@article{GschossmannSchedelSuessetal., author = {Gschoßmann, Lukas and Schedel, Valentin and S{\"u}ß, Franz and Weber, Markus and Pfingsten, Andrea and Dendorfer, Sebastian}, title = {Comparing kinematic and kinetic demands on the knee joint during selected physiotherapy exercises and activities of daily living}, series = {Technology and health care ; Special issue: BIOMDLORE}, journal = {Technology and health care ; Special issue: BIOMDLORE}, publisher = {Sage}, doi = {10.1177/09287329251413413}, pages = {14}, abstract = {Background: The knee is one of the most common areas to suffer injuries or be affected by surgery. Physiotherapy rehabilitation was shown to support recovery, but evidence guiding optimal rehabilitation practices is limited. To recommend appropriate exercises, it is essential to understand the musculoskeletal requirements involved in both physiotherapy and activities of daily living (ADLs).ObjectiveThis study aimed to evaluate and compare the knee joint kinematics, joint forces and muscle activity in knee flexors and extensors during selected rehabilitation exercises and ADLs.MethodsKinematic and kinetic data from 30 healthy participants were collected during 20 different tasks. Full-body musculoskeletal simulations were performed to estimate peak knee joint angles, angular velocities, joint reaction forces, and muscle activity of the knee flexors and extensors.ResultsComparatively high requirements were observed for lunges, squats, stair walking and gait. Medium requirements were observed for sitting down and rising from a chair. Low requirements were observed for balance shifts and variations of the single leg stand.ConclusionOverall, ADLs like gait and stair walking show surprisingly high requirements compared to many exercises employed in physiotherapy. These findings are a step towards biomechanically informed exercise selection and the development of personalized rehabilitation programs.}, language = {en} } @article{KrausKnipferJacobetal., author = {Kraus, Richard and Knipfer, Maximilian and Jacob, Matthias and Kienninger, Baerbel and Alikhani, Jasmine and Ghamsary, Parham Heydarzadeh and Reinker, Lukas and Adler, Ina and Dendorfer, Sebastian and Kieninger, Martin}, title = {Effectiveness and safety of techniques for cervical spine immobilization in mountain rescue}, series = {Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine}, volume = {34}, journal = {Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine}, publisher = {Springer}, doi = {10.1186/s13049-025-01530-z}, pages = {10}, abstract = {Background Cervical spine injuries in alpine sports require immediate immobilization at the site of the accident to avoid possible secondary damage caused by transportation. Using special sensor technology, this study investigated whether a cervical spine orthosis (cervical collar, Stifneck collar (Laerdal Medical GmbH, Puchheim, Germany)) provides greater stability than a vacuum mattress alone. Methods Using one male test person, we simulated transporting a patient with a spinal injury in steep alpine terrain. A wireless motion capture system (Xsens Technologies, Movella™ Inc., Henderson, USA) was used to record motion in three-dimensional space within a standardized environment. All tests were performed on a set course by the Bavarian Mountain Rescue Service. The test person lay on a mountain rescue stretcher and was immobilized with a vacuum mattress, either with or without a cervical orthosis. The axes of cervical spine movements were analyzed separately. Results There were no significant differences between immobilization with and without a cervical orthosis with regard to lateral flexion (max. 3.7° compared to 3.0°) in the frontal plane and maximum excursion in flexion (max. 1.6° compared to 2.8°) or extension (max. -1.6° compared to -1.7°). There was significantly greater rotation movement around the craniocaudal axis without an orthosis (max. 2.4° compared to 1.3°). Conclusion During mountain rescues, the cervical spine can be immobilized without a rigid cervical spine orthosis. Future research should explore the fundamental benefits of cervical spine immobilization, while the findings of this work contribute to the safe care of patients by avoiding the disadvantages associated with rigid cervical orthoses.}, language = {en} } @misc{GschossmannSchedelSuessetal., author = {Gschoßmann, Lukas and Schedel, Valentin and S{\"u}ß, Franz and Weber, Markus and Pfingsten, Andrea and Dendorfer, Sebastian}, title = {Evaluating Knee Joint Loads Across Exercises and Activities of Daily Living to Personalize TKA Rehabilitation}, series = {ISB 2025 - The XXX Congress of the International Society of Biomechanics, 27.-31. July 2025, Stockholm}, journal = {ISB 2025 - The XXX Congress of the International Society of Biomechanics, 27.-31. July 2025, Stockholm}, doi = {10.35096/othr/pub-8725}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-87252}, pages = {1}, abstract = {This study assessed knee joint loading during various physiotherapy exercises and activities of daily living in 30 healthy subjects. Results showed that lunges and squats caused the highest joint forces, while gait and stair activities also imposed substantial loads. These findings support datadriven exercise selection for personalized rehabilitation after total knee arthroplasty.}, language = {en} } @misc{AdlerFoerstlČechovaetal., author = {Adler, Ina and F{\"o}rstl, Nikolas and Čechov{\´a}, Hana and Nov{\´a}ček, V{\´i}t and S{\"u}ß, Franz and Dendorfer, Sebastian}, title = {Mechanistic analysis of pelvic floor functionality using musculoskeletal simulation}, series = {ISB 2025 - The XXX Congress of the International Society of Biomechanics, 27-31 July 2025, Stockholm}, journal = {ISB 2025 - The XXX Congress of the International Society of Biomechanics, 27-31 July 2025, Stockholm}, doi = {10.35096/othr/pub-8729}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-87294}, pages = {1}, abstract = {There is consensus that knowledge about the fundamentals of the pelvic floor remains incomplete, particularly regarding the sensitivity of individual pelvic floor muscles to posture variations. This study aimed to investigate the effects of variations in pelvic tilt and the point of force application induced by changes in posture on pelvic floor activity using musculoskeletal simulation. A parameter study analysed various loading cases, highlighting the coherent response of individual pelvic floor muscles to loads. Muscle activities and forces were compared across different force application points and pelvic tilt angles. A key finding was identifying peak muscle activity conditions that could help better understand the causes of pelvic floor disorders.}, language = {en} } @misc{BarthelSuessDendorfer, author = {Barthel, Mareike and S{\"u}ß, Franz and Dendorfer, Sebastian}, title = {Predicting intra-abdominal pressure during walking and running}, series = {ISB 2025 - The XXX Congress of the International Society of Biomechanics, 27-31. July 2025, Stockholm}, journal = {ISB 2025 - The XXX Congress of the International Society of Biomechanics, 27-31. July 2025, Stockholm}, abstract = {Intra-abdominal pressure (IAP) is an important physiological parameter, which is difficult to measure during physical activity. In this study, motion capture, musculoskeletal modeling and a transformer encoder model are used to predict IAP during walking and running. The model showed promising results with an overall mean percentage error of 13.5\% and a Pearson correlation coefficient of 0.85. Minor challenges included the lower accuracy for fast walking and running and the limited amount of data. All in all, the prediction of IAP was successful, which opens up prospects for further applications.}, language = {en} } @misc{FoerstlAdlerSuessetal., author = {F{\"o}rstl, Nikolas and Adler, Ina and S{\"u}ß, Franz and Jansov{\´a}, Magdalena and Vychytil, Jan and Dendorfer, Sebastian}, title = {Evaluating the loads on the female pelvic floor during full-body activities using computational models}, abstract = {This work investigated the loads on the female pelvic floor during various full-body movements using computational models to calculate abdominal pressure and organ dynamic loads. While high-impact exercises resulted in higher loads, other movements showed lower loads, potentially indicating, which movements may be performed without risking pelvic floor overload and subsequent dysfunctions.}, language = {en} } @misc{SteinSchmitzKretschmeretal., author = {Stein, Leonhard and Schmitz, Paul and Kretschmer, Rainer and Dendorfer, Sebastian}, title = {Gait parameter based fall risk scoring}, abstract = {This study explored the connection between subjective self-assessed gait insecurities and objective movement scores. 93 subjects answered detailed fall risk questionnaires and performed functional tests. Significantly different movement patterns between fallers and non-fallers were found.}, language = {en} } @misc{GschossmannSuessDendorfer, author = {Gschoßmann, Lukas and S{\"u}ß, Franz and Dendorfer, Sebastian}, title = {Impact of Model Parameters on Ground Reaction Force Predictions in Musculoskeletal Modelling}, series = {ISB 2025 - The XXX Congress of the International Society of Biomechanics, 27-31 July, Stockholm}, journal = {ISB 2025 - The XXX Congress of the International Society of Biomechanics, 27-31 July, Stockholm}, abstract = {This study evaluated how model parameters affect ground reaction force (GRF) predictions in musculoskeletal simulations. A parameter study varying contact height and velocity thresholds and marker weights was conducted. While height and velocity thresholds had minimal impact, marker weights impact prediction errors. These findings highlight the importance of carefully selecting model parameters.}, language = {en} } @article{TroesterEcksteinKenneletal., author = {Tr{\"o}ster, Mark and Eckstein, Simon and Kennel, Paula and Kopp, Verna and Benkiser, Alina and Bihlmeier, Felicitas and Daub, Urban and Maufroy, Christophe and Dendorfer, Sebastian and Fritzsche, Lars and Schneider, Urs and Bauernhasl, Thomas}, title = {Person-specific evaluation method for occupational exoskeletons - Biomechanical body heat map}, series = {Applied Ergonomics}, volume = {132}, journal = {Applied Ergonomics}, publisher = {Elsevier}, doi = {10.1016/j.apergo.2025.104671}, pages = {30}, abstract = {Human-centred and ergonomic work design is one of the most important drivers for increasing the competitiveness of the European Union. As a flexible, person-specific occupational measure, exoskeletons promise great potential for effectively reducing individual ergonomic stress. Digital human models can provide important insights and offer great potential for systematising the effect and targeted use of exoskeletons, supporting their effective implementation in practice. In this article, digital human models are applied on two levels. Firstly, a realistic industrial logistics scenario in which boxes had to be relocated is designed with the help of a digital human model for workplace and process planning and secondly, a new biomechanical evaluation methodology to analyse intended and unintended effects on internal stress on the human body is demonstrated by applying musculoskeletal exoskeleton human models of four test subjects. Finally, the modelled biomechanical support tendencies of one exoskeleton are preliminary validated using EMG measurement data of the back muscles collected from the four male workers. The preliminary analysis of two back-support exoskeletons to demonstrate the new methodological approach confirms the expected, intended effects in the lower back and reveals unintended effects, such as e.g. changes in knee kinetics when applying a soft or hard-frame exoskeleton. Furthermore, the exemplary results to demonstrate the methodological approach expose notable differences between the test subjects, which underlines the relevance of person-specific evaluation and consideration of exoskeleton support. The preliminary validation shows a correlation between the modelled and the EMG-measured biomechanical exoskeleton support of the considered back muscles.}, language = {en} } @article{BarthelSuessDendorfer, author = {Barthel, Mareike and S{\"u}ß, Franz and Dendorfer, Sebastian}, title = {Application of a transformer encoder for the prediction of intra-abdominal pressure}, series = {Computer Methods in Biomechanics and Biomedical Engineering}, journal = {Computer Methods in Biomechanics and Biomedical Engineering}, publisher = {Taylor \& Francis}, doi = {10.1080/10255842.2025.2586143}, pages = {11}, abstract = {Intra-abdominal pressure is a significant physiological parameter influencing spinal stability and pelvic floor health. This study investigates the potential of a transformer encoder model to predict IAP using motion capture data and musculoskeletal modeling. Data from 211 subjects performing walking, fast walking, and running were used to train a transformer encoder. The model showed promising results with an overall Mean Absolute Percentage Error of 13.5\% and a Pearson correlation coefficient of 0.85. Predictions for fast walking and running proved to be more challenging compared to walking, which was attributed to the greater variability and complexity of faster movements.}, language = {en} } @misc{Dendorfer, author = {Dendorfer, Sebastian}, title = {Towards a deeper understanding of Pelvic Floor Disorders via Biomechanical Models}, language = {en} } @misc{Dendorfer, author = {Dendorfer, Sebastian}, title = {Zahlen statt Meinung - virtuelle Ganzk{\"o}rpermodelle f{\"u}r die Mensch-Fahrzeug-Interaktion}, language = {de} } @inproceedings{SchaefferSchmausserHerrmannetal., author = {Schaeffer, Leon and Schmaußer, Theresa and Herrmann, David and Lehmann, Lukas and Dendorfer, Sebastian and B{\"o}hm, Valter}, title = {Multi-Body Simulation of a Dynamic Hand Orthosis based on a Prestressed Compliant Structure Incorporating the Human Hand}, series = {2025 International Symposium on Medical Robotics (ISMR), May 14-16, 2025, Atlanta, GA, USA,}, booktitle = {2025 International Symposium on Medical Robotics (ISMR), May 14-16, 2025, Atlanta, GA, USA,}, publisher = {IEEE}, doi = {10.1109/ISMR67322.2025.11025982}, pages = {80 -- 86}, abstract = {Many dynamic hand orthoses use one degree of freedom joints, such as hinge joints. Therefore, these orthoses can only partially replicate the complex, multi-axis movement of the hand. A possible solution for this is the use of prestressed compliant structures as the basis for orthoses. Determining the joint forces in the wrist and optimizing the dynamic orthosis to influence these forces as well as acting muscle forces are important steps in the development of these orthoses. For this reason, in this work multi-body simulation models of an orthosis with human hand models are presented. Based on these theoretical investigations, more detailed orthosis models as well as initial prototypes of prestressed compliant dynamic hand orthoses can be developed.}, language = {en} } @article{RusavyCechovaDendorferetal., author = {Rusavy, Zdenek and Cechova, Hana and Dendorfer, Sebastian and Kalis, Vladimir and Ismail, Khaled M.}, title = {Is the Finnish grip tight enough? A manometric study of two manual perineal protection techniques}, series = {Acta Obstetricia et Gynecologica Scandinavica}, volume = {104}, journal = {Acta Obstetricia et Gynecologica Scandinavica}, number = {2}, publisher = {Wiley}, doi = {10.1111/aogs.15033}, pages = {423 -- 425}, language = {en} } @article{SchaefferHerrmannSchratzenstalleretal., author = {Schaeffer, Leon and Herrmann, David and Schratzenstaller, Thomas and Dendorfer, Sebastian and B{\"o}hm, Valter}, title = {Theoretical considerations on stiffness characteristics of a 3-dimensional tensegrity joint model for the use in dynamic hand orthoses}, series = {Journal of Medical Robotics Research}, journal = {Journal of Medical Robotics Research}, publisher = {World Scientific}, doi = {10.1142/S2424905X25400069}, language = {en} } @article{RusavyCechovaDendorferetal., author = {Rusavy, Zdenek and Cechova, Hana and Dendorfer, Sebastian and Kalis, Vladimir and Ismail, Khaled M.}, title = {Is the Finnish grip tight enough? A manometric study of two manual perineal protection techniques}, series = {Acta Obstetricia et Gynecologica Scandinavica}, journal = {Acta Obstetricia et Gynecologica Scandinavica}, edition = {Early view}, publisher = {Wiley}, doi = {10.1111/aogs.15033}, 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{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{AdlerFoerstlSuessetal., author = {Adler, Ina and F{\"o}rstl, Nikolas and S{\"u}ß, Franz and Dendorfer, Sebastian}, title = {Biomechanical exposition of the factors influencing the pelvic floor muscle activity}, 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 About 40 \% of the women worldwide suffer from Pelvic Floor Dysfunctions [1]. In previous studies, musculoskeletal simulations helped to understand and facilitate the complex issues of musculoskeletal disorders in several different branches [2, 3]. A fundamental prerequisite for the generation of these models is to have a basic understanding of the stresses acting on the pelvic floor. The aim of this study is to investigate the biomechanical factors influencing the activity of the pelvic floor muscles by establishing a parameterised model. Methods To identify the factors that affect the pelvic floor muscles, the process is divided into several stages. The first step is to investigate the loads acting on the pelvic floor. For this, a simplified sagittal cross-sectional model of the upper body is analysed. The discretization of the abdominal cavity is presented with resulting force vectors representing the organs in the abdominal and pelvic region, the tensile force of the structures that fixate the organs as well as the intraabdominal pressure. A second step is the examination of the basic mechanics of the pelvic floor muscles. As the functional anatomy of these muscles demonstrate differences compared to other muscle groups [4], the understanding of how they differ is crucial for the construction of musculoskeletal models. After a static examination of loads on a simplified muscle model, an extended model including the physiological properties of a muscle must be involved in the considerations. Therefore, the influence of parameters such as the ideal muscle strength and fibre length, as well as elasticity or passive stiffness of the elements must be taken into account. The influencing factors of the variables can be analysed in a simplified pelvic floor muscle model by systematically changing the parameters. Results The process of analysing the factors influencing the activity of the pelvic floor muscles follows two main strategies. The review of the effects of the whole body identifies the forces acting on the pelvic floor muscles and effect their activity. With the examination of the basic mechanics of a simplified pelvic floor muscle model a better understanding is achieved of how the pelvic floor muscles absorb the loads acting in the body. Discussion This process results in the main influence factors on the activity of the pelvic floor. The consequent parameters form the basis for a biomechanically justified construction of musculoskeletal simulation models of the pelvic floor. Nevertheless, it must be considered, that these mechanical studies represent simplifications of the reality. References 1. Wang et al, Front Public Health, 10:975829, 2022. 2. Bulat et al., Curr Sports Med Rep, 18(6):210-216, 2019 3. Melzner et al., Eur J Obstet Gynecol Reprod Biol, 264:306-313, 2021 4. Ashton-Miller et al., Ann N Y Acad Sci, 1101:266-96, 2007}, 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} } @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} } @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} } @article{MuehlingSandriesserDendorferetal., author = {M{\"u}hling, Mischa and Sandriesser, Sabrina and Dendorfer, Sebastian and Augat, Peter}, title = {Assessment of implant internal stresses under physiological femoral loading: Translation to a simplified bending load model}, series = {Journal of Biomechanics}, journal = {Journal of Biomechanics}, number = {112229}, publisher = {Elsevier}, issn = {1873-2380}, doi = {10.1016/j.jbiomech.2024.112229}, pages = {17}, abstract = {The success of surgical treatment for fractures hinges on various factors, notably accurate surgical indication. The process of developing and certifying a new osteosynthesis device is a lengthy and costly process that requires multiple cycles of review and validation. Current methods, however, often rely on predecessor standards rather than physiological loads in specific anatomical locations. This study aimed to determine actual loads experienced by an osteosynthesis plate, exemplified by a standard locking plate for the femoral shaft, utilizing finite elements analysis (FEA) and to obtain the bending moments for implant development standard tests. A protocol was developed, involving the creation and validation of a fractured femur model fixed with a locking plate, mechanical testing, and FEA. The model's validation demonstrated exceptional accuracy in predicting deformations, and the FEA revealed peak stresses in the fracture bridging zone. Results of a parametric analysis indicate that larger fracture gaps significantly impact implant mechanical behavior, potentially compromising stability. This study underscores the critical need for realistic physiological conditions in implant evaluations, providing an innovative translational approach to identify internal loads and optimize implant designs. In conclusion, this research contributes to enhancing the understanding of implant performance under physiological conditions, promoting improved designs and evaluations in fracture treatments.}, language = {en} } @article{AuerSuessDendorfer, author = {Auer, Simon and S{\"u}ß, Franz and Dendorfer, Sebastian}, title = {Using markerless motion capture and musculoskeletal models: An evaluation of joint kinematics}, series = {Technology and Health Care}, journal = {Technology and Health Care}, publisher = {IOS Press}, issn = {0928-7329}, doi = {10.3233/THC-240202}, pages = {1 -- 10}, abstract = {BACKGROUND: This study presents a comprehensive comparison between a marker-based motion capture system (MMC) and a video-based motion capture system (VMC) in the context of kinematic analysis using musculoskeletal models. OBJECTIVE: Focusing on joint angles, the study aimed to evaluate the accuracy of VMC as a viable alternative for biomechanical research. METHODS: Eighteen healthy subjects performed isolated movements with 17 joint degrees of freedom, and their kinematic data were collected using both an MMC and a VMC setup. The kinematic data were entered into the AnyBody Modelling System, which enables the calculation of joint angles. The mean absolute error (MAE) was calculated to quantify the deviations between the two systems. RESULTS: The results showed good agreement between VMC and MMC at several joint angles. In particular, the shoulder, hip and knee joints showed small deviations in kinematics with MAE values of 4.8∘, 6.8∘ and 3.5∘, respectively. However, the study revealed problems in tracking hand and elbow movements, resulting in higher MAE values of 13.7∘ and 27.7∘. Deviations were also higher for head and thoracic movements. CONCLUSION: Overall, VMC showed promising results for lower body and shoulder kinematics. However, the tracking of the wrist and pelvis still needs to be refined. The research results provide a basis for further investigations that promote the fusion of VMC and musculoskeletal models.}, language = {en} } @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{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{SchaefferHerrmannSchratzenstalleretal., author = {Schaeffer, Leon and Herrmann, David and Schratzenstaller, Thomas and Dendorfer, Sebastian and B{\"o}hm, Valter}, title = {Preliminary theoretical considerations on the stiffness characteristics of a tensegrity joint for the use in dynamic orthoses}, series = {Journal of Medical Robotics Research}, journal = {Journal of Medical Robotics Research}, publisher = {World Scientific}, doi = {10.1142/S2424905X23400081}, abstract = {Early motion therapy plays an important role for effective long-term healing of joint injuries. In many cases, conventional dynamic orthoses fail to address the intricate movement possibilities of the underlying joints, limited by their simplistic joint representations, often represented by revolute joints, enabling rotations by only one axis. In this paper, a two-dimensional compliant tensegrity joint for use in biomedical applications is investigated. It consists of two compressed members and five compliant tensioned members. Relative movement possibilities are realized by the intrinsic compliance of the structure. In the development of these systems, the first step is the determination of the static stable equilibrium. This analysis is conducted in this paper by considering the potential energy approach or by using the geometric nonlinear finite element method. The mechanical behavior of the structure is assessed with a specific emphasis on its mechanical compliance. The primary objective of this study is the investigation of the influence of structural parameters on the overall stiffness and movability of the structure. The results underscore the significant effect of member parameters on the stiffness and movability of the compliant tensegrity joint, particularly under varying load magnitudes. These findings provide insights for optimizing the joint's performance, contributing to its potential application in advanced orthotic and exoskeleton devices.}, language = {en} } @article{MoragKieningerEissnertetal., author = {Morag, Sarah and Kieninger, Martin and Eissnert, Christoph and Auer, Simon and Dendorfer, Sebastian and Popp, Daniel and Hoffmann, Johannes and Kieninger, B{\"a}rbel}, title = {Comparison of different techniques for prehospital cervical spine immobilization: Biomechanical measurements with a wireless motion capture system}, series = {PLOS ONE}, volume = {18}, journal = {PLOS ONE}, number = {11}, publisher = {PLOS}, address = {San Francisco, California}, doi = {10.1371/journal.pone.0292300}, pages = {1 -- 14}, language = {en} } @misc{Dendorfer, author = {Dendorfer, Sebastian}, title = {Patientenindividuelle biomechanisch optimierte Rehabilitation}, series = {Prim{\"a}r- und Revisionsendoprothetik des Kniegelenks. Trends und zuk{\"u}nftige Herausforderungen. Regensburg 2023}, journal = {Prim{\"a}r- und Revisionsendoprothetik des Kniegelenks. Trends und zuk{\"u}nftige Herausforderungen. Regensburg 2023}, language = {de} } @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{AuerKubowitschDendorfer, author = {Auer, Simon and Kubowitsch, Simone and Dendorfer, Sebastian}, title = {Kombinierter Einfluss von psychologischen und biomechanischen Faktoren auf die muskul{\"a}ren Belastungen beim Fußballspielen}, series = {Die Orthop{\"a}die}, volume = {52}, journal = {Die Orthop{\"a}die}, number = {11}, publisher = {Springer}, doi = {10.1007/s00132-023-04437-8}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-65113}, pages = {1 -- 6}, abstract = {When mental stress and musculoskeletal loading interact, the risk for injury increases due to altered body kinematics and increased muscle tension. These changes can be detected with musculoskeletal models, and mental loading and stress must be analyzed at emotional, cognitive, and behavioral levels. To investigate these kinematic and loading changes under stress, competitive athletes were subjected to mental stress during highly dynamic movements, and musculoskeletal models were used to analyze the biomechanical loading. It was shown that under mental stress, independent of the subjective perception, a strong change in muscle forces can occur. Accordingly, competitive athletes should undergo screenings to assess individual movement patterns and promote general stress resilience.}, language = {de} } @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} } @article{ReinkerDendorfer, author = {Reinker, Lukas and Dendorfer, Sebastian}, title = {Evaluation of acceleration patterns during high-impact jumping exercises}, series = {Gait \& Posture}, volume = {100}, journal = {Gait \& Posture}, number = {Supplement 1, March}, publisher = {Elsevier}, address = {Amsterdam [u.a.]}, doi = {10.1016/j.gaitpost.2022.11.051}, pages = {93 -- 94}, 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{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} } @article{ReinkerBlaesingBierletal., author = {Reinker, Lukas and Bl{\"a}sing, Dominic and Bierl, Rudolf and Ulbricht, Sabina and Dendorfer, Sebastian}, title = {Correlation of Acceleration Curves in Gravitational Direction for Different Body Segments during High-Impact Jumping Exercises}, series = {sensors}, volume = {23}, journal = {sensors}, number = {4}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/s23042276}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-58217}, abstract = {Osteoporosis is a common disease of old age. However, in many cases, it can be very well prevented and counteracted with physical activity, especially high-impact exercises. Wearables have the potential to provide data that can help with continuous monitoring of patients during therapy phases or preventive exercise programs in everyday life. This study aimed to determine the accuracy and reliability of measured acceleration data at different body positions compared to accelerations at the pelvis during different jumping exercises. Accelerations at the hips have been investigated in previous studies with regard to osteoporosis prevention. Data were collected using an IMU-based motion capture system (Xsens) consisting of 17 sensors. Forty-nine subjects were included in this study. The analysis shows the correlation between impacts and the corresponding drop height, which are dependent on the respective exercise. Very high correlations (0.83-0.94) were found between accelerations at the pelvis and the other measured segments at the upper body. The foot sensors provided very weak correlations (0.20-0.27). Accelerations measured at the pelvis during jumping exercises can be tracked very well on the upper body and upper extremities, including locations where smart devices are typically worn, which gives possibilities for remote and continuous monitoring of programs.}, language = {en} } @article{AuerSchieblIversenetal., author = {Auer, Simon and Schiebl, Jonas and Iversen, Kristoffer and Subhash Chander, Divyaksh and Damsgaard, Michael and Dendorfer, Sebastian}, title = {Biomechanical assessment of the design and efficiency of occupational exoskeletons with the AnyBody Modeling System}, series = {Zeitschrift f{\"u}r Arbeitswissenschaften}, volume = {76}, journal = {Zeitschrift f{\"u}r Arbeitswissenschaften}, number = {4}, publisher = {Springer Nature}, doi = {10.1007/s41449-022-00336-4}, pages = {440 -- 449}, abstract = {Exoskeletons were invented over 100 years ago but have only become popular in the last two decades, especially in the working industry as they can decrease work-related loads significantly. The most often used exoskeletons are for the lower back and shoulder since these are commonly affected body regions. All devices have in common that their purpose is to reduce internal loads of vulnerable body regions. Nevertheless, there is still little understanding on how biomechanical loading in the human body changes when exoskeletons are used. Therefore, further analyses are needed. A promising candidate for these are musculoskeletal models, which are based on an inverse dynamics approach and can calculate external parameters such as ground reaction forces or other interaction forces as well as internal parameters such as joint reaction forces or muscle activities. The various examples in the literature show that these models are increasingly used for assessing the biomechanical effects of exoskeletons on the human body. Furthermore, musculoskeletal models can calculate biomechanical loadings of humans with and without exoskeletons for all kinds of applications and allow an evaluation of their purpose. Practical Relevance: This article highlights the possibilities of musculoskeletal models for assessing the design and efficiency of occupational exoskeletons. Several practical use cases are described along with distinct descriptions of common implications of musculoskeletal and exoskeleton modeling.}, language = {en} } @misc{Dendorfer, author = {Dendorfer, Sebastian}, title = {Muskuloskelettale Simulation - Implikationen f{\"u}r die H{\"u}ftendoprothetik}, series = {Prim{\"a}r- und Revisionsendoprothetik des H{\"u}ftgelenks Trends und zuk{\"u}nftige Herausforderungen, 11.-12.11.2022, OTH Ostbayerische Technische Hochschule, Regensburg}, journal = {Prim{\"a}r- und Revisionsendoprothetik des H{\"u}ftgelenks Trends und zuk{\"u}nftige Herausforderungen, 11.-12.11.2022, OTH Ostbayerische Technische Hochschule, Regensburg}, language = {de} } @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} } @misc{Dendorfer, author = {Dendorfer, Sebastian}, title = {KI-basierte mechanische Modelle f{\"u}r Pr{\"a}vention, Diagnostik und Rehabilitation}, series = {Serien-Webmeeting zu AI - KI-basierte Bildanalyse zur computer-unterst{\"u}tzten Frakturerkennung, 09.11.22}, journal = {Serien-Webmeeting zu AI - KI-basierte Bildanalyse zur computer-unterst{\"u}tzten Frakturerkennung, 09.11.22}, organization = {Deutsche Gesellschaft f{\"u}r Orthop{\"a}die und Orthop{\"a}dische Chirurgie}, language = {de} } @article{MelznerPfeifferSuessetal., author = {Melzner, Maximilian and Pfeiffer, Christian and Suess, Franz and Dendorfer, Sebastian}, title = {Musculoskeletal simulation of elbow stability for common injury patterns}, series = {Journal of Orthopaedic Research}, volume = {41}, journal = {Journal of Orthopaedic Research}, number = {6}, publisher = {Wiley}, issn = {1554-527X}, doi = {10.1002/jor.25460}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-54819}, pages = {1356 -- 1364}, abstract = {Elbow stability is derived from a combination of muscular, ligamentous, and bony structures. After an elbow trauma the stability of the joint is an important decision criterion for the subsequent treatment. The decision regarding non-operative/operative care depends mostly on subjective assessments of medical experts. Therefore, the aim of this study is to use musculoskeletal simulations as an objective assessment tool to investigate the extent to which failure of different stabilizers affects the elbow stability and how these observations correspond to the assessment from clinical practice. A musculoskeletal elbow simulation model was developed for this aim. To investigate the stability of the elbow, varus/valgus moments were applied under 0°, 45°and 90° flexion while the respective cubital angle was analyzed. This was performed for nine different injury scenarios, which were also evaluated for stability by clinical experts. With the results, it can be determined by which injury pattern and under which flexion angle the elbow stability is impaired regarding varus/valgus moments. The scenario with a complete failure of the medial and lateral ligaments and a fracture of the radial head was identified as having the greatest instability. The study presented a numerical determination of elbow stability against varus/valgus moments regarding clinical injury patterns, as well as a comparison of the numerical outcome with experience gained in clinical practice. The numerical predictions agree well with the assessments of the clinical specialists. Thus, the results from musculoskeletal simulation can make an important contribution to a more objective assessment of the elbow stability.}, language = {en} } @misc{MelznerPfeiferSuessetal., author = {Melzner, Maximilian and Pfeifer, Christian and S{\"u}ß, Franz and Dendorfer, Sebastian}, title = {Muskuloskeletal analysis of elbow stability for common injury patterns}, series = {27th Congress of the European Society of Biomechanics, 26 - 29 June 2022, Porto, Portugal}, journal = {27th Congress of the European Society of Biomechanics, 26 - 29 June 2022, Porto, Portugal}, pages = {654}, language = {en} } @misc{MelznerDendorfer, author = {Melzner, Maximilian and Dendorfer, Sebastian}, title = {Biomechanik und muskuloskeletale Simulation}, series = {Jahreskongress des ISPO Deutschland e.V., 2./3. Juni 2022, Hedelberg}, journal = {Jahreskongress des ISPO Deutschland e.V., 2./3. Juni 2022, Hedelberg}, organization = {International Society for Prosthetics and Orthotics}, language = {de} } @misc{AuerReinkerSuessetal., author = {Auer, Simon and Reinker, Lukas and S{\"u}ß, Franz and Dendorfer, Sebastian}, title = {Comparing calculated and measured muscle activity of thigh muscles in dynamic motion.}, series = {27th Congress of the European Society of Biomechanics, 26 - 29 June 2022, Porto, Portugal}, journal = {27th Congress of the European Society of Biomechanics, 26 - 29 June 2022, Porto, Portugal}, pages = {640}, language = {en} } @misc{Dendorfer, author = {Dendorfer, Sebastian}, title = {Biomechanische Aspekte bei Sportverletzungen}, series = {OT World Leipzig, Internationale Fachmesse und Weltkongress f{\"u}r Orthop{\"a}die und Rehatechnik, 10.-13. Mai 2022}, journal = {OT World Leipzig, Internationale Fachmesse und Weltkongress f{\"u}r Orthop{\"a}die und Rehatechnik, 10.-13. Mai 2022}, language = {de} } @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{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} } @article{SaffertMelznerDendorfer, author = {Saffert, Anne-Sophie and Melzner, Maximilian and Dendorfer, Sebastian}, title = {Biomechanical analysis of the right elevated glenohumeral joint in violinists during legato-playing}, series = {Technology and Health Care}, volume = {30}, journal = {Technology and Health Care}, number = {1}, publisher = {IOS Press}, doi = {10.3233/THC-219001}, pages = {177 -- 186}, abstract = {BACKGROUND: Many statistics reveal that violin players suffer most often from musculoskeletal disorders compared to musicians of other instrument groups. A common phenomenon, especially observed in violin beginners, is the tendency to elevate the right shoulder during playing the violin. This can probably lead to serious disorders in long-term practice with repetitive movements. OBJECTIVE: For this reason, this study investigated the relationship between the right shoulder elevation and the force in the right glenohumeral joint during violin playing. It was hypothesized that the forces in the right glenohumeral joint are higher during playing with the right shoulder raised compared to playing in normal posture. METHODS: Motion capture data from four experienced violinists was recorded and processed by means of musculoskeletal simulation to get the force and elevation angle while playing with raised shoulder and in normal position. RESULTS: The results indicate that the absolute values of the resulting force, as well as the forces in the mediolateral, inferosuperior, and anteroposterior directions, are higher in playing the violin with the shoulder raised than in a normal posture. CONCLUSIONS: Elevating the right shoulder while playing the violin may pose a potential problem.}, subject = {Biomechanische Analyse}, language = {en} } @misc{SaffertMelznerDendorfer, author = {Saffert, Anne-Sophie and Melzner, Maximilian and Dendorfer, Sebastian}, title = {Biomechanical Analysis of the Right Elevated Glenohumeral Joint in Violinists during Legato-Playing}, series = {Biomdlore 2021: 21-23 October 2021 Vilnius/Trakai, Lithuania}, journal = {Biomdlore 2021: 21-23 October 2021 Vilnius/Trakai, Lithuania}, doi = {10.3233/THC-219001}, abstract = {BACKGROUND: Many statistics reveal that violin players suffer most often from musculoskeletal disorders compared to musicians of other instrument groups. A common phenomenon, especially observed in violin beginners, is the tendency to elevate the right shoulder during playing the violin. This can probably lead to serious disorders in long-term practice with repetitive movements. OBJECTIVE: For this reason, this study investigated the relationship between the right shoulder elevation and the force in the right glenohumeral joint during violin playing. It was hypothesized that the forces in the right glenohumeral joint are higher during playing with the right shoulder raised compared to playing in normal posture. METHODS: Motion capture data from four experienced violinists was recorded and processed by means of musculoskeletal simulation to get the force and elevation angle while playing with raised shoulder and in normal position. RESULTS: The results indicate that the absolute values of the resulting force, as well as the forces in the mediolateral, inferosuperior, and anteroposterior directions, are higher in playing the violin with the shoulder raised than in a normal posture. CONCLUSIONS: Elevating the right shoulder while playing the violin may pose a potential problem.}, 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} } @article{MelznerEngelhardtSimonetal., author = {Melzner, Maximilian and Engelhardt, Lucas and Simon, Ulrich and Dendorfer, Sebastian}, title = {Electromyography-Based Validation of a Musculoskeletal Hand Model}, series = {Journal of Biomechanical Engineering}, volume = {144}, journal = {Journal of Biomechanical Engineering}, number = {2}, publisher = {American Society of Mechanical Engineers, ASME}, doi = {10.1115/1.4052115}, pages = {8}, abstract = {Regarding the prevention of injuries and rehabilitation of the human hand, musculoskeletal simulations using an inverse dynamics approach allow for insights of the muscle recruitment and thus acting forces on the hand. Currently, several hand models from various research groups are in use, which are mainly validated by the comparison of numerical and anatomical moment arms. In contrast to this validation and model-building technique by cadaver studies, the aim of this study is to further validate a recently published hand model [1] by analyzing numerically calculated muscle activities in comparison to experimentally measured electromyographical signals of the muscles. Therefore, the electromyographical signals of 10 hand muscles of five test subjects performing seven different hand movements were measured. The kinematics of these tasks were used as input for the hand model, and the numerical muscle activities were computed. To analyze the relationship between simulated and measured activities, the time difference of the muscle on- and off-set points was calculated, which resulted in a mean on- and off-set time difference of 0.58 s between the experimental data and the model. The largest differences were detected for movements that mainly addressed the wrist. One major issue comparing simulated and measured muscle activities of the hand is cross-talk. Nevertheless, the results show that the hand model fits the experiment quite accurately despite some limitations and is a further step toward patient-specific modeling of the upper extremity.}, subject = {Elektromyographie}, language = {en} }