TY - JOUR A1 - Hoenicka, Markus A1 - Kaspar, Marcel A1 - Schmid, Christof A1 - Liebold, Andreas A1 - Schrammel, Siegfried T1 - Contact-free monitoring of vessel graft stiffness - proof of concept as a tool for vascular tissue engineering JF - Journal of tissue engineering and regenerative medicine N2 - Tissue-engineered vessel grafts have to mimic the biomechanical properties of native blood vessels. Manufacturing processes often condition grafts to adapt them to the target flow conditions. Graft stiffness is influenced by material properties and dimensions and determines graft compliance. This proof-of-concept study evaluated a contact-free method to monitor biomechanical properties without compromising sterility. Forced vibration response analysis was performed on human umbilical vein (HUV) segments mounted in a buffer-filled tubing system. A linear motor and a dynamic signal analyser were used to excite the fluid by white noise (0-200 Hz). Vein responses were read out by laser triangulation and analysed by fast Fourier transformation. Modal analysis was performed by monitoring multiple positions of the vessel surface. As an inverse model of graft stiffening during conditioning, HUV were digested proteolytically, and the course of natural frequencies (NFs) was monitored over 120 min. Human umbilical vein showed up to five modes with NFs in the range of 5-100 Hz. The first natural frequencies of HUV did not alter over time while incubated in buffer (p = 0.555), whereas both collagenase (-35%, p = 0.0061) and elastase (-45%, p < 0.001) treatments caused significant decreases of NF within 120 min. Decellularized HUV showed similar results, indicating that changes of the extracellular matrix were responsible for the observed shift in NF. Performing vibration response analysis on vessel grafts is feasible without compromising sterility or integrity of the samples. This technique allows direct measurement of stiffness as an important biomechanical property, obviating the need to monitor surrogate parameters. Copyright (C) 2016 John Wiley & Sons, Ltd. KW - ANEURYSMS KW - ARTERIES KW - Biomechanics KW - BIOREACTOR KW - BLOOD-VESSELS KW - BYPASS GRAFTS KW - CONSTRUCTS KW - design KW - extracellular matrix KW - human umbilical vein KW - IN-VITRO KW - MECHANICAL-PROPERTIES KW - proteolysis KW - small calibre graft KW - vascular tissue engineering Y1 - 2017 U6 - https://doi.org/10.1002/term.2186 VL - 11 IS - 10 SP - 2828 EP - 2835 PB - Wiley ER - TY - JOUR A1 - Hornberger, Helga A1 - Striegl, Birgit A1 - Trahanofsky, M. A1 - Kneissl, F. A1 - Kronseder, Matthias T1 - Degradation and bioactivity studies of Mg membranes for dental surgery JF - Materials Letter X N2 - Bioresorbable materials are under investigation due to their promising properties for applications as implant material. This study is about the degradation and bioactivity behaviour of magnesium foils, which allegorize dental membranes. The degradation behaviour including pitting corrosion during immersion tests can be precisely observed using micro-computed tomography. Using the bioactivity test according to Kokubo, it is shown that magnesium has strong Ca-phosphate layer formation correlated with high degradation. Therefore, magnesium foils appear to hold a great potential for bone implant application. KW - Magnesium KW - Dental membrane KW - Bioactivity KW - Corrosion rate Y1 - 2019 U6 - https://doi.org/10.1016/j.mlblux.2019.100007 VL - 2 IS - June SP - 1 EP - 5 PB - Elsevier ER - TY - CHAP A1 - Horner, Marc A1 - Dendorfer, Sebastian A1 - Kiis, Arne A1 - Lawrenchuk, Mike A1 - Verma, Gunjan T1 - A Patient based simulation workflow for orthopedic device design and analysis T2 - SBC Ortho Workshop, June 2011 Y1 - 2011 ER - TY - JOUR A1 - Hölscher, Thomas A1 - Weber, Tim A. A1 - Lazarev, Igor A1 - Englert, Carsten A1 - Dendorfer, Sebastian T1 - The influence of rotator cuff tears on glenohumeral stability during abduction tasks JF - Journal of Orthopaedic Research N2 - One of the main goals in reconstructing rotator cuff tears is the restoration of glenohumeral joint stability, which is subsequently of utmost importance in order to prevent degenerative damage such as superior labral anterior posterior (SLAP) lesion, arthrosis, and malfunction. The goal of the current study was to facilitate musculoskeletal models in order to estimate glenohumeral instability introduced by muscle weakness due to cuff lesions. Inverse dynamics simulations were used to compute joint reaction forces for several static abduction tasks with different muscle weakness. Results were compared with the existing literature in order to ensure the model validity. Further arm positions taken from activities of daily living, requiring the rotator cuff muscles were modeled and their contribution to joint kinetics computed. Weakness of the superior rotator cuff muscles (supraspinatus; infraspinatus) leads to a deviation of the joint reaction force to the cranial dorsal rim of the glenoid. Massive rotator cuff defects showed higher potential for glenohumeral instability in contrast to single muscle ruptures. The teres minor muscle seems to substitute lost joint torque during several simulated muscle tears to maintain joint stability. Joint instability increases with cuff tear size. Weakness of the upper part of the rotator cuff leads to a joint reaction force closer to the upper glenoid rim. This indicates the comorbidity of cuff tears with SLAP lesions. The teres minor is crucial for maintaining joint stability in case of massive cuff defects and should be uprated in clinical decision-making. KW - Abduction tasks KW - Glenohumeral stability KW - Musculoskeletal Modeling KW - Muscle weakness KW - Rotator cuff tears KW - Rotatorenmanschettenriss KW - Schultergelenk KW - Stabilität Y1 - 2016 U6 - https://doi.org/10.1002/jor.23161 VL - 34 IS - 9 SP - 1628 EP - 1635 ER - TY - JOUR A1 - Ignasiak, Dominika A1 - Dendorfer, Sebastian A1 - Ferguson, Stephen J. T1 - Thoracolumbar spine model with articulated ribcage for the prediction of dynamic spinal loading JF - Journal of Biomechanics N2 - Musculoskeletal modeling offers an invaluable insight into the spine biomechanics. A better understanding of thoracic spine kinetics is essential for understanding disease processes and developing new prevention and treatment methods. Current models of the thoracic region are not designed for segmental load estimation, or do not include the complex construct of the ribcage, despite its potentially important role in load transmission. In this paper, we describe a numerical musculoskeletal model of the thoracolumbar spine with articulated ribcage, modeled as a system of individual vertebral segments, elastic elements and thoracic muscles, based on a previously established lumbar spine model and data from the literature. The inverse dynamics simulations of the model allow the prediction of spinal loading as well as costal joints kinetics and kinematics. The intradiscal pressure predicted by the model correlated well (R2=0.89) with reported intradiscal pressure measurements, providing a first validation of the model. The inclusion of the ribcage did not affect segmental force predictions when the thoracic spine did not perform motion. During thoracic motion tasks, the ribcage had an important influence on the predicted compressive forces and muscle activation patterns. The compressive forces were reduced by up to 32%, or distributed more evenly between thoracic vertebrae, when compared to the predictions of the model without ribcage, for mild thoracic flexion and hyperextension tasks, respectively. The presented musculoskeletal model provides a tool for investigating thoracic spine loading and load sharing between vertebral column and ribcage during dynamic activities. Further validation for specific applications is still necessary. KW - Inverse dynamics KW - Musculoskeletal model KW - Thoracolumbar spine KW - Brustwirbelsäule KW - Brustkorb KW - Biomechanik KW - Mechanische Belastung KW - Prognose Y1 - 2016 U6 - https://doi.org/10.1016/j.jbiomech.2015.10.010 VL - vol. 49 IS - 6 SP - 959 EP - 966 PB - Elsevier Science 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 - Jungtäubl, Dominik A1 - Aurbach, Maximilian A1 - Melzner, Maximilian A1 - Spicka, Jan A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - EMG-Based Validation of Musculoskeletal Models Considering Crosstalk T2 - International Conference BIOMDLORE, June 28 - 30 2018, Białystok, Poland N2 - BACKGROUND: Validation and verification of multibody musculoskeletal models sEMG is a difficult process because of the reliability of sEMG data and the complex relationship of muscle force and sEMG. OBJECTIVE: This work aims at comparing experimentally recorded and simulated muscle activities considering a numerical model for crosstalk. METHODS: For providing an experimentally derived reference data set, subjects were performing elevations of the arm, where the activities of the contemplated muscle groups were measured by sEMG sensors. Computed muscle activities were further processed and transformed into an artificial electromyographical signal, which includes a numerical crosstalk model. In order to determine whether the crosstalk model provides a better agreement with the measured muscle activities, the Pearson correlation coefficient has been computed as a qualitative way of assessing the curve progression of the data sets. RESULTS: The results show an improvement in the correlation coefficient between the experimental data and the simulated muscle activities when taking crosstalk into account. CONCLUSIONS: Although the correlation coefficient increased when the crosstalk model was utilized, it is questionable if the discretization of both, the crosstalk and the musculoskeletal model, is accurate enough. KW - musculoskeletal modeling KW - validation KW - surface electromyography KW - crosstalk Y1 - 2018 U6 - https://doi.org/10.1109/BIOMDLORE.2018.8467211 ER - TY - CHAP A1 - Jungtäubl, Dominik A1 - Schmitz, Paul A1 - Gross, Simon A1 - Dendorfer, Sebastian ED - Badnjevic, Almir T1 - FEA of the transiliacal internal fixator as an osteosynthesis of pelvic ring fractures T2 - CMBEBIH 2017, Proceedings of the International Conference on Medical and Biological Engineering 2017 N2 - Common Schanz screw systems can be used to stabilize pelvic ring fractures. In order to accommodate for different patient’s requirements, implants can be placed in cranio-caudal direction into the os ilium (T1), or into the supraacetabular bone canal, and thus, in dorso-ventral direction (T2). Whereas both techniques are currently used, no data of the biomechanical behavior is available up to this date. The aim of this study is to analyze, whether T2 shows biomechanical advantages with respect to tissue and implant stresses due to the enlarged bone-implant interface. Forces acting on the pelvis were analyzed using motion capture data of a gait cycle obtained by the utilization of a musculoskeletal simulation program. A three dimensional finite element (FE) model of the pelvis with grayscale-based material properties was generated. The muscle and joint reaction forces at toe-off were applied to the FE model and instable pelvis fractures were implemented. The osteosynthesis systems were positioned within the model in order to enable the comparison between the two different surgical techniques. Stresses and displacements were analyzed for bone tissue, fracture zone and implant. T2 lead to approx. 30% larger displacements in the fracture zone. Von-Mises stresses were larger for T2 in the implant (80 MPa vs. 227 MPa), whereas T1 leads to larger stresses in the bone tissue (200 MPa vs. 140 MPa). Both implantation techniques showed a good biomechanical behavior. Differences could be found with respect to tissue strains and deformations in the fracture zone. If bone quality or fracture healing are of concern, T2 or T1 should be used, respectively. However, both techniques seem to be applicable for cases with no special requirements. Further analyses aim to investigate the behavior under cyclic loading. KW - Finite element analysis KW - Musculoskeletal simulation KW - Internal fixator KW - Pelvic ring fracture KW - Beckenbruch KW - Operationstechnik KW - Finite-Elemente-Methode KW - Biomechanik KW - Simulation Y1 - 2017 SN - 978-981-10-4165-5 U6 - https://doi.org/10.1007/978-981-10-4166-2_32 SP - 212 EP - 217 PB - Springer CY - Singapore 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 - GEN A1 - Krefting, Dagmar A1 - Zaunseder, Sebastian A1 - Säring, Dennis A1 - Wittenberg, Thomas A1 - Palm, Christoph A1 - Schiecke, Karin A1 - Krenkel, Lars A1 - Hennemuth, Anja A1 - Schnell, Susanne A1 - Spicher, Nicolai T1 - Blutdruck, Hämodynamik und Gefäßzustand: Innovative Erfassung und Bewertung – Schwerpunkt bildbasierte Verfahren T2 - 66. Jahrestagung der Deutschen Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie e. V. (GMDS), 12. Jahreskongress der Technologie- und Methodenplattform für die vernetzte medizinische Forschung e. V. (TMF), 26. - 30.09.2021, online N2 - Einleitung: Blutdruck gilt als sogenannter Vitalparameter als einer der grundlegenden Indikatoren für den Gesundheitszustand einer Person. Sowohl zu niedriger als auch zu hoher Blutdruck kann lebensbedrohend sein, letzerer ist darüber hinaus ein Risikofaktor insbesondere für Herz-Kreislauferkrankungen, die trotz wichtiger Fortschritte in der Behandlung immer noch die häufigste Todesursache in Deutschland darstellen. Die Hämodynamik, also die raumzeitliche Dynamik des Blutflusses, und der Gefäßzustand sind eng verbunden mit dem Blutdruck und ebenfalls von hoher klinischer Relevanz, u.a. zur Identifikation von Durchblutungsstörungen und ungünstigen Druckverteilungen der Gefäßwand. Innovationen in der Messtechnik als auch in der Datenanalyse bieten heute neue Möglichkeiten der Erfassung und Bewertung von Blutdruck, Hämodynamik und Gefäßzustand [1], [2], [3], [4]. Methodik: In einer gemeinsamen Workshopserie der AG Medizinische Bild- und Signalverarbeitung der GMDS und des Fachausschusses Biosignale der DGBMT werden wir neue Ansätze und Lösungen für Mess- und Analyseverfahren zu Blutdruck und -fluss sowie zum Gefäßzustand vorstellen und diskutieren. Dabei stehen im ersten Workshop auf der GMDS Jahrestagung Bildbasierte Verfahren im Zentrum, während der zweite Workshop auf der DGBMT Jahrestagung den Fokus auf Biosignalbasierten Verfahren legt. Es werden aktuelle Forschungsergebnisse vorgestellt und diskutiert. Es sind jeweils mehrere Vorträge geplant mit ausreichend Zeit zur Diskussion. Folgende Vorträge sind geplant (Arbeitstitel): Sebastian Zaunseder: Videobasierte Erfassung des Blutdrucks Anja Hennemuth: A Visualization Toolkit for the Analysis of Aortic Anatomy and Pressure Distribution Lars Krenkel: Numerische Analyse der Rupturwahrscheinlichkeit zerebraler Aneurysmata Susanne Schnell: Messung des Blutflusses und hämodynamischer Parameter mit 4D flow MRI: Möglichkeiten und Herausforderungen Ergebnisse: Ziel des Workshops ist die Identifikation von innovativen Ansätzen und neuen Methoden zur qualitativen und quantitativen Bestimmung von hämodynamischen Parametern sowie deren kritische Bewertung durch die Community für die Eignung in der klinischen Entscheidungsunterstützung. Diskussion: Der Workshop leistet inhaltlich einen Beitrag zu zentralen Aspekten für die Herz-Kreislauf-Medizin. Er bringt dabei Expertise aus verschiedenen Bereichen zusammen und schlägt die Brücke zwischen Kardiologie, Medizininformatik und Medizintechnik. Schlussfolgerung: Innovative Technologien aus Medizintechnik und Informatik ermöglichen zunehmend einfache und raumzeitlich aufgelöste Erfassung und Bewertung wichtiger Informationen zur Unterstützung von Diagnose und Therapieverfolgung. [1] Zaunseder S, Trumpp A, Wedekind D, Malberg H. Cardiovascular assessment by imaging photoplethysmography - a review. Biomed Tech (Berl). 2018 Oct 25;63(5):617–34. [2] Huellebrand M, Messroghli D, Tautz L, Kuehne T, Hennemuth A. An extensible software platform for interdisciplinary cardiovascular imaging research. Comput Methods Programs Biomed. 2020 Feb;184:105277. [3] Schmitter S, Adriany G, Waks M, Moeller S, Aristova M, Vali A, et al. Bilateral Multiband 4D Flow MRI of the Carotid Arteries at 7T. Magn Reson Med. 2020 Oct;84(4):1947–60. [4] Birkenmaier C, and Krenkel, L. Flow in Artificial Lungs. In: New Results in Numerical and Experimental Fluid Mechanics XIII. Contributions to the 22nd STAB/DGLR Symposium. Springer; 2021. KW - Bildbasierte Verfahren KW - Blutdruck KW - Hämodynamik KW - Blutgefäß KW - Bildgebendes Verfahren Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0183-21gmds0167 ER - TY - GEN A1 - Krenkel, Lars T1 - Relevanz von Aerosolen im klinischen Kontext T2 - Innovationstag Hygiene 2021, Continental Arena, Regensburg, Deutschland Y1 - 2021 ER - TY - GEN A1 - Krenkel, Lars T1 - Maskenpflicht für Aerosole – wie wir medizinisches Personal in der Pandemie schützen T2 - TRIOKON Digital 2021 : Zukunft Ostbayern, 29.09.2021, Weiden, Deutschland KW - Aerosole KW - Pandemie KW - SARS-CoV-2 Y1 - 2021 UR - https://www.youtube.com/watch?v=bYRFpp_Xxvc ER - TY - GEN A1 - Krenkel, Lars A1 - Michel, Johanna A1 - Keil, Niklas A1 - Daschner, Jan T1 - Experimental Investigation of Logitudinal Folds in Endotracheal Tube Cuffs and their Correlation to Silent Breathing T2 - 23. DGLR Fach-Symposium Strömungen mit Ablösung, 09./10. November 2022, Berlin, Deutschland N2 - Air leakage past High-Volume-Low-Pressure (HVLP) endotracheal tube (ETT) cuffs creates a potential infection risk for health care professionals during ventilation of patients suffering from contagious airborne diseases. However, unlike silent aspiration, a phenomenon where fluids enter the airways of intubated patients, the aspect of aerosol emergence through cuff folds -what we called accordingly “silent breathing” (SB)- has not been investigated in detail so far. This study investigates air leakage past HVLP cuffs with varying cuff pressures under realistic artificial breathing scenarios experimentally and in addition numerically. The focus was laid on the parametric investigation of the occurrence and furthermore on different influencing factors of silent breathing. The morphology of the folds responsible for the leakage was captured using high-resolution 3D microcomputed tomography (μCT). For the numerical investigations (Com-putational Fluid Dynamics - CFD), the commercial CFD Software package FLUENT 2021 R2 (ANSYS, Inc., Canonsburg, PA, US), as well as the DLR in-house research code THETA has been used. KW - Silent Breathing KW - Aerosols KW - CFD KW - Endotracheal Intubation Y1 - 2022 UR - https://www.dlr.de/as/Portaldata/5/Resources/dokumente/veranstaltungen/stab_workshop/Jahresbericht2022.pdf CY - Göttingen ER - TY - CHAP A1 - Krenkel, Lars A1 - Wagner, C. A1 - Wolf, U. A1 - Scholz, A. A1 - Terekhov, Maxim A1 - Rivoire, Julien A1 - Schreiber, W. ED - Hirschel, Ernst Heinrich ED - Schröder, Wolfgang ED - Fujii, Kozo ED - Haase, Werner ED - Leer, Bram ED - Leschziner, Michael A. ED - Pandolfi, Maurizio ED - Periaux, Jacques ED - Rizzi, Arthur ED - Roux, Bernard ED - Shokin, Yurii I. ED - Dillmann, Andreas ED - Heller, Gerd ED - Klaas, Michael ED - Kreplin, Hans-Peter ED - Nitsche, Wolfgang T1 - Protective Artificial Lung Ventilation: Impact of an Endotracheal Tube on the Flow in a Generic Trachea T2 - New Results in Numerical and Experimental Fluid Mechanics VII : Contributions to the 16th STAB/DGLR Symposium Aachen, Germany 2008 N2 - Computational Fluid Dynamics (CFD) and experimental investigations on a generic model of the trachea have been carried out focusing on the impact of an endotracheal tube (ETT) on the resulting flow regime. It could be shown that detailed modelling of the airway management devices is essential for proper flow prediction, but secondary details as Murphy Eyes can be neglected. Models with bending and connector promote the formation of stronger secondary flows and disturbances which persist for a longer time. KW - computational fluid dynamics KW - Computational Fluid Dynamics Simulation KW - Endotracheal Tube KW - Particle Image Velocimetry KW - Turbulent Kinetic Energy Y1 - 2010 SN - 978-3-642-14242-0 U6 - https://doi.org/10.1007/978-3-642-14243-7_62 SP - 505 EP - 512 PB - Springer Berlin Heidelberg CY - Berlin, Heidelberg 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 - CHAP A1 - Kubowitsch, Simone A1 - Süß, Franz A1 - Jansen, Petra A1 - Dendorfer, Sebastian T1 - Comparison of dynamic muscular imbalances in back pain patients and healthy controls T2 - World Congress Biomechanics Dublin, 2018 Y1 - 2018 ER - TY - CHAP A1 - Kubowitsch, Simone A1 - Süß, Franz A1 - Jansen, Petra A1 - Dendorfer, Sebastian T1 - Muscular imbalances during experimentally induced stress T2 - 23th Congress of the European Society of Biomechanics, Sevilla, Spain, 2017 Y1 - 2017 ER - TY - GEN A1 - Kubowitsch, Simone A1 - Süß, Franz A1 - Jansen, Petra A1 - Dendorfer, Sebastian T1 - Effect of dual tasking on muscular imbalances T2 - European Society of Biomechanics meeting 2019, Vienna, Austria Y1 - 2019 UR - https://owncloud.tuwien.ac.at/index.php/s/dovqqcj02VeZHze ER - TY - JOUR A1 - Kummerlin, Jana A1 - Fabro, Hannah Katharina A1 - Pedersen, Peter Heide A1 - Jensen, Kenneth Krogh A1 - Pedersen, Dennis A1 - Andersen, Michael Skipper T1 - Measuring Knee Joint Laxity in Three Degrees-of-Freedom In Vivo Using a Robotics- and Image-Based Technology JF - Journal of Biomechanical Engineering N2 - Accurate and reliable information about three-dimensional (3D) knee joint laxity can prevent misdiagnosis and avoid incorrect treatments. Nevertheless, knee laxity assessments presented in the literature suffer from significant drawbacks such as soft tissue artifacts, restricting the knee within the measurement, and the absence of quantitative knee ligament property information. In this study, we demonstrated the applicability of a novel methodology for measuring 3D knee laxity, combining robotics- and image-based technology. As such technology has never been applied to healthy living subjects, the aims of this study were to develop novel technology to measure 3D knee laxity in vivo and to provide proof-of-concept 3D knee laxity measurements. To measure tibiofemoral movements, four healthy subjects were placed on a custom-built arthrometer located inside a low dose biplanar X-ray system with an approximately 60 deg knee flexion angle. Anteroposterior and mediolateral translation as well as internal and external rotation loads were subsequently applied to the unconstrained leg, which was placed inside a pneumatic cast boot. Bone contours were segmented in the obtained X-rays, to which subject-specific bone geometries from magnetic resonance imaging (MRI) scans were registered. Afterward, tibiofemoral poses were computed. Measurements of primary and secondary laxity revealed considerable interpersonal differences. The method differs from those available by the ability to accurately track secondary laxity of the unrestricted knee and to apply coupled forces in multiple planes. Our methodology can provide reliable information for academic knee ligament research as well as for clinical diagnostics in the future. KW - ANTERIOR CRUCIATE LIGAMENT KW - COMPLEX KW - COORDINATE SYSTEM KW - INJURY KW - INSTABILITY KW - MOTION KW - OSTEOARTHRITIS KW - QUANTIFICATION KW - STIFFNESS Y1 - 2022 U6 - https://doi.org/10.1115/1.4053792 SN - 1528-8951 VL - 144 IS - 8 PB - The American Society of Mechanical Engineers (ASME) ER - TY - JOUR A1 - Köck, Hannah A1 - Striegl, Birgit A1 - Kraus, Annalena A1 - Zborilova, Magdalena A1 - Christiansen, Silke H. A1 - Schäfer, Nicole A1 - Grässel, Susanne A1 - Hornberger, Helga T1 - In Vitro Analysis of Human Cartilage Infiltrated by Hydrogels and Hydrogel-Encapsulated Chondrocytes JF - Bioengineering N2 - Osteoarthritis (OA) is a degenerative joint disease causing loss of articular cartilage and structural damage in all joint tissues. Given the limited regenerative capacity of articular cartilage, methods to support the native structural properties of articular cartilage are highly anticipated. The aim of this study was to infiltrate zwitterionic monomer solutions into human OA-cartilage explants to replace lost proteoglycans. The study included polymerization and deposition of methacryloyloxyethyl-phosphorylcholine- and a novel sulfobetaine-methacrylate-based monomer solution within ex vivo human OA-cartilage explants and the encapsulation of isolated chondrocytes within hydrogels and the corresponding effects on chondrocyte viability. The results demonstrated that zwitterionic cartilage–hydrogel networks are formed by infiltration. In general, cytotoxic effects of the monomer solutions were observed, as was a time-dependent infiltration behavior into the tissue accompanied by increasing cell death and penetration depth. The successful deposition of zwitterionic hydrogels within OA cartilage identifies the infiltration method as a potential future therapeutic option for the repair/replacement of OA-cartilage extracellular suprastructure. Due to the toxic effects of the monomer solutions, the focus should be on sealing the OA-cartilage surface, instead of complete infiltration. An alternative treatment option for focal cartilage defects could be the usage of monomer solutions, especially the novel generated sulfobetaine-methacrylate-based monomer solution, as bionic for cell-based 3D bioprintable hydrogels. KW - osteoarthritis KW - human articular cartilage KW - chondrocytes KW - hydrogels KW - zwitterionic monomers KW - infiltration Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-61235 N1 - Corresponding author: Helga Hornberger VL - 10 SP - 1 EP - 21 PB - MDPI 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 - 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 - Lazarev, I.A. A1 - Ryabokon, P.V. A1 - Haller, M. A1 - Dendorfer, Sebastian T1 - Effect of the fractured calcaneus's peripheral fragment displacement on the triceps surae function JF - ЖУРНАЛ «ТРАВМА» Ukrainian Trauma Journal Y1 - 2015 VL - 2, TOM 16 ER - TY - JOUR A1 - Lenich, Andreas A1 - Bachmeier, S. A1 - Dendorfer, Sebastian A1 - Mayr, E. A1 - Nerlich, Michael A1 - Füchtmeier, Bernd T1 - Development of a test system to analyze different hip fracture osteosyntheses under simulated walking JF - Biomedizinische Technik. Biomedical engineering N2 - The mechanical complications of osteosyntheses after hip fractures are previously investigated by mostly static or dynamic uniaxial loading test systems. However, the physiologic loading of the hip joint during a normal gait is a multiplanar, dynamic movement. Therefore, we constructed a system to test osteosyntheses for hip fractures under physiologic multiplanar loading representative of normal gait. To evaluate the testing system, 12 femora pairs were tested under 25,000 cycles with two standard osteosyntheses (Proximal Femoral Nail Antirotation/Gamma3 Nail). For angular movement, the varus collapse to cut out (∝CO) (∝CO=4.8°±2.1° for blade and ∝CO=7.8°±3.8° for screw) was the dominant failure mode, and only slight rotational angle shifts (∝Rot) (∝Rot=1.7°±0.4° for blade and ∝Rot=2.4°±0.3° for screw) of the femoral head around the implant axis were observed. Angular displacements in varus direction and rotation were higher in specimens reinforced with screws. Hence, the cut out model and the migration directions showed a distinction between helical blade and hip screw. However, there were no significant differences between the different implants. The new setup is able to create clinical failures and allows to give evidence about the anchorage stability of different implant types under dynamic gait motion pattern. KW - biomechanical implant test KW - dynamic multiplanar loading KW - hip fractureg KW - implant migration KW - patient specific loading KW - Hüftgelenk KW - Knochenbruch KW - Osteosynthese KW - Bewegungsanalyse KW - Simulation Y1 - 2012 U6 - https://doi.org/10.1515/bmt-2011-0999 VL - 57 IS - 2 SP - 113 EP - 119 ER - TY - JOUR A1 - Lichtenauer, Norbert A1 - Ettl, Katrin A1 - Mohr, Christa A1 - Weber, Karsten A1 - Meussling-Sentpali, Annette T1 - Der Pflegeroboter für zu Hause JF - Die Schwester, der Pfleger N2 - Ein interdisziplinäres Forschungsprojekt der Ostbayerischen Hochschule Regensburg untersucht, inwiefern Telemedizin und digitale Anwendungen die Therapie und Pflege von Menschen mit Schlaganfall in ihrem häuslichen Umfeld unterstützen, ihre Lebensqualität beeinflussen und die intersektorale Versorgung verbessern kann. Y1 - 2021 UR - https://www.bibliomed-pflege.de/sp/artikel/44176-der-pflegeroboter-fuer-zu-hause VL - 11 IS - 21 SP - 48 EP - 52 PB - Bibliomed-Medizinische Verlagsgesellschaft mbH ER - TY - JOUR A1 - Lingel, Maximilian P. A1 - Haus, Moritz A1 - Paschke, Lukas A1 - Foltan, Maik A1 - Lubnow, Matthias A1 - Gruber, Michael A1 - Krenkel, Lars A1 - Lehle, Karla T1 - Clinical relevance of cell-free DNA during venovenous extracorporeal membrane oxygenation JF - Artificial organs N2 - BACKGROUND: Thrombosis remains a critical complication during venovenous extracorporeal membrane oxygenation (VV ECMO). The involvement of neutrophil extracellular traps (NETs) in thrombogenesis has to be discussed. The aim was to verify NETs in the form of cell-free DNA (cfDNA) in the plasma of patients during ECMO. METHODS: A fluorescent DNA-binding dye (QuantifFluor®, Promega) was used to detect cell-free DNA in plasma samples. cfDNA concentrations from volunteers (n = 21) and patients (n = 9) were compared and correlated with clinical/technical data before/during support, ECMO end and time of a system exchange. RESULTS: Before ECMO, patients with a median (IQR) age of 59 (51/63) years, SOFA score of 11 (10/15), and ECMO run time of 9.0 (7.0/19.5) days presented significantly higher levels of cfDNA compared to volunteers (6.4 (5.8/7.9) ng/μL vs. 5.9 (5.4/6.3) ng/μL; p = 0.044). Within 2 days after ECMO start, cfDNA, inflammatory, and hemolysis parameters remained unchanged, while platelets decreased (p = 0.005). After ECMO removal at the end of therapy, cfDNA, inflammation, and coagulation data (except antithrombin III) remained unchanged. The renewal of a system resulted in known alterations in fibrinogen, d-dimers, and platelets, while cfDNA remained unchanged. CONCLUSION: Detection of cfDNA in plasma of ECMO patients was not an indicator of acute and circuit-induced thrombogenesis. KW - blood KW - cell- free DNA KW - coagulation KW - ECMO KW - inflammation KW - neutrophil extracellular traps Y1 - 2023 U6 - https://doi.org/10.1111/aor.14616 SN - 1525-1594 VL - 47 IS - 11 SP - 1720 EP - 1731 PB - Wiley ER - TY - JOUR A1 - Lotter, Luisa A1 - Brebant, Vanessa A1 - Eigenberger, Andreas A1 - Hartmann, Robin A1 - Mueller, Karolina A1 - Baringer, Magnus A1 - Prantl, Lukas A1 - Schiltz, Daniel T1 - "Topographic Shift": a new digital approach to evaluating topographic changes of the female breast JF - Archives of Gynecology and Obstetrics N2 - Purpose To assess precise topographic changes of the breast, objective documentation and evaluation of pre- and postoperative results are crucial. New technologies for mapping the body using digital, three-dimensional surface measurements have offered novel ways to numerically assess the female breast. Due to the lack of clear demarcation points of the breast contour, the selection of landmarks on the breast is highly dependent on the examiner, and, therefore, is prone to error when conducting before-after comparisons of the same breast. This study describes an alternative to volumetric measurements, focusing on topographic changes of the female breast, based on three-dimensional scans. Method The study was designed as an interventional prospective study of 10 female volunteers who had planned on having aesthetic breast augmentation with anatomical, textured implants. Three dimensional scans of the breasts were performed intraoperatively, first without and then with breast implants. The topographic change was determined as the mean distance between two three-dimensional layers before and after augmentation. This mean distance is defined as the Topographic Shift. Results The mean implant volume was 283 cc (SD = 68.6 cc, range = 210-395 cc). The mean Topographic Shift was 7.4 mm (SD = 1.9 mm, range = 4.8-10.7 mm). The mean Topographic Shifts per quadrant were: I: 8.0 mm (SD = 3.3 mm); II: 9.2 mm (SD = 3.1 mm); III: 6.9 mm (SD = 3.5 mm); IV: 1.9 mm (SD = 4.3 mm). Conclusion The Topographic Shift, describing the mean distance between two three-dimensional layers (for example before and after a volume changing therapy), is a new approach that can be used for assessing topographic changes of a body area. It was found that anatomical, textured breast implants cause a topographic change, particularly on the upper breast, in quadrant II, the decollete. KW - 3D measurement KW - 3D scan KW - 3D volumetry KW - AUGMENTATION KW - Breast augmentation KW - Breast implant KW - MAMMAPLASTY KW - SHAPE KW - Topographic shift Y1 - 2021 U6 - https://doi.org/10.1007/s00404-020-05837-3 VL - 303 IS - 2 SP - 515 EP - 520 PB - Springer Nature 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 - GEN A1 - Melzner, Maximilian A1 - Dendorfer, Sebastian T1 - Biomechanik und muskuloskeletale Simulation T2 - Jahreskongress des ISPO Deutschland e.V., 2./3. Juni 2022, Hedelberg Y1 - 2022 ER - TY - GEN A1 - Melzner, Maximilian A1 - Engelhardt, Leonard A1 - Süß, Friedrich A1 - Dendorfer, Sebastian T1 - Sensitivity evaluation of a musculoskeletal hand model using Latin hypercube sampling T2 - ESMAC 2020 Abstracts Y1 - 2020 U6 - https://doi.org/10.1016/j.gaitpost.2020.08.008 VL - 81 IS - Suppl. 1 PB - Elsevier ER - TY - VIDEO A1 - Melzner, Maximilian A1 - Engelhardt, Lucas T1 - AnyBody Webcast - A new musculoskeletal AnyBody™ detailed hand model Y1 - 2020 UR - https://www.youtube.com/watch?v=E4xnbjRJYm8&t=631s ER - TY - CHAP A1 - Melzner, Maximilian A1 - Engelhardt, Lucas A1 - Havelkova, Leonard A1 - Simon, Ulrich A1 - Dendorfer, Sebastian T1 - A new musculoskeletal AnyBody detailed hand model validated by electromyography T2 - 16th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering (CMBBE) 2019, New York City, USA N2 - The AnyBody™ Modeling System (AMS) [1], is an universally used musculoskeletal simulation software using inverse dynamics. Until now, no complete human hand model is known in the AMS. Also considering other musculoskeletal software platforms, just one detailed entire hand model is recently published [2] but is only based on one subject. The aim of this work is to implement a full detailed hand model for the AMS including all extrinsic and intrinsic muscles using data by the UWB gained through an anatomical study of ten cadaver hands. Y1 - 2019 UR - https://www.researchgate.net/publication/336944957_A_NEW_MUSCULOSKELETAL_ANYBODY_DETAILED_HAND_MODEL_VALIDATED_BY_ELECTROMYOGRAPHY ER - TY - JOUR A1 - Melzner, Maximilian A1 - Engelhardt, Lucas A1 - Simon, Ulrich A1 - Dendorfer, Sebastian T1 - Electromyography-Based Validation of a Musculoskeletal Hand Model JF - Journal of Biomechanical Engineering N2 - Regarding the prevention of injuries and rehabilitation of the human hand, musculoskeletal simulations using an inverse dynamics approach allow for insights of the muscle recruitment and thus acting forces on the hand. Currently, several hand models from various research groups are in use, which are mainly validated by the comparison of numerical and anatomical moment arms. In contrast to this validation and model-building technique by cadaver studies, the aim of this study is to further validate a recently published hand model [1] by analyzing numerically calculated muscle activities in comparison to experimentally measured electromyographical signals of the muscles. Therefore, the electromyographical signals of 10 hand muscles of five test subjects performing seven different hand movements were measured. The kinematics of these tasks were used as input for the hand model, and the numerical muscle activities were computed. To analyze the relationship between simulated and measured activities, the time difference of the muscle on- and off-set points was calculated, which resulted in a mean on- and off-set time difference of 0.58 s between the experimental data and the model. The largest differences were detected for movements that mainly addressed the wrist. One major issue comparing simulated and measured muscle activities of the hand is cross-talk. Nevertheless, the results show that the hand model fits the experiment quite accurately despite some limitations and is a further step toward patient-specific modeling of the upper extremity. KW - Elektromyographie KW - Biomechanik KW - Simulation KW - Electromyography KW - Muscle KW - Musculoskeletal system KW - Signals KW - Simulation Y1 - 2021 U6 - https://doi.org/10.1115/1.4052115 VL - 144 IS - 2 PB - American Society of Mechanical Engineers, ASME ER - TY - JOUR A1 - Melzner, Maximilian A1 - Ismail, Khaled A1 - Rušavy, Zdenek A1 - Kališ, Vladimír A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Musculoskeletal lower back load of accoucheurs during childbirth – A pilot and feasibility study JF - European Journal of Obstetrics & Gynecology and Reproductive Biology N2 - Introduction: Back problems represent one of the leading causes of accouchers' work-related musculoskeletal morbidities. The correct execution of birth-related maneuvers including manual perineal protection is crucial not only for the mother and child but also for obstetricians and midwives to reduce any strain on their musculoskeletal system. Therefore, the overall aim of this study was to test the feasibility of determining the effect of different accouchers' postures (standing and kneeling) on their musculoskeletal system. Methods: The biomechanical analysis is based on musculoskeletal simulations that included motion recordings of real deliveries as well as deliveries conducted on a birthing simulator. These simulations were then used to determine individual joints' loads. Results: In the kneeling posture, both a low intra-operator variability and a lower average maximum load of the lower back was observed. For the standing position the spine load was reduced by pivoting the elbow on the accouchers' thigh, which in turn was associated with a significantly greater load on the shoulder joint. Conclusion: The study demonstrated the feasibility of our technique to assess joints loads. It also provided initial data indicating that a posture that reduces spinal flexion and tilt, achieved in this study by the kneeling, can significantly reduce the strain on the practitioner's musculoskeletal system. KW - lower back load KW - Accoucheur KW - Musculoskeletal simulation Y1 - 2021 U6 - https://doi.org/10.1016/j.ejogrb.2021.07.042 IS - 264 SP - 306 EP - 313 PB - Elsevier ER - TY - GEN A1 - Melzner, Maximilian A1 - Ismail, Khaled A1 - Rušavý, Zdeněk A1 - Kališ, Vladimír A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Musculoskeletal Lower Back Load of Accoucheurs During Delivery T2 - 26th Congress of the European Society of Biomechanics, July 11-14, 2021, Milan, Italy N2 - With the progress in modern medicine, it was possible to significantly reduce the risks of birth for mother and child. One aspect that has received less attention so far is the risk of injury to the accoucheurs (obstetricians and midwives) during the birth process. Indeed, studies indicate that 92% of midwives suffer from musculoskeletal disorders, with the lower back being the main cause of complaints (72%). The aim of this study was to investigate two commonly used postural techniques used by accoucheurs during childbirth and to analyze the resulting load on the lower back using the AnyBodyTM musculoskeletal simulation software. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-20208 CY - Milan ER - TY - GEN A1 - Melzner, Maximilian A1 - Pfeifer, Christian A1 - Alt, V. A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Änderung der Gelenkreaktionskraft bei Schädigung des medialen Bandapparates im Ellenbogen T2 - Zeitschrift fur Orthopadie und Unfallchirurgie KW - Muskuloskelettale Simulation KW - Ellenbogenstabilität Y1 - 2020 U6 - https://doi.org/10.1055/s-0040-1717270 N1 - Poster VL - 158 IS - S01 PB - Thieme ER - TY - GEN A1 - Melzner, Maximilian A1 - Pfeifer, Christian A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Muskuloskeletal analysis of elbow stability for common injury patterns T2 - 27th Congress of the European Society of Biomechanics, 26 - 29 June 2022, Porto, Portugal Y1 - 2022 UR - https://drive.google.com/uc?id=1RBguxyHZE-Wr2y6ktOWK06_3lQg2M9Rb&export=download&confirm=t SP - 654 ER - TY - JOUR A1 - Melzner, Maximilian A1 - Pfeiffer, Christian A1 - Suess, Franz A1 - Dendorfer, Sebastian T1 - Musculoskeletal simulation of elbow stability for common injury patterns JF - Journal of Orthopaedic Research N2 - Elbow stability is derived from a combination of muscular, ligamentous, and bony structures. After an elbow trauma the stability of the joint is an important decision criterion for the subsequent treatment. The decision regarding non-operative/operative care depends mostly on subjective assessments of medical experts. Therefore, the aim of this study is to use musculoskeletal simulations as an objective assessment tool to investigate the extent to which failure of different stabilizers affects the elbow stability and how these observations correspond to the assessment from clinical practice. A musculoskeletal elbow simulation model was developed for this aim. To investigate the stability of the elbow, varus/valgus moments were applied under 0°, 45°and 90° flexion while the respective cubital angle was analyzed. This was performed for nine different injury scenarios, which were also evaluated for stability by clinical experts. With the results, it can be determined by which injury pattern and under which flexion angle the elbow stability is impaired regarding varus/valgus moments. The scenario with a complete failure of the medial and lateral ligaments and a fracture of the radial head was identified as having the greatest instability. The study presented a numerical determination of elbow stability against varus/valgus moments regarding clinical injury patterns, as well as a comparison of the numerical outcome with experience gained in clinical practice. The numerical predictions agree well with the assessments of the clinical specialists. Thus, the results from musculoskeletal simulation can make an important contribution to a more objective assessment of the elbow stability. KW - AnyBody KW - musculoskeletal simulation KW - elbow stability Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-54819 SN - 1554-527X N1 - Corresponding author: Maximilian Melzner VL - 41 IS - 6 SP - 1356 EP - 1364 PB - Wiley ER - TY - JOUR A1 - Melzner, Maximilian A1 - Suess, Franz A1 - Dendorfer, Sebastian T1 - The impact of anatomical uncertainties on the predictions of a musculoskeletal hand model – a sensitivity study JF - Computer Methods in Biomechanics and Biomedical Engineering N2 - Outputs of musculoskeletal models should be considered probabilistic rather than deterministic as they are affected by inaccuracies and estimations associated with the development of the model. One of these uncertainties being critical for modeling arises from the determination of the muscles' line of action and the physiological cross-sectional area. Therefore, the aim of this study was to evaluate the outcome sensitivity of model predictions from a musculoskeletal hand model in comparison to the uncertainty of these input parameters. For this purpose, the kinematics and muscle activities of different hand movements (abduction of the fingers, abduction of the thumb, and flexion of the thumb) were recorded. One thousand simulations were calculated for each movement using the Latin hypercube sampling method with a corresponding variation of the muscle origin/insertion points and the cross-sectional area. Comparing the standard hand to simulations incorporating uncertainties of input parameters shows no major deviations in on- and off-set time point of muscle activities. About 60% of simulations are located within a ± 30% interval around the standard model concerning joint reaction forces. The comparison with the variation of the input data leads to the conclusion that the standard hand model is able to provide not over-scattered outcomes and, therefore, can be considered relatively stable. These results are of practical importance to the personalization of a musculoskeletal model with subject-specific bone geometries and hence changed muscle line of action. KW - Biomechanik KW - Simulation Y1 - 2021 U6 - https://doi.org/10.1080/10255842.2021.1940974 SN - 1476-8259 N1 - Corresponding author: Maximilian Melzner VL - 25 IS - 2 SP - 156 EP - 164 PB - Taylor & Francis ER - TY - JOUR A1 - Morag, Sarah A1 - Kieninger, Martin A1 - Eissnert, Christoph A1 - Auer, Simon A1 - Dendorfer, Sebastian A1 - Popp, Daniel A1 - Hoffmann, Johannes A1 - Kieninger, Bärbel T1 - Comparison of different techniques for prehospital cervical spine immobilization: Biomechanical measurements with a wireless motion capture system JF - PLOS ONE Y1 - 2023 U6 - https://doi.org/10.1371/journal.pone.0292300 VL - 18 IS - 11 SP - 1 EP - 14 PB - PLOS CY - San Francisco, California ER - TY - CHAP A1 - Muehling, M. A1 - Englert, Carsten A1 - Dendorfer, Sebastian T1 - Influence of biceps tenotomy and tenodesis on post-operative shoulder strength T2 - Jahrestagung der Deutschen Gesellschaft für Biomechanik, March 2017, Hannover, Germany Y1 - 2017 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 - JOUR A1 - Obermaier, Lisa A1 - Lehle, Karla A1 - Schmid, Stefanie A1 - Schmid, Christof A1 - Schratzenstaller, Thomas T1 - Introduction of a new ex vivo porcine coronary artery model: Evaluation of the direct vascular injury after stent implantation with and without dogbone effect JF - European Surgical Research N2 - Introduction: Neointimal hyperplasia after percutaneous coronary intervention remains a major determinant of in-stent restenosis (ISR). The extent of mechanical vessel injury correlates with ISR. A new ex vivo porcine stent model was introduced and evaluated comparing different stent designs. Methods: Coronary arteries were prepared from pig hearts from the slaughterhouse and used for ex vivo implantations of coronary stents. One basic stent design in two configurations (dogbone, DB; non-dogbone, NDB) was used. Vascular injury was determined according to a modified injury score (IS). Results: Standardized experimental conditions ensured comparable vessel dimensions and overstretch data. DB stents caused more severe IS compared to NDB stents. The mean IS and the IS at the distal end of all stents were significantly reduced for NDB stents (ISMean, DB, 1.16 ±0.12; NDB, 1.02 ±0.12; p=0.018; ISDist, DB, 1.39 ±0.28; NDB, 1.13 ±0.24; p=0.03). Discussion/Conclusion: The introduced ex-vivo model allowed the evaluation of different stent designs exclude unfavorable stent designs. KW - Stent screening KW - Stent design KW - Injury score KW - Ex vivo porcine stent model Y1 - 2022 U6 - https://doi.org/10.1159/000527883 SN - 1421-9921 VL - 63 IS - 4 SP - 285 EP - 293 PB - Karger CY - Basel ER - TY - JOUR A1 - Ott, Christian A1 - Rosengarth, Katharina A1 - Doenitz, Christian A1 - Hoehne, Julius A1 - Wendl, Christina A1 - Dodoo-Schittko, Frank A1 - Lang, Elmar Wolfgang A1 - Schmidt, Nils Ole A1 - Goldhacker, Markus T1 - Preoperative Assessment of Language Dominance through Combined Resting-State and Task-Based Functional Magnetic Resonance Imaging JF - Journal of personalized medicine N2 - Brain lesions in language-related cortical areas remain a challenge in the clinical routine. In recent years, the resting-state fMRI (RS-fMRI) was shown to be a feasible method for preoperative language assessment. The aim of this study was to examine whether language-related resting-state components, which have been obtained using a data-driven independent-component-based identification algorithm, can be supportive in determining language dominance in the left or right hemisphere. Twenty patients suffering from brain lesions close to supposed language-relevant cortical areas were included. RS-fMRI and task-based (TB-fMRI) were performed for the purpose of preoperative language assessment. TB-fMRI included a verb generation task with an appropriate control condition (a syllable switching task) to decompose language-critical and language-supportive processes. Subsequently, the best fitting ICA component for the resting-state language network (RSLN) referential to general linear models (GLMs) of the TB-fMRI (including models with and without linguistic control conditions) was identified using an algorithm based on the Dice index. Thereby, the RSLNs associated with GLMs using a linguistic control condition led to significantly higher laterality indices than GLM baseline contrasts. LIs derived from GLM contrasts with and without control conditions alone did not differ significantly. In general, the results suggest that determining language dominance in the human brain is feasible both with TB-fMRI and RS-fMRI, and in particular, the combination of both approaches yields a higher specificity in preoperative language assessment. Moreover, we can conclude that the choice of the language mapping paradigm is crucial for the mentioned benefits. KW - resting-state fMRI KW - task-based fMRI KW - brain mapping KW - language assessment KW - data-driven analysis Y1 - 2021 U6 - https://doi.org/10.3390/jpm11121342 VL - 11 IS - 12 PB - MDPI ER - TY - JOUR A1 - Penzkofer, Rainer A1 - Barnsteiner, K. A1 - Dendorfer, Sebastian T1 - The influence of age, shoe type and kicking direction on the severity of head trauma JF - Journal of Forensic Biomechanics N2 - In the last few years, increasingly kicks to the head were observed as a criminal offense. This study examined the influence of age, shoe type and kicking direction on the severity of head trauma. Male test persons were divided into two groups “Old” and “Young”. Both groups were equipped with light sneakers and combat boots. A standard laboratory crash dummy was used to simulate the victim’s body. First, the dummy’s head, free floating above the ground, was kicked vertically. Second, the dummy’s head was kicked horizontally. Established injury criteria were used to quantify the injury risk. No influence concerning the type of foot wear and no difference between the groups “Old” and “Young” could be found. For all analyses, kicking vertically generally lead to a higher risk for the subject compared to kicking horizontally. In this study, only the integral effect of the kicks could be analyzed. A detailed injury pattern cannot directly be derived from the data. Nevertheless, the presented data show the massive potential of injuries associated with head kicks. KW - Head trauma KW - Biomechanics KW - Kicks KW - Kopfverletzung KW - Schädel-Hirn-Trauma KW - Einflussgröße Y1 - 2014 UR - https://www.longdom.org/open-access/the-influence-of-age-shoe-type-and-kicking-direction-on-the-severity-of-head-trauma-2090-2697-1000116.pdf U6 - https://doi.org/10.4172/2090-2697.1000116 VL - 5 IS - 1 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 - JOUR A1 - Pfeifer, Christian A1 - Müller, Michael A1 - Prantl, Lukas A1 - Berner, Arne A1 - Dendorfer, Sebastian A1 - Englert, Carsten T1 - Cartilage labelling for mechanical testing in T-peel configuration JF - International Orthopaedics N2 - PURPOSE: The purpose of this study was to find a suitable method of labelling cartilage samples for the measurement of distraction distances in biomechanical testing. METHODS: Samples of bovine cartilage were labelled using five different methods: hydroquinone and silver nitrate (AgNO3), potassium permanganate (KMnO4) with sodium thiosulphate (Na2S2O3), India ink, heat, and laser energy. After the labelling, we analysed the cartilage samples with regard to cytotoxity by histochemical staining with ethidiumbromide homodimer (EthD-1) and calcein AM. Furthermore, we tested cartilages labelled with India ink and heat in a T-peel test configuration to analyse possible changes in the mechanical behaviour between marked and unlabelled samples. RESULTS: Only the labelling methods with Indian ink or a heated needle showed acceptable results in the cytotoxity test with regard to labelling persistence, accuracy, and the influence on consistency and viability of the chondrocytes. In the biomechanical T-peel configuration, heat-labelled samples collapsed significantly earlier than unlabelled samples. CONCLUSION: Labelling bovine cartilage samples with Indian ink in biomechanical testing is a reliable, accurate, inexpensive, and easy-to-perform method. This labelling method influenced neither the biomechanical behaviour nor the viability of the tissue compared to untreated bovine cartilage. KW - Bovine cartilage KW - Cartilage samples KW - Indian ink KW - T-peel configuration KW - Method labeling KW - Knorpel KW - Rind KW - Kennzeichnung KW - Tinte KW - Biomechanik KW - Prüfung Y1 - 2012 U6 - https://doi.org/10.1007/s00264-011-1468-3 VL - 36 IS - 7 SP - 1493 EP - 1499 PB - Springer ER - TY - JOUR A1 - Philipp, Alois A1 - de Somer, Filip A1 - Foltan, Maik A1 - Bredthauer, Andre A1 - Krenkel, Lars A1 - Zeman, Florian A1 - Lehle, Karla T1 - Life span of different extracorporeal membrane systems for severe respiratory failure in the clinical practice JF - PLOS ONE N2 - Over the past decade, veno-venous extracorporeal membrane oxygenation (vvECMO) has been increasingly utilized in respiratory failure in patients. This study presents our institution´s experience focusing on the life span of ECMO systems reflecting the performance of a particular system. A retrospective review of our ECMO database identified 461 adult patients undergoing vvECMO (2010-2017). Patients that required more than one system and survived the first exchange >24 hours (n = 139) were included. Life span until the first exchange and exchange criteria were analyzed for all systems (PLS, Cardiohelp HLS-set, both Maquet Cardiopulmonary, Rastatt, Germany; Deltastream/Hilite7000LT, iLA-activve, Xenios/NovaLung, Heilbronn, Germany; ECC.O5, LivaNova, Mirandola, Italy). At our ECMO center, the frequency of a system exchange was 30%. The median (IQR) life span was 9 (6-12) days. There was no difference regarding the different systems (p = 0.145 and p = 0.108, respectively). However, the Deltastream systems were exchanged more frequently due to elective technical complications (e. g. worsened gas transfer, development of coagulation disorder, increased bleedings complications) compared to the other exchanged systems (p = 0.013). In summary, the used ECMO systems are safe and effective for acute respiratory failure. There is no evidence for the usage of a specific system. Only the increased predictability of an imminent exchange preferred the usage of a Deltastream system. However, the decision to use a particular system should not depend solely on the possible criteria for an exchange. KW - Equipment Failure Analysis/statistics & numerical data KW - Extracorporeal Membrane Oxygenation/instrumentation KW - Membrane/classification/standards/statistics & numerical data KW - Primary Health Care/statistics & numerical data KW - Respiratory Distress Syndrome/therapy KW - Retrospective Studies KW - Severity of Illness Index KW - Time factors KW - MULTIDETECTOR COMPUTED-TOMOGRAPHY KW - THROMBOTIC DEPOSITS KW - ECMO SYSTEMS KW - Flow KW - OXYGENATION Y1 - 2018 U6 - https://doi.org/10.1371/journal.pone.0198392 VL - 13 IS - 6 SP - 1 EP - 10 PB - PLOS ER - TY - CHAP A1 - Pilling, A. A1 - Süß, Franz A1 - Kubowitsch, Simone A1 - Dendorfer, Sebastian T1 - Experimental workflow for determining psychological stress from physiological biosignals T2 - Jahrestagung der BIOMEDIZINISCHEN TECHNIK und Dreiländertagung der MEDIZINISCHEN PHYSIK, Dresden, Germany, 2017 Y1 - 2017 ER - TY - JOUR A1 - Plank, Tina A1 - Rosengarth, Katharina A1 - Schmalhofer, Carolin A1 - Goldhacker, Markus A1 - Brandl-Rühle, Sabine A1 - Greenlee, Mark W. T1 - Perceptual learning in patients with macular degeneration JF - Frontiers in psychology N2 - Patients with age-related macular degeneration (AMD) or hereditary macular dystrophies (JMD) rely on an efficient use of their peripheral visual field. We trained eight AMD and five JMD patients to perform a texture-discrimination task (TDT) at their preferred retinal locus (PRL) used for fixation. Six training sessions of approximately one hour duration were conducted over a period of approximately 3 weeks. Before, during and after training twelve patients and twelve age-matched controls (the data from two controls had to be discarded later) took part in three functional magnetic resonance imaging (fMRI) sessions to assess training-related changes in the BOLD response in early visual cortex. Patients benefited from the training measurements as indexed by significant decrease (p = 0.001) in the stimulus onset asynchrony (SOA) between the presentation of the texture target on background and the visual mask, and in a significant location specific effect of the PRL with respect to hit rate (p = 0.014). The following trends were observed: (i) improvement in Vernier acuity for an eccentric line-bisection task; (ii) positive correlation between the development of BOLD signals in early visual cortex and initial fixation stability (r = 0.531); (iii) positive correlation between the increase in task performance and initial fixation stability (r = 0.730). The first two trends were non-significant, whereas the third trend was significant at p = 0.014, Bonferroni corrected. Consequently, our exploratory study suggests that training on the TDT can enhance eccentric vision in patients with central vision loss. This enhancement is accompanied by a modest alteration in the BOLD response in early visual cortex. KW - perceptual learning KW - fMRI BOLD KW - cortical plasticity KW - visual cortex KW - macular degeneration Y1 - 2014 U6 - https://doi.org/10.3389/fpsyg.2014.01189 SN - 1664-1078 VL - 5 SP - 1 EP - 14 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Prantl, Lukas A1 - Eigenberger, Andreas A1 - Gehmert, Sebastian A1 - Haerteis, Silke A1 - Aung, Thiha A1 - Rachel, Reinhard A1 - Jung, Ernst Michael A1 - Felthaus, Oliver T1 - Enhanced Resorption of Liposomal Packed Vitamin C Monitored by Ultrasound JF - Journal of Clinical Medicine N2 - Vitamin C is an essential nutrient for humans and is involved in a plethora of health-related functions. Several studies have shown a connection between vitamin C intake and an improved resistance to infections that involves the immune system. However, the body cannot store vitamin C and both the elevated oral intake, and the intravenous application have certain disadvantages. In this study, we wanted to show a new formulation for the liposomal packaging of vitamin C. Using freeze etching electron microscopy, we show the formed liposomes. With a novel approach of post-processing procedures of real-time sonography that combines enhancement effects by contrast-like ultrasound with a transducer, we wanted to demonstrate the elevated intestinal vitamin C resorption on four participants. With the method presented in this study, it is possible to make use of the liposomal packaging of vitamin C with simple household materials and equipment for intake elevation. For the first time, we show the enhanced resorption of ingested liposomes using microbubble enhanced ultrasound imaging. KW - ASCORBIC-ACID KW - CEUS KW - CONTRAST AGENT KW - CULTURES KW - DEFICIENCY KW - enhanced resorption KW - GULO KW - immune system KW - liposomal packing KW - MITOCHONDRIAL DYSFUNCTION KW - OXIDATIVE STRESS KW - PHOSPHATIDYLCHOLINE KW - sonography KW - vitamin C Y1 - 2020 U6 - https://doi.org/10.3390/jcm9061616 VL - 9 IS - 6 SP - 1 EP - 12 PB - MDPI CY - Basel ER - TY - JOUR A1 - Prantl, Lukas A1 - Eigenberger, Andreas A1 - Klein, Silvan A1 - Limm, Katharina A1 - Oefner, Peter J. A1 - Schratzenstaller, Thomas A1 - Felthaus, Oliver T1 - Shear Force Processing of Lipoaspirates for Stem Cell Enrichment Does Not Affect Secretome of Human Cells Detected by Mass Spectrometry In Vitro JF - Plastic and Reconstructive Surgery N2 - Background: Lipofilling is one of the most often performed surgical procedures in plastic and reconstructive surgery. Lipoaspirates provide a ready source of stem cells and secreted factors that contribute to neoangiogenesis and fat graft survival. However, the regulations about the enrichment of these beneficial cells and factors are ambiguous. In this study, the authors tested whether a combination of centrifugation and homogenization allowed the enrichment of viable stem cells in lipoaspirates through the selective removal of tumescent solution, blood, and released lipids without significantly affecting the cell secretome. Methods: Human lipoaspirate was harvested from six different patients using water jet–assisted liposuction. Lipoaspirate was homogenized by first centrifugation (3584 rpm for 2 minutes), shear strain (10 times intersyringe processing), and second centrifugation (3584 rpm for 2 minutes). Stem cell enrichment was shown by cell counting after stem cell isolation. Lipoaspirate from different processing steps (unprocessed, after first centrifugation, after homogenization, after second centrifugation) was incubated in serum-free cell culture medium for mass spectrometric analysis of secreted proteins. Results: Lipoaspirate homogenization leads to a significant 2.6 ± 1.75-fold enrichment attributable to volume reduction without reducing the viability of the stem cells. Protein composition of the secretome did not change significantly after tissue homogenization. Considering the enrichment effects, there were no significant differences in the protein concentration of the 83 proteins found in all processing steps. Conclusions: Stem cells can be enriched mechanically without significantly affecting the composition of secreted proteins. Shear-assisted enrichment of lipoaspirate constitutes no substantial manipulation of the cells’ secretome. Y1 - 2020 U6 - https://doi.org/10.1097/PRS.0000000000007343 VL - 146 IS - 6 SP - 749e EP - 758e PB - American Society of Plastic Surgeons ER - TY - JOUR A1 - Prantl, Lukas A1 - Eigenberger, Andreas A1 - Reinhard, Ruben A1 - Siegmund, Andreas A1 - Heumann, Kerstin A1 - Felthaus, Oliver T1 - Cell-Enriched Lipotransfer (CELT) Improves Tissue Regeneration and Rejuvenation without Substantial Manipulation of the Adipose Tissue Graft JF - Cells N2 - The good availability and the large content of adult stem cells in adipose tissue has made it one of the most interesting tissues in regenerative medicine. Although lipofilling is one of the most frequent procedures in plastic surgery, the method still struggles with high absorption rates and volume losses of up to 70%. Therefore, many efforts have been made to optimize liposuction and to process the harvested tissue in order to increase fat graft retention. Because of their immunomodulatory properties, their cytokine secretory activity, and their differentiation potential, enrichment with adipose tissue-derived stem cells was identified as a promising tool to promote transplant survival. Here, we review the important parameters for lipofilling optimization. Finally, we present a new method for the enrichment of lipoaspirate with adipose tissue-derived stem cells and discuss the parameters that contribute to fat graft survival. Y1 - 2022 U6 - https://doi.org/10.3390/cells11193159 VL - 11 IS - 19 SP - 1 EP - 11 PB - MDPI ER - TY - THES A1 - Putzer, Michael T1 - Development of subject-specific musculoskeletal models for studies of lumbar loading N2 - Anatomical differences between individuals are often neglected in musculoskeletal models, but they are necessary in case of subject-specific questions regarding the lumbar spine. A modification of models to each subject is complex and the effects on lumbar loading are difficult to assess. One objective of this work is to create a validated musculoskeletal human model, which facilitates a subject-specific modification of the lumbar geometry. In a second step, important parameters are identified in sensitivity studies and at last, a case study regarding multifidus muscle atrophy after a disc herniation is conducted. The results of the studies indicate that lumbar motion and loading is dependent on lumbar ligament stiffness. Furthermore, subject-specific modelling of the lumbar spine should include at least the vertebral height, disc height and lumbar lordosis. The results of the case study suggest that an overloading of the multifidus muscle could follow disc herniation. Additionally, a subsequent atrophy of the muscles could expose adjacent levels to an increased loading, but these findings are highly dependent on the individual. KW - ligaments KW - lumbar geometry KW - lumbar spine KW - multifidus KW - musculoskeletal simulation KW - sensitivity study Y1 - 2019 SN - 978-3-8440-6695-1 U6 - https://doi.org/10.2370/9783844066951 N1 - Kooperative Promotion an der Universität der Bundeswehr München und an der OTH Regensburg PB - Shaker Verlag CY - Düren ER - TY - THES A1 - Putzer, Michael T1 - Development of subject-specific musculoskeletal models for studies of lumbar loading N2 - Anatomical differences between individuals are often neglected in musculoskeletal models, but they are necessary in case of subject-specific questions regarding the lumbar spine. A modification of models to each subject is complex and the effects on lumbar loading are difficult to assess. The objective of this thesis is to create a validated musculoskeletal model of the human body, which facilitates a subject-specific modification of the geometry of the lumbar spine. Furthermore, important parameters are identified in sensitivity studies and a case study regarding multifidus muscle atrophy after a disc herniation is conducted. Therefore, a generic model is heavily modified and a semi-automatic process is implemented. This procedure remodels the geometry of the lumbar spine to a subject-specific one on basis of segmented medical images. The resulting five models are validated with regard to the lumbar loading at the L4/L5 level. The influence of lumbar ligament stiffness is determined by changing the stiffness values of all lumbar ligaments in eleven steps during a flexion motion. Sensitivities of lumbar loading to an altered geometry of the lumbar spine are identified by varying ten lumbar parameters in simulations with each model in four postures. The case study includes an analysis of the loading of the multifidus muscle and of the lumbar discs throughout various stages of disc herniation. This time each model performs four motions with two different motion rhythms. The results indicate that lumbar motion and loading is dependent on lumbar ligament stiffness. Furthermore, subject-specific modelling of the lumbar spine should include at least the vertebral height, disc height and lumbar lordosis. The results of the case study suggest that an overloading of the multifidus muscle could follow disc herniation. Additionally, a subsequent atrophy of the muscles could expose adjacent levels to an increased loading, but these findings are highly dependent on the individual. KW - Lendenwirbelsäule KW - Geometrie KW - Lendenwirbelsäulenkrankheit KW - Computertomografie KW - Modell KW - Hochschulschrift Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:706-5924 N1 - Kooperative Promotion an der Fakultät Maschinenbau der Ostbayerischen Technischen Hochschule Regensburg (OTH.R) im Labor für Biomechanik (LBM) bei Prof. Dr.-Ing. Sebastian Dendorfer und Labor für Faserverbundtechnik (LFT) bei Prof. Dr.-Ing. Ingo Ehrlich ER - TY - JOUR A1 - Putzer, Michael A1 - Auer, Stefan A1 - Malpica, William A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - A numerical study to determine the effect of ligament stiffness on kinematics of the lumbar spine during flexion JF - BMC Musculoskeletal Disorders N2 - Background There is a wide range of mechanical properties of spinal ligaments documented in literature. Due to the fact that ligaments contribute in stabilizing the spine by limiting excessive intersegmental motion, those properties are of particular interest for the implementation in musculoskeletal models. The aim of this study was to investigate the effect of varying ligament stiffness on the kinematic behaviour of the lumbar spine. Methods A musculoskeletal model with a detailed lumbar spine was modified according to fluoroscopic recordings and corresponding data files of three different subjects. For flexion, inverse dynamics analysis with a variation of the ligament stiffness matrix were conducted. The influence of several degrees of ligament stiffness on the lumbar spine model were investigated by tracking ligament forces, disc forces and resulting moments generated by the ligaments. Additionally, the kinematics of the motion segments were evaluated. Results An increase of ligament stiffness resulted in an increase of ligament and disc forces, whereas the relative change of disc force increased at a higher rate at the L4/L5 level (19 %) than at the L3/L4 (10 %) level in a fully flexed posture. The same behaviour applied to measured moments with 67 % and 45 %. As a consequence, the motion deflected to the lower levels of the lumbar spine and the lower discs had to resist an increase in loading. Conclusions Higher values of ligament stiffness over all lumbar levels could lead to a shift of the loading and the motion between segments to the lower lumbar levels. This could lead to an increased risk for the lower lumbar parts. KW - Lumbar spine KW - Ligament stiffness KW - Musculoskeletal Modeling KW - Biomechanics Y1 - 2016 U6 - https://doi.org/10.1186/s12891-016-0942-x VL - 17 IS - 95 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 - JOUR A1 - Putzer, Michael A1 - Ehrlich, Ingo A1 - Rasmussen, John A1 - Gebbeken, Norbert A1 - Dendorfer, Sebastian T1 - Sensitivity of lumbar spine loading to anatomical parameters JF - Journal of Biomechanics N2 - Musculoskeletal simulations of lumbar spine loading rely on a geometrical representation of the anatomy. However, this data has an inherent inaccuracy. This study evaluates the influence of defined geometrical parameters on lumbar spine loading utilising five parametrised musculoskeletal lumbar spine models for four different postures. The influence of the dimensions of vertebral body, disc, posterior parts of the vertebrae as well as the curvature of the lumbar spine was studied. Additionally, simulations with combinations of selected parameters were conducted. Changes in L4/L5 resultant joint force were used as outcome variable. Variations of the vertebral body height, disc height, transverse process width and the curvature of the lumbar spine were the most influential. These parameters can be easily acquired from X-rays and should be used to morph a musculoskeletal lumbar spine model for subject-specific approaches with respect to bone geometry. Furthermore, the model was very sensitive to uncommon configurations and therefore, it is advised that stiffness properties of discs and ligaments should be individualised. KW - Musculoskeletal simulation KW - Lumbar spine KW - Parameter study KW - Vertebra KW - Wirbelsäule KW - Belastung KW - Simulation Y1 - 2015 U6 - https://doi.org/10.1016/j.jbiomech.2015.11.003 VL - 49 IS - 6 SP - 953 EP - 958 PB - Elsevier Science ER - TY - CHAP A1 - Putzer, Michael A1 - Galibarov, Pavel E. A1 - Dendorfer, Sebastian T1 - Influence of vertebral parameters on lumbar spine loading T2 - Pre-meeting SpineFX, Eurospine 2013, Liverpool, UK Y1 - 2013 ER - TY - CHAP A1 - Putzer, Michael A1 - Penzkofer, Rainer A1 - Ehrlich, Ingo A1 - Rasmussen, John A1 - Gebbeken, Norbert A1 - Dendorfer, Sebastian T1 - Musculoskeletal simulations to investigate the influence of vertebral geometrical parameters on lumbar spine loading T2 - 7th World Congress of Biomechanics, Boston, United States, 04/07/14 -11/07/14 Y1 - 2014 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 - 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 - Rasmussen, John A1 - Bichler, R. A1 - Christensen, Soeren Toerholm A1 - Wirix-Speetjens, Roel A1 - Dendorfer, Sebastian A1 - Renkawitz, Tobias T1 - Subject-specific Musculoskeletal Simulation of Hip Dislocation Risk in Activities of Daily Living T2 - Proceedings of the 2011 ORS Annual Meeting, Long Beach, CA. Y1 - 2011 UR - http://www.ors.org/Transactions/57/0306.pdf IS - Paper No. 306 ER - TY - JOUR A1 - Reich, Sven A1 - Hornberger, Helga T1 - The effect of multicolored machinable ceramics on the esthetics of all-ceramic crowns JF - Journal of Prosthetic Dentistry N2 - Statement of problems: Computer-aided design/computer-assisted machining systems offer the possibility of fabricating restorations from one machinable ceramic block. Whether multishaded blocks improve esthetic results and are a viable alternative to individually stained ceramics has not been fully determined. Purpose: The aim of this investigation was to examine the effect of multishaded blocks on the esthetic appearance of all-ceramic CEREC crowns and compare these crowns with single-shade and stained restorations. Material and methods: Ten subjects were included in this study. For each subject, 6 different crowns were milled with the use of a CEREC machine. One crown was milled from each of the following machinable ceramic materials: CEREC Vitablocs Mark II in classic colors; Vitablocs Mark II in 3D-Master colors; Vitablocs Mark II in either classic or 3D-Master colors, with additional staining; Megadenta Bloxx multishaded; Mark II experimental multilayer; and an experimental multilayer leucite ceramic. Three independent examiners assessed the esthetic appearance of crowns fabricated to match each subject's anterior tooth shade. A scale of 1 to 6 was used to score the shade match and esthetic adaptation of each crown, with 1 representing excellent characteristics and 3.5 serving as the threshold for clinical acceptability. The examiners' scores were averaged, and the mean values were analyzed with the Wilcoxon signed rank test (P 87% in both groups. There was a significant difference between the navigated and the conventional groups' Harris hip scores six weeks after surgery (p = 0.010). There were no significant differences with respect to any clinical outcome at six months and one year of follow-up. The navigated 'femur-first' technique improves the potential ROM for ADL without prosthetic impingement, although there was no observed clinical difference between the two treatment groups. KW - combined anteversion KW - computer-assisted orthopaedic surgery KW - THA KW - Hüftgelenkprothese KW - Operationstechnik KW - Computerunterstütztes Verfahren KW - Beweglichkeit Y1 - 2015 U6 - https://doi.org/10.1302/0301-620X.97B7.34729 VL - 97-B SP - 890 EP - 898 ER - TY - JOUR A1 - Renkawitz, Tobias A1 - Weber, Tim A. A1 - Dullien, Silvia A1 - Woerner, Michael A1 - Dendorfer, Sebastian A1 - Grifka, Joachim A1 - Weber, Markus T1 - Leg length and offset differences above 5 mm after total hip arthroplasty are associated with altered gait kinematics JF - Gait & Posture N2 - We aimed to investigate the relationship between postoperative leg length/offset (LL/OS) reconstruction and gait performance after total hip arthroplasty (THA). In the course of a prospective randomized controlled trial, 60 patients with unilateral hip arthrosis received cementless THA through a minimally-invasive anterolateral surgical approach. One year post-operatively, LL and global OS restoration were analyzed and compared to the contralateral hip on AP pelvic radiographs. The combined postoperative limb length/OS reconstruction of the operated hip was categorized as restored (within 5 mm) or non-restored (more than 5 mm reduction or more than 5 mm increment). The acetabular component inclination, anteversion and femoral component anteversion were evaluated using CT scans of the pelvis and the femur. 3D gait analysis of the lower extremity and patient related outcome measures (HHS, HOOS, EQ-5D) were obtained pre-operatively, six months and twelve months post-operatively by an observer blinded to radiographic results. Component position of cup and stem was comparable between the restored and non-restored group. Combined LL and OS restoration within 5 mm resulted in higher Froude number (p < 0.001), normalized walking speed (p < 0.001) and hip range-of-motion (ROM) (p = 0.004) during gait twelve months postoperatively, whereas gait symmetry was comparable regardless of LL and OS reconstruction at both examinations. Clinical scores did not show any relevant association between the accuracy of LL or OS reconstruction and gait six/twelve months after THA. In summary, postoperative LL/OS discrepancies larger than 5 mm relate to unphysiological gait kinematics within the first year after THA. DRKS00000739, German Clinical Trials Register. KW - THA KW - Leg length KW - Offset KW - Gait analysis KW - Biomechanics Y1 - 2016 U6 - https://doi.org/10.1016/j.gaitpost.2016.07.011 VL - vol. 49 SP - 196 EP - 201 ER - TY - CHAP A1 - Robie, Bruce A1 - Dendorfer, Sebastian A1 - Rasmussen, John A1 - Christensen, Soeren Toerholm T1 - Axial Rotation Requires Greatest Load in Multifidus Muscle – Potential Association with Low Back Pain? T2 - Annual Meeting of the AANS/CNS Section on Disorders of the Spine and Peripheral Nerves, 2011, Phoenix, Arizona Y1 - 2011 UR - https://paperpile.com/shared/o0LQEG 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 - JOUR A1 - Roldán, J.C. A1 - Moralis, A. A1 - Dendorfer, Sebastian A1 - Witte, J. A1 - Reicheneder, C. T1 - Controlled central advancement of the midface after Le Fort III osteotomy by a 3-point skeletal anchorage JF - The Journal of craniofacial surgery N2 - A 3-point skeletal anchorage with taping screws for distraction osteogenesis after a Le Fort III osteotomy was applied for the first time in a severely mentally impaired patient where intraoral devices had to be avoided. All 3-force application points included the center of resistance, which allowed an optimal control on the resulting moment. A novel device for skeletal long-term retention into the nasal dorsum prevented a relapse, whereas adjustment of the midface position was observed. Fusioned three-dimensional computed tomography analysis revealed real movements not accessible by a conventional cephalometry. KW - Mund-Kiefer-Gesichts-Chirurgie KW - Le Fort III KW - distraction KW - vector KW - anchorage KW - three-dimensional computed tomography analysis KW - Distraktion KW - Knochenbildung KW - Osteotomie KW - Dreidimensionale Bildverarbeitung KW - Computertomografie Y1 - 2011 U6 - https://doi.org/10.1097/SCS.0b013e318231fc8d VL - 22 IS - 6 SP - 2384 EP - 2386 ER - TY - GEN A1 - Saffert, Anne-Sophia A1 - Melzner, Maximilian A1 - Dendorfer, Sebastian T1 - Biomechanical Analysis of the Right Elevated Glenohumeral Joint in Violinists during Legato-Playing T2 - Biomdlore 2021: 21-23 October 2021 Vilnius/Trakai, Lithuania N2 - BACKGROUND: Many statistics reveal that violin players suffer most often from musculoskeletal disorders compared to musicians of other instrument groups. A common phenomenon, especially observed in violin beginners, is the tendency to elevate the right shoulder during playing the violin. This can probably lead to serious disorders in long-term practice with repetitive movements. OBJECTIVE: For this reason, this study investigated the relationship between the right shoulder elevation and the force in the right glenohumeral joint during violin playing. It was hypothesized that the forces in the right glenohumeral joint are higher during playing with the right shoulder raised compared to playing in normal posture. METHODS: Motion capture data from four experienced violinists was recorded and processed by means of musculoskeletal simulation to get the force and elevation angle while playing with raised shoulder and in normal position. RESULTS: The results indicate that the absolute values of the resulting force, as well as the forces in the mediolateral, inferosuperior, and anteroposterior directions, are higher in playing the violin with the shoulder raised than in a normal posture. CONCLUSIONS: Elevating the right shoulder while playing the violin may pose a potential problem. Y1 - 2021 U6 - https://doi.org/10.3233/THC-219001 N1 - Veröffentlicht in: Technology and Health Care, vol. 30, no. 1 (Selected Papers From the 13th International Conference BIOMDLORE 2021), pp. 177-186, 2022 ER - TY - JOUR A1 - Saffert, Anne-Sophie A1 - Melzner, Maximilian A1 - Dendorfer, Sebastian T1 - Biomechanical analysis of the right elevated glenohumeral joint in violinists during legato-playing JF - Technology and Health Care N2 - BACKGROUND: Many statistics reveal that violin players suffer most often from musculoskeletal disorders compared to musicians of other instrument groups. A common phenomenon, especially observed in violin beginners, is the tendency to elevate the right shoulder during playing the violin. This can probably lead to serious disorders in long-term practice with repetitive movements. OBJECTIVE: For this reason, this study investigated the relationship between the right shoulder elevation and the force in the right glenohumeral joint during violin playing. It was hypothesized that the forces in the right glenohumeral joint are higher during playing with the right shoulder raised compared to playing in normal posture. METHODS: Motion capture data from four experienced violinists was recorded and processed by means of musculoskeletal simulation to get the force and elevation angle while playing with raised shoulder and in normal position. RESULTS: The results indicate that the absolute values of the resulting force, as well as the forces in the mediolateral, inferosuperior, and anteroposterior directions, are higher in playing the violin with the shoulder raised than in a normal posture. CONCLUSIONS: Elevating the right shoulder while playing the violin may pose a potential problem. KW - Biomechanische Analyse KW - Schultergelenk KW - Verletzung KW - Violinspiel KW - biomechanics KW - violin KW - shoulder elevation KW - shoulder joint force KW - musculoskeletal disease Y1 - 2022 U6 - https://doi.org/10.3233/THC-219001 N1 - Corresponding author: Anne-Sophie Saffert VL - 30 IS - 1 SP - 177 EP - 186 PB - IOS Press ER - TY - CHAP A1 - Schaeffer, Leon A1 - Herrmann, David A1 - Böhm, Valter T1 - Concept of a wrist Hand Orthosis based on a prestressed compliant structure T2 - Proceedings of the 7th International Conference on Biomedical Engineering and Applications (ICBEA), Hangzhou, China, 21-23 April 2023 N2 - In the treatment of hand injuries in the context of orthopedic care, movable wrist hand orthoses are used in numerous instances. Early motion therapy is in most cases advantageous for adequate, rapid and successful long-term healing of the hand. Conventional dynamic wrist hand orthoses can only be used for movement therapy to a limited extent since they represent the wrist as a simple rotating joint and neglect the complexity of the hand movement possibilities. In this paper, a preliminary concept for dynamic wrist hand orthoses based on prestressed compliant structures is presented. The distinctive feature of this concept lies in the enabling of multiaxial motion capabilities of the human hand without applying conventional joints. According to the concept the wrist region is surrounded by a prestressed compliant structure. Besides the derivation and description of the concept, a first three-dimensional computer-aided design is shown. Additionally, the necessary steps in the development of such a novel dynamic wrist orthosis are discussed. Y1 - 2023 U6 - https://doi.org/10.1109/ICBEA58866.2023.00024 SP - 98 EP - 103 PB - IEEE ER - TY - CHAP A1 - Schaeffer, Leon A1 - Herrmann, David A1 - Böhm, Valter T1 - Preliminary theoretical considerations of a hand orthosis based on a prestressed, compliant structure T2 - Proceedings of the 2023 International Symposium on Medical Robotics (ISMR), Atlanta, 19-21 April 2023 N2 - In the treatment of hand injuries in the context of orthopedic care, movable hand orthoses are used in many cases. Early motion therapy is in most cases advantageous for adequate, rapid, and successful long-term healing of the hand. Conventional mobile hand orthoses can only be used for movement therapy to a limited extent since they represent the wrist as a simple rotating joint and neglect the complexity of the movement possibilities of the hand. In this paper, a novel concept for movable hand orthoses based on prestressed compliant structures is presented. The advantage with this concept is that it replicates the multiaxial motion capabilities without the need for conventional joints. Besides the derivation and description of the concept, a first three-dimensional CAD design is shown. Additionally, the next planned steps in the development of such a novel dynamic hand orthosis are described. Y1 - 2023 U6 - https://doi.org/10.1109/ISMR57123.2023.10130230 SP - 1 EP - 7 PB - IEEE ER - TY - CHAP A1 - Schaeffer, Leon A1 - Herrmann, David A1 - Böhm, Valter T1 - Theoretical considerations on a 2D compliant tensegrity joint in context of a biomedical application T2 - Engineering for a changing world : 60th ISC, Ilmenau Scientific Colloquium, Technische Universität Ilmenau, September 4-8, 2023 N2 - In this paper, a two-dimensional compliant tensegrity joint was investigated for potential biomedical applications such as orthotics or exoskeletons. The structure consists of two compressed members connected by five compliant tensioned members. The concept is based on the tensegrity principle, which allows the realization of dynamic orthoses without conventional hinge joints. Another advantage is the adaptability to the individual needs of the patient through a suitable design of the structure and the careful selection of the characteristics of the elements. Using geometric nonlinear analysis, the mechanical behavior of the structure was investigated, focusing on mechanical compliance. The main objective was to determine the influence of the initial length and stiffness of the tensioned members and the influence of the magnitude of external forces on the overall stiffness of the movable member of the structure. The results highlight the significant impact of member parameters on the structure's stiffness and movability under varying load magnitudes. The research laid the foundation for future development of dynamic orthoses based on this structure. Y1 - 2023 U6 - https://doi.org/10.22032/dbt.58879 SP - 1 EP - 15 PB - Technische Universität Ilmenau CY - Ilmenau ER - TY - CHAP A1 - Schaeffer, Leon A1 - Herrmann, David A1 - Böhm, Valter T1 - Voruntersuchung einer vorgespannten nachgiebigen Struktur für den Einsatz in dynamischen Handorthesen T2 - 9. IFToMM D-A-CH Konferenz, 16./17. März 2023, Universität Basel N2 - In diesem Beitrag erfolgt die theoretische Untersuchung einer zweidimensionalen nachgiebigen Tensegrity-Struktur in Hinsicht auf ihre potenzielle Eignung als Basisstruktur für eine dynamische Handorthese. Translatorische und rotatorische relative Bewegungsmöglichkeiten zwischen den Drucksegmenten der Struktur sind möglich, da diese Segmente durch nachgiebige Zugsegmente miteinander verbunden sind. Die Form der Struktur und ihre Vorspannung in einer statisch stabilen Gleichgewichtskonfiguration werden mit Hilfe der Minimierung des Kräfte- und Momentenungleichgewichts, der Betrachtung der potentiellen Energie der Struktur und einem Ansatz mittels statischer Finite-Elemente-Methode (FEM) in Abhängigkeit der Segmentparameter untersucht. N2 - This paper presents a theoretical investigation of a two-dimensional compliant tensegrity structure with respect to its potential suitability as a base structure for a dynamic hand orthosis. Translational and rotational relative motion possibilities between the pressure segments of the structure are possible, as these segments are connected by compliant tension segments. The shape of the structure and its preload in a static stable equilibrium configuration are investigated using minimization of force and moment imbalance, consideration of the potential energy of the structure, and a static finite element method (FEM) approach as a function of segment parameters. T2 - Preliminary investigation of a prestressed compliant structure for use in dynamic hand orthoses Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:465-20230314-153711-8 PB - DuEPublico CY - Duisburg-Essen ER - TY - CHAP A1 - Schaeffer, Leon A1 - Herrmann, David A1 - Böhm, Valter T1 - Preliminary considerations on the form-finding of a tensegrity joint to be used in dynamic orthoses T2 - 8th International Conference on Biomedical Engineering and Applications (ICBEA 2024), Tokio, 18-21. March 2024 Y1 - 2024 PB - ACM ET - accepted paper ER - TY - JOUR A1 - Schaeffer, Leon A1 - Herrmann, David A1 - Schratzenstaller, Thomas A1 - Dendorfer, Sebastian A1 - Böhm, Valter T1 - Preliminary theoretical considerations on the stiffness characteristics of a tensegrity joint for the use in dynamic orthoses JF - Journal of Medical Robotics Research N2 - Early motion therapy plays an important role for effective long-term healing of joint injuries. In many cases, conventional dynamic orthoses fail to address the intricate movement possibilities of the underlying joints, limited by their simplistic joint representations, often represented by revolute joints, enabling rotations by only one axis. In this paper, a two-dimensional compliant tensegrity joint for use in biomedical applications is investigated. It consists of two compressed members and five compliant tensioned members. Relative movement possibilities are realized by the intrinsic compliance of the structure. In the development of these systems, the first step is the determination of the static stable equilibrium. This analysis is conducted in this paper by considering the potential energy approach or by using the geometric nonlinear finite element method. The mechanical behavior of the structure is assessed with a specific emphasis on its mechanical compliance. The primary objective of this study is the investigation of the influence of structural parameters on the overall stiffness and movability of the structure. The results underscore the significant effect of member parameters on the stiffness and movability of the compliant tensegrity joint, particularly under varying load magnitudes. These findings provide insights for optimizing the joint’s performance, contributing to its potential application in advanced orthotic and exoskeleton devices. KW - mechanical compliance KW - flexibility ellipsis KW - form-finding KW - tensegrity joint Y1 - 2023 U6 - https://doi.org/10.1142/S2424905X23400081 PB - World Scientific ER - TY - JOUR A1 - Schecklmann, Martin A1 - Schmausser, Maximilian A1 - Klinger, Felix A1 - Kreuzer, Peter M. A1 - Krenkel, Lars A1 - Langguth, Berthold T1 - Resting motor threshold and magnetic field output of the figure-of-8 and the double-cone coil JF - scientific reports N2 - The use of the double-cone (DC) coil in transcranial magnetic stimulation (TMS) is promoted with the notion that the DC coil enables stimulation of deeper brain areas in contrast to conventional figure-of-8 (Fo8) coils. However, systematic comparisons of these two coil types with respect to the spatial distribution of the magnetic field output and also to the induced activity in superficial and deeper brain areas are limited. Resting motor thresholds of the left and right first dorsal interosseous (FDI) and tibialis anterior (TA) were determined with the DC and the Fo8 coil in 17 healthy subjects. Coils were orientated over the corresponding motor area in an angle of 45 degrees for the hand area with the handle pointing in posterior direction and in medio-lateral direction for the leg area. Physical measurements were done with an automatic gantry table using a Gaussmeter. Resting motor threshold was higher for the leg area in contrast to the hand area and for the Fo8 in contrast to the DC coil. Muscle by coil interaction was also significant providing higher differences between leg and hand area for the Fo8 (about 27%) in contrast to the DC coil (about 15%). Magnetic field strength was higher for the DC coil in contrast to the Fo8 coil. The DC coil produces a higher magnetic field with higher depth of penetration than the figure of eight coil. KW - ANTERIOR CINGULATE CORTEX KW - CONNECTIVITY KW - Depression KW - FRONTAL-CORTEX KW - PREDICTOR KW - RTMS KW - STIMULATION KW - TMS Y1 - 2020 U6 - https://doi.org/10.1038/s41598-020-58034-2 VL - 10 IS - 1 PB - Nature ER - TY - JOUR A1 - Scheer, Clara A1 - Kubowitsch, Simone A1 - Dendorfer, Sebastian A1 - Jansen, Petra T1 - Happy Enough to Relax? How Positive and Negative Emotions Activate Different Muscular Regions in the Back - an Explorative Study JF - Frontiers in Psychology N2 - Embodiment theories have proposed a reciprocal relationship between emotional state and bodily reactions. Besides large body postures, recent studies have found emotions to affect rather subtle bodily expressions, such as slumped or upright sitting posture. This study investigated back muscle activity as an indication of an effect of positive and negative emotions on the sitting position. The electromyography (EMG) activity of six back muscles was recorded in 31 healthy subjects during exposure to positive and negative affective pictures. A resting period was used as a control condition. Increased muscle activity patterns in the back were found during the exposure to negative emotional stimuli, which was mainly measured in the lumbar and thorax regions. The positive emotion condition caused no elevated activity. The findings show that negative emotions lead to increased differential muscle activity in the back and thus corroborate those of previous research that emotion affects subtle bodily expressions. KW - electromyography KW - muscle activity KW - emotion KW - sadness KW - happiness KW - embodiment Y1 - 2021 U6 - https://doi.org/10.3389/fpsyg.2021.511746 SN - 1664-1078 VL - Volume 12 IS - May 2021 PB - Frontiers Media ER - TY - JOUR A1 - Schmidt, Ulf A1 - Penzkofer, Rainer A1 - Bachmaier, Samuel A1 - Augat, Peter T1 - Implant Material and Design Alter Construct Stiffness in Distal Femur Locking Plate Fixation: A Pilot Study JF - Clinical Orthopaedics and Related Research® N2 - BACKGROUND: Construct stiffness affects healing of bones fixed with locking plates. However, variable construct stiffness reported in the literature may be attributable to differing test configurations and direct comparisons may clarify these differences. QUESTIONS/PURPOSES: We therefore asked whether different distal femur locking plate systems and constructs will lead to different (1) axial and rotational stiffness and (2) fatigue under cyclic loading. METHODS: We investigated four plate systems for distal femur fixation (AxSOS, LCP, PERI-LOC, POLYAX) of differing designs and materials using bone substitutes in a distal femur fracture model (OTA/AO 33-A3). We created six constructs of each of the four plating systems. Stiffness under static and cyclic loading and fatigue under cyclic loading were measured. RESULTS: Mean construct stiffness under axial loading was highest for AxSOS (100.8 N/mm) followed by PERI-LOC (80.8 N/mm) and LCP (62.6 N/mm). POLYAX construct stiffness testing showed the lowest stiffness (51.7 N/mm) with 50% stiffness of AxSOS construct testing. Mean construct stiffness under torsional loading was similar in the group of AxSOS and PERI-LOC (3.40 Nm/degree versus 3.15 Nm/degree) and in the group of LCP and POLYAX (2.63 Nm/degree versus 2.56 Nm/degree). The fourth load level of > 75,000 cycles was reached by three of six AxSOS, three of six POLYAX, and two of six PERI-LOC constructs. All others including all LCP constructs failed earlier. CONCLUSIONS: Implant design and material of new-generation distal femur locking plate systems leads to a wide range of differences in construct stiffness. CLINICAL RELEVANCE: Assuming construct stiffness affects fracture healing, these data may influence surgical decision-making in choosing an implant system. Y1 - 2013 U6 - https://doi.org/10.1007/s11999-013-2867-0 VL - 471 IS - 9 SP - 2808 EP - 2814 PB - The Association of Bone and Joint Surgeons ER - TY - JOUR A1 - Schmitz, Paul A1 - Neumann, Christoph Cornelius A1 - Neumann, Carsten A1 - Nerlich, Michael A1 - Dendorfer, Sebastian T1 - Biomechanical analysis of iliac crest loading following cortico-cancellous bone harvesting JF - Journal of Orthopaedic Surgery and Research N2 - Background Iliac crest bone harvesting is a frequently performed surgical procedure widely used to treat bone defects. The objective of this study is to assess the biomechanical quantities related to risk for pelvic fracture after harvesting an autologous bone graft at the anterior iliac crest. Methods Finite element models with a simulated harvest site (sized 15 × 20 mm, 15 × 35 mm, 30 × 20 mm and 30 × 35 mm) in the iliac wing are created. The relevant loading case is when the ipsilateral leg is lifted off the ground. Musculoskeletal analysis is utilized to compute the muscle and joint forces involved in this motion. These forces are used as boundary conditions for the finite element analyses. Bone tissue stress is analyzed. Results Critical stress peaks are located between the anterior superior iliac spine (ASIS) and the anterior edge of the harvest site. Irrespective of the graft size, the iliac wing does not show any significant stress peaks with the harvest site being 20 to 25 mm posterior to the ASIS. The harvest area itself inhibits the distribution of the forces applied on the ASIS to extend to the posterior iliac wing. This leads to a lack of stress posterior to the harvest site. A balanced stress distribution with no stress peaks appears when the bone graft is taken below the iliac crest. Conclusion A harvest site located at least 20 to 25 mm posterior to the ASIS should be preferred to minimize the risk of iliac fatigue fracture. KW - Bone harvesting KW - Autologous bone graft KW - Iliac crest KW - Fatigue fracture KW - Pelvis KW - ASIS KW - FEA KW - Biomechanical investigation KW - Beckenkammknochen KW - Knochenentnahme KW - Spongiosa KW - Biomechanische Analyse Y1 - 2018 U6 - https://doi.org/10.1186/s13018-018-0822-1 VL - 13 IS - 108 SP - 1 EP - 8 PB - Springer Nature ER - TY - CHAP A1 - Seefried, C. A1 - Aurbach, Maximilian A1 - Wyss, C. A1 - Dendorfer, Sebastian T1 - Achilles tendon lengthening alters stresses in the growth plate T2 - International Conference BIOMDLORE, June 28 - 30 2018, Białystok, Poland Y1 - 2018 ER - TY - JOUR A1 - Sellmer, Andreas A1 - Stangl, Hubert A1 - Beyer, Mandy A1 - Grünstein, Elisabeth A1 - Leonhardt, Michel A1 - Pongratz, Herwig A1 - Eichhorn, Emerich A1 - Elz, Sigurd A1 - Striegl, Birgit A1 - Jenei-Lanzl, Zsuzsa A1 - Dove, Stefan A1 - Straub, Rainer H. A1 - Krämer, Oliver H. A1 - Mahboobi, Siavosh T1 - Marbostat-100 Defines a New Class of Potent and Selective Antiinflammatory and Antirheumatic Histone Deacetylase 6 Inhibitors JF - Journal of medicinal chemistry N2 - Epigenetic modifiers of the histone deacetylase (HDAC) family contribute to autoimmunity, cancer, HIV infection, inflammation, and neurodegeneration. Hence, histone deacetylase inhibitors (HDACi), which alter protein acetylation, gene expression patterns, and cell fate decisions, represent promising new drugs for the therapy of these diseases. Whereas pan-HDACi inhibit all 11 Zn2+-dependent histone deacetylases (HDACs) and cause a broad spectrum of side effects, specific inhibitors of histone deacetylase 6 (HDAC6i) are supposed to have less side effects. We present the synthesis and biological evaluation of Marbostats, novel HDAC6i that contain the hydroxamic acid moiety linked to tetrahydro-β-carboline derivatives. Our lead compound Marbostat-100 is a more potent and more selective HDAC6i than previously established well-characterized compounds in vitro as well as in cells. Moreover, Marbostat-100 is well tolerated by mice and effective against collagen type II induced arthritis. Thus, Marbostat-100 represents a most selective known HDAC6i and the possibility for clinical evaluation of a HDAC isoform-specific drug. KW - Animals KW - anti-Inflammatory agent KW - chemical synthesis KW - pharmacology KW - therapeutic use KW - toxicity Y1 - 2018 U6 - https://doi.org/10.1021/acs.jmedchem.7b01593 VL - 61 IS - 8 SP - 3454 EP - 3477 PB - ACS Publications 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 - GEN A1 - Singh, Max Diamond T1 - MDR Implementation Status and Lessons Learned from the Past Months: A Notified Body Perspective T2 - Cambridge Healthtech Institute's 2nd Annual Medical Device Clinical Trial Design and Operations: Trial Design and Technology to Optimize Medical Device Trials, Orlando, Florida + Virtual, 02.-03.03.2021 Y1 - PB - Cambridge Innovation Institute ER - TY - GEN A1 - Singh, Max Diamond T1 - MDR implementation status & lessons learned BT - MDR-Audtis – Best Practive & Learning, Tuttlingen, 10.02.2021 Y1 - 2021 ER - TY - GEN A1 - Singh, Max Diamond T1 - European Union MDRs impact on device manufacturers: Reprocessing of surgical invasive devices, critical timeliness and technical documentation requirements under MDR BT - [Vortrag gehalten am 26.03.2019] T2 - The validation of sterile medical devices: sterilization, packaging, biocompatibility, toxicology and reprocessing, Amsterdam, 26.03. - 28.03.2019 [Veranstalter: Nelson Labs ; Sterigenics] Y1 - 2019 ER - TY - GEN A1 - Singh, Max Diamond T1 - Challenges to innovate in the medical device industry under the light of the new EU MDR : a notified body perspective BT - Keynote Presentation. - Amsterdam, 21.-22.11.2019 // [Veranstalter: Samtek Group] T2 - Intelligent medical devices - the next disruptor in healthcare ; challenges and oppoertunieties: technical, clinical, regulatory and health economics/market access Y1 - 2019 ER - TY - GEN A1 - Singh, Max Diamond T1 - Zusätzliche Anforderungen an Produktdaten und technische Dokumentation durch die MDR T2 - Medizintechnik Kongress 2018: Effizienz in der Medizinprodukteentwicklung vor dem Hintergrund von MDR und IVDR ; Frankfurt am Main, 08.11.2018, [Veranstalter: Velten Consulting & ILC Consulting] Y1 - 2018 ER - TY - GEN A1 - Singh, Max Diamond T1 - EU-MDR from a Notified Body Perspective - aktuelle Situation hinsichtlich der Anforderungen zum Lieferantenmanagement BT - Tuttlingen, Technology Mountains / Medical Mountains, 2019 Y1 - 2019 ER - TY - GEN A1 - Singh, Max Diamond T1 - EU Medical Device Regulation: Top Challenges of Orthopedic Manufacturers T2 - OMTEC 2019 : 15th Annual Orthopedic Manufacturing & Technology Exposition and Conference, Chicago, 11.6.2019 Y1 - 2019 ER - TY - GEN A1 - Singh, Max Diamond T1 - Conformity Assessment Procedure MDR BT - [Vortrag gehalten am 24.02.2020] T2 - MDR Training: Person Responsible for Regulatory Compliance Course, 24.-25.02.2020, Tel Aviv, Obelis Academy Y1 - 2020 ER - TY - GEN A1 - Singh, Max Diamond T1 - Managing Innovation from the Notified Body Perspective - Understanding the 3 C’s of EU Regulations to Ensure Product Compliance: Changes, Challenges and Contributions T2 - 3rd annual european medical device and diagnostic product development and management meeting, 12-13 February 2019, Brussels Y1 - 2019 ER - TY - GEN A1 - Singh, Max Diamond T1 - Notified body feedback: PSUR Forms. Post Market Surveillance & Vigilance BT - [Vortrag gehalten am 24.06.2020] T2 - MedTech Summit 2020: EU MDR & IVDR: the end is in sight, Dublin/virtual, 20.-26.06.2020 Y1 - 2020 ER - TY - GEN A1 - Singh, Max Diamond T1 - MDR - Die neuen rechtlichen Bedingungen für Händler und Hersteller: aus der Sicht einer benannten Stelle T2 - MEGRA Jahrestagung. - Wien, 18.05.2020 [Veranstalter: Mitteleuropäische Gesellschaft für Regulatory Affairs] Y1 - 2020 ER - TY - GEN A1 - Singh, Max Diamond T1 - Innovation challenges for orthopedic device manufacturers under the new EU MDR BT - a notified body perspective T2 - ORS (Orthopaedic Research Society) Annual Meeting. - Phoenix, Arizona, 08. - 11.02.2020 Y1 - 2020 ER - TY - GEN A1 - Singh, Max Diamond T1 - KARL STORZ Navigation Panel Unit - Navigation for ENT surgery T2 - FESS 2010 : International Workshop on FESS ; Lectures & Live Surgery. - Royal Pearl Hospital, Tiruchirappalli (Indien), 10.-11.04.2010 Y1 - 2010 ER -