@misc{Dendorfer, author = {Dendorfer, Sebastian}, title = {Diagnostische Genauigkeit und klinische Anwendungen tragbarer Bewegungssensoren f{\"u}r die Kniegelenksrehabilitation}, address = {N{\"u}rnberg}, language = {de} } @article{Dendorfer, author = {Dendorfer, Sebastian}, title = {{\"A}lterwerden muss auch mal wehtun!}, series = {Gesunde Hochschule, OTH Regensburg, 4.7.2016}, journal = {Gesunde Hochschule, OTH Regensburg, 4.7.2016}, language = {de} } @misc{Dendorfer, author = {Dendorfer, Sebastian}, title = {The influence of modeling parameters in the AnyBody Modeling System on muscle and joint loading in the shoulder}, series = {International Shoulder Group Meeting}, volume = {05}, journal = {International Shoulder Group Meeting}, language = {en} } @misc{Dendorfer, author = {Dendorfer, Sebastian}, title = {The influence of mental stress on the musculoskeletal system}, language = {en} } @inproceedings{Dendorfer, author = {Dendorfer, Sebastian}, title = {Virtuelle Menschmodelle - von der Bewegung zur Belastung}, series = {Medbo Bezirksklinikum Regensburg, April 2016}, booktitle = {Medbo Bezirksklinikum Regensburg, April 2016}, language = {de} } @inproceedings{Dendorfer, author = {Dendorfer, Sebastian}, title = {Biomechanik des Alterns}, series = {Kolpingfortbildung Lambach, April 2016}, booktitle = {Kolpingfortbildung Lambach, April 2016}, language = {de} } @inproceedings{Dendorfer, author = {Dendorfer, Sebastian}, title = {Mechanobiology - Impact on regeneration and degradation}, series = {Translations in Regenerative Medicine, TIRM and FIFA Symposium, Regensburg, 2015}, booktitle = {Translations in Regenerative Medicine, TIRM and FIFA Symposium, Regensburg, 2015}, language = {en} } @inproceedings{Dendorfer, author = {Dendorfer, Sebastian}, title = {Einf{\"u}hrung in die Mechanik}, series = {Biomechanik Workshop, Klinikum Bad Abbach, Nov. 2013}, booktitle = {Biomechanik Workshop, Klinikum Bad Abbach, Nov. 2013}, language = {de} } @inproceedings{Dendorfer, author = {Dendorfer, Sebastian}, title = {Innovationen in der Medizintechnik}, series = {Oberpfalztag Weiherhammer, Nov. 2013}, booktitle = {Oberpfalztag Weiherhammer, Nov. 2013}, language = {de} } @inproceedings{Dendorfer, author = {Dendorfer, Sebastian}, title = {The effect of multifidus muscles atrophy following disc herniation on disc loading}, series = {Deutsche Gesellschaft f{\"u}r Biomechanik, Murnau, 2011}, booktitle = {Deutsche Gesellschaft f{\"u}r Biomechanik, Murnau, 2011}, language = {en} } @inproceedings{Dendorfer, author = {Dendorfer, Sebastian}, title = {How much iron to pump? The determination of muscle forces for activities of daily living}, series = {DGU, Berlin, 2008}, booktitle = {DGU, Berlin, 2008}, language = {en} } @misc{Dendorfer, author = {Dendorfer, Sebastian}, title = {Virtuelle Modelle der oberen Extremit{\"a}t}, series = {22. Interdisziplin{\"a}res Symposium Medizin-Physiotherapie-Sportwissenschaften, 22.-23.11.2019, Regensburg, Germany}, journal = {22. Interdisziplin{\"a}res Symposium Medizin-Physiotherapie-Sportwissenschaften, 22.-23.11.2019, Regensburg, Germany}, language = {de} } @inproceedings{Dendorfer, author = {Dendorfer, Sebastian}, title = {Biomechanical evaluation and optimisation of countermeasure exercises}, series = {ESA/ESTEC Bedrest Strategy Workshop, Noordwijk, NL, 2009}, booktitle = {ESA/ESTEC Bedrest Strategy Workshop, Noordwijk, NL, 2009}, language = {en} } @misc{Dendorfer, author = {Dendorfer, Sebastian}, title = {Sturz- und Frakturpr{\"a}vention: Use it or lose it!}, series = {10 Jahre Alterstraumatologie Caritas Krankenhaus St. Josef Regensburg}, journal = {10 Jahre Alterstraumatologie Caritas Krankenhaus St. Josef Regensburg}, language = {de} } @inproceedings{DendorferCarbesRasmussen, author = {Dendorfer, Sebastian and Carbes, S. and Rasmussen, John}, title = {The influence of muscle forces on biomechanical fracture fixation simulations - from in-vivo forces to tissue strains}, series = {World Congress on Medical Physics and Biomedical Engineering, 7 - 12, 2009, Munich}, booktitle = {World Congress on Medical Physics and Biomedical Engineering, 7 - 12, 2009, Munich}, language = {en} } @inproceedings{DendorferEnglert, author = {Dendorfer, Sebastian and Englert, Carsten}, title = {Forces on a clavicles midshaft fracture and influence of fracture type}, series = {AO Symposium, Regensburg, 2009}, booktitle = {AO Symposium, Regensburg, 2009}, language = {en} } @inproceedings{DendorferFeldottoWalchetal., author = {Dendorfer, Sebastian and Feldotto, Benedikt and Walch, Blasius and Koch, Patrick and Knoll, Alois}, title = {Co-Development of an Infant Prototype in Hardware and Simulation based on CT Imaging Data}, series = {IEEE International Conference on Cyborg and Bionic Systems (CBS), 2019, Munich}, booktitle = {IEEE International Conference on Cyborg and Bionic Systems (CBS), 2019, Munich}, pages = {6}, abstract = {The development of biomimetic robots has gained research interest in the last years as it may both help under-standing processes of motion execution in biological systems as well as developping a novel generation of intelligent and energy efficient robots. However, exact model generation that builds up on observations and robot design is very time intensive. In this paper we present a novel pipeline for co-development of biomimetic hardware and simulation models based on biological Computer Tomography (CT) data. For this purpose we exploit State of the Art rapid prototyping technologies such as 3D Printing and the Neurorobotics Platform for musculoskeletal simulations in virtual environments. The co-development integrates both advantages of virtual and physical experimental models and is expected to increase development speed of controllers that can be tested on the simulated counterpart before application to a printed robot model. We demonstrate the pipeline by generating a one year old infant model as a musculoskeletal simulation model and a print-in-place 3D printed skeleton as a single movable part. Even though we hereonly introduce the initial body generation and only a first testsetup for a modular sensory and control framework, we can clearly spot advantages in terms of rapid model generation and highly biological related models. Engineering costs are reducedand models can be provided to a wide research community for controller testing in an early development phase.}, subject = {Biomechanische Analyse}, language = {en} } @article{DendorferGschossman, author = {Dendorfer, Sebastian and Gschoßman, Lukas}, title = {Hightech in der Rehabiliation}, series = {BVOU Infobrief: Hightech in Orthop{\"a}die und Unfallchirurgie}, journal = {BVOU Infobrief: Hightech in Orthop{\"a}die und Unfallchirurgie}, number = {1}, publisher = {BVOU - Berufsverband f{\"u}r Orthop{\"a}die und Unfallchirurgie e.V.}, address = {Berlin}, issn = {2747-5913}, pages = {9 -- 11}, abstract = {Aufgrund der steigenden Lebenserwartung und dem damit einhergehenden demographischen Wandel wird der Bedarf an Rehabilitations-Behandlungen in absehbarer Zukunft stark ansteigen. Ein Beispiel f{\"u}r diesen Trend ist die physiotherapeutische Behandlung nach Erhalt einer Knie-Totalendoprothese (Knie-TEP). So gehen Modellrechnungen basierend auf dem Bev{\"o}lkerungswachstum und der bisherigen Pr{\"a}valenz von Knie-TEPs davon aus, dass die Anzahl an durchgef{\"u}hrten Eingriffen in einkommensstarken L{\"a}ndern wie Deutschland weiter zunehmen wird. Weiterhin stoßen traditionelle Rehabilitationsverfahren, gerade in strukturschwachen Regionen, schon heute an ihre Grenzen. Deutlich zu sehen war das w{\"a}hrend den Hochphasen der aktuellen Covid-19-Pandemie, als der Kontakt zwischen Therapeut*in und Patient*in fl{\"a}chendeckend eingeschr{\"a}nkt war. Eine erh{\"o}hte Nachfrage nach neuartigen Reha-Angeboten ist die logische Konsequenz. Innovative Konzepte sind daher dringend notwendig, um die daraus resultierenden technischen, sozialen und {\"o}konomischen Herausforderungen zu bew{\"a}ltigen.}, language = {de} } @article{DendorferHammerLenich, author = {Dendorfer, Sebastian and Hammer, Joachim and Lenich, Andreas}, title = {Characterisation and testing of biomaterials}, series = {Technology and Health Care}, volume = {19}, journal = {Technology and Health Care}, number = {5}, doi = {10.3233/THC-2011-0644}, pages = {357 -- 371}, subject = {Biomaterial}, language = {en} } @incollection{DendorferHammerLenich, author = {Dendorfer, Sebastian and Hammer, Joachim and Lenich, Andreas}, title = {Characterisation and testing of biomaterials}, series = {Basic Engineering for Medics and Biologists: An ESEM Primer}, booktitle = {Basic Engineering for Medics and Biologists: An ESEM Primer}, number = {Chapter IV.4.}, editor = {Lee, T. Clive and Niederer, Peter F.}, publisher = {Non Basic Stock Line}, isbn = {978-1607505266}, subject = {Biomaterial}, language = {en} } @inproceedings{DendorferKubowitsch, author = {Dendorfer, Sebastian and Kubowitsch, Simone}, title = {The interaction of mental stress and biomechanics}, series = {Health Technology Triangle, Weiden, 2016}, booktitle = {Health Technology Triangle, Weiden, 2016}, language = {en} } @inproceedings{DendorferKubowitschSuess, author = {Dendorfer, Sebastian and Kubowitsch, Simone and S{\"u}ß, Franz}, title = {How to determine the effect of working conditions on the human body}, series = {11th International Scientific Conference on Production Engineering DEVELOPMENT AND MODERNIZATION OF PRODUCTION (RIM 2017), Sarajevo, Bosnia and Herzegovina}, booktitle = {11th International Scientific Conference on Production Engineering DEVELOPMENT AND MODERNIZATION OF PRODUCTION (RIM 2017), Sarajevo, Bosnia and Herzegovina}, abstract = {Work places and conditions strains the human body, both psychologically and biomechanically. In order to analyse working conditions and in the following to improve them, detailed knowledge about the effect of the different stressors on the body is needed. This manuscript discusses methods on how to evaluate biomechanical and mental loading and its effect on the musculoskeletal system. A possible workflow for the analysis is presented.}, subject = {Arbeitsbedingungen}, language = {en} } @article{DendorferMaierHammer, author = {Dendorfer, Sebastian and Maier, Hans J{\"u}rgen and Hammer, Joachim}, title = {Fatigue damage in cancellous bone: an experimental approach from continuum to micro scale}, series = {Journal of the Mechanical Behavior of Biomedical Materials}, volume = {2}, journal = {Journal of the Mechanical Behavior of Biomedical Materials}, number = {1}, doi = {10.1016/j.jmbbm.2008.03.003}, pages = {113 -- 119}, abstract = {Repeated loadings may cause fatigue fractures in bony structures. Even if these failure types are known, data for trabecular bone exposed to cyclic loading are still insufficient as the majority of fatigue analyses on bone concentrate on cortical structures. Despite its highly anisotropic and inhomogeneous structure, trabecular bone is treated with continuum approaches in fatigue analyses. The underlying deformation and damage mechanism within trabecular specimens are not yet sufficiently investigated. In the present study different types of trabecular bone were loaded in monotonic and cyclic compression. In addition to the measurement of integral specimen deformations, optical deformation analysis was employed in order to obtain strain distributions at different scale levels, from the specimens' surface to the trabeculae level. These measurements allowed for the possibility of linking the macroscopic and microscopic mechanical behaviour of cancellous bone. Deformations were found to be highly inhomogeneous across the specimen. Furthermore strains were found to already localise at very low load levels and after few load cycles. Microcracks in individual trabeculae were induced in the very early stage of cyclic testing. The results provide evidence of the capability of the method to supply essential data on the failure behaviour of individual trabeculae in future studies.}, subject = {Knochen}, language = {en} } @incollection{DendorferMaierHammer, author = {Dendorfer, Sebastian and Maier, Hans J{\"u}rgen and Hammer, Joachim}, title = {How do age and anisotropy affect the fatigue behaviour of cancellous bone?}, series = {Medicine Meets Engineering}, booktitle = {Medicine Meets Engineering}, publisher = {IOS Press}, pages = {68 -- 74}, abstract = {The fatigue behaviour of materials is of particular interest for the failure prediction of materials and structures exposed to cyclic loading. For trabecular bone structures only a few sets of lifetime data have been reported in the literature and structural measures are commonly not considered. The influence of load contributions not aligned with the main physiological axis remains unclear. Furthermore age effects on the fatigue behaviour are not well described. In the present study, different groups of human vertebral cancellous bone were exposed to cyclic compression. The inital modulus and therefore lifetimes were found to be highly dependent on age. The decrease in both with increasing age was much more pronounced in specimens which were not aligned with the main physiological axis. This implies that old bone is much more sensitive to (cyclic) failure loads in general but particularly to loads which are not coincident with the physiological main axis.}, subject = {Knochenbruch}, language = {en} } @article{DendorferMaierTayloretal., author = {Dendorfer, Sebastian and Maier, Hans J{\"u}rgen and Taylor, David and Hammer, Joachim}, title = {Anisotropy of the fatigue behaviour of cancellous bone}, series = {Journal of Biomechanics}, volume = {41}, journal = {Journal of Biomechanics}, number = {3}, doi = {10.1016/j.jbiomech.2007.09.037}, pages = {636 -- 641}, abstract = {The fatigue behaviour of materials is of particular interest for the failure prediction of materials and structures exposed to cyclic loading. For trabecular bone structures only a few sets of lifetime data have been reported in the literature and structural measures are commonly not considered. The influence of load contributions which are not aligned with the main physiological axis remains unclear. Furthermore site and species dependent relationships are not well described. In this study five different groups of trabecular bone, defined in terms of orientation, species and site were exposed to cyclic compression. In total, 108 fatigue tests were analysed. The lifetimes were found to decrease drastically when off-axis loads were applied. Additionally, species and site strongly affect fatigue lifetimes. Strains at failure were also found to be a function of orientation.}, subject = {Erm{\"u}dung}, language = {en} } @article{DendorferMelzner, author = {Dendorfer, Sebastian and Melzner, Maximilian}, title = {R{\"u}ckenschmerzen bei Geburtshelfer:innen. Die Haltung macht's.}, series = {Deutsche Hebammen-Zeitschrift}, volume = {74}, journal = {Deutsche Hebammen-Zeitschrift}, number = {11}, publisher = {Staude}, address = {Hannover}, issn = {0012-026X}, pages = {60 -- 62}, abstract = {F{\"u}r Mutter und Kind konnte das Risiko der Geburt durch die Weiterentwicklung der Medizin drastisch reduziert werden. Doch wie ist es um das Wohl derer bestellt, die die Geb{\"a}rende unterst{\"u}tzen? Eine Studie der Ostbayerischen Technischen Hochschule Regensburg hat sich mit den muskuloskelettalen Beschwerden von Geburtshelfer:innen auseinandergesetzt}, language = {de} } @inproceedings{DendorferPenzkofer, author = {Dendorfer, Sebastian and Penzkofer, Rainer}, title = {Experimentelle Untersuchung der Belastungen im Kopf beim Treten}, series = {Fachsymposium "Treten gegen den Kopf", April 2013, N{\"u}rnberg}, booktitle = {Fachsymposium "Treten gegen den Kopf", April 2013, N{\"u}rnberg}, language = {de} } @inproceedings{DendorferRasmussen, author = {Dendorfer, Sebastian and Rasmussen, John}, title = {The influence of in-vivo muscle forces on the stress distribution in a vertebral body during activities of daily living}, series = {Eurospine Warsaw, Poland 2009}, booktitle = {Eurospine Warsaw, Poland 2009}, language = {en} } @inproceedings{DendorferRasmussenChristensenetal., author = {Dendorfer, Sebastian and Rasmussen, John and Christensen, Soeren Toerholm and Robie, Bruce}, title = {The Effect of Spinal Disc Herniation on Multifidus Muscles}, series = {56th Orthopaedic Research Society Meeting, New Orleans, USA, 2010}, booktitle = {56th Orthopaedic Research Society Meeting, New Orleans, USA, 2010}, language = {en} } @article{DendorferWeberKennedy, author = {Dendorfer, Sebastian and Weber, Tim and Kennedy, O.}, title = {Musculoskeletal modeling for hip replacement outcome analyses and other applications}, series = {The Journal of the American Academy of Orthopaedic Surgeons}, volume = {22}, journal = {The Journal of the American Academy of Orthopaedic Surgeons}, number = {4}, doi = {10.5435/JAAOS-22-04-268}, pages = {268 -- 269}, subject = {H{\"u}ftgelenkprothese}, language = {en} } @article{DeuterHajBrawanskietal., author = {Deuter, Daniel and Haj, Amer and Brawanski, Alexander and Krenkel, Lars and Schmidt, Nils Ole and Doenitz, Christian}, title = {Fast simulation of hemodynamics in intracranial aneurysms for clinical use}, series = {Acta Neurochirurgica}, volume = {167}, journal = {Acta Neurochirurgica}, publisher = {Springer}, doi = {10.1007/s00701-025-06469-9}, pages = {14}, abstract = {BACKGROUND: A widely accepted tool to assess hemodynamics, one of the most important factors in aneurysm pathophysiology, is Computational Fluid Dynamics (CFD). As current workflows are still time consuming and difficult to operate, CFD is not yet a standard tool in the clinical setting. There it could provide valuable information on aneurysm treatment, especially regarding local risks of rupture, which might help to optimize the individualized strategy of neurosurgical dissection during microsurgical aneurysm clipping. METHOD: We established and validated a semi-automated workflow using 3D rotational angiographies of 24 intracranial aneurysms from patients having received aneurysm treatment at our centre. Reconstruction of vessel geometry and generation of volume meshes was performed using AMIRA 6.2.0 and ICEM 17.1. For solving ANSYS CFX was used. For validational checks, tests regarding the volumetric impact of smoothing operations, the impact of mesh sizes on the results (grid convergence), geometric mesh quality and time tests for the time needed to perform the workflow were conducted in subgroups. RESULTS: Most of the steps of the workflow were performed directly on the 3D images requiring no programming experience. The workflow led to final CFD results in a mean time of 22 min 51.4 s (95\%-CI 20 min 51.562 s-24 min 51.238 s, n = 5). Volume of the geometries after pre-processing was in mean 4.46\% higher than before in the analysed subgroup (95\%-CI 3.43-5.50\%). Regarding mesh sizes, mean relative aberrations of 2.30\% (95\%-CI 1.51-3.09\%) were found for surface meshes and between 1.40\% (95\%-CI 1.07-1.72\%) and 2.61\% (95\%-CI 1.93-3.29\%) for volume meshes. Acceptable geometric mesh quality of volume meshes was found. CONCLUSIONS: We developed a semi-automated workflow for aneurysm CFD to benefit from hemodynamic data in the clinical setting. The ease of handling opens the workflow to clinicians untrained in programming. As previous studies have found that the distribution of hemodynamic parameters correlates with thin-walled aneurysm areas susceptible to rupture, these data might be beneficial for the operating neurosurgeon during aneurysm surgery, even in acute cases.}, language = {en} } @misc{EgerBergstraesserDendorferetal., author = {Eger, Maximilian and Bergstraesser, Marcel and Dendorfer, Sebastian and Lenich, Andreas and Pfeifer, Christian}, title = {Influence of radial head prosthetic design on humeroradial stability: Validation of a test rig therefore}, series = {DOKU2022, Deutscher Kongress f{\"u}r Orthop{\"a}die und Unfallchirurgie, 25.-28. 10.2022, Berlin}, journal = {DOKU2022, Deutscher Kongress f{\"u}r Orthop{\"a}die und Unfallchirurgie, 25.-28. 10.2022, Berlin}, publisher = {German Medical Science GMS Publishing House}, address = {D{\"u}sseldorf}, doi = {10.3205/22dkou611}, url = {http://nbn-resolving.de/urn:nbn:de:0183-22dkou6115}, language = {en} } @phdthesis{Eigenberger, author = {Eigenberger, Andreas}, title = {Die Auswirkungen der mechanischen Kr{\"a}fte eines innovativen Operationsverfahrens f{\"u}r die intraoperative Gewebezubereitung bei autologem Fetttransfer auf das Fettgewebe und dessen Stammzellen}, address = {Regensburg}, pages = {235 Bl{\"a}tter}, language = {de} } @article{EigenbergerFelthausSchratzenstalleretal., author = {Eigenberger, Andreas and Felthaus, Oliver and Schratzenstaller, Thomas and Haerteis, Silke and Utpatel, Kirsten and Prantl, Lukas}, title = {The Effects of Shear Force-Based Processing of Lipoaspirates on White Adipose Tissue and the Differentiation Potential of Adipose Derived Stem Cells}, series = {cells}, volume = {11}, journal = {cells}, number = {16}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/cells11162543}, pages = {13}, abstract = {Autologous lipotransfer is a promising method for tissue regeneration, because white adipose tissue contains a heterogeneous cell population, including mesenchymal stem cells, endothelial cells, immune cells, and adipocytes. In order to improve the outcome, adipose tissue can be processed before application. In this study, we investigated changes caused by mechanical processing. Lipoaspirates were processed using sedimentation, first-time centrifugation, shear-force homogenization, and second-time centrifugation. The average adipocyte size, stromal vascular cell count, and adipocyte depot size were examined histologically at every processing step. In addition, the adipose derived stem cells (ADSCs) were isolated and differentiated osteogenically and adipogenically. While homogenization causes a disruption of adipocyte depots, the shape of the remaining adipocytes is not changed. On average, these adipocytes are smaller than the depot adipocytes, they are surrounded by the ECM, and therefore mechanically more stable. The volume loss of adipocyte depots leads to a significant enrichment of stromal vascular cells such as ADSCs. However, the mechanical processing does not change the potential of the ADSCs to differentiate adipogenically or steogenically. It thus appears that mechanically processed lipoaspirates are promising for the reparation of even mechanically stressed tissue as that found in nasolabial folds. The changes resulting from the processing correspond more to a filtration of mechanically less stable components than to a manipulation of the tissue.}, language = {en} } @misc{EngelhardtMelznerHavelkovaetal., author = {Engelhardt, Lucas and Melzner, Maximilian and Havelkova, Linda and Fiala, Pavel and Rybarova, Martina and Christen, Patrik and Dendorfer, Sebastian and Simon, Ulrich}, title = {A new musculoskeletal AnyBody detailed hand model}, series = {European Society of Biomechanics meeting 2019, Vienna, Austria}, journal = {European Society of Biomechanics meeting 2019, Vienna, Austria}, abstract = {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.}, language = {en} } @article{EnglertAngeleFierlbecketal., author = {Englert, Carsten and Angele, Peter and Fierlbeck, J. and Dendorfer, Sebastian and Schubert, T. and M{\"u}ller, R. and Lienhard, S. and Zellner, Johannes and Nerlich, Michael and Neumann, Carsten}, title = {Conductive bone substitute material with variable antibiotic delivery}, series = {Der Unfallchirurg}, volume = {110}, journal = {Der Unfallchirurg}, number = {5}, publisher = {Springer}, doi = {10.1007/s00113-007-1229-3}, pages = {408 -- 413}, abstract = {A new bone substitute, consisting of hydroxylapatite and calcium sulphate, was prepared in two formulations and analysed for its mechanical strength and antibiotic elution.The bone substitute PerOssal has osteoconductive and degradable properties. The material has a built-in capillary structure, which results in an immediate fluid uptake. Antibiotics absorbed to the bone substitute resulted in a prolonged release rate. Mechanical strength was investigated by an unconfined compression test up to failure under both wet and dry conditions for both formulations of the bone substitute. Antibiotic release was analysed microbiologically for two antibiotics, vancomycin and gentamicin, over an elution period of 10 days using the agar diffusion method.The drug release analysis resulted in a prolonged release rate of both antibiotics over 10 days. In vitro the amount of gentamicin and vancomycin eluted at day 10. From one pellet still exceeded the minimal inhibitory concentration of most aetiologically important pathogens. Formulation two of the present bone substitute is significantly harder in both wet and dry conditions when compared to formulation one. Both formulations lose strength in the wet condition relative to their performance in the dry condition. However, formulation two is as hard under wet conditions as formulation one is when dry.PerOssal is a suitable new degradable osteoconductive bone substitute that can be loaded with antibiotic solutions, which are released in effective doses over 10 days. The mechanical strength of PerOssal is sufficient to support cancellous bone defects in non-weight-bearing areas or in combination with osteosynthesis.}, subject = {Knochenersatz}, language = {en} } @misc{EnglertDendorfer, author = {Englert, Carsten and Dendorfer, Sebastian}, title = {Einfluss der Rotatorenmanschette auf die glenohumerale Stabilit{\"a}t}, series = {20. Intensivkurs Schulterendoprothetik Marburg}, journal = {20. Intensivkurs Schulterendoprothetik Marburg}, address = {Marburg}, language = {de} } @inproceedings{EnglertMuellerDendorfer, author = {Englert, Carsten and M{\"u}ller, F. and Dendorfer, Sebastian}, title = {Einfluss der Muskelkr{\"a}fte, des Bewegungsausmaßes und der Bruchform auf die Kraft{\"u}bertragung des Implantat-Knochenverbundes am Beispiel der Claviculafraktur im mittleren Drittel}, series = {17. Jahreskongress der Deutschen Vereinigung f{\"u}r Schulter- und Ellenbogenchirurgie (DVSE), Rosenheim 2010}, booktitle = {17. Jahreskongress der Deutschen Vereinigung f{\"u}r Schulter- und Ellenbogenchirurgie (DVSE), Rosenheim 2010}, abstract = {Fragestellung Es soll in dieser Computersimulationsstudie untersucht werden, wie der Osteosyntheseverbund Platte mit Schrauben im Verbund mit einer im mittleren Drittel gebrochenen Clavicula durch das Bewegungsausmaß in vivo belastet ist. Was sind die grundlegenden Kr{\"a}fte die auf Clavicula und Implantat wirken und welchen Einfl uss hat die Bruchform. Methodik Die Muskel- und Gelenkkr{\"a}fte sowie die Belastung des Implantatverbundes wurden mit einer muskuloskelletalen Simulationssoftware (AnyBody Technology, V.4) berechnet. Hierf{\"u}r wurden mit einem komplexen Model des menschlichen K{\"o}rpers folgende Bewegungen analysiert: eine Flexion von 160° und Abduktion 160° mit einem Gewicht von 2 kg in der Hand. Aus CT-Patientendaten wurden zwei dreidimensionale Modelle des Clavicula-Implantat Verbundes gebildet, die sich in der Frakturform unterscheiden (Querfraktur und vertikale Fraktur). In beiden Modellen wurde eine Claviculaosteosynthese in superiorer Position mit einer 6 Loch LCP mit 2 Schrauben pro Hauptfragment verwendet. Die Materialeigenschaften wurden aus der Dichte des Materials sowie aus Literaturdaten verwendet. Die Muskel- und Gelenkkr{\"a}fte aus der muskuloskelletalen Berechnung wurden auf das Finite Elemente Modell {\"u}bertragen und die Spannungen und Dehnungen des Implantat-Knochenverbundes wurden berechnet. Ergebnisse Es zeigte sich, dass die simulierte in vivo Belastung stark abh{\"a}ngig vom Flexionswinkel ist. Das Implantat ist in der superioren Lage auf Biegung belastet, welche maximale Werte im {\"U}berschulterniveau erreicht. Die Bruchform mit anatomischer Reposition und Kontakt der Hauptfragmente zueinander f{\"u}hrt zu einer deutlichen Entlastung des Osteosyntheseverbundes im Vergleich zu einer Bruchform mit vertikaler Fraktur. Schlussfolgerung Aus den Analysen ist eine Positionierung der Plattenosteosynthese f{\"u}r die im mittleren Drittel frakturierte Clavicula in anterior-superiorer Lage w{\"u}nschenswert. Die anatomische Reposition entlastet den Osteosyntheseverbund und sollte m{\"o}glichst erreicht werden. Die Nachbehandlung sollte ein Bewegungsausmaß f{\"u}r den Arm f{\"u}r 4 Wochen f{\"u}r einfache Bruchformen auf 70° Flexion und Abduktion limitieren und f{\"u}r komplexe Bruchformen diese Limitierung ausgedehnt werden.}, language = {de} } @article{FoltanDinhGruberetal., author = {Foltan, Maik and Dinh, D. and Gruber, Michael and M{\"u}ller, Thomas and Hart, C. and Krenkel, Lars and Schmid, C. and Lehle, Karla}, title = {Incidence of neutrophil extracellular traps (NETs) in different membrane oxygenators: pilot in vitro experiments in commercially available coated membranes}, series = {Journal of artificial organs : the official journal of the Japanese Society for Artificial Organs}, journal = {Journal of artificial organs : the official journal of the Japanese Society for Artificial Organs}, doi = {10.1007/s10047-024-01486-4}, abstract = {Neutrophil extracellular traps (NETs) were detected in blood samples and in cellular deposits of oxygenator membranes during extracorporeal membrane oxygenation (ECMO) therapy and may be responsible for thrombogenesis. The aim was to evaluate the effect of the base material of gas fiber (GF, polymethylpentene) and heat exchange (HE) membranes and different antithrombogenic coatings on isolated granulocytes from healthy volunteers under static culture conditions. Contact of granulocytes with membranes from different ECMO oxygenators (with different surface coatings) and uncoated-GFs allowed detection of adherent cells and NETotic nuclear structures (normal, swollen, ruptured) using nuclear staining. Flow cytometry was used to identify cell activation (CD11b/CD62L, oxidative burst) of non-adherent cells. Uncoated-GFs were used as a reference. Within 3 h, granulocytes adhered to the same extent on all surfaces. In contrast, the ratio of normal to NETotic cells was significantly higher for uncoated-GFs (56-83\%) compared to all coated GFs (34-72\%) (p < 0.001) with no difference between the coatings. After material contact, non-adherent cells remained vital with unchanged oxidative burst function and the proportion of activated cells remained low. The expression of activation markers was independent of the origin of the GF material. In conclusion, the polymethylpentene surfaces of the GFs already induce NET formation. Antithrombogenic coatings can already reduce the proportion of NETotic nuclei. However, it cannot be ruled out that NET formation can induce thrombotic events. Therefore, new surfaces or coatings are required for future ECMO systems and long-term implantable artificial lungs.}, language = {en} } @inproceedings{Fuhrmann, author = {Fuhrmann, Thomas}, title = {Semi-Structured Lab Projects in Communication Engineering Education}, series = {2023 IEEE Global Engineering Education Conference (EDUCON), 01-04 May 2023, Kuwait}, booktitle = {2023 IEEE Global Engineering Education Conference (EDUCON), 01-04 May 2023, Kuwait}, publisher = {IEEE}, doi = {10.1109/EDUCON54358.2023.10125244}, pages = {1 -- 5}, abstract = {It is generally known that project-based learning is a very important part of engineering education to connect theoretical knowledge with practical work. Students learn to apply their knowledge to real-world challenges as it is the case in their later professional life. If students are not used to project work or the scientific topic is new and relatively complex, they may be overwhelmed. The consequence is that students achieve poor results, are frustrated, and therefore learning success is low. Semi-structured projects are introduced that combine the advantages of structured experiments with projects. The project work is structured into several parts with detailed descriptions of the tasks. In the end, students get similar results to doing a free project, but the success rate is higher due to higher guidance. Therefore, these semi-structured projects are seen to be an appropriate method to guide students to learn how to do project work. The feedback from most students is very positive. Some students with no previous lab experience complained about the project work and wished for more guidance to become familiar with lab work. In sum, the student feedback is encouraging to develop semi-structured projects further.}, language = {en} } @misc{FoerstlAdlerSuessetal., author = {F{\"o}rstl, Nikolas and Adler, Ina and Suess, Franz and Čechov{\´a}, Hana and Jansov{\´a}, Magdalena and Cimrman, Robert and Vychytil, Jan and Dendorfer, Sebastian}, title = {Workflow for the development of a non-invasive feedback device to assess pelvic floor contractions}, series = {ESB 2024, 29th Congress of the European Society of Biomechanics, 30 June-3 July 2024, Edinburgh, Scotland}, journal = {ESB 2024, 29th Congress of the European Society of Biomechanics, 30 June-3 July 2024, Edinburgh, Scotland}, abstract = {Introduction Pelvic floor disorders affect about 40\% of women worldwide [1]. Pelvic floor muscle (PFM) training is both a preventive and a therapeutic intervention. Current PFM training devices are invasive and have little scientific evidence. The idea is to develop a noninvasive feedback device to assess adequate PFM contraction. Therefore, evidence-based female musculoskeletal models, non-invasive data acquisition, sensor technology and artificial intelligence (AI) will be combined. This work presents the workflow to achieve such a feedback device and describes the interaction of the technologies used. Methods Exercises that induce PFM contractions have been evaluated and defined. Motion capture of these exercises will provide input for female musculoskeletal models. A combination of biomechanical rigid body and FEM simulations will be used to estimate PFM contractions. In addition, a non-invasive sensor will measure pelvic floor activity. The simulated and measured data will be used to develop an AI model that provides feedback on PFM contractions based on non-invasive data collection. Results The AMMR (AnyBody Managed Model Repository) of the AnyBody modelling system (AMS, Aalborg, Denmark) serves as the initial model for performing inverse dynamic simulations of the exercises. To calculate the PFM forces, the full-body model must be supplemented with the relevant pelvic floor structures and a mass model of the internal organs. A modified abdominal pressure model must also be incorporated. The AMS calculates the PFM activities caused by the internal organ loads and the generated abdominal pressure during the exercises. The muscle activities are transferred to a FEM model of the female pelvic floor (SfePy, simple finite elements in Python). The identical pelvic floor structures were integrated into the FEM model as in the AMS. Active PFM contractions can be simulated using the FEM model. Movement of the coccyx due to PFM contractions has been reported in the literature [2,3]. Therefore, a noninvasive coccyx motion sensor will be developed to provide additional information on PFM contractions. The measured data (coccyx motion sensor, motion capture) and the simulation results of the models will be combined to create an AI feedback model using Python. The final feedback device will consist of the AI model and the developed coccyx motion sensor, which can reproduce the resulting PFM contractions based on the sensor data and simplified motion tracking. Discussion The creation of the AMS and the FEM model is a prerequisite for the development of the feedback device. The relevant structures in the models are located inside the body. This limits the ability to observe the structures during the exercises, which can lead to difficulties in model validation. The development of a user-friendly sensor with sufficient measuring accuracy of the coccyx motion is another challenge. Nevertheless, the workflow represents a promising approach to develop a noninvasive feedback system to assess PFM contraction. References 1. Wang et al, Front Public Health, 10:975829, 2022. 2. B{\o} et al, Neurourol Urodyn, 20:167-174, 2001. 3. Fujisaki et al, J Phys Ther Sci, 30:544-548, 2018. Acknowledgements This work was supported by the project no. BYCZ01-014 of the Program INTERREG Bavaria - Czechia 2021-2027.}, language = {en} } @unpublished{FoerstlAdlerSuessetal., author = {F{\"o}rstl, Nikolas and Adler, Ina and S{\"u}ß, Franz and Dendorfer, Sebastian}, title = {Technologies for Evaluation of Pelvic Floor Functionality: A Systematic Review}, publisher = {Center for Open Science}, doi = {10.31219/osf.io/dcqyg}, abstract = {Pelvic floor dysfunction is a common problem in women and has a negative impact ontheir quality of life. The aim of this review was to provide a general overview of the current state oftechnology used to assess pelvic floor functionality. It also provides literature research of the phys-iological and anatomical factors that correlate with pelvic floor health. The systematic review wasconducted according to the PRISMA guidelines. PubMed, ScienceDirect, Cochrane Library andIEEE databases were searched for publications on sensor technology for the assessment of pelvicfloor functionality. Anatomical and physiological parameters were identified through a manualsearch. In the systematic review 115 publications were included. 12 different sensor technologieswere identified. Information on the obtained parameters, sensor position, test activities and subjectcharacteristics were prepared in tabular form from each publication. 16 anatomical and physiologi- cal parameters influencing pelvic floor health were identified in 17 published studies and rankedfor their statistical significance. Taken together, this review could serve as a basis for the develop-ment of novel sensors which could allow for quantifiable prevention and diagnosis, as well as par-ticularized documentation of rehabilitation processes related to pelvic floor dysfunctions.}, language = {en} } @article{FoerstlAdlerSuessetal., author = {F{\"o}rstl, Nikolas and Adler, Ina and S{\"u}ß, Franz and Dendorfer, Sebastian}, title = {Technologies for Evaluation of Pelvic Floor Functionality: A Systematic Review}, series = {Sensors}, volume = {24}, journal = {Sensors}, number = {12}, publisher = {MDPI}, doi = {10.3390/s24124001}, abstract = {Pelvic floor dysfunction is a common problem in women and has a negative impact on their quality of life. The aim of this review was to provide a general overview of the current state of technology used to assess pelvic floor functionality. It also provides literature research of the physiological and anatomical factors that correlate with pelvic floor health. This systematic review was conducted according to the PRISMA guidelines. The PubMed, ScienceDirect, Cochrane Library, and IEEE databases were searched for publications on sensor technology for the assessment of pelvic floor functionality. Anatomical and physiological parameters were identified through a manual search. In the systematic review, 114 publications were included. Twelve different sensor technologies were identified. Information on the obtained parameters, sensor position, test activities, and subject characteristics was prepared in tabular form from each publication. A total of 16 anatomical and physiological parameters influencing pelvic floor health were identified in 17 published studies and ranked for their statistical significance. Taken together, this review could serve as a basis for the development of novel sensors which could allow for quantifiable prevention and diagnosis, as well as particularized documentation of rehabilitation processes related to pelvic floor dysfunctions.}, language = {en} } @article{FoerstlSuessEnglertetal., author = {F{\"o}rstl, Nikolas and S{\"u}ß, Franz and Englert, Carsten and Dendorfer, Sebastian}, title = {Design of a reverse shoulder implant to measure shoulder stiffness during implant component positioning}, series = {Medical Engineering \& Physics}, volume = {121}, journal = {Medical Engineering \& Physics}, edition = {Journal Pre-proof}, publisher = {Elsevier}, doi = {10.1016/j.medengphy.2023.104059}, pages = {22}, abstract = {To avoid dislocation of the shoulder joint after reverse total shoulder arthroplasty, it is important to achieve sufficient shoulder stability when placing the implant components during surgery. One parameter for assessing shoulder stability can be shoulder stiffness. The aim of this research was to develop a temporary reverse shoulder implant prototype that would allow intraoperative measurement of shoulder stiffness while varying the position of the implant components. Joint angle and torque measurement techniques were developed to determine shoulder stiffness. Hall sensors were used to measure the joint angles by converting the magnetic flux densities into angles. The accuracy of the joint angle measurements was tested using a test bench. Torques were determined by using thin-film pressure sensors. Various mechanical mechanisms for variable positioning of the implant components were integrated into the prototype. The results of the joint angle measurements showed measurement errors of less than 5° in a deflection range of ±15° adduction/abduction combined with ±45° flexion/extension. The proposed design provides a first approach for intra-operative assessment of shoulder stiffness. The findings can be used as a technological basis for further developments.}, language = {en} } @misc{FoerstlSuessEnglertetal., author = {F{\"o}rstl, Nikolas and S{\"u}ß, Franz and Englert, Carsten and Dendorfer, Sebastian}, title = {Design of a reverse shoulder implant to measure shoulder stiffness during implant component positioning}, series = {Book of abstracts / ESB 2023, 28th Congress of the European Society of Biomechanics, 9-12 July 2023, Maastricht, The Netherlands.}, journal = {Book of abstracts / ESB 2023, 28th Congress of the European Society of Biomechanics, 9-12 July 2023, Maastricht, The Netherlands.}, abstract = {Introduction Dislocation of the shoulder joint is one of the more common complications after reverse total shoulder arthroplasty [1], which is often associated with malposition of the prosthetic components [2]. Therefore, achieving sufficient shoulder stability should not be neglected when positioning the implant components. One parameter for assessing shoulder stability can be shoulder stiffness. The aim of this work is to develop a reverse shoulder implant prototype that allows intraoperative measurement of shoulder stiffness while varying the position of the implant components. The measured stiffness could provide a quantitative statement regarding the optimal positioning of the implant components, which can be adjusted accordingly in the final reverse shoulder prosthesis. Methods To measure the stiffness of the shoulder joint, it is necessary to record the joint angles and the torques generated during movement. The changes in the rotation angles were measured using 3D hall sensors and magnets. The magnets were placed under the humerosocket, and the hall sensors were integrated into the glenosphere. The strength of the magnetic field was used to determine the position of the humerosocket in relation to the glenosphere. The accuracies of the angle measurements were tested using a test bench. Three thin film pressure sensors were used to record forces at different points under the humerosocket. To obtain a force value from the sensor signal, the sensors were calibrated using a load cell. The variation of the implant components positions was integrated into the prototype implant through different constructive mechanisms to adjust the stiffness of the shoulder joint. Results In the range of ±45° flexion/extension combined with ±15° adduction/abduction, the joint position could be determined with sufficient accuracy (error e ≤ 5°). The areas near the combined maximum deflections of ±45° flexion/extension and ±45° adduction/abduction indicate the greatest deviation from the target angle. The force values of the thin film sensors enable the calculation of moments around two axes. As variable component position parameters, the tray offset, the neck-shaft angle and the humerus version were integrated into the implant prototype. Discussion Ideally, the accuracy of the angle measurements should only depend on the amount of deflection and not on the direction of deflection. The asymmetric behavior indicates a deviation from the correct positioning of the hall sensors. The application of a calibration matrix could compensate for the measurement errors and could demonstrate the potential of the new method for joint angle measurements. The accuracy of the torque measurements and the functionality of the mechanical arresting mechanisms must be investigated in further studies. Overall, the developed measurement method can help to avoid malpositioning of the implant components in reverse total shoulder arthroplasty. References 1. Clark et al, J Shoulder and elbow surgery, 21:36-41 2012. 2. Randelli et al, J Musculoskeletal surgery, 98:15-18, 2014.}, language = {en} } @inproceedings{GalibarovAlMunajjedDendorferetal., author = {Galibarov, Pavel E. and Al-Munajjed, Amir Andreas and Dendorfer, Sebastian and Christensen, Soeren Toerholm and Rasmussen, John}, title = {The effect of varying the stiffness of spinal fusion devices on the adjacent levels using multibody dynamics simulation}, series = {Orthopaedic Proceedings}, volume = {94-B}, booktitle = {Orthopaedic Proceedings}, number = {SUPP_XL01 Sep 2012}, pages = {2}, abstract = {INTRODUCTION Several clinical studies demonstrated long-term adjacent-level effects after implantation of spinal fusion devices[1]. These effects have been reported as adjacent joint degeneration and the development of new symptoms correlating with adjacent segment degeneration[2] and the trend has therefore gone to motion preservation devices; however, these effects have not been understood very well and have not been investigated thoroughly[3]. The aim of this study is to investigate the effect of varying the stiffness of spinal fusion devices on the adjacent vertebral levels. Disc forces, moments and facet joint forces were analyzed. METHODS The AnyBody Modeling System was used to compute the in-vivo muscle and joint reaction forces of a musculoskeletal model. The full body model used in this study consists of 188 muscle fascicles in the lumbar spine and more than 1000 individual muscle branches in total. The model has been proposed by de Zee et al.[3], validated by Rasmussen et al.[4] and by Galibarov et al.[5]. The new model[5] determines the individual motions between vertebrae based on the equilibrium between forces acting on the vertebrae from muscles and joints and the passive stiffness in disks and ligaments, figure 1a. An adult of 1.75 m and 75 kg with a spinal implant in L4L5 was modeled. This model was subjected to a flexion-extension motion using different elastic moduli to analyze and compare to a non-implanted scenario. The analyzed variables were vertebral motion, the disc reaction forces and moments, as well as facet joint forces in the treated and the adjacent levels: L2L3, L3L4, L4L5 and L5-Sacrum. RESULTS When introducing a spinal fusion device in the L4L5 joint the reaction forces and moments decreased in this joint with stiffer devices leading to lower joint loads. However, in the adjacent joints, L3L4 and L5Sacrum, an increase was observed when implanting stiffer devices. Similar trends could be found for the L2L3 joint. The loads in the facet joints showed the same trends. While introducing a spinal fusion device reduced the facet joint forces in the treated joint, the loads in the adjacent facet joints were increased according to the stiffness of the implanted device, figure 1b. DISCUSSION While the treated disc joint showed reduced motion and loads, the adjacent levels demonstrated a significant increase. In particular, the increased facet joint forces in the adjacent levels can lead to adjacent level facet pain or accelerated facet joint degeneration. Introducing a device resulted in preventing facet contact and therefore facet joint loads, even using the device with the lowest stiffness. CONCLUSION The presented model shows that clinical complications such as facet joint degeneration in adjacent levels after implantation of spinal fusion device are consistent with the change in the mechanical-stimulus distribution in the system.}, language = {en} } @inproceedings{GalibarovDendorferChristensen, author = {Galibarov, Pavel E. and Dendorfer, Sebastian and Christensen, Soeren Toerholm}, title = {On modelling spine curvature dependent on muscular and external forces in multibody dynamics system}, series = {International Society of Biomechanics (ISB), 13th congress, 2011, Brussels, Belgium}, booktitle = {International Society of Biomechanics (ISB), 13th congress, 2011, Brussels, Belgium}, pages = {2}, abstract = {This paper presents a computational approach for investigating effect of muscular and external forces on curvature of the lumbar spine. Multibody dynamics system is used to compute the lumbar spine curvature using a force-dependent kinematics facility, e.g. this method allows releasing some degrees of freedom in order to be computed based on the current load configuration.}, language = {en} } @inproceedings{GalibarovDendorferRasmussen, author = {Galibarov, Pavel E. and Dendorfer, Sebastian and Rasmussen, John}, title = {Two Computational Models of the Lumbar Spine:}, series = {Proceedings of the 2011 ORS Annual Meeting, Long Beach, CA, vol. Marie Curie Initial Training Network "SpineFX"}, booktitle = {Proceedings of the 2011 ORS Annual Meeting, Long Beach, CA, vol. Marie Curie Initial Training Network "SpineFX"}, language = {en} } @article{GeithEckmannHaspingeretal., author = {Geith, Markus A. and Eckmann, Jakob D. and Haspinger, Daniel Ch. and Agrafiotis, Emmanouil and Maier, Dominik and Szabo, Patrick and Sommer, Gerhard and Schratzenstaller, Thomas and Holzapfel, Gerhard A.}, title = {Experimental and mathematical characterization of coronary polyamide-12 balloon catheter membranes}, series = {PLoS One}, volume = {15}, journal = {PLoS One}, number = {6}, publisher = {PLOS}, doi = {10.1371/journal.pone.0234340}, pages = {1 -- 22}, abstract = {The experimental quantification and modeling of the multiaxial mechanical response of polymer membranes of coronary balloon catheters have not yet been carried out. Due to the lack of insights, it is not shown whether isotropic material models can describe the material response of balloon catheter membranes expanded with nominal or higher, supra-nominal pressures. Therefore, for the first time, specimens of commercial polyamide-12 balloon catheters membranes were investigated during uniaxial and biaxial loading scenarios. Furthermore, the influence of kinematic effects on the material response was observed by comparing results from quasi-static and dynamic biaxial extension tests. Novel clamping techniques are described, which allow to test even tiny specimens taken from the balloon membranes. The results of this study reveal the semi-compliant, nonlinear, and viscoelastic character of polyamide-12 balloon catheter membranes. Above nominal pressure, the membranes show a pronounced anisotropic mechanical behavior with a stiffer response in the circumferential direction. The anisotropic feature intensifies with an increasing strain-rate. A modified polynomial model was applied to represent the realistic mechanical response of the balloon catheter membranes during dynamic biaxial extension tests. This study also includes a compact set of constitutive model parameters for the use of the proposed model in future finite element analyses to perform more accurate simulations of expanding balloon catheters.}, language = {en} } @article{GeithNothdurfterHeimletal., author = {Geith, Markus A. and Nothdurfter, Laurenz and Heiml, Manuel and Agrafiotis, Emmanouil and Gruber, Markus and Sommer, Gerhard and Schratzenstaller, Thomas and Holzapfel, Gerhard A.}, title = {Quantifying stent-induced damage in coronary arteries by investigating mechanical and structural alterations}, series = {Acta Biomaterialia}, volume = {116}, journal = {Acta Biomaterialia}, number = {October}, publisher = {Elsevier}, doi = {10.1016/j.actbio.2020.08.016}, pages = {285 -- 301}, abstract = {Vascular damage develops with diverging severity during and after percutaneous coronary intervention with stent placement and is the prevailing stimulus for in-stent restenosis. Previous work has failed to link mechanical data obtained in a realistic in vivo or in vitro environment with data collected during imaging processes. We investigated whether specimens of porcine right coronary arteries soften when indented with a stent strut shaped structure, and if the softening results from damage mechanisms inside the fibrillar collagen structure. To simulate the multiaxial loading scenario of a stented coronary artery, we developed the testing device 'LAESIO' that can measure differences in the stress-stretch behavior of the arterial wall before and after the indentation of a strut-like stamp. The testing protocol was optimized according to preliminary experiments, more specifically equilibrium and relaxation tests. After chemical fixation of the specimens and subsequent tissue clearing, we performed three-dimensional surface and second-harmonic generation scans on the deformed specimens. We analyzed and correlated the mechanical response with structural parameters of high-affected tissue located next to the stamp indentation and low-affected tissue beyond the injured area. The results reveal that damage mechanisms, like tissue compression as well as softening, fiber dispersion, and the lesion extent, are direction-dependent, and the severity of them is linked to the strut orientation, indentation pressure, and position. The findings highlight the need for further investigations by applying the proposed methods to human coronary arteries. Additional data and insights might help to incorporate the observed damage mechanisms into material models for finite element analyses to perform more accurate simulations of stent-implantations.}, language = {en} } @article{GeithSommerSchratzenstalleretal., author = {Geith, Markus A. and Sommer, Gerhard and Schratzenstaller, Thomas and Holzapfel, Gerhard A.}, title = {Biomechanical and structural quantification of vascular damage: A unique investigation of stent implantation}, series = {Artery Research}, volume = {20}, journal = {Artery Research}, number = {Issue C}, doi = {10.1016/j.artres.2017.10.025}, pages = {50}, language = {en} } @inproceedings{GeithSommerSchratzenstalleretal., author = {Geith, Markus A. and Sommer, Gerhard and Schratzenstaller, Thomas and Holzapfel, Gerhard A.}, title = {First Approaches in Quantifying Acute Vascular Damage due to Stenting}, series = {23rd Congress of the European Society of Biomechanics, July 2-5,2017, Seville, Spain}, booktitle = {23rd Congress of the European Society of Biomechanics, July 2-5,2017, Seville, Spain}, subject = {Stent}, language = {en} } @article{GeithSwidergalHochholdingeretal., author = {Geith, Markus A. and Swidergal, Krzysztof and Hochholdinger, Bernd and Schratzenstaller, Thomas and Wagner, Marcus and Holzapfel, Gerhard A.}, title = {On the importance of modeling balloon folding, pleating, and stent crimping: An FE study comparing experimental inflation tests}, series = {International Journal for Numerical Methods in Biomedical Engineering}, volume = {35}, journal = {International Journal for Numerical Methods in Biomedical Engineering}, number = {11}, publisher = {Wiley}, doi = {10.1002/cnm.3249}, abstract = {Finite element (FE)-based studies of preoperative processes such as folding,pleating, and stent crimping with a comparison with experimental inflation tests are not yet available. Therefore, a novel workflow is presented in which residual stresses of balloon folding and pleating, as well as stent crimping, and the geometries of all contact partners were ultimately implemented in an FE code to simulate stent expansion by using an implicit solver. The numerical results demonstrate that the incorporation of residual stresses and strains experienced during the production step significantly increased the accuracy of the subsequent simulations, especially of the stent expansion model. During the preoperative processes, stresses inside the membrane and the stent material also reached a rather high level. Hence, there can be no presumption that balloon catheters or stents are undamaged before the actual surgery. The implementation of the realistic geometry, in particular the balloon tapers, and the blades of the process devices improved the simulation of the expansion mech-anisms, such as dogboning, concave bending, or overexpansion of stent cells. This study shows that implicit solvers are able to precisely simulate the mentioned preoperative processes and the stent expansion procedure without a preceding manipulation of the simulation time or physical mass.}, subject = {Stent}, language = {en} } @misc{GeithSwidergalSchratzenstalleretal., author = {Geith, Markus A. and Swidergal, Krzysztof and Schratzenstaller, Thomas and Holzapfel, Gerhard A. and Wagner, Marcus}, title = {Numerical analysis of stent delivery systems during pre- and intraoperative processes}, series = {15. Deutsches LS-DYNA Forum, 15.-17.10.2018, Bamberg}, journal = {15. Deutsches LS-DYNA Forum, 15.-17.10.2018, Bamberg}, language = {en} } @inproceedings{GeithWagner, author = {Geith, Markus A. and Wagner, Marcus}, title = {Numerical Analysis Of Stent Delivery Systems During Pre- And Intraoperative Processes}, series = {Deutsches LS-DYNA Forum 2018, Bamberg}, booktitle = {Deutsches LS-DYNA Forum 2018, Bamberg}, language = {en} } @article{GoldhackerRosengarthAnstisetal., author = {Goldhacker, Markus and Rosengarth, Katharina and Anstis, Stuart and Wirth, Anna and Plank, Tina and Greenlee, Mark W.}, title = {FMRI evidence for perceptual filling-in in patients with macular dystrophy}, series = {Perception}, volume = {42}, journal = {Perception}, issn = {1468-4233}, pages = {72 -- 73}, language = {en} } @article{GoldhackerRosengarthPlanketal., author = {Goldhacker, Markus and Rosengarth, Katharina and Plank, Tina and Greenlee, Mark W.}, title = {The effect of feedback on performance and brain activation during perceptual learning}, series = {Vision research}, volume = {99}, journal = {Vision research}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1878-5646}, doi = {10.1016/j.visres.2013.11.010}, pages = {99 -- 110}, abstract = {We investigated the role of informative feedback on the neural correlates of perceptual learning in a coherent-motion detection paradigm. Stimulus displays consisted of four patches of moving dots briefly (500 ms) presented simultaneously, one patch in each visual quadrant. The coherence level was varied in the target patch from near threshold to high, while the other three patches contained only noise. The participants judged whether coherent motion was present or absent in the target patch. To guarantee central fixation, a secondary RSVP digit-detection task was performed at fixation. Over six training sessions subjects learned to detect coherent motion in a predefined quadrant (i.e., the learned location). Half of our subjects were randomly assigned to the feedback group, where they received informative feedback after each response during training, whereas the other group received non-informative feedback during training that a response button was pressed. We investigated whether the presence of informative feedback during training had an influence on the learning success and on the resulting BOLD response. Behavioral data of 24 subjects showed improved performance with increasing practice. Informative feedback promoted learning for motion displays with high coherence levels, whereas it had little effect on learning for displays with near-threshold coherence levels. Learning enhanced fMRI responses in early visual cortex and motion-sensitive area MT+ and these changes were most pronounced for high coherence levels. Activation in the insular and cingulate cortex was mainly influenced by coherence level and trained location. We conclude that feedback modulates behavioral performance and, to a lesser extent, brain activation in areas responsible for monitoring perceptual learning.}, language = {en} } @article{GradNadammalSchultheissetal., author = {Grad, Marius and Nadammal, Naresh and Schultheiss, Ulrich and Lulla, Philipp and Noster, Ulf}, title = {An Integrative Experimental Approach to Design Optimization and Removal Strategies of Supporting Structures Used during L-PBF of SS316L Aortic Stents}, series = {Applied Sciences}, volume = {11}, journal = {Applied Sciences}, number = {19}, publisher = {MPDL}, doi = {10.3390/app11199176}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-25612}, pages = {1 -- 22}, abstract = {One of the fundamental challenges in L-PBF of filigree geometries, such as aortic stents used in biomedical applications, is the requirement for a robust yet easily removable support structure that allows each component to be successfully fabricated without distortion. To solve this challenge, an integrative experimental approach was attempted in the present study by identifying an optimal support structure design and an optimized support removal strategy for this design. The specimens were manufactured using four different support structure designs based on the geometry exposed to the laser beam during the L-PBF. Support removal procedures included sand blasting (SB), glass bead blasting (GB), and electrochemical polishing (ECP). The two best-performing designs (line and cross) were chosen due to shorter lead times and lower material consumption. As an additional factor that indicates a stable design, the breaking load requirement to remove the support structures was determined. A modified line support with a 145° included angle was shown to be the best support structure design in terms of breaking load, material consumption, and manufacturing time. All three procedures were used to ensure residue-free support removal for this modified line support design, with ECP proving to be the most effective.}, language = {en} } @misc{GreenleeAnstisRosengarthetal., author = {Greenlee, Mark W. and Anstis, Stuart and Rosengarth, Katharina and Goldhacker, Markus and Brandl-R{\"u}hle, Sabine and Plank, Tina}, title = {Neural correlates of perceptual filling-in: fMRI evidence in the foveal projection zone of patients with central scotoma}, series = {Journal of Vision / Vision Sciences Society Annual Meeting Abstract}, volume = {12}, journal = {Journal of Vision / Vision Sciences Society Annual Meeting Abstract}, number = {9}, publisher = {ARVO}, issn = {1534-7362}, doi = {10.1167/12.9.1303}, abstract = {Patients with juvenile retinal dystrophy often report that they are unaware of their central scotoma, suggesting the presence of perceptual filling-in. We used functional Magnetic Resonance Imaging (fMRI) to determine possible neural correlates of perceptual filling-in in patients with retinal distrophy and clinically established central scotoma in both eyes. The data of 5 patients (Stargardt disease, cone-rod dystrophy; mean age 45 yrs; scotoma diameter 10-20°) and of 5 normally sighted controls were analyzed. Fixation behaviour and perimetry were measured with a Nidek microperimeter. Magnetic resonance imaging was performed using a Siemens 3T Allegra scanner. We stimulated the central visual field (30 deg) with a vertically oriented, low spatial frequency (1 c/deg) high-contrast sinewave grating that was either a) continuous, or b) was interrupted by a central grey disk. The disk was either slightly larger than the scotoma (detectable on 75\% of trials) or slightly smaller (detectable on 25\% of trials). To control for attention, an eccentric fixation task was performed during scanning. Data were analyzed using SPM8 (GLM with ROI analysis to obtain percent signal change for foveal projection zone). Results: for all patients, the BOLD signal in the foveal projection area was significantly higher for the small disk (i.e., condition leading to complete filling-in) than for the large disk (i.e., no filling-in). This effect was absent in the control subjects. Our findings support the existence of an active neural process that leads to filling-in in patients with central visual field scotomata.}, language = {en} } @article{GreenleeRosengarthSchmalhoferetal., author = {Greenlee, Mark W. and Rosengarth, Katharina and Schmalhofer, Carolin and Goldhacker, Markus and Brandl-R{\"u}hle, Sabine and Plank, Tina}, title = {Perceptual learning in patients with central scotomata due to hereditary and age-related macular dystrophy}, series = {Journal of Vision}, volume = {14}, journal = {Journal of Vision}, number = {10}, publisher = {ARVO}, issn = {1468-4233}, doi = {10.1167/14.10.666}, abstract = {Hereditary and age-related forms of macular dystrophy (MD) are characterized by loss of cone function in the fovea, leading to central scotomata and eccentric fixation at the so-called preferred retinal locus (PRL). We investigated whether perceptual learning enhances visual abilities at the PRL. We also determined the neural correlates (3-Tesla fMRI) of learning success. Twelve MD patients (eight with age-related macular dystrophy, four with hereditary macular dystrophies) were trained on a texture discrimination task (TDT) over six days. Patients underwent three fMRI sessions (before, during and after training) while performing the TDT (target at PRL or opposite PRL). Reading speed, visual acuity (Vernier task) and contrast sensitivity were also assessed before and after training. With one exception, all patients showed improved performance (i.e. significant decrease in stimulus onset asynchronies and reaction times, significant increase in hit rates) on the TDT. Eight patients also showed moderate increases in reading speed, six patients showed improved thresholds in contrast sensitivity and nine patients showed improved thresholds in a vernier visual acuity task after TDT training. We found an increase in BOLD response in the projections zone of the PRL in the primary visual cortex in nine of twelve patients after training. The change in fMRI signal correlated (r = .8; p = .02) with the patients{\^a}€™ performance enhancements when the target was in the PRL. The results suggest that perceptual learning can enhance eccentric vision and cortical processing in MD patients.}, language = {en} } @inproceedings{GrossSuessVerkerkeetal., author = {Gross, Simon and S{\"u}ß, Franz and Verkerke, Gijsbertus Jacob and Dendorfer, Sebastian}, title = {Simulating fatigue in musculoskeletal models using surface electromyography, ECCOMAS Congress, Crete, Greece, 201}, series = {ECCOMAS Congress, Crete, Greece, 2016}, booktitle = {ECCOMAS Congress, Crete, Greece, 2016}, language = {en} } @inproceedings{GrossVerkerkeDendorfer, author = {Gross, Simon and Verkerke, Gijsbertus Jacob and Dendorfer, Sebastian}, title = {Combined Experimental and Numerical Approach to Investigate Changes in Muscle Recruitment Pattern of the Back Muscles during Exhausting Exercise}, series = {World Congress Biomechanics Dublin, 2018}, booktitle = {World Congress Biomechanics Dublin, 2018}, abstract = {In recent years, musculoskeletal computation has become a widely used tool to investigate joint and muscle forces within the human body. However, the issue of muscle fatigue is not considered adequately in most models and is a challenging task. One aspect that needs to be examined is the interaction of muscles during an exhausting task. Therefore, an experimental study was designed to analyze the changes of back muscle recruitment pattern during such exercises. In this study 38 subjects (27 male, 11 female, height = 177±8.5 cm, weight = 74.0±13.6 kg) participated. Each subject had to perform three static and three dynamic exhausting exercises where the back muscles were loaded with subject specific forces using a dynamometer adapter especially designed for the trunk muscles. To collect the muscle activity, twelve surface electromyography sensors were applied on the back, and four on the abdominal muscles. Muscle activity and fatigue were analyzed by calculating the maximum voluntary contraction normalized signal and the median frequency. At first the fatigue of m. erector spinae and m. multifidi was analyzed, since these muscles carry the main load during the exercises. Subsequently the activity of the m. trapezius, m. rectus abdominis and m. obliquus externus were investigated to determine recruitment patterns. To gain more detailed information of these patterns a numerical model was built using the AnyBody Modeling System™. Analyzing the measurements, we can observe an increasing muscle activity during isokinetic exercises while the force is constant. Since the activity in the simulation is defined as the current force output divided by the strength of the muscle, the strength parameter was scaled down based on the measured data, assuming a linear force - activity correlation, and using a numerical algorithm considering the influence of cross talk. The results show, that changes in recruitment pattern can be divided into three major subgroups. Prior to total exhaustion, some of the subjects show additional activation of muscles in the trapezius region, while other subjects show an additional activation of abdominal muscles, increasing the intra-abdominal pressure which supports the spine. In the third group an activation in both regions can be observed. The numerical simulations show an increasing activity of abdominal muscles as well as muscles in the upper back. Especially the m. latissimus dorsi shows a significantly higher activity. The results lead to the conclusion that prior to total exhaustion, additional muscles are recruited to support the main muscles. It was shown that abdominal muscles are activated to support back muscles by pressurizing the trunk cavity to delay total exhaustion as long as possible. In conclusion, the results show that changes in muscle recruitment pattern need to be considered when introducing muscle fatigue to musculoskeletal models.}, language = {en} } @inproceedings{GrossVerkerkeDendorfer, author = {Gross, Simon and Verkerke, Gijsbertus Jacob and Dendorfer, Sebastian}, title = {Investigation of external load dependent static and dynamic muscle fatigue}, series = {23th Congress of the European Society of Biomechanics, Sevilla, Spain, 2017}, booktitle = {23th Congress of the European Society of Biomechanics, Sevilla, Spain, 2017}, language = {en} } @misc{GschossmannDendorfer, author = {Gschoßmann, Lukas and Dendorfer, Sebastian}, title = {Personalized Rehabilitation after Total Knee Arthroplasty}, series = {32nd Annual Meeting of the European Orthopaedic Research Society (EORS 2024), 18 - 20 September 2024, Aalborg}, journal = {32nd Annual Meeting of the European Orthopaedic Research Society (EORS 2024), 18 - 20 September 2024, Aalborg}, language = {en} } @misc{GschossmannSteinDendorfer, author = {Gschoßmann, Lukas and Stein, Leonhard and Dendorfer, Sebastian}, title = {Subject Specific Scaling Of Muscle Strengths In The Lower Extremity For Musculoskeletal Models}, series = {ESB 2024, 29th Congress of the European Society of Biomechanics, 30 June-3 July 2024, Edinburgh, Scotland}, journal = {ESB 2024, 29th Congress of the European Society of Biomechanics, 30 June-3 July 2024, Edinburgh, Scotland}, language = {en} } @inproceedings{HammerDendorfer, author = {Hammer, Joachim and Dendorfer, Sebastian}, title = {Cyclic loading and microstructure of cancellous bone}, series = {Journal of Biomechanics}, volume = {41}, booktitle = {Journal of Biomechanics}, number = {Suppl. 1, July 2008}, doi = {10.1016/S0021-9290(08)70409-3}, pages = {S410}, language = {en} } @article{HausFoltanPhilippetal., author = {Haus, Moritz and Foltan, Maik and Philipp, Alois and M{\"u}ller, Thomas and Lingel, Maximilian P. and Krenkel, Lars and Gruber, Michael and Lehle, Karla}, title = {Neutrophil extracellular traps -a potential trigger for the development of thrombocytopenia during extracorporeal membrane oxygenation}, volume = {15}, publisher = {frontiers}, doi = {10.3389/fimmu.2024.1339235}, abstract = {Neutrophil extracellular traps (NETs) have recently emerged as a potential link between inflammation, immunity, and thrombosis, as well as other coagulation disorders which present a major challenge in the context of extracorporeal membrane oxygenation (ECMO). By examining blood from ECMO patients for NETs and their precursors and correlating them with clinical and laboratory biomarkers of coagulation and inflammation, this study aims to evaluate the association between the presence of NETs in the bloodstream of ECMO patients and the development of potentially severe coagulation disorders during ECMO therapy. Therefore, blood samples were collected from healthy volunteers (n=13) and patients receiving veno-venous (VV) ECMO therapy (n=10). To identify NETs and their precursors, DNA and myeloperoxidase as well as granulocyte marker CD66b were visualized simultaneously by immunofluorescence staining in serial blood smears. Differentiation of DNA-containing objects and identification of NETs and their precursors was performed semiautomatically by a specific algorithm using the shape and size of DNA staining and the intensity of MPO and CD66b signal. Neutrophil extracellular traps and their precursors could be detected in blood smears from patients requiring VV ECMO. Compared to volunteers, ECMO patients presented significantly higher rates of NETs and NET precursors as well as an increased proportion of neutrophil granulocytes in all detected nucleated cells. A high NET rate prior to the initiation of ECMO therapy was associated with both increased iL-6 and TNF-α levels as an expression of a high cytokine burden. These patients with increased NET release also presented an earlier and significantly more pronounced decrease in platelet counts and ATIII activity following initiation of therapy compared with patients with less elevated NETs. These findings provide further indications for the development of immune-mediated acquired thrombocytopenia in ECMO patients.}, language = {en} } @article{HausleiterKastratiWesselyetal., author = {Hausleiter, J{\"o}rg and Kastrati, Adnan and Wessely, Rainer and Dibra, Alban and Mehilli, Julinda and Schratzenstaller, Thomas and Graf, Isolde and Renke-Gluszko, Magdalena and Behnisch, Boris and Dirschinger, Josef and Wintermantel, Erich and Sch{\"o}mig, Albert}, title = {Prevention of restenosis by a novel drug-eluting stent system with a dose-adjustable, polymer-free, on-site stent coating}, series = {European Heart Journal - Clinical research}, volume = {26}, journal = {European Heart Journal - Clinical research}, number = {15}, doi = {10.1093/eurheartj/ehi405}, pages = {1475 -- 1481}, abstract = {Aims Drug-eluting stents (DES) represent a major advance in interventional cardiology. Along with the success shown, current DES also present limitations related to the presence of polymer-coating, fixed drug, and dose used. With the ISAR (Individualized Drug-Eluting Stent System to Abrogate Restenosis) project, a DES system has been developed that permits individualized choice of the drug and dose to use for the given patient. The objective of this prospective dose finding study was to assess the feasibility, safety, and efficacy of a polymer-free on-site stent coating with increasing rapamycin doses. Methods and results In this dose finding study, 602 patients were sequentially enrolled in four groups: microporous bare metal stent (BMS), DES stents coated with a 0.5, 1.0, and 2.0\% rapamycin solution. The angiographic in-segment restenosis rate at follow-up angiography was the primary study endpoint. In-segment restenosis was significantly reduced from 25.9\% with BMS to 18.9, 17.2, and 14.7\% with 0.5, 1.0, and 2.0\% rapamycin-eluting stents, respectively (P=0.024). Similarly, the need for target lesion revascularization at 1 year follow-up was reduced from 21.5\% with BMS to 16.4, 12.6, and 8.8\% with 0.5, 1.0, and 2.0\% rapamycin-eluting stents, respectively (P=0.006). Conclusion The placement of polymer-free stents coated on-site with rapamycin is feasible and safe. Furthermore, a dose-dependent efficacy in restenosis prevention is achievable with this new DES concept.}, language = {en} } @article{HeineEigenbergerBrebantetal., author = {Heine, Norbert and Eigenberger, Andreas and Brebant, Vanessa and Hoesl, Vanessa and Brix, Eva and Prantl, Lukas and Kempa, Sally}, title = {Comparison of skin sensitivity following breast reconstruction with three different techniques: Autologous fat grafting, DIEP flap and expander/implant}, series = {Clinical Hemorheology and Microcirculation}, volume = {80}, journal = {Clinical Hemorheology and Microcirculation}, number = {4}, publisher = {IOS Press}, issn = {1875-8622}, doi = {10.3233/ch-219203}, pages = {389 -- 397}, abstract = {BACKGROUND: Autologous fat grafting (AFG) has been established over the past two decades as an additive technique during and after breast reconstruction. Complete reconstruction of the breast mound with AFG alone represents an exceptional technique that has been published mostly in case reports or in studies with limited cases.The purpose of this study is to investigate the influence of three different techniques for breast reconstruction on the recovery of skin sensitivity at the reconstructed breast. METHODS: The study included 30 patients after mastectomy following breast cancer. Three groups were examined: A) breast reconstruction by autologous fat grafting (AFG), B) breast reconstruction by deep inferior epigastric artery perforator flap (DIEP) and C) breast reconstruction by expander/implant (TE).Biometric data were compared; sensitivity tests were performed using Semmes-Weinstein monofilaments.The non-operated, healthy contralateral breasts of the patients were used as a reference. RESULTS: While the traditional reconstruction techniques by microsurgical anastomosed perforator flap or expander/implant showed a strongly decreased or completely missing sensitivity of the skin, the tests after reconstruction by AFG represented high values of sensory recovery, which came close to the reference group of non-operated breasts. CONCLUSION: To our knowledge, this is the first study to compare skin sensitivity after AFG-based reconstruction to established techniques for breast reconstruction. We could demonstrate in a limited group of patients, that breast reconstruction by autologous fat grafting can achieve higher values of skin sensitivity compared to traditional techniques.}, subject = {Mammoplastik}, language = {en} } @article{HeineEigenbergerBrebantetal., author = {Heine, Norbert and Eigenberger, Andreas and Brebant, Vanessa and Kempa, Sally and Seitz, Stephan and Prantl, Lukas and Kuehlmann, Britta}, title = {The effect of radiotherapy on fat engraftment for complete breast reconstruction using lipofilling only}, series = {Archives of Gynecology and Obstetrics}, journal = {Archives of Gynecology and Obstetrics}, publisher = {Springer}, doi = {10.1007/s00404-022-06610-4}, pages = {7}, abstract = {Purpose Lipofilling has been established as a standard technique for contour enhancement following breast reconstruction. However, there is a paucity in current literature regarding the use of this technique for complete reconstruction of the female breast as an alternative to conventional techniques, such as expander or flap-based procedures. In particular, the influence of pre-operative irradiation for successful reconstruction has rarely been examined in published studies. Here, the authors describe their experience with successful fat injection in pre-radiated breasts in comparison with non-pre-radiated patients. Methods In this retrospective study, we examined a total of 95 lipofilling treatments on 26 patients (28 breasts). All of them experienced mastectomy following breast cancer; local breast defects after partial resection of the gland were not included in this study. In total, 47 lipofilling procedures in 12 non-irradiated patients (14 breasts) and 48 procedures in 14 irradiated women (also 14 breasts) were performed. Per session, approximately 297 +/- 112 cc of adipose tissue was grafted in group A (no radiotherapy) and approximately 259 +/- 93 cc was grafted in group B (radiotherapy). Results Among the group of women without pre-operative radiation, 71\% of breast reconstructions limited to lipofilling only showed constant engraftment of fat tissue with a successful reconstructive result, whereas only 21\% of the patients with pre-radiated breasts showed complete reconstruction of the breast with a permanent fat in-growth. Conclusion Preoperative radiotherapy significantly impedes successful completion of breast reconstructions planned only by autologous fat transfer. Patients should be selected individually and carefully for complete breast reconstruction using lipofilling only.}, language = {en} } @article{HimmeleinPerezRuizdeGaribayBrandeletal., author = {Himmelein, Susanne and Perez Ruiz de Garibay, Aritz and Brandel, Veronika and Zierfuß, Frank and Bingold, Tobias Michael}, title = {The ADVanced Organ Support (ADVOS) hemodialysis system removes IL-6: an in vitro proof-of-concept study}, series = {Intensive care medicine experimental}, volume = {12}, journal = {Intensive care medicine experimental}, number = {1}, publisher = {SpringerOpen}, address = {Berlin ; Heidelberg}, issn = {2197-425X}, doi = {10.1186/s40635-024-00652-5}, abstract = {BACKGROUND IL-6 is a pleiotropic cytokine modulating inflammation and metabolic pathways. Its proinflammatory effect plays a significant role in organ failure pathogenesis, commonly elevated in systemic inflammatory conditions. Extracorporeal blood purification devices, such as the Advanced Organ Support (ADVOS) multi hemodialysis system, might offer potential in mitigating IL-6's detrimental effects, yet its efficacy remains unreported. METHODS We conducted a proof-of-concept in vitro study to assess the ADVOS multi system's efficacy in eliminating IL-6. Varying concentrations of IL-6 were introduced into a swine blood model and treated with ADVOS multi for up to 12 h, employing different blood and concentrate flow rates. IL-6 reduction rate, clearance, and dynamics in blood and dialysate were analyzed. RESULTS IL-6 clearance rates of 0.70 L/h and 0.42 L/h were observed in 4 and 12-h experiments, respectively. No significant differences were noted across different initial concentrations. Reduction rates ranged between 40 and 46\% within the first 4 h, increasing up to 72\% over 12 h, with minimal impact from flow rate variations. Our findings suggest that an IL-6-albumin interaction and convective filtration are implicated in in vitro IL-6 elimination with ADVOS multi. CONCLUSIONS This study demonstrates for the first time an efficient and continuous in vitro removal of IL-6 by ADVOS multi at low blood flow rates. Initial concentration-dependent removal transitions to more consistent elimination over time. Further clinical investigations are imperative for comprehensive data acquisition.}, language = {en} } @article{HoenickaKasparSchmidetal., author = {Hoenicka, Markus and Kaspar, Marcel and Schmid, Christof and Liebold, Andreas and Schrammel, Siegfried}, title = {Contact-free monitoring of vessel graft stiffness - proof of concept as a tool for vascular tissue engineering}, series = {Journal of tissue engineering and regenerative medicine}, volume = {11}, journal = {Journal of tissue engineering and regenerative medicine}, number = {10}, publisher = {Wiley}, doi = {10.1002/term.2186}, pages = {2828 -- 2835}, abstract = {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.}, language = {en} } @article{HoenickaLehleJacobsetal., author = {Hoenicka, Markus and Lehle, Karla and Jacobs, V. R. and Dendorfer, Sebastian and Kostorz, A. and Schmid, F. X. and Birnbaum, D. E.}, title = {Mechanical and seeding properties of human umbilical vein - a potential scaffold for a tissue-engineered vessel graft}, series = {The Thoracic and Cardiovascular Surgeon}, volume = {55}, journal = {The Thoracic and Cardiovascular Surgeon}, number = {S 1}, publisher = {Thieme}, doi = {10.1055/s-2007-967592}, pages = {P_37}, abstract = {Objectives: The mechanical properties and seeding with endothelial cells were investigated in fresh and cryopreserved human umbilical vein. Methods: Human umbilical veins (HUV) were frozen in Euro-Collins/1M DMSO at -1°C/min and stored in liquid nitrogen. Stress-strain relationships of fresh and thawed veins were determined in an uniaxial tension-testing rig. HUV endothelial cells (HUVEC) were seeded onto denuded HUV under static conditions and grown for 3d. Luminal surfaces were analyzed by scanning electron microscopy. Calcein-stained cells were seeded hyperconfluently to determine the cell retention capacity of fresh and cryopreserved veins. Results: The stress-strain relationships of HUV followed a biphasic pattern typical for natural vessels. Neither the failure stress (2.71±0.36 vs. 3.25±0.97 N, n=3) nor the displacement required to achieve failure (9.73±0.9 vs. 7.43±2.07mm, n=3) were altered by cryopreservation. The burst pressure was estimated as approx. 1000mm Hg within the limitations of the uniaxial model. HUVEC seeded onto denuded HUV formed patches (at 9E3 cells per cm2) or an almost confluent endothelium (at 3E4 cells per cm2) within three days. The capacity to retain seeded HUVEC of denuded HUV was not altered by cryopreservation (1.15±0.08E5 vs. 1.26±0.14E5 cells per cm2, n=6). Conclusions: The burst pressure of HUV seems to be sufficiently high for the human arterial circulation and is not altered by cryopreservation. HUVEC can establish a confluent endothelium on denuded HUV. Therefore HUV appears to be a suitable storable scaffold for vascular tissue engineering.}, subject = {Nabelvene}, language = {en} } @article{HornbergerStrieglTrahanofskyetal., author = {Hornberger, Helga and Striegl, Birgit and Trahanofsky, M. and Kneissl, F. and Kronseder, Matthias}, title = {Degradation and bioactivity studies of Mg membranes for dental surgery}, series = {Materials Letter X}, volume = {2}, journal = {Materials Letter X}, number = {June}, publisher = {Elsevier}, doi = {10.1016/j.mlblux.2019.100007}, pages = {1 -- 5}, abstract = {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.}, language = {en} } @inproceedings{HornerDendorferKiisetal., author = {Horner, Marc and Dendorfer, Sebastian and Kiis, Arne and Lawrenchuk, Mike and Verma, Gunjan}, title = {A Patient based simulation workflow for orthopedic device design and analysis}, series = {SBC Ortho Workshop, June 2011}, booktitle = {SBC Ortho Workshop, June 2011}, language = {en} } @article{HoelscherWeberLazarevetal., author = {H{\"o}lscher, Thomas and Weber, Tim A. and Lazarev, Igor A. and Englert, Carsten and Dendorfer, Sebastian}, title = {The influence of rotator cuff tears on glenohumeral stability during abduction tasks}, series = {Journal of Orthopaedic Research}, volume = {34}, journal = {Journal of Orthopaedic Research}, number = {9}, doi = {10.1002/jor.23161}, pages = {1628 -- 1635}, abstract = {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.}, subject = {Rotatorenmanschettenriss}, language = {en} } @article{IgnasiakDendorferFerguson, author = {Ignasiak, Dominika and Dendorfer, Sebastian and Ferguson, Stephen J.}, title = {Thoracolumbar spine model with articulated ribcage for the prediction of dynamic spinal loading}, series = {Journal of Biomechanics}, volume = {vol. 49}, journal = {Journal of Biomechanics}, number = {6}, publisher = {Elsevier Science}, doi = {10.1016/j.jbiomech.2015.10.010}, pages = {959 -- 966}, abstract = {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.}, subject = {Brustwirbels{\"a}ule}, language = {en} } @inproceedings{IgnasiakDendorferFerguson, author = {Ignasiak, Dominika and Dendorfer, Sebastian and Ferguson, Stephen J.}, title = {Thoracolumbar spine model with articulated rigcage for the prediction of dynamic spinal loading}, series = {International Workshop on Spine Loading and Deformation: From Loading to Recovery, 2-4 July 2015, Julius Wolff Institute, Charit{\´e}-Universitatsmedizin Berlin, Germany}, booktitle = {International Workshop on Spine Loading and Deformation: From Loading to Recovery, 2-4 July 2015, Julius Wolff Institute, Charit{\´e}-Universitatsmedizin Berlin, Germany}, language = {en} } @inproceedings{JungtaeublAurbachMelzneretal., author = {Jungt{\"a}ubl, Dominik and Aurbach, Maximilian and Melzner, Maximilian and Spicka, Jan and S{\"u}ß, Franz and Dendorfer, Sebastian}, title = {EMG-Based Validation of Musculoskeletal Models Considering Crosstalk}, series = {International Conference BIOMDLORE, June 28 - 30 2018, Białystok, Poland}, booktitle = {International Conference BIOMDLORE, June 28 - 30 2018, Białystok, Poland}, doi = {10.1109/BIOMDLORE.2018.8467211}, abstract = {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.}, language = {en} } @inproceedings{JungtaeublSchmitzGrossetal., author = {Jungt{\"a}ubl, Dominik and Schmitz, Paul and Gross, Simon and Dendorfer, Sebastian}, title = {FEA of the transiliacal internal fixator as an osteosynthesis of pelvic ring fractures}, series = {CMBEBIH 2017, Proceedings of the International Conference on Medical and Biological Engineering 2017}, booktitle = {CMBEBIH 2017, Proceedings of the International Conference on Medical and Biological Engineering 2017}, editor = {Badnjevic, Almir}, publisher = {Springer}, address = {Singapore}, isbn = {978-981-10-4165-5}, doi = {10.1007/978-981-10-4166-2_32}, pages = {212 -- 217}, abstract = {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.}, subject = {Beckenbruch}, language = {en} } @article{KheiroddinSchoeberlAlthammeretal., author = {Kheiroddin, Parastoo and Sch{\"o}berl, Patricia and Althammer, Michael and Cibali, Ezgi and W{\"u}rfel, Thea and Wein, Hannah and Kulawik, Birgit and Buntrock-D{\"o}pke, Heike and Weigl, Eva and Gran, Silvia and Gr{\"u}ndl, Magdalena and Langguth, Jana and Lampl, Benedikt and Judex, Guido and Niggel, Jakob and Pagel, Philipp and Schratzenstaller, Thomas and Schneider-Brachert, Wulf and Gastiger, Susanne and Bodenschatz, Mona and Konrad, Maike and Levchuk, Artem and Roth, Cornelius and Sch{\"o}ner, David and Schneebauer, Florian and Rohrmanstorfer, Ren{\´e} and Burkovski, Andreas and Ambrosch, Andreas and Wagner, Thomas and Kabesch, Michael}, title = {Results of WICOVIR Gargle Pool PCR Testing in German Schools Based on the First 100,000 Tests}, series = {Frontiers in Pediatrics}, volume = {9}, journal = {Frontiers in Pediatrics}, editor = {Buonsenso, Danilo}, publisher = {frontiers}, issn = {2296-2360}, doi = {10.3389/fped.2021.721518}, abstract = {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.}, subject = {Covid-19}, language = {en} } @article{KieningerSchneiderAueretal., author = {Kieninger, Martin and Schneider, Corinna and Auer, Simon and Reinker, Lukas and Adler, Ina and Dendorfer, Sebastian and Rosenberger, Johanna and Popp, Daniel and Eissnert, Christoph and Ludsteck, Dominik and Cyrus, Christopher and Hoffmann, Johannes and Morag, Sarah and Graf, Bernhard and Kieninger, B{\"a}rbel}, title = {Transport von schwer verletzten Traumapatienten im Rettungswagen mit und ohne starre Halsorthese: vergleichende biomechanische Messungen}, series = {Die Anaesthesiologie}, volume = {73}, journal = {Die Anaesthesiologie}, number = {10}, publisher = {Springer Nature}, doi = {10.1007/s00101-024-01462-w}, pages = {668 -- 675}, abstract = {Hintergrund: Der tats{\"a}chliche Stellenwert der pr{\"a}hospitalen Immobilisation der Halswirbels{\"a}ule (HWS) bei schwer verletzten Traumapatienten ist weiterhin unklar. In Anbetracht m{\"o}glicher negativer Implikationen durch das Anbringen einer starren HWS-Orthese muss deren Anwendung w{\"a}hrend der gesamten pr{\"a}hospitalen Phase kritisch hinterfragt werden. Ziel der Arbeit: Es sollten vergleichende biomechanische Messungen zur Beweglichkeit der HWS bei Immobilisation mittels Vakuummatratze mit und ohne zus{\"a}tzliches Anbringen einer starren HWS-Orthese nach Lagerung auf der Trage durchgef{\"u}hrt werden. Material und Methoden: Die Bewegungen der HWS beim Ein- und Ausladeprozess in einen modernen RTW sowie w{\"a}hrend der Fahrt entlang eines vordefinierten Parkours wurden mit einem Motion-Capture-System aufgezeichnet. Die Probandin, an der die Messungen durchgef{\"u}hrt wurden, wurde auf einer Vakuummatratze mit der M{\"o}glichkeit zur seitlichen Fixierung des Kopfes sowie Kinn- und Stirngurt auf einer elektrohydraulischen Fahrtrage immobilisiert. Bei der einen H{\"a}lfte der Versuche erfolgte die zus{\"a}tzliche Immobilisation der HWS mittels starrer Orthese, bei der anderen wurde auf die Anwendung einer HWS-Orthese verzichtet. Ergebnisse: Statistisch signifikante Unterschiede ergaben sich nur bei einigen biomechanischen Parametern in der sagittalen Ebene (Flexion und Extension). F{\"u}r die anderen Bewegungsrichtungen (axiale Rotation, laterale Beugung) wurden keine signifikanten Unterschiede f{\"u}r die gemessenen Parameter ermittelt. Generell wurden sowohl bei den Versuchen mit HWS-Orthese als auch ohne HWS-Orthese nur sehr geringe Winkelauslenkungen (im Mittel bei axialer Rotation und Flexion/Extension im Bereich von einem bis 2 Grad, bei der lateralen Beugung h{\"o}chstens 3 Grad) gemessen. Schlussfolgerung: Bei einer korrekt durchgef{\"u}hrten Immobilisation mittels einer Vakuummatratze mit der M{\"o}glichkeit zur seitlichen Stabilisierung des Kopfes sowie Kinn- und Stirngurt auf einer elektrohydraulischen Fahrtrage mit Beladesystem ergeben sich f{\"u}r den Ein- und Ausladeprozess sowie w{\"a}hrend der Fahrt in einem modernen RTW mit luftgefederter Tragenlagerung und Luftfederung der Hinterachse keine relevanten Vorteile bez{\"u}glich der Einschr{\"a}nkung der Bewegung der HWS durch die zus{\"a}tzliche Verwendung einer starren HWS-Orthese.}, language = {de} } @misc{KreftingZaunsederSaeringetal., author = {Krefting, Dagmar and Zaunseder, Sebastian and S{\"a}ring, Dennis and Wittenberg, Thomas and Palm, Christoph and Schiecke, Karin and Krenkel, Lars and Hennemuth, Anja and Schnell, Susanne and Spicher, Nicolai}, title = {Blutdruck, H{\"a}modynamik und Gef{\"a}ßzustand: Innovative Erfassung und Bewertung - Schwerpunkt bildbasierte Verfahren}, series = {66. Jahrestagung der Deutschen Gesellschaft f{\"u}r Medizinische Informatik, Biometrie und Epidemiologie e. V. (GMDS), 12. Jahreskongress der Technologie- und Methodenplattform f{\"u}r die vernetzte medizinische Forschung e. V. (TMF), 26. - 30.09.2021, online}, journal = {66. Jahrestagung der Deutschen Gesellschaft f{\"u}r Medizinische Informatik, Biometrie und Epidemiologie e. V. (GMDS), 12. Jahreskongress der Technologie- und Methodenplattform f{\"u}r die vernetzte medizinische Forschung e. V. (TMF), 26. - 30.09.2021, online}, doi = {10.3205/21gmds016}, url = {http://nbn-resolving.de/urn:nbn:de:0183-21gmds0167}, abstract = {Einleitung: Blutdruck gilt als sogenannter Vitalparameter als einer der grundlegenden Indikatoren f{\"u}r den Gesundheitszustand einer Person. Sowohl zu niedriger als auch zu hoher Blutdruck kann lebensbedrohend sein, letzerer ist dar{\"u}ber hinaus ein Risikofaktor insbesondere f{\"u}r Herz-Kreislauferkrankungen, die trotz wichtiger Fortschritte in der Behandlung immer noch die h{\"a}ufigste Todesursache in Deutschland darstellen. Die H{\"a}modynamik, also die raumzeitliche Dynamik des Blutflusses, und der Gef{\"a}ßzustand sind eng verbunden mit dem Blutdruck und ebenfalls von hoher klinischer Relevanz, u.a. zur Identifikation von Durchblutungsst{\"o}rungen und ung{\"u}nstigen Druckverteilungen der Gef{\"a}ßwand. Innovationen in der Messtechnik als auch in der Datenanalyse bieten heute neue M{\"o}glichkeiten der Erfassung und Bewertung von Blutdruck, H{\"a}modynamik und Gef{\"a}ßzustand [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 Ans{\"a}tze und L{\"o}sungen f{\"u}r Mess- und Analyseverfahren zu Blutdruck und -fluss sowie zum Gef{\"a}ßzustand vorstellen und diskutieren. Dabei stehen im ersten Workshop auf der GMDS Jahrestagung Bildbasierte Verfahren im Zentrum, w{\"a}hrend der zweite Workshop auf der DGBMT Jahrestagung den Fokus auf Biosignalbasierten Verfahren legt. Es werden aktuelle Forschungsergebnisse vorgestellt und diskutiert. Es sind jeweils mehrere Vortr{\"a}ge geplant mit ausreichend Zeit zur Diskussion. Folgende Vortr{\"a}ge 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 h{\"a}modynamischer Parameter mit 4D flow MRI: M{\"o}glichkeiten und Herausforderungen Ergebnisse: Ziel des Workshops ist die Identifikation von innovativen Ans{\"a}tzen und neuen Methoden zur qualitativen und quantitativen Bestimmung von h{\"a}modynamischen Parametern sowie deren kritische Bewertung durch die Community f{\"u}r die Eignung in der klinischen Entscheidungsunterst{\"u}tzung. Diskussion: Der Workshop leistet inhaltlich einen Beitrag zu zentralen Aspekten f{\"u}r die Herz-Kreislauf-Medizin. Er bringt dabei Expertise aus verschiedenen Bereichen zusammen und schl{\"a}gt die Br{\"u}cke zwischen Kardiologie, Medizininformatik und Medizintechnik. Schlussfolgerung: Innovative Technologien aus Medizintechnik und Informatik erm{\"o}glichen zunehmend einfache und raumzeitlich aufgel{\"o}ste Erfassung und Bewertung wichtiger Informationen zur Unterst{\"u}tzung 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.}, subject = {Blutdruck}, language = {de} } @misc{Krenkel, author = {Krenkel, Lars}, title = {Maskenpflicht f{\"u}r Aerosole - wie wir medizinisches Personal in der Pandemie sch{\"u}tzen}, series = {TRIOKON Digital 2021 : Zukunft Ostbayern, 29.09.2021, Weiden, Deutschland}, journal = {TRIOKON Digital 2021 : Zukunft Ostbayern, 29.09.2021, Weiden, Deutschland}, language = {de} } @misc{Krenkel, author = {Krenkel, Lars}, title = {Relevanz von Aerosolen im klinischen Kontext}, series = {Innovationstag Hygiene 2021, Continental Arena, Regensburg, Deutschland}, journal = {Innovationstag Hygiene 2021, Continental Arena, Regensburg, Deutschland}, language = {de} } @misc{KrenkelMichelKeiletal., author = {Krenkel, Lars and Michel, Johanna and Keil, Niklas and Daschner, Jan}, title = {Experimental Investigation of Logitudinal Folds in Endotracheal Tube Cuffs and their Correlation to Silent Breathing}, series = {23. DGLR Fach-Symposium Str{\"o}mungen mit Abl{\"o}sung, 09./10. November 2022, Berlin, Deutschland}, journal = {23. DGLR Fach-Symposium Str{\"o}mungen mit Abl{\"o}sung, 09./10. November 2022, Berlin, Deutschland}, address = {G{\"o}ttingen}, organization = {Deutsche Gesellschaft f{\"u}r Luft- und Raumfahrt e.V. / Arbeitsgemeinschaft Str{\"o}mungen mit Abl{\"o}sung, AG STAB}, abstract = {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.}, language = {en} } @inproceedings{KrenkelWagnerWolfetal., author = {Krenkel, Lars and Wagner, Claus and Wolf, Ursula and Scholz, Alexander-Wigbert K. and Terekhov, Maxim and Rivoire, Julien and Schreiber, W.}, title = {Protective Artificial Lung Ventilation: Impact of an Endotracheal Tube on the Flow in a Generic Trachea}, series = {New Results in Numerical and Experimental Fluid Mechanics VII : Contributions to the 16th STAB/DGLR Symposium Aachen, Germany 2008}, booktitle = {New Results in Numerical and Experimental Fluid Mechanics VII : Contributions to the 16th STAB/DGLR Symposium Aachen, Germany 2008}, editor = {Hirschel, Ernst Heinrich and Schr{\"o}der, Wolfgang and Fujii, Kozo and Haase, Werner and Leer, Bram and Leschziner, Michael A. and Pandolfi, Maurizio and Periaux, Jacques and Rizzi, Arthur and Roux, Bernard and Shokin, Yurii I. and Dillmann, Andreas and Heller, Gerd and Klaas, Michael and Kreplin, Hans-Peter and Nitsche, Wolfgang}, publisher = {Springer Berlin Heidelberg}, address = {Berlin, Heidelberg}, isbn = {978-3-642-14242-0}, doi = {10.1007/978-3-642-14243-7_62}, pages = {505 -- 512}, abstract = {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.}, language = {en} } @inproceedings{KubowitschDendorfer, author = {Kubowitsch, Simone and Dendorfer, Sebastian}, title = {Psychologie und Biomechanik - Integrierte Betrachtung von Muskelrekrutierung}, series = {Jahrestagung der Deutschen Gesellschaft f{\"u}r Biofeedback e. V., Regensburg, 2018}, booktitle = {Jahrestagung der Deutschen Gesellschaft f{\"u}r Biofeedback e. V., Regensburg, 2018}, language = {de} } @misc{KubowitschSuessJansenetal., author = {Kubowitsch, Simone and S{\"u}ß, Franz and Jansen, Petra and Dendorfer, Sebastian}, title = {Effect of dual tasking on muscular imbalances}, series = {European Society of Biomechanics meeting 2019, Vienna, Austria}, journal = {European Society of Biomechanics meeting 2019, Vienna, Austria}, language = {en} } @inproceedings{KubowitschSuessJansenetal., author = {Kubowitsch, Simone and S{\"u}ß, Franz and Jansen, Petra and Dendorfer, Sebastian}, title = {Comparison of dynamic muscular imbalances in back pain patients and healthy controls}, series = {World Congress Biomechanics Dublin, 2018}, booktitle = {World Congress Biomechanics Dublin, 2018}, language = {en} } @inproceedings{KubowitschSuessJansenetal., author = {Kubowitsch, Simone and S{\"u}ß, Franz and Jansen, Petra and Dendorfer, Sebastian}, title = {Muscular imbalances during experimentally induced stress}, series = {23th Congress of the European Society of Biomechanics, Sevilla, Spain, 2017}, booktitle = {23th Congress of the European Society of Biomechanics, Sevilla, Spain, 2017}, language = {en} } @article{KummerlinFabroPedersenetal., author = {Kummerlin, Jana and Fabro, Hannah Katharina and Pedersen, Peter Heide and Jensen, Kenneth Krogh and Pedersen, Dennis and Andersen, Michael Skipper}, title = {Measuring Knee Joint Laxity in Three Degrees-of-Freedom In Vivo Using a Robotics- and Image-Based Technology}, series = {Journal of Biomechanical Engineering}, volume = {144}, journal = {Journal of Biomechanical Engineering}, number = {8}, publisher = {The American Society of Mechanical Engineers (ASME)}, issn = {1528-8951}, doi = {10.1115/1.4053792}, pages = {7}, abstract = {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.}, language = {en} } @article{KoeckStrieglKrausetal., author = {K{\"o}ck, Hannah and Striegl, Birgit and Kraus, Annalena and Zborilova, Magdalena and Christiansen, Silke H. and Sch{\"a}fer, Nicole and Gr{\"a}ssel, Susanne and Hornberger, Helga}, title = {In Vitro Analysis of Human Cartilage Infiltrated by Hydrogels and Hydrogel-Encapsulated Chondrocytes}, series = {Bioengineering}, volume = {10}, journal = {Bioengineering}, publisher = {MDPI}, doi = {10.3390/bioengineering10070767}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-61235}, pages = {1 -- 21}, abstract = {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.}, language = {en} } @misc{KoeglerIsmailRusavyetal., author = {K{\"o}gler, Michael and Ismail, Khaled M. and Rusavy, Zdenek and Kalis, Vladimir and S{\"u}ß, Franz and Dendorfer, Sebastian}, title = {Influence of bed height and stance on accoucheurs lower back and glenohumeral load during simulated childbirth}, series = {31st meeting of Czech Urogynaecological Society, Prague, 2022}, journal = {31st meeting of Czech Urogynaecological Society, Prague, 2022}, language = {en} } @article{LazarevRiabokonHalleretal., author = {Lazarev, Igor A. and Riabokon, P. V. and Haller, M. and Dendorfer, Sebastian}, title = {Effect of the Displacement of Calcaneal Bone Peripheral Fragment in its Fracture on the Function of the Three-Headed Calf Muscle}, series = {TRAUMA}, volume = {16}, journal = {TRAUMA}, number = {2}, publisher = {Zaslavsky}, doi = {10.22141/1608-1706.2.16.2015.80247}, pages = {20 -- 24}, abstract = {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.}, language = {en} } @article{LazarevRyabokonHalleretal., author = {Lazarev, Igor A. and Ryabokon, P.V. and Haller, M. and Dendorfer, Sebastian}, title = {Effect of the fractured calcaneus's peripheral fragment displacement on the triceps surae function}, series = {ЖУРНАЛ «ТРАВМА» Ukrainian Trauma Journal}, volume = {2, TOM 16}, journal = {ЖУРНАЛ «ТРАВМА» Ukrainian Trauma Journal}, language = {en} } @article{LehlePhilippKrenkeletal., author = {Lehle, Karla and Philipp, Alois and Krenkel, Lars and Gruber, Michael and Hiller, Karl-Anton and M{\"u}ller, Thomas and Lubnow, Matthias}, title = {Thrombocytopenia During Venovenous Extracorporeal Membrane Oxygenation in Adult Patients With Bacterial, Viral, and COVID-19 Pneumonia}, series = {ASAIO Journal}, journal = {ASAIO Journal}, publisher = {Wolters Kluwer}, issn = {1058-2916}, doi = {10.1097/MAT.0000000000002383}, abstract = {Contact of blood with artificial surfaces triggers platelet activation. The aim was to compare platelet kinetics after venovenous extracorporeal membrane oxygenation (V-V ECMO) start and after system exchange in different etiologies of acute lung failure. Platelet counts and coagulation parameters were analyzed from adult patients with long and exchange-free (≥8 days) ECMO runs (n = 330) caused by bacterial (n = 142), viral (n = 76), or coronavirus disease 2019 (COVID-19) (n = 112) pneumonia. A subpopulation requiring a system exchange and with long, exchange-free runs of the second oxygenator (≥7 days) (n = 110) was analyzed analogously. Patients with COVID-19 showed the highest platelet levels before ECMO implantation. Independent of the underlying disease and ECMO type, platelet counts decreased significantly within 24 hours and reached a steady state after 5 days. In the subpopulation, at the day of a system exchange, platelet counts were lower compared with ECMO start, but without differences between underlying diseases. Subsequently, platelets remained unchanged in the bacterial pneumonia group, but increased in the COVID-19 and viral pneumonia groups within 2-4 days, whereas D-dimers decreased and fibrinogen levels increased. Thus, overall platelet counts on V-V ECMO show disease-specific initial dynamics followed by an ongoing consumption by the ECMO device, which is not boosted by new artificial surfaces after a system exchange.}, language = {en} } @article{LenichBachmeierDendorferetal., author = {Lenich, Andreas and Bachmeier, S. and Dendorfer, Sebastian and Mayr, E. and Nerlich, Michael and F{\"u}chtmeier, Bernd}, title = {Development of a test system to analyze different hip fracture osteosyntheses under simulated walking}, series = {Biomedizinische Technik. Biomedical engineering}, volume = {57}, journal = {Biomedizinische Technik. Biomedical engineering}, number = {2}, doi = {10.1515/bmt-2011-0999}, pages = {113 -- 119}, abstract = {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.}, subject = {H{\"u}ftgelenk}, language = {en} } @article{LichtenauerEttlMohretal., author = {Lichtenauer, Norbert and Ettl, Katrin and Mohr, Christa and Weber, Karsten and Meussling-Sentpali, Annette}, title = {Der Pflegeroboter f{\"u}r zu Hause}, series = {Die Schwester, der Pfleger}, volume = {11}, journal = {Die Schwester, der Pfleger}, number = {21}, publisher = {Bibliomed-Medizinische Verlagsgesellschaft mbH}, pages = {48 -- 52}, abstract = {Ein interdisziplin{\"a}res Forschungsprojekt der Ostbayerischen Hochschule Regensburg untersucht, inwiefern Telemedizin und digitale Anwendungen die Therapie und Pflege von Menschen mit Schlaganfall in ihrem h{\"a}uslichen Umfeld unterst{\"u}tzen, ihre Lebensqualit{\"a}t beeinflussen und die intersektorale Versorgung verbessern kann.}, language = {de} } @article{LingelHausPaschkeetal., author = {Lingel, Maximilian P. and Haus, Moritz and Paschke, Lukas and Foltan, Maik and Lubnow, Matthias and Gruber, Michael and Krenkel, Lars and Lehle, Karla}, title = {Clinical relevance of cell-free DNA during venovenous extracorporeal membrane oxygenation}, series = {Artificial organs}, volume = {47}, journal = {Artificial organs}, number = {11}, publisher = {Wiley}, issn = {1525-1594}, doi = {10.1111/aor.14616}, pages = {1720 -- 1731}, abstract = {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.}, language = {en} }