery JF - Journal of the Mechanical Behavior of Biomedical Materials N2 - Customized additively manufactured (laser powder bed fused (L-PBF)) stents could improve the treatment of complex lesions by enhancing stent-artery conformity. However, geometric irregularities inherent for L-PBF stents are expected to influence not only their mechanical behavior but also their interaction with the artery. In this study, the influence of geometrical irregularities on stent-artery interaction is evaluated within a numerical framework. Thus, computed arterial stresses induced by a reconstructed L-PBF stent model are compared to those induced by the intended stent model (also representing a stent geometry obtained from conventional manufacturing processes) and a modified CAD stent model that accounts for the increased strut thickness inherent for L-PBF stents. It was found that, similar to conventionally manufactured stents, arterial stresses are initially related to the basic stent design/topology, with the highest stresses occurring at the indentations of the stent struts. Compared to the stent CAD model, the L-PBF stent induces distinctly higher and more maximum volume stresses within the plaque and the arterial wall. In return, the modified CAD model overestimates the arterial stresses induced by the L-PBF stent due to its homogeneously increased strut thickness and thus its homogeneously increased geometric stiffness compared with the L-PBF stent. Therefore, the L-PBF-induced geometric irregularities must be explicitly considered when evaluating the L-PBF stent-induced stresses because the intended stent CAD model underestimates the arterial stresses, whereas the modified CAD model overestimates them. The arterial stresses induced by the L-PBF stent were still within the range of values reported for conventional stents in literature, suggesting that the use of L-PBF stents is conceivable in principle. However, because geometric irregularities, such as protruding features from the stent surface, could potentially damage the artery or lead to premature stent failure, further improvement of L-PBF stents is essential. KW - Laser powder bed fusion (L-PBF) KW - Cardiovascular stents KW - Finite element analysis (FEA) KW - Geometrical imperfections KW - Stent-artery interaction Y1 - 2022 U6 - https://doi.org/10.1016/j.jmbbm.2021.104878 SN - 1751-6161 VL - 125 PB - Elsevier ER - TY - CHAP A1 - Nonn, Aida A1 - Kalwa, Christoph T1 - Application of damage mechanics approach for crack propagation in pipeline T2 - 19th Biennial Joint Technical Meeting (JTM) on Pipeline Research, April 29 - May 3, 2013, Sydney, Australia Y1 - 2013 ER - TY - CHAP A1 - Siegl, Marco A1 - Rieger, David A1 - Kovárík, Tomáš A1 - Ehrlich, Ingo T1 - Long-Term Behavior of Thermoplastics under UV Light tested by a self-build Device T2 - 3. OTH-Clusterkonferenz, 13. April 2018, Weiden, Tagungsband; Festschrift, 5 Jahre OTH-Verbund N2 - This article presents first results of artificial aging experi-ments by ultraviolet (UV) irradiation on thermoplasticmaterials conducted as an intent of the research project Thermoplastic Composite Structures (TheCoS) in colla-boration of the Ostbayerische Technische Hochschule(OTH) Regensburg and the University of West Bohemia(UWB) in Pilsen as part of a cross-border cooperation. In technical applications, thermoplastic materials are oftenaffected by aging and a related deterioration of the mechanical properties. Therefore, it is necessary to identifythe aging behavior of thermoplastic materials. For this,experiments were performed for three thermoplasticmaterials, namely polypropylene (PP), ultra high mole -cular weight polyethylene (UHMWPE) and high impactstrength polystyrene (HIPS). For these experiments, a UV chamber was constructed according to the internationalstandard EN ISO 4892-3 for simulation of exposurebehind window glass. The results are evaluated by testing the flexural strength and the dynamic mechanicalresponse after a selected period of time under UV lightand then compared to untreated test specimens. Y1 - 2018 UR - https://www.oth-regensburg.de/fileadmin/media/forschung/Dateien_2018/Clusterkonferenz-Tagungsband-2018.pdf SP - 118 EP - 122 ER - TY - CHAP A1 - Singh, Max Diamond A1 - Capanni, Felix ED - Pfannstiel Mario A., ED - Da-Cruz, Patrick ED - Rasche, Christoph T1 - Medizintechnik-Spin-offs aus der Hochschule - Ein Prozessbeispiel T2 - Entrepreneurship im Gesundheitswesen II N2 - Die Aufmerksamkeit für Unternehmensgründungen hat in den letzten Jahren extrem zugenommen. Grundsätzlich muss ein Start-up in einem kompetitiven Umfeld erfolgreich sein, um bestehen zu können. Der Weg dorthin wird maßgeblich beeinflusst durch Planung und finanzielle Ressourcen, die die Gründer bereitstellen müssen. In der Medizinprodukteindustrie kommen zusätzlich große Hürden hinzu, die u. a. einen kurzen Produktlebenszyklus, lange Projektlaufzeiten, aufwendige klinische Studien und aktuell neue gesetzliche Verordnungen betreffen. Dieser Beitrag konzentriert sich zunächst auf mögliche Fördermittel und Beratung von Start-up-Projekten aus dem Hochschulbereich. Aus einer Analyse derzeit existierender Gründerwettbewerbe im Hinblick auf das Gesundheitswesen werden dem Leser entsprechende Adressen zum Einwerben von Fördermitteln geliefert. Darüber hinaus wird ein Pilot-Prozess vorgestellt, wie eine Ausgründungsberatung an der Hochschule Ulm im Studiengang Medizintechnik derzeit verläuft. Dies kann möglicherweise ein Anknüpfungspunkt für eine zukünftige Institutionalisierung von Spin-off-Vorhaben aus dem Hochschulbereich sein. Y1 - 2018 SN - 978-3-658-14781-5 SN - 978-3-658-14780-8 PB - Springer Gabler CY - Wiesbaden ER - TY - CHAP A1 - Singh, Max Diamond ED - Schwegel, Philipp ED - Da-Cruz, Patrick ED - Hemel, Ulrich ED - Oberender, Peter T1 - Produktmanagement in der Medizintechnik T2 - Medizinprodukte Management N2 - Das Management in der Medizinprodukteindustrie steht vor vielfältigen Herausforderungen. So sinken einerseits die Produktpreise, anderseits wird auch für die kommenden Jahre in vielen Segmenten ein Mengenwachstum erwartet. Dies stellt die internen Prozesse, vom Customer Service bis hin zur Forschung & Entwicklung, auf den Prüfstand. Die Entscheidungsträger auf Kundenseite verändern sich, weg vom Produktanwender hin zu professionellen Einkaufsgemeinschaften mit immer größerer Verhandlungsmacht. Der hohe Internationalisierungsgrad der Unternehmen führt zu einer steigenden Komplexität bei der Implementierung von Marketing-, Vertriebs- und Produktentwicklungsstrategien auf Länderebene. Darüber hinaus werden zunehmend neue Geschäftsmodelle mit hohem Dienstleistungsanteil entwickelt, die mit der traditionellen Lieferantenrolle wenig zu tun haben und von Managern eine neue Fähigkeiten für die Umsetzung erfordern. Die Autoren des Sammelbands greifen die genannten Herausforderungen auf und bieten mit ihren Beiträgen Lösungsansätze, die sowohl für Manager im Medizinprodukteunternehmen als auch für Wissenschaftler und Studierende relevant sind. Y1 - 2014 SN - 978-3-941678-47-7 SP - 148 EP - 161 PB - PCO-Verlag CY - Bayreuth ER - TY - JOUR A1 - Lazarev, I. A. A1 - Riabokon, P. V. A1 - Haller, M. A1 - Dendorfer, Sebastian T1 - Effect of the Displacement of Calcaneal Bone Peripheral Fragment in its Fracture on the Function of the Three-Headed Calf Muscle JF - TRAUMA N2 - In the structure of musculoskeletal injuries, calcaneal fractures account for up to 4 % of all skeletal fractures and up to 60 % of hindfoot fractures. The effect of the displacement of the peripheral fragment of the calcaneus on the calf muscles’s reaction forces at the time of the adoption of the simplified squatting position was investigated by modeling in AnyBody Modeling System 6.0 software. M.gastrocnemius (lateralis et medialis) in the initial phase of motion in all variants of the peripheral fragment displacement did not develop sufficient muscular effort in comparison to the intact calcaneus. M.soleus medialis et lateralis showed significant increase in muscle activity rates in the initial phase of motion (41.87 ± 1.90 H and 52.07 ± 2.10 H) before reaching its maximum values, as compared with those of the intact calcaneus. In the final phase of the movement, upon muscle reaches its maximum length, muscular strength indicators of the m.soleus returned to their original values or were significantly below them. The decline in muscle strength was due to shortening of the moment arm or muscle excursion in case of convergence of muscle attachment points. When the peripheral fragment is displaced, due to putting down the heel to the surface of the support in terms of anatomical muscle lengthening, it takes extra effort to achieve rest length and its maximum power. In all types of the displacement of the peripheral fragment, the function of three-headed calf muscle is disturbed with involvement of additional muscular effort and energy expenditure. This fact should motivate the surgeon on the need for accurate repositioning of bone fragments in calcaneal fractures with the displacement of the peripheral fragment. Y1 - 2016 U6 - https://doi.org/10.22141/1608-1706.2.16.2015.80247 VL - 16 IS - 2 SP - 20 EP - 24 PB - Zaslavsky ER - TY - JOUR A1 - Dendorfer, Sebastian A1 - Maier, Hans Jürgen A1 - Taylor, David A1 - Hammer, Joachim T1 - Anisotropy of the fatigue behaviour of cancellous bone JF - Journal of Biomechanics N2 - The fatigue behaviour of materials is of particular interest for the failure prediction of materials and structures exposed to cyclic loading. For trabecular bone structures only a few sets of lifetime data have been reported in the literature and structural measures are commonly not considered. The influence of load contributions which are not aligned with the main physiological axis remains unclear. Furthermore site and species dependent relationships are not well described. In this study five different groups of trabecular bone, defined in terms of orientation, species and site were exposed to cyclic compression. In total, 108 fatigue tests were analysed. The lifetimes were found to decrease drastically when off-axis loads were applied. Additionally, species and site strongly affect fatigue lifetimes. Strains at failure were also found to be a function of orientation. KW - Ermüdung KW - Knochen KW - Spongiosa KW - Anisotropie Y1 - 2008 U6 - https://doi.org/10.1016/j.jbiomech.2007.09.037 VL - 41 IS - 3 SP - 636 EP - 641 ER - TY - GEN A1 - Auer, Simon A1 - Krutsch, Werner A1 - Renkawitz, Tobias A1 - Kubowitsch, Simone A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Effect of mental demand on leg loading in highly dynamic motion T2 - AnyBody online Webinar, Oct 2020 N2 - Football players have a high risk of leg muscle injuries, especially when exposed to mental stress. Injuries to muscles of the thigh are common in amateur and professional football, representing almost a third of all injuries. These injuries occur primarily in non-contact situations and from overuse. They can lead to a range of costs, including financial costs associated with treatment as well as those associated with long-term recovery, and absence from training and/or competition. Further, there is a high risk of injury recurrence and subsequent injury. Y1 - 2020 ER - TY - RPRT A1 - Putzer, Michael A1 - Rasmussen, John A1 - Ehrlich, Ingo A1 - Gebbeken, Norbert A1 - Dendorfer, Sebastian ED - Baier, Wolfgang T1 - Muskuloskelettale Simulation zur Untersuchung des Einflusses geometrischer Parameter der Wirbelkörper auf die Belastung der Lendenwirbelsäule T2 - Forschungsbericht 2013 / Ostbayerische Technische Hochschule Regensburg Y1 - 2013 UR - https://doi.org/10.35096/othr/pub-799 SP - 60 EP - 61 CY - Regensburg ER -