@misc{Singh, author = {Singh, Max Diamond}, title = {Market Access for Devices under MDD and MDR: Obligations for Manufacturers}, series = {OSMA - Orthopedic Surgical Manufacturers Association, Winter Educational Program - virtual}, journal = {OSMA - Orthopedic Surgical Manufacturers Association, Winter Educational Program - virtual}, language = {en} } @misc{Singh, author = {Singh, Max Diamond}, title = {Innovationsmanagement}, language = {de} } @misc{Singh, author = {Singh, Max Diamond}, title = {General Overview of the Medical Device Regulation}, series = {MDR-Roadshow - T{\"U}V S{\"U}D MHS, India}, journal = {MDR-Roadshow - T{\"U}V S{\"U}D MHS, India}, language = {en} } @misc{Singh, author = {Singh, Max Diamond}, title = {Stakeholder view on Post Market Surveillance under the EU MDR: Timelines, Compliance and Requirements ; Post Market Surveillance \& Vigilance}, series = {MedTech summit 2020: EU MDR \& IVDR: the end ist in sight, 22.-26.06.2020, Dublin/virtual}, journal = {MedTech summit 2020: EU MDR \& IVDR: the end ist in sight, 22.-26.06.2020, Dublin/virtual}, language = {en} } @misc{Singh, author = {Singh, Max Diamond}, title = {Quality in Medical Device Innovation for Start-ups, SME, and large enterprises through the new Medical Device Regulation}, series = {3rd European QA Conference, Dublin, 06. - 08.11.2019}, journal = {3rd European QA Conference, Dublin, 06. - 08.11.2019}, language = {en} } @misc{Singh, author = {Singh, Max Diamond}, title = {Technical Documentation MDR / IVDR, including the Declaration of Conformity}, series = {MDR Training: Person Responsible for Regulatory Compliance, 24.-25.02.2020, Tel Aviv, Obelis Academy}, journal = {MDR Training: Person Responsible for Regulatory Compliance, 24.-25.02.2020, Tel Aviv, Obelis Academy}, language = {en} } @misc{Singh, author = {Singh, Max Diamond}, title = {Notified Body Viewpoint : Preparing for MDR/IVDR}, series = {MDR/IVDR - Status Report from Stakeholders. Where are we now in November 2018? - Bern, 22.11.2018 - [Veranstalter: RAPS : Regulatory Affairs Professionals Society]}, journal = {MDR/IVDR - Status Report from Stakeholders. Where are we now in November 2018? - Bern, 22.11.2018 - [Veranstalter: RAPS : Regulatory Affairs Professionals Society]}, language = {en} } @misc{Singh, author = {Singh, Max Diamond}, title = {Reclassification of Orthopedic Devices per the Medical Device Regulation}, series = {OSMA Winter Educational Program, St. Petersburg/USA, 2019. - [Veranstalter: Orthopedic Surgical Manufacturers Association (OSMA)]}, journal = {OSMA Winter Educational Program, St. Petersburg/USA, 2019. - [Veranstalter: Orthopedic Surgical Manufacturers Association (OSMA)]}, language = {en} } @misc{Singh, author = {Singh, Max Diamond}, title = {Strategies to Navigate to the EU MDR and Clinical Requirements}, series = {Regulatory Affairs Professionals Society (RAPS): Session 1 - Tampa, Florida 2019}, journal = {Regulatory Affairs Professionals Society (RAPS): Session 1 - Tampa, Florida 2019}, language = {en} } @misc{Singh, author = {Singh, Max Diamond}, title = {Herausforderungen der Medizinprodukteindustrie bei der Internationalisierung}, series = {Studienwoche an der HNU (Hochschule Neu-Ulm) 2020}, journal = {Studienwoche an der HNU (Hochschule Neu-Ulm) 2020}, language = {de} } @misc{Singh, author = {Singh, Max Diamond}, title = {Technical Aspects for Navigated Sinus Surgery}, series = {4th Workshop on Endoscopic Surgery of the Maxillary Sinus and Navigation, T{\"u}bingen University Hospital, 2009}, journal = {4th Workshop on Endoscopic Surgery of the Maxillary Sinus and Navigation, T{\"u}bingen University Hospital, 2009}, language = {en} } @misc{Singh, author = {Singh, Max Diamond}, title = {Overview of the Medical Device Regulation (MDR)}, language = {en} } @article{Singh, author = {Singh, Max Diamond}, title = {Orthopedic Medical Devices Under The Scope of The EU MDR}, series = {MedTech Outlook}, journal = {MedTech Outlook}, language = {en} } @misc{Singh, author = {Singh, Max Diamond}, title = {Joint NB-Position Paper on Spinal Classification per the MDR}, language = {en} } @phdthesis{Singh, author = {Singh, Max Diamond}, title = {Aspects of the Dynamics of Spine Surgery Technologies: Assessing the Reality of Innovation and Entrepreneurship in the U.S. Medical Device Industry}, publisher = {Karlsruhe Institute of Technology}, address = {Karlsruhe}, pages = {xix, 254 S.}, language = {en} } @incollection{Singh, author = {Singh, Max Diamond}, title = {Produktmanagement in der Medizintechnik}, series = {Medizinprodukte Management}, booktitle = {Medizinprodukte Management}, editor = {Schwegel, Philipp and Da-Cruz, Patrick and Hemel, Ulrich and Oberender, Peter}, publisher = {PCO-Verlag}, address = {Bayreuth}, isbn = {978-3-941678-47-7}, pages = {148 -- 161}, abstract = {Das Management in der Medizinprodukteindustrie steht vor vielf{\"a}ltigen Herausforderungen. So sinken einerseits die Produktpreise, anderseits wird auch f{\"u}r die kommenden Jahre in vielen Segmenten ein Mengenwachstum erwartet. Dies stellt die internen Prozesse, vom Customer Service bis hin zur Forschung \& Entwicklung, auf den Pr{\"u}fstand. Die Entscheidungstr{\"a}ger auf Kundenseite ver{\"a}ndern sich, weg vom Produktanwender hin zu professionellen Einkaufsgemeinschaften mit immer gr{\"o}ßerer Verhandlungsmacht. Der hohe Internationalisierungsgrad der Unternehmen f{\"u}hrt zu einer steigenden Komplexit{\"a}t bei der Implementierung von Marketing-, Vertriebs- und Produktentwicklungsstrategien auf L{\"a}nderebene. Dar{\"u}ber hinaus werden zunehmend neue Gesch{\"a}ftsmodelle mit hohem Dienstleistungsanteil entwickelt, die mit der traditionellen Lieferantenrolle wenig zu tun haben und von Managern eine neue F{\"a}higkeiten f{\"u}r die Umsetzung erfordern. Die Autoren des Sammelbands greifen die genannten Herausforderungen auf und bieten mit ihren Beitr{\"a}gen L{\"o}sungsans{\"a}tze, die sowohl f{\"u}r Manager im Medizinprodukteunternehmen als auch f{\"u}r Wissenschaftler und Studierende relevant sind.}, language = {de} } @incollection{SinghCapanni, author = {Singh, Max Diamond and Capanni, Felix}, title = {Medizintechnik-Spin-offs aus der Hochschule - Ein Prozessbeispiel}, series = {Entrepreneurship im Gesundheitswesen II}, booktitle = {Entrepreneurship im Gesundheitswesen II}, editor = {Pfannstiel Mario A., and Da-Cruz, Patrick and Rasche, Christoph}, publisher = {Springer Gabler}, address = {Wiesbaden}, isbn = {978-3-658-14781-5}, abstract = {Die Aufmerksamkeit f{\"u}r Unternehmensgr{\"u}ndungen hat in den letzten Jahren extrem zugenommen. Grunds{\"a}tzlich muss ein Start-up in einem kompetitiven Umfeld erfolgreich sein, um bestehen zu k{\"o}nnen. Der Weg dorthin wird maßgeblich beeinflusst durch Planung und finanzielle Ressourcen, die die Gr{\"u}nder bereitstellen m{\"u}ssen. In der Medizinprodukteindustrie kommen zus{\"a}tzlich große H{\"u}rden hinzu, die u. a. einen kurzen Produktlebenszyklus, lange Projektlaufzeiten, aufwendige klinische Studien und aktuell neue gesetzliche Verordnungen betreffen. Dieser Beitrag konzentriert sich zun{\"a}chst auf m{\"o}gliche F{\"o}rdermittel und Beratung von Start-up-Projekten aus dem Hochschulbereich. Aus einer Analyse derzeit existierender Gr{\"u}nderwettbewerbe im Hinblick auf das Gesundheitswesen werden dem Leser entsprechende Adressen zum Einwerben von F{\"o}rdermitteln geliefert. Dar{\"u}ber hinaus wird ein Pilot-Prozess vorgestellt, wie eine Ausgr{\"u}ndungsberatung an der Hochschule Ulm im Studiengang Medizintechnik derzeit verl{\"a}uft. Dies kann m{\"o}glicherweise ein Ankn{\"u}pfungspunkt f{\"u}r eine zuk{\"u}nftige Institutionalisierung von Spin-off-Vorhaben aus dem Hochschulbereich sein.}, language = {de} } @article{SinghRussTerzidis, author = {Singh, Max Diamond and Russ, Jochen and Terzidis, Orestis}, title = {The Impact of the ObamaCare Excise Tax on Innovation and Entrepreneurship - Early Empirical Findings}, series = {International Journal of Innovation Science}, volume = {7}, journal = {International Journal of Innovation Science}, number = {2}, publisher = {Emerald}, doi = {10.1260/1757-2223.7.2.75}, pages = {75 -- 90}, abstract = {This study addresses aspects of governmental influence on innovation by analyzing the impact of the ObamaCare excise tax on the medical device industry. We initially give an overview of common approaches to measuring innovativeness and entrepreneurship, empirically assess whether existing metrics are suitable for investigating the innovation performance of the U.S. medical device industry, and define a new measure (firm innovation activity) for entrepreneurship. Then we perform a quantitative analysis to explore the impact of the tax. We analyze more than 60,000 product clearances from 1996 to 2013, using the FDA database. We find a significant relationship between product counts and revenues for one segment. Contrary to the present criticism of the excise tax, we find hardly any noteworthy response in either firm innovation activity or number of products launched in the year after the tax was introduced. The 2013 reduction of new product submissions is well within the limits of typical annual fluctuations observed in previous years. This provides a first indication that the excise tax act did not have a strong impact on innovative activities through the present.}, language = {en} } @misc{SinghSchlagintweitReischle2020, author = {Singh, Max Diamond and Schlagintweit, S. and Reischle, G.}, title = {Additive-Manufactured Orthopedic Implants Under MDR}, number = {08.11.20}, year = {2020}, language = {en} } @article{SinghTerzidis, author = {Singh, Max Diamond and Terzidis, O.}, title = {Introducing Innovation Phase Transition}, series = {International Journal of Innovation Science}, volume = {7}, journal = {International Journal of Innovation Science}, number = {4}, publisher = {Emerald}, issn = {1757-2223}, doi = {10.1108/IJIS-07-04-2015-B003}, pages = {249 -- 262}, abstract = {Innovation diffusion points toward how innovations spread into the market after launch. This paper investigates diffusion dynamics at market entry time and proposes a new evolution pattern at the intersection between inventions and innovations. With this in mind, we initially prove that patent filings correlate with new product introductions in the U.S. spine market. Then we test our new theory supposing that certain patent filing threshold numbers accelerate strong economic returns in terms of innovations. We find that firms hitting certain patent filing thresholds significantly increase their product launches in the mentioned market. Moreover, the results seem to indicate that economic returns of inventions may be measured substantially. Thus, this paper suggests a new research area by utilizing our proposed concept about an Innovation Outcome Trigger Value (IOTV). Furthermore, the implications may also be interesting for practitioners, since we empirically prove that inventive activities turn out to be worthwhile, indeed.}, language = {en} } @inproceedings{SpreiterGalibarovDendorferetal., author = {Spreiter, G. and Galibarov, Pavel E. and Dendorfer, Sebastian and Ferguson, Stephen J.}, title = {Influence of kyphosis on spinal loading}, series = {10th International Symposium Computer Methods in Biomechanics and Biomedical Engineering (CMBBE) Meeting, 11. - 14. April 2012, Berlin}, booktitle = {10th International Symposium Computer Methods in Biomechanics and Biomedical Engineering (CMBBE) Meeting, 11. - 14. April 2012, Berlin}, language = {en} } @article{SteigerFoltanPhilippetal., author = {Steiger, Tamara and Foltan, Maik and Philipp, Alois and Mueller, Thomas and Gruber, Michael Andreas and Bredthauer, Andre and Krenkel, Lars and Birkenmaier, Clemens and Lehle, Karla}, title = {Accumulations of von Willebrand factor within ECMO oxygenators: Potential indicator of coagulation abnormalities in critically ill patients?}, series = {Artificial Organs}, volume = {43}, journal = {Artificial Organs}, number = {11}, publisher = {Wiley}, address = {Hoboken}, issn = {1525-1594}, doi = {10.1111/aor.13513}, pages = {1065 -- 1076}, abstract = {Clot formation within membrane oxygenators (MOs) remains a critical problem during extracorporeal membrane oxygenation (ECMO). The composition of the clots-in particular, the presence of von Willebrand factor (vWF)-may be an indicator for prevalent nonphysiological flow conditions, foreign body reactions, or coagulation abnormalities in critically ill patients. Mats of interwoven gas exchange fibers from randomly collected MOs (PLS, Maquet, Rastatt, Germany) of 21 patients were stained with antibodies (anti-vWF and anti-P-selectin) and counterstained with 4 ',6-diamidino-2-phenylindole. The extent of vWF-loading was correlated with patient and technical data. While 12 MOs showed low vWF-loadings, 9 MOs showed high vWF-loading with highest accumulations close to crossing points of adjacent gas fibers. The presence and the extent of vWF-fibers/"cobwebs," leukocytes, platelet-leukocyte aggregates (PLAs), and P-selectin-positive platelet aggregates were independent of the extent of vWF-loading. However, the highly loaded MOs were obtained from patients with a significantly elevated SOFA score, severe thrombocytopenia, and persistent liver dysfunction. The coagulation abnormalities of these critically ill patients may cause an accumulation of the highly thrombogenic and elongated high-molecular-weight vWF multimers in the plasma which will be trapped in the MOs during the ECMO therapy.}, language = {en} } @techreport{SteigerFoltanPhilippetal., type = {Working Paper}, author = {Steiger, Tamara and Foltan, Maik and Philipp, Alois and M{\"u}ller, Thomas and Gruber, Michael Andreas and Bredthauer, Andre and Krenkel, Lars and Birkenmaier, Clemens and Lehle, Karla}, title = {Accumulations of von Willebrand factor within ECMO oxygenators: Potential indicator of coagulation abnormalities in critically ill patients?}, abstract = {Clot formation within membrane oxygenators (MOs) remains a critical problem during extracorporeal membrane oxygenation (ECMO). The composition of the clots—in particular, the presence of von Willebrand factor (vWF)—may be an indicator for prevalent nonphysiological flow conditions, foreign body reactions, or coagulation abnormalities in critically ill patients. Mats of interwoven gas exchange fibers from randomly collected MOs (PLS, Maquet, Rastatt, Germany) of 21 patients were stained with antibodies (anti-vWF and anti-P-selectin) and counterstained with 4′,6-diamidino-2-phenylindole. The extent of vWF-loading was correlated with patient and technical data. While 12 MOs showed low vWF-loadings, 9 MOs showed high vWF-loading with highest accumulations close to crossing points of adjacent gas fibers. The presence and the extent of vWF-fibers/"cobwebs," leukocytes, platelet-leukocyte aggregates (PLAs), and P-selectin-positive platelet aggregates were independent of the extent of vWF-loading. However, the highly loaded MOs were obtained from patients with a significantly elevated SOFA score, severe thrombocytopenia, and persistent liver dysfunction. The coagulation abnormalities of these critically ill patients may cause an accumulation of the highly thrombogenic and elongated high-molecular-weight vWF multimers in the plasma which will be trapped in the MOs during the ECMO therapy.}, language = {en} } @article{StelzerKrenkel, author = {Stelzer, Vera and Krenkel, Lars}, title = {2D numerical investigations derived from a 3D dragonfly wing captured with a high-resolution micro-CT}, series = {Technology and health care : official journal of the European Society for Engineering and Medicine}, volume = {30}, journal = {Technology and health care : official journal of the European Society for Engineering and Medicine}, number = {1}, publisher = {IOS Press}, doi = {10.3233/THC-219010}, pages = {283 -- 289}, abstract = {BACKGROUND: Due to their corrugated profile, dragonfly wings have special aerodynamic characteristics during flying and gliding. OBJECTIVE: The aim of this study was to create a realistic 3D model of a dragonfly wing captured with a high-resolution micro-CT. To represent geometry changes in span and chord length and their aerodynamic effects, numerical investigations are carried out at different wing positions. METHODS: The forewing of a Camacinia gigantea was captured using a micro-CT. After the wing was adapted an error-free 3D model resulted. The wing was cut every 5 mm and 2D numerical analyses were conducted in Fluent® 2020 R2 (ANSYS, Inc., Canonsburg, PA, USA). RESULTS: The highest lift coefficient, as well as the highest lift-to-drag ratio, resulted at 0 mm and an angle of attack (AOA) of 5∘. At AOAs of 10∘ or 15∘, the flow around the wing stalled and a K{\´a}rm{\´a}n vortex street behind the wing becomes CONCLUSIONS: The velocity is higher on the upper side of the wing compared to the lower side. The pressure acts vice versa. Due to the recirculation zones that are formed in valleys of the corrugation pattern the wing resembles the form of an airfoil.}, language = {en} } @misc{StelzerRuettenKrenkel, author = {Stelzer, Vera and R{\"u}tten, Markus and Krenkel, Lars}, title = {Numerical Investigation of a 3D Dragonfly Wing Captured with a High-Resolution Micro-CT}, series = {8th European Congress on Computational Methods in Applied Sciences and Engineering, ECCOMAS Congress 2022, 5-9 June 2022, Oslo, Norway}, journal = {8th European Congress on Computational Methods in Applied Sciences and Engineering, ECCOMAS Congress 2022, 5-9 June 2022, Oslo, Norway}, abstract = {The special wing geometry of dragonflies consisting of veins and a membrane forming a corrugated profile leads to special aerodynamic characteristics. To capture the governing flow regimes of a dragonfly wing in detail, a realistic wing model has to be investigated. Therefore, this study aimed to analyze the aerodynamic characteristics of a 3D dragonfly wing reconstructed from a high-resolution micro-CT scan. Afterwards, a spatially high discretized mesh was generated using the mesh generator CENTAUR™ 14.5.0.2 (CentaurSoft, Austin, TX, US) to finally conduct Computational Fluid Dynamics (CFD) investigations in Fluent® 2020 R2 (ANSYS, Inc., Canonsburg, PA, US). Due to the small dimensions of the wing membrane, only the vein structure of a Camacinia Gigantea was captured at a micro-CT voxel size of 7 microns. The membrane was adapted and connected to the vein structure using a Boolean union operation. Occurring nconsistencies after combining the veins and the membrane were corrected using an adapted pymesh script [1]. As an initial study, only one quarter of the wing (outer wing section) was investigated to reduce the required computational effort. The resulting hybrid mesh consisting of 10 pseudo-structured prism layers along the wing surface and tetrahedra in the farfield area has 43 mio. nodes. The flow around the wing was considered to be incompressible and laminar using transient calculations. When the flow passes the vein structures, steady vortices occur in the corrugation valleys leading to recirculation zones. Therefore, the dragonfly wing resembles the profile of an airfoil. This leads to comparable lift coefficients of dragonfly wings and airfoil profiles at significantly reduced structural weight. The reconstructed geometry also included naturally occurring triangular prismlike serrated structures at the leading edge of the wing, which have comparable effects to micro vortex generators and might stabilize the recirculation zones. Further work aims to investigate the aerodynamic properties of a complete dragonfly wing during wing flapping.}, language = {en} } @misc{StelzerTauwaldVielsmeieretal., author = {Stelzer, Vera and Tauwald, Sandra Melina and Vielsmeier, Veronika and Cieplik, Fabian and Kandulski, Arne and Schneider-Brachert, Wulf and Wuensch, Olaf and R{\"u}tten, Markus and Krenkel, Lars}, title = {Generation, Distribution, and Contagiousness of Surgical Smoke during Tracheotomies}, 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 = {Surgical smoke has been a little discussed topic in the context of the current pandemic. Surgical smoke is generated during the cauterization of tissue with heat-generating devices and consists of 95\% water vapor and 5\% cellular debris in the form of particulate matter. In-vivo investigations are performed during tracheotomies where surgical smoke is produced during tissue electrocautery. Furthermore, in-vitro parametric studies to investigate the particle number and size distribution and the spatial distribution of surgical smoke with laser light sheet technique are conducted. The higher the power of the high-frequency-device the larger the particles in size and the higher the resulting particle counts. The images taken show the densest smoke at 40W with artificial saliva. The resulting characteristic size distribution, which may include viruses and bacterial components, confirms that the risk arising from surgical smoke should be considered. Furthermore, the experiments will provide the database for further numerical investigations.}, language = {en} } @inproceedings{StelzerTauwaldVielsmeieretal., author = {Stelzer, Vera and Tauwald, Sandra Melina and Vielsmeier, Veronika and Cieplik, Fabian and Kandulski, Arne and Schneider-Brachert, Wulf and W{\"u}nsch, Olaf and R{\"u}tten, Markus and Krenkel, Lars}, title = {Generation and Distribution of Surgical Smoke During High Frequency Electrocauterization}, series = {New Results in Numerical and Experimental Fluid Mechanics XIV. STAB/DGLR Symposium 2022}, booktitle = {New Results in Numerical and Experimental Fluid Mechanics XIV. STAB/DGLR Symposium 2022}, editor = {Dillman, Andreas and Heller, Gerd and Kraemer, Ewald and Wagner, Claus and Weiss, Julien}, publisher = {Springer Nature Switzerland AG}, address = {Cham, Switzerland}, isbn = {978-3-031-40481-8}, doi = {10.1007/978-3-031-40482-5_53}, pages = {559 -- 568}, abstract = {Surgical Smoke is generated during the cauterization of tissue with high-frequency (HF) devices and consists of 95\% water vapor and 5\% cellular debris. When the coagulation tweezers, which are supplied with HF voltage by the HF device, touch tissue, the electric circuit is closed, and smoke is generated by the heat. In-vivo investigations are performed during tracheotomies where surgical smoke is produced during coagulation of tissue. Furthermore, in-vitro parametric studies to investigate the particle number and size distribution and the spatial distribution of surgical smoke with laser light sheet technique are conducted. With higher power of the HF device, the particles generated are larger in size and the total number of particles generated is also higher. Adding artificial saliva to the tissue shows even higher particle counts. The study by laser light sheet also confirms this. The resulting characteristic size distribution, which may include viruses and bacterial components, confirms considering the risk arising from surgical smoke. Furthermore, the experiments will provide the database for further numerical investigations.}, language = {en} } @inproceedings{StrieglKujatDendorfer, author = {Striegl, B. and Kujat, Richard and Dendorfer, Sebastian}, title = {Quantitative analysis of cartilage surface by confocal laser scanning microscopy}, series = {Biomedizinische Technik}, volume = {59}, booktitle = {Biomedizinische Technik}, number = {s1-A}, doi = {10.1515/bmt-2014-4012}, pages = {24}, language = {en} } @misc{SuessMelznerDendorfer, author = {Suess, Franz and Melzner, Maximilian and Dendorfer, Sebastian}, title = {Towards Ergonomic working - machine learning algorithms and musculoskeletal modeling}, series = {RIM 2021, 13th International Scientific Conference on Manufacturing Engineering, 29 Sept. - 1 Oct 2021, Sarajevo, Bosnia and Herzegovina}, journal = {RIM 2021, 13th International Scientific Conference on Manufacturing Engineering, 29 Sept. - 1 Oct 2021, Sarajevo, Bosnia and Herzegovina}, language = {en} } @inproceedings{SuessMelznerDendorfer, author = {Suess, Franz and Melzner, Maximilian and Dendorfer, Sebastian}, title = {Towards ergonomics working - machine learning algorithms and musculoskeletal modeling}, series = {IOP Conference Series: Materials Science and Engineering}, volume = {1208}, booktitle = {IOP Conference Series: Materials Science and Engineering}, publisher = {IOP Publishing}, issn = {1757-899X}, doi = {10.1088/1757-899X/1208/1/012001}, abstract = {Ergonomic workplaces lead to fewer work-related musculoskeletal disorders and thus fewer sick days. There are various guidelines to help avoid harmful situations. However, these recommendations are often rather crude and often neglect the complex interaction of biomechanical loading and psychological stress. This study investigates whether machine learning algorithms can be used to predict mechanical and stress-related muscle activity for a standardized motion. For this purpose, experimental data were collected for trunk movement with and without additional psychological stress. Two different algorithms (XGBoost and TensorFlow) were used to model the experimental data. XGBoost in particular predicted the results very well. By combining it with musculoskeletal models, the method shown here can be used for workplace analysis but also for the development of real-time feedback systems in real workplace environments.}, language = {en} } @inproceedings{SuessKubowitschRasmussenetal., author = {S{\"u}ß, Franz and Kubowitsch, Simone and Rasmussen, John and Verkerke, Gijsbertus Jacob and Dendorfer, Sebastian}, title = {The influence of cognitive stress on muscle activation and spinal disc load}, series = {European Society of Biomechanics meeting 2019, Vienna, Austria}, booktitle = {European Society of Biomechanics meeting 2019, Vienna, Austria}, language = {en} } @inproceedings{SuessKubowitschVerkerkeetal., author = {S{\"u}ß, Franz and Kubowitsch, Simone and Verkerke, Gijsbertus Jacob and Dendorfer, Sebastian}, title = {The influence of stress on spinal loading}, series = {ESEM webconference, Dez. 2017}, booktitle = {ESEM webconference, Dez. 2017}, language = {en} } @inproceedings{SuessKubowitschVerkerkeetal., author = {S{\"u}ß, Franz and Kubowitsch, Simone and Verkerke, Gijsbertus Jacob and Dendorfer, Sebastian}, title = {The influence of mental stress on spinal disc loading and muscle activity}, 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} } @inproceedings{SuessKubowitschVerkerkeetal., author = {S{\"u}ß, Franz and Kubowitsch, Simone and Verkerke, Gijsbertus Jacob and Dendorfer, Sebastian}, title = {Investigation of cognitive stress induced changes in spinal disc forces due to altered kinematics and muscle activity}, series = {World Congress Biomechanics, Dublin, 2018}, booktitle = {World Congress Biomechanics, Dublin, 2018}, language = {en} } @inproceedings{SuessPutzerDendorfer, author = {S{\"u}ß, Franz and Putzer, Michael and Dendorfer, Sebastian}, title = {Numerische und experimentelle Untersuchungen an der Wirbels{\"a}ule}, series = {Forschungssymposium Bad Abbach, Germany, 2015}, booktitle = {Forschungssymposium Bad Abbach, Germany, 2015}, language = {de} } @article{TauwaldErzingerQuadrioetal., author = {Tauwald, Sandra Melina and Erzinger, Florian and Quadrio, Maurizio and R{\"u}tten, Markus and Stemmer, Christian and Krenkel, Lars}, title = {Tomo-PIV in a patient-specific model of human nasal cavities: a methodological approach}, series = {Measurement Science and Technology}, volume = {35}, journal = {Measurement Science and Technology}, number = {5}, publisher = {IOP Publishing}, doi = {10.1088/1361-6501/ad282c}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-70393}, abstract = {The human nose serves as the primary gateway for air entering the respiratory system and plays a vital role in breathing. Nasal breathing difficulties are a significant health concern, leading to substantial healthcare costs for patients. Understanding nasal airflow dynamics is crucial for comprehending respiratory mechanisms. This article presents a detailed study using tomo-Particle Image Velocimetry (PIV) to investigate nasal airflow dynamics while addressing its accuracy. Embedded in the OpenNose project, the work described aims to provide a validation basis for different numerical approaches to upper airway flow. The study includes the manufacturing of a transparent silicone model based on a clinical CT scan, refractive index matching to minimize optical distortions, and precise flow rate adjustments based on physiological breathing cycles. This method allows for spatial high-resolution investigations in different regions of interest within the nasopharynx during various phases of the breathing cycle. The results demonstrate the accuracy of the investigations, enabling detailed analysis of flow structures and gradients. This spatial high-resolution tomo-PIV approach provides valuable insights into the complex flow phenomena occurring during the physiological breathing cycle in the nasopharynx. The study's findings contribute to advancements in non-free-of-sight experimental flow investigation of complex cavities under nearly realistic conditions. Furthermore, reliable and accurate experimental data is crucial for properly validating numerical approaches that compute this patient-specific flow for clinical purposes.}, language = {en} } @misc{TauwaldKrenkel, author = {Tauwald, Sandra Melina and Krenkel, Lars}, title = {Elementary experimental setup for flow visualization in upper human respiratory tract}, series = {25th Congress of the European Society of Biomechanics, July 7-10, 2019, Vienna, Austria}, journal = {25th Congress of the European Society of Biomechanics, July 7-10, 2019, Vienna, Austria}, language = {en} } @article{TauwaldMichelBrandtetal., author = {Tauwald, Sandra Melina and Michel, Johanna and Brandt, Marie and Vielsmeier, Veronika and Stemmer, Christian and Krenkel, Lars}, title = {Experimental studies and mathematical modeling of the viscoelastic rheology of tracheobronchial mucus from respiratory healthy patients}, series = {Multidisciplinary Respiratory Medicine}, volume = {18}, journal = {Multidisciplinary Respiratory Medicine}, number = {1}, publisher = {PAGEPress}, address = {Pavia, Italy}, issn = {2049-6958}, doi = {10.4081/mrm.2023.923}, pages = {12}, abstract = {BACKGROUND: Tracheobronchial mucus plays a crucial role in pulmonary function by providing protection against inhaled pathogens. Due to its composition of water, mucins, and other biomolecules, it has a complex viscoelastic rheological behavior. This interplay of both viscous and elastic properties has not been fully described yet. In this study, we characterize the rheology of human mucus using oscillatory and transient tests. Based on the transient tests, we describe the material behavior of mucus under stress and strain loading by mathematical models. METHODS: Mucus samples were collected from clinically used endotracheal tubes. For rheological characterization, oscillatory amplitude-sweep and frequency-sweep tests, and transient creep-recovery and stress-relaxation tests were performed. The results of the transient test were approximated using the Burgers model, the Weibull distribution, and the six-element Maxwell model. The three-dimensional microstructure of the tracheobronchial mucus was visualized using scanning electron microscope imaging. RESULTS: Amplitude-sweep tests showed storage moduli ranging from 0.1 Pa to 10000 Pa and a median critical strain of 4 \%. In frequency-sweep tests, storage and loss moduli increased with frequency, with the median of the storage modulus ranging from 10 Pa to 30 Pa, and the median of the loss modulus from 5 Pa to 14 Pa. The Burgers model approximates the viscoelastic behavior of tracheobronchial mucus during a constant load of stress appropriately (R2 of 0.99), and the Weibull distribution is suitable to predict the recovery of the sample after the removal of this stress (R2 of 0.99). The approximation of the stress-relaxation test data by a six-element Maxwell model shows a larger fit error (R2 of 0.91). CONCLUSIONS: This study provides a detailed description of all process steps of characterizing the rheology of tracheobronchial mucus, including sample collection, microstructure visualization, and rheological investigation. Based on this characterization, we provide mathematical models of the rheological behavior of tracheobronchial mucus. These can now be used to simulate mucus flow in the respiratory system through numerical approaches.}, language = {en} } @misc{TauwaldQuadrioRuettenetal., author = {Tauwald, Sandra Melina and Quadrio, Maurizio and R{\"u}tten, Markus and Stemmer, Christian and Krenkel, Lars}, title = {High Spatial Resolution Tomo-PIV of the Nasopharynx Focussing on the Physiological Breathing Cycle}, 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 = {Investigations of complex patient-specific flow in the nasopharynx requires high resolution numerical calculations validated by reliable experiments. When building the validation base and the benchmark of computational fluid dynamics, an experimental setup of the nasal airways was developed. The applied optical measurement technique of tomo-PIV supplies information on the governing flow field in three dimensions. This paper presents tomo-PIV measurements of the highly complex patient-specific geometry of the human trachea. A computertomographic scan of a person's head builds the basis of the experimental silicone model of the nasal airways. An optimised approach for precise refractive index matching avoids optical distortions even in highly complex non-free-of-sight 3D geometries. A linear-motor-driven pump generates breathing scenarios, based on measured breathing cycles. Adjusting of the CCD cameras' double-frame-rate PIV-Δt enables the detailed analysis of flow structures during different cycle phases. Merging regions of interest enables high spatial resolution acquisition of the flow field.}, language = {en} } @inproceedings{TauwaldQuadrioRuettenetal., author = {Tauwald, Sandra Melina and Quadrio, Maurizio and R{\"u}tten, Markus and Stemmer, Christian and Krenkel, Lars}, title = {High Spatial Resolution Tomo-PIV of the Trachea Focussing on the Physiological Breathing Cycle}, series = {New Results in Numerical and Experimental Fluid Mechanics XIV - Contributions to the 23nd STAB/DGLR Symposium}, booktitle = {New Results in Numerical and Experimental Fluid Mechanics XIV - Contributions to the 23nd STAB/DGLR Symposium}, publisher = {Springer}, abstract = {Investigations of complex patient-specific flow in the nasopharynx requires high resolution numerical calculations validated by reliable experiments. When building the validation base and the benchmark of computational fluid dynamics, an experimental setup of the nasal airways was developed. The applied optical measurement technique of tomo-PIV supplies information on the governing flow field in three dimensions. This paper presents tomo-PIV measurements of the highly complex patient-specific geometry of the human trachea. A computertomographic scan of a person's head builds the basis of the experimental silicone model of the nasal airways. An optimised approach for precise refractive index matching avoids optical distortions even in highly complex non-free-of-sight 3D geometries. A linear-motor-driven pump generates breathing scenarios, based on measured breathing cycles. Adjusting of the CCD cameras' double-frame-rate PIV-Δt enables the detailed analysis of flow structures during different cycle phases. Merging regions of interest enables high spatial resolution acquisition of the flow field.}, language = {en} } @article{VisscherWyssSinghetal., author = {Visscher, Rosa and Wyss, C. and Singh, Navrag B. and Taylor, William R. and Dendorfer, Sebastian and Rutz, E. and Brunner, Reinald}, title = {Influence of TAL-TATS surgery on energy production of Tricepts Surae - A musculoskeletal modeling evaluation}, series = {Gait \& Posture}, volume = {81}, journal = {Gait \& Posture}, number = {Suppl. 1}, publisher = {Elsevier}, doi = {10.1016/j.gaitpost.2020.08.090}, pages = {381 -- 382}, language = {en} } @article{VoellnerWeberWeberetal., author = {V{\"o}llner, Florian and Weber, Tim A. and Weber, Markus and Renkawitz, Tobias and Dendorfer, Sebastian and Grifka, Joachim and Craiovan, Benjamin}, title = {A simple method for determining ligament stiffness during total knee arthroplasty in vivo}, series = {Scientific Reports}, volume = {9}, journal = {Scientific Reports}, publisher = {Nature}, doi = {10.1038/s41598-019-41732-x}, pages = {1 -- 8}, abstract = {A key requirement in both native knee joints and total knee arthroplasty is a stable capsular ligament complex. However, knee stability is highly individual and ranges from clinically loose to tight. So far, hardly any in vivo data on the intrinsic mechanical of the knee are available. This study investigated if stiffness of the native ligament complex may be determined in vivo using a standard knee balancer. Measurements were obtained with a commercially available knee balancer, which was initially calibrated in vitro. 5 patients underwent reconstruction of the force-displacement curves of the ligament complex. Stiffness of the medial and lateral compartments were calculated to measure the stability of the capsular ligament complex. All force-displacement curves consisted of a non-linear section at the beginning and of a linear section from about 80 N onwards. The medial compartment showed values of 28.4 ± 1.2 N/mm for minimum stiffness and of 39.9 ± 1.1 N/mm for maximum stiffness; the respective values for the lateral compartment were 19.9 ± 0.9 N/mm and 46.6 ± 0.8 N/mm. A commercially available knee balancer may be calibrated for measuring stiffness of knee ligament complex in vivo, which may contribute to a better understanding of the intrinsic mechanical behaviour of knee joints.}, subject = {Biomechanische Analyse}, language = {en} } @article{WagnerKranzKrenkeletal., author = {Wagner, Maria Stella and Kranz, Michael and Krenkel, Lars and Pointner, Daniel and Foltan, Maik and Lubnow, Matthias and Lehle, Karla}, title = {Computer based visualization of clot structures in extracorporeal membrane oxygenation and histological clot investigations for understanding thrombosis in membrane lungs}, series = {Frontiers in Medicine}, journal = {Frontiers in Medicine}, number = {11}, editor = {Becatti, Matteo}, publisher = {Frontiers}, doi = {10.3389/fmed.2024.1416319}, abstract = {Extracorporeal membrane oxygenation (ECMO) was established as a treatment for severe cardiac or respiratory disease. Intra-device clot formation is a common risk. This is based on complex coagulation phenomena which are not yet sufficiently understood. The objective was the development and validation of a methodology to capture the key properties of clots deposed in membrane lungs (MLs), such as clot size, distribution, burden, and composition. One end-oftherapy PLS ML was examined. Clot detection was performed using multidetector computed tomography (MDCT), microcomputed tomography (μCT), and photography of fiber mats (fiber mat imaging, FMI). Histological staining was conducted for von Willebrand factor (vWF), platelets (CD42b, CD62P), fibrin, and nucleated cells (4′, 6-diamidino-2-phenylindole, DAPI). The three imaging methods showed similar clot distribution inside the ML. Independent of the imaging method, clot loading was detected predominantly in the inlet chamber of the ML. The μCT had the highest accuracy. However, it was more expensive and time consuming than MDCT or FMI. The MDCT detected the clots with low scanning time. Due to its lower resolution, it only showed clotted areas but not the exact shape of clot structures. FMI represented the simplest variant, requiring little effort and resources. FMI allowed clot localization and calculation of clot volume. Histological evaluation indicated omnipresent immunological deposits throughout the ML. Visually clot-free areas were covered with leukocytes and platelets forming platelet-leukocyte aggregates (PLAs). Cells were embedded in vWF cobwebs, while vWF fibers were negligible. In conclusion, the presented methodology allowed adequate clot identification and histological classification of possible thrombosis markers such as PLAs.}, language = {en} } @misc{WagnerKrenkelDoenitzetal., author = {Wagner, Thomas and Krenkel, Lars and D{\"o}nitz, Christian and Brawanski, Alexander}, title = {Influence of CFD Strategy on WSS and OSI Determination for Intracranial Aneurysm Rupture Assessment}, series = {25th Congress of the European Society of Biomechanics, July 7-10, 2019, Vienna, Austria}, journal = {25th Congress of the European Society of Biomechanics, July 7-10, 2019, Vienna, Austria}, language = {en} } @article{WeberMerleNawabietal., author = {Weber, Markus and Merle, Christian and Nawabi, Danyal H. and Dendorfer, Sebastian and Grifka, Joachim and Renkawitz, Tobias}, title = {Inaccurate offset restoration in total hip arthroplasty results in reduced range of motion}, series = {Scientific Reports}, volume = {10}, journal = {Scientific Reports}, number = {13208}, publisher = {Nature}, doi = {10.1038/s41598-020-70059-1}, pages = {9}, abstract = {Offset restoration in total hip arthroplasty (THA) is associated with postoperative range of motion (ROM) and gait kinematics. We aimed to research into the impact of high offset (HO) and standard stems on postoperative ROM. 121 patients received cementless THA through a minimally-invasive anterolateral approach. A 360° hip ROM analysis software calculated impingement-free hip movement based on postoperative 3D-CTs compared to ROM values necessary for activities of daily living (ADL). The same model was then run a second time after changing the stem geometry between standard and HO configuration with the implants in the same position. HO stems showed higher ROM for all directions between 4.6 and 8.9° (p < 0.001) compared with standard stems but with high interindividual variability. In the subgroup with HO stems for intraoperative offset restoration, the increase in ROM was even higher for all ROM directions with values between 6.1 and 14.4° (p < 0.001) compared to offset underrestoration with standard stems. Avoiding offset underrestoration resulted in a higher amount of patients of over 20\% for each ROM direction that fulfilled the criteria for ADL (p < 0.001). In contrast, in patients with standard stems for offset restoration ROM did increase but not clinically relevant by offset overcorrection for all directions between 3.1 and 6.1° (p < 0.001). Offset overcorrection by replacing standard with HO stems improved ROM for ADL in a low number of patients below 10\% (p > 0.03). Patient-individual restoration of offset is crucial for free ROM in THA. Both over and underrestoration of offset should be avoided.}, language = {en} } @article{WeberSuessJerabeketal., author = {Weber, Markus and Suess, Franz and Jerabek, Seth and Meyer, Matthias and Grifka, Joachim and Renkawitz, Tobias and Dendorfer, Sebastian}, title = {Kinematic pelvic tilt during gait alters functional cup position in total hip arthroplasty}, series = {Journal of Orthopaedic Research}, volume = {40}, journal = {Journal of Orthopaedic Research}, number = {4}, publisher = {Wiley}, issn = {1554-527X}, doi = {10.1002/jor.25106}, pages = {846 -- 853}, abstract = {Static pelvic tilt impacts functional cup position in total hip arthroplasty (THA). In the current study we investigated the effect of kinematic pelvic changes on cup position. In the course of a prospective controlled trial postoperative 3D-computed tomography (CT) and gait analysis before and 6 and 12 months after THA were obtained in 60 patients. Kinematic pelvic motion during gait was measured using Anybody Modeling System. By fusion with 3D-CT, the impact of kinematic pelvic tilt alterations on cup anteversion and inclination was calculated. Furthermore, risk factors correlating with high pelvic mobility were evaluated. During gait a high pelvic range of motion up to 15.6° exceeding 5° in 61.7\% (37/60) of patients before THA was found. After surgery, the pelvis tilted posteriorly by a mean of 4.0 ± 6.6° (p < .001). The pelvic anteflexion led to a mean decrease of -1.9 ± 2.2° (p < .001) for cup inclination and -15.1 ± 6.1° (p < .001) for anteversion in relation to the anterior pelvic plane (APP). Kinematic pelvic changes resulted in a further change up to 2.3° for inclination and up to 12.3° for anteversion. In relation to the preoperative situation differences in postoperative cup position ranged from -4.4 to 4.6° for inclination and from -7.8 to 17.9° for anteversion, respectively. Female sex (p < .001) and normal body weight (p < .001) correlated with high alterations in pelvic tilt. Kinematic pelvic changes highly impact cup anteversion in THA. Surgeons using the APP as reference should aim for a higher anteversion of about 15° due to the functional anteflexion of the pelvis during gait.}, subject = {H{\"u}ftgelenkprothese}, language = {en} } @article{WeberWeberWoerneretal., author = {Weber, Markus and Weber, Tim A. and Woerner, Michael and Craiovan, Benjamin and Worlicek, Michael and Winkler, Sebastian and Grifka, Joachim and Renkawitz, Tobias}, title = {The impact of standard combined anteversion definitions on gait and clinical outcome within one year after total hip arthroplasty}, series = {International Orthopaedics}, volume = {39}, journal = {International Orthopaedics}, number = {12}, doi = {10.1007/s00264-015-2777-8}, pages = {2323 -- 2333}, abstract = {Different target areas within the concept of combined cup and stem anteversion have been published for total hip arthroplasty (THA). We asked whether component positioning according to eight standard combined anteversion rules is associated with (1) more physiological gait patterns, (2) higher improvement of gait variables and (3) better clinical outcome after THA.In a prospective clinical study, 60 patients received cementless THA through an anterolateral MIS approach in a lateral decubitus position. Six weeks postoperatively, implant position was analysed using 3D-CT by an independent external institute. Preoperatively, six and 12 months postoperatively range of motion, normalized walking speed and hip flexion symmetry index were measured using 3D motion-capture gait analysis. Patient-related outcome measures (HHS, HOOS, EQ-5D) were obtained by an observer blinded to 3D-CT results. Eight combined anteversion definitions and Lewinnek's "safe zone" were evaluated regarding their impact on gait patterns and clinical outcome.Combined cup and stem anteversion according to standard combined anteversion definitions as well as cup placement within Lewinnek's "safe zone" did not influence range of motion, normalized walking speed and/or hip flexion symmetry index six and 12 months after THA. Similarly, increase of gait parameters within the first year after THA was comparable between all eight combined anteversion rules. Clinical outcome measures like HHS, HOOS and EQ-5D did not show any benefit for either of the combined anteversion definitions.Standard combined cup and stem anteversion rules do not improve postoperative outcome as measured by gait analysis and clinical scores within one year after THA.}, subject = {H{\"u}ftgelenkprothese}, language = {en} } @article{WeberDendorferBulstraetal., author = {Weber, Tim A. and Dendorfer, Sebastian and Bulstra, Sjoerd K. and Grifka, Joachim and Verkerke, Gijsbertus Jacob and Renkawitz, Tobias}, title = {Gait six month and one-year after computer assisted Femur First THR vs. conventional THR. Results of a patient- and observer- blinded randomized controlled trial}, series = {Gait \& Posture}, volume = {vol. 49}, journal = {Gait \& Posture}, doi = {10.1016/j.gaitpost.2016.06.035}, pages = {418 -- 425}, abstract = {A prospective randomized controlled trial is presented that is used to compare gait performance between the computer assisted Femur First (CAS FF) operation method and conventional THR (CON). 60 patients underwent a 3D gait analysis of the lower extremity at pre-operative, 6 months post-operative and twelve months post-operative. Detailed verification experiments were facilitated to ensure the quality of data as well as to avoid over-interpreting of the data. The results confirm a similar data-quality as reported in the literature. Walking speed, range of motion and symmetry thereof improved over the follow-up period, without significant differences between the groups. While all parameters do significantly increase over the follow-up period for both groups, there were no significant differences between them at any given time-point. Patients undergoing CAS FF showed a trend to improved hip flexion angle indicating a possible long-term benefit.}, language = {en} } @inproceedings{WeberDendorferDullienetal., author = {Weber, Tim A. and Dendorfer, Sebastian and Dullien, Silvia and Grifka, Joachim and Verkerke, Gijsbertus Jacob and Renkawitz, Tobias}, title = {Measuring functional outcome after total hip replacement with subject-specific hip joint loading}, series = {Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine}, volume = {226}, booktitle = {Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine}, number = {12}, doi = {10.1177/0954411912447728}, pages = {939 -- 946}, abstract = {Total hip replacement is an often-performed orthopedic surgical procedure; the amount of procedures undertaken will increase since our life expectancy is growing. In order to optimize function, hip biomechanics should be restored to as near normal as possible. The goal of this pilot study was to determine whether or not it is feasible to compute the vectorial hip reaction force pathways on the head of the prosthesis and the force angles relative to the cup of the prosthesis that occur during gait in total hip replacement patients, serving as an objective measurement of the functional outcome following hip replacement. A three-dimensional gait analysis, measuring ground reaction forces and kinematics, was performed. The data retrieved from the gait analysis was used as the input for the musculoskeletal model to compute vectorial joint reaction forces for data processing. To evaluate the position and orientation of the joint reaction forces, the force path, as well as the force angles for the operated and non-operated joint, has been calculated during the stance phase of the specific leg. The force path for subject 2 on the non-operated side is only located in the posterior-lateral quarter, as is the force path for subject 1. In contrast to this subject, the force path for subject 2 at the operated hip joint can be found only within the anterior quarter of the head of the implant, where it is nearly equally distributed in the medio-lateral half of the prosthesis head. The force-inclination angles on the cup of subject 1, with respect to the plane of the socket face, indicates that the force vector is mainly positioned in the same quadrant when compared with subject 2 (in a cup-fixed coordinate system). The force-anteversion angle behaves similarly to the force-inclination angle, even when the effects are not as pronounced. The proposed methods in this article are aiming to define two functional outcomes of total hip replacement that are related to wear and rim loading. It is accepted that wear is not only a function of time, but a function of use. Owing to the methods listed in this article, we are able to determine a) the applied force and b) the sliding distance (force pathway) in a subject-specific manner. The computed hip-reaction force angles and the distance to the rim cup are a measurement for cup or rim loading, and occurs in the so-called safe-zones. This method may well give us insight into the biomechanical situation during gait, after receiving total hip replacement, that we need to fully understand the mechanisms acting on a hip joint and to prove a possible increase of functional outcome after receiving total hip replacement.}, subject = {H{\"u}ftgelenkprothese}, language = {en} } @article{WeberDendorferGrifkaetal., author = {Weber, Tim A. and Dendorfer, Sebastian and Grifka, Joachim and Verkerke, Gijsbertus Jacob and Renkawitz, Tobias}, title = {Does Computer-Assisted Femur First THR Improve Musculoskeletal Loading Conditions?}, series = {BioMed Research International}, volume = {2015}, journal = {BioMed Research International}, editor = {Takagi, Michiaki}, doi = {10.1155/2015/625317}, pages = {ID 625317}, abstract = {We have developed a novel, computer-assisted operation method for minimal-invasive total hip replacement (THR) following the concept of "femur first/combined anteversion," which incorporates various aspects of performing a functional optimization of the prosthetic stem and cup position (CAS FF). The purpose of this study is to assess whether the hip joint reaction forces and patient's gait parameters are being improved by CAS FF in relation to conventional THR (CON). We enrolled 60 patients (28 CAS FF/32 CON) and invited them for gait analysis at three time points (preoperatively, postop six months, and postop 12 months). Data retrieved from gait analysis was processed using patient-specific musculoskeletal models. The target parameters were hip reaction force magnitude (hrf), symmetries, and orientation with respect to the cup. Hrf in the CAS FF group were closer to a young healthy normal. Phase-shift symmetry showed an increase in the CAS FF group. Hrf orientation in the CAS FF group was closer to optimum, though no edge or rim-loading occurred in the CON group as well. The CAS FF group showed an improved hrf orientation in an early stage and a trend to an improved long-term outcome.}, subject = {H{\"u}ftgelenkprothese}, language = {en} }