• Deutsch
Login

Open Access

  • Home
  • Search
  • Browse
  • Publish
  • FAQ

Refine

Author

  • Dendorfer, Sebastian (139)
  • Süß, Franz (30)
  • Renkawitz, Tobias (26)
  • Kubowitsch, Simone (18)
  • Verkerke, Gijsbertus Jacob (18)
  • Weber, Tim (18)
  • Melzner, Maximilian (16)
  • Rasmussen, John (16)
  • Grifka, Joachim (15)
  • Putzer, Michael (11)
+ more

Year of publication

  • 2022 (6)
  • 2021 (12)
  • 2020 (14)
  • 2019 (10)
  • 2018 (10)
  • 2017 (9)
  • 2016 (12)
  • 2015 (14)
  • 2014 (8)
  • 2013 (7)
+ more

Document Type

  • conference proceeding (article) (69)
  • Article (41)
  • conference proceeding (presentation, abstract) (13)
  • conference talk (7)
  • Part of Periodical (5)
  • Part of a Book (2)
  • Moving Images (1)
  • Report (1)

Language

  • English (113)
  • German (26)

Has Fulltext

  • no (133)
  • yes (6)

Is part of the Bibliography

  • no (139)

Keywords

  • Biomechanik (11)
  • Simulation (9)
  • Biomechanics (7)
  • Biomechanische Analyse (7)
  • Hüftgelenkprothese (7)
  • Bewegungsapparat (4)
  • Spongiosa (4)
  • AnyBody (3)
  • Lumbar spine (3)
  • Musculoskeletal simulation (3)
+ more

Institute

  • Fakultät Maschinenbau (134)
  • Labor Biomechanik - LBM (131)
  • Regensburg Center of Biomedical Engineering - RCBE (114)
  • Regensburg Center of Health Sciences and Technology - RCHST (6)
  • Hochschulleitung (5)
  • Institut für Angewandte Forschung und Wirtschaftskooperationen (IAFW) (5)
  • Labor Faserverbundtechnik - LFT (2)
  • Technologie-Campus Neustadt an der Donau (2)
  • Labor Biomaterialien - BMA (1)

Begutachtungsstatus

  • peer-reviewed (19)

139 search hits

  • 1 to 100
  • BibTeX
  • CSV
  • RIS
  • XML
  • 10
  • 20
  • 50
  • 100

Sort by

  • Year
  • Year
  • Title
  • Title
  • Author
  • Author
Forschungsbericht 2012 (2012)
Lautenschläger, Toni ; Leis, Alexander ; Dendorfer, Sebastian ; Palm, Christoph ; Schreiner, Rupert ; Langer, Christoph ; Prommesberger, Christian ; Ławrowski, Robert Damian ; Dams, Florian ; Bornmann, Benjamin ; Navitski,, Aliaksandr ; Serbun, Pavel ; Müller, Günter ; Liebetruth, Thomas ; Kohlert, Dieter ; Pernsteiner, Jochen ; Schreier, Franz ; Heerklotz, Sabrina ; Heerklotz, Allwin ; Boos, Alexander ; Herwald, Dominik ; Monkman, Gareth J. ; Treiber, Daniel ; Mayer, Matthias ; Hörner, Eva ; Bentz, Alex ; Shamonin (Chamonine), Mikhail ; Johansen, Søren Peter ; Reichel, Marco ; Stoll, Andrea ; Briem, Ulrich ; Dullien, Silvia ; Renkawitz, Tobias ; Weber, Tim ; Dendorfer, Sebastian ; Grifka, Joachim ; Penzkofer, Rainer ; Barnsteiner, K. ; Jovanovik, M. ; Wernecke, P. ; Vögele, A. ; Bachmann, T. ; Plötz, Martin ; Schliekmann, Claus ; Wels, Harald ; Helmberger, Paul ; Kaspar, M. ; Hönicka, M. ; Schrammel, S. ; Enser, Markus ; Schmidmeier, Monika ; Schroll-Decker, Irmgard ; Haug, Sonja ; Gelfert, Verena ; Vernim, Matthias
Forschungsbericht 2016 (2016)
Mauerer, Wolfgang ; Rexhepaj, Tanja ; Monkman, Gareth J. ; Sindersberger, Dirk ; Diermeier, Andreas ; Neidhart, Thomas ; Wolfrum, Dominik ; Sterner, Michael ; Heberl, Michael ; Nusko, Robert ; Maier, Georg ; Nagl, Klaus ; Reuter, Monika ; Hofrichter, Andreas ; Lex, Thomas ; Lesch, Florian ; Kieninger, Bärbel ; Szalo, Alexander Eduard ; Zehner, Alexander ; Palm, Christoph ; Joblin, Mitchell ; Apel, Sven ; Ramsauer, Ralf ; Lohmann, Daniel ; Westner, Markus ; Strasser, Artur ; Munndi, Maximilian ; Ebner, Lena ; Elsner, Michael ; Weiß, Nils ; Segerer, Matthias ; Hackenberg, Rudolf ; Steger, Sebastian ; Schmailzl, Anton ; Dostalek, Michael ; Armbruster, Dominik ; Koch, Fabian ; Hierl, Stefan ; Thumann, Philipp ; Swidergal, Krzysztof ; Wagner, Marcus ; Briem, Ulrich ; Diermeier, Andreas ; Spreitzer, Stefan ; Beiderbeck, Sabrina ; Hook, Christian ; Zobel, Martin ; Weber, Tim ; Groß, Simon ; Penzkofer, Rainer ; Dendorfer, Sebastian ; Schillitz, Ingo ; Bauer, Thomas ; Rudolph, Clarissa ; Schmidt, Katja ; Liebetruth, Thomas ; Hamer, Markus ; Haug, Sonja ; Vernim, Matthias ; Weber, Karsten ; Saßmannshausen, Sean Patrick ; Books, Sebastian ; Neuleitner, Nikolaus ; Rechenauer, Christian ; Steffens, Oliver ; Kusterle, Wolfgang ; Gömmel, Roland ; Wellnitz, Felix ; Stierstorfer, Johannes ; Stadler, Dominik ; Hofmann, Matthias J. ; Motschmann, Hubert ; Shamonin (Chamonine), Mikhail ; Bleicher, Veronika ; Fischer, Sebastian ; Hackenberg, Rudolf ; Horn, Anton ; Kawasch, Raphael ; Petzenhauser, Michael ; Probst, Tobias ; Udalzow, Anton ; Dams, Florian ; Schreiner, Rupert ; Langer, Christoph ; Prommesberger, Christian ; Ławrowski, Robert Damian
Stem cell-based tissue-engineering for treatment of meniscal tears in the avascular zone (2013)
Zellner, Johannes ; Hierl, Katja ; Mueller, Michael ; Pfeifer, Christian ; Berner, Arne ; Dienstknecht, Thomas ; Krutsch, Werner ; Geis, Sebastian ; Gehmert, Sebastian ; Kujat, Richard ; Dendorfer, Sebastian ; Prantl, Lukas ; Nerlich, Michael ; Angele, Peter
Meniscal tears in the avascular zone have a poor self-healing potential, however partial meniscectomy predisposes the knee for early osteoarthritis. Tissue engineering with mesenchymal stem cells and a hyaluronan collagen based scaffold is a promising approach to repair meniscal tears in the avascular zone. 4 mm longitudinal meniscal tears in the avascular zone of lateral menisci of New Zealand White Rabbits were performed. The defect was left empty, sutured with a 5-0 suture or filled with a hyaluronan/collagen composite matrix without cells, with platelet rich plasma or with autologous mesenchymal stem cells. Matrices with stem cells were in part precultured in chondrogenic medium for 14 days prior to the implantation. Menisci were harvested at 6 and 12 weeks. The developed repair tissue was analyzed macroscopically, histologically and biomechanically. Untreated defects, defects treated with suture alone, with cell-free or with platelet rich plasma seeded implants showed a muted fibrous healing response. The implantation of stem cell-matrix constructs initiated fibrocartilage-like repair tissue, with better integration and biomechanical properties in the precultured stem cell-matrix group. A hyaluronan-collagen based composite scaffold seeded with mesenchymal stem cells is more effective in the repair avascular meniscal tear with stable meniscus-like tissue and to restore the native meniscus.
Forschung 2018 (2018)
Broser, Christian ; Falter, Thomas ; Ławrowski, Robert Damian ; Altenbuchner, Amelie ; Vögele, Daniel ; Koss, Claus ; Schlampp, Matthias ; Dunnweber, Jan ; Steffens, Oliver ; Heckner, Markus ; Jaritz, Sabine ; Schiegl, Thomas ; Corsten, Sabine ; Lauer, Norina ; Gürtler, Katherine ; Koenig, Eric ; Haug, Sonja ; Huber, Dominik ; Birkenmaier, Clemens ; Krenkel, Lars ; Wagner, Thomas ; Justus, Xenia ; Saßmannshausen, Sean Patrick ; Kleine, Nadine ; Weber, Karsten ; Braun, Carina ; Giacoppo, Giuliano ; Heinrich, Michael ; Just, Tobias ; Schreck, Thomas ; Schnabl, Andreas ; Gilmore, Amador Téran ; Roeslin, Samuel ; Schmid, Sandra ; Wellnitz, Felix ; Malz, Sebastian ; Maurial, Andreas ; Hauser, Florian ; Mottok, Jürgen ; Klettke, Meike ; Scherzinger, Stefanie ; Störl, Uta ; Heckner, Markus ; Bazo, Alexander ; Wolff, Christian ; Kopper, Andreas ; Westner, Markus ; Pongratz, Christian ; Ehrlich, Ingo ; Briem, Ulrich ; Hederer, Sebastian ; Wagner, Marcus ; Schillinger, Moritz ; Görlach, Julien ; Hierl, Stefan ; Siegl, Marco ; Langer, Christoph ; Hausladen, Matthias ; Schreiner, Rupert ; Haslbeck, Matthias ; Kreuzer, Reinhard ; Brückl, Oliver ; Dawoud, Belal ; Rabl, Hans-Peter ; Gamisch, Bernd ; Schmidt, Ottfried ; Heberl, Michael ; Gänsbauer, Bianca ; Bick, Werner ; Ellermeier, Andreas ; Monkman, Gareth J. ; Prem, Nina ; Sindersberger, Dirk ; Tschurtschenthaler, Karl ; Aurbach, Maximilian ; Dendorfer, Sebastian ; Betz, Michael ; Szecsey, Tamara ; Mauerer, Wolfgang ; Murr, Florian
Forschungsbericht 2013 (2014)
Beimler, Josef ; Leißl, Caroline ; Ebner, Lena ; Elsner, Michael ; Mühlbauer, Gerhard ; Kohlert, Dieter ; Schubert, Martin J. W. ; Weiß, Andreas P. ; Sterner, Michael ; Raith, Thomas ; Afranseder, Martin ; Krapf, Tobias ; Mottok, Jürgen ; Siemers, Christian ; Großmann, Benjamin ; Höcherl, Johannes ; Schlegl, Thomas ; Schneider, Ralph ; Milaev, Johannes ; Rampelt, Christina ; Roduner, Christian ; Glowa, Christoph ; Bachl, Christoph ; Schliekmann, Claus ; Gnan, Alfons ; Grill, Martin ; Ruhland, Karl ; Piehler, Thomas ; Friers, Daniel ; Wels, Harald ; Pflug, Kenny ; Kucera, Markus ; Waas, Thomas ; Schlachetzki, Felix ; Boy, Sandra ; Pemmerl, Josef ; Leis, Alexander ; Welsch, Andreas F.X. ; Graf, Franz ; Zenger, Gerhard ; Volbert, Klaus ; Waas, Thomas ; Scherzinger, Stefanie ; Klettke, Meike ; Störl, Uta ; Heyl, C. ; Boldenko, A. ; Monkman, Gareth J. ; Kujat, R. ; Briem, Ulrich ; Hierl, Stefan ; Talbot, Sebastian ; Schmailzl, Anton ; Ławrowski, Robert Damian ; Prommesberger, Christian ; Langer, Christoph ; Dams, Florian ; Schreiner, Rupert ; Valentino, Piergiorgio ; Romano, Marco ; Ehrlich, Ingo ; Furgiuele, Franco ; Gebbeken, Norbert ; Eisenried, Michael ; Jungbauer, Bastian ; Hutterer, Albert ; Bauhuber, Michael ; Mikrievskij, Andreas ; Argauer, Monika ; Hummel, Helmut ; Lechner, Alfred ; Liebetruth, Thomas ; Schumm, Michael ; Joseph, Saskia ; Reschke, Michael ; Soska, Alexander ; Schroll-Decker, Irmgard ; Putzer, Michael ; Rasmussen, John ; Dendorfer, Sebastian ; Weber, Tim ; Al-Munajjed, Amir Andreas ; Verkerke, Gijsbertus Jacob ; Renkawitz, Tobias ; Haug, Sonja ; Rudolph, Clarissa ; Zeitler, Annika ; Schaubeck, Simon ; Steffens, Oliver ; Rechenauer, Christian ; Schulz-Brize, Thekla ; Fleischmann, Florian ; Kusterle, Wolfgang ; Beer, Anne ; Wagner, Bernd ; Neidhart, Thomas
Forschungsbericht 2017 (2017)
Weber, Karsten ; Dendorfer, Sebastian ; Süß, Franz ; Kubowitsch, Simone ; Schratzenstaller, Thomas ; Haug, Sonja ; Mohr, Christa ; Kiesl, Hans ; Drechsler, Jörg ; Westner, Markus ; Kobus, Jörn ; Schubert, Martin J. W. ; Zenger, Stefan ; Pietsch, Alexander ; Weiß, Josef ; Hinterseer, Sebastian ; Schieck, Roland ; Scherzinger, Stefanie ; Klettke, Meike ; Ringlstetter, Andreas ; Störl, Uta ; Bissyandé, Tegawendé F. ; Seeburger, Achim ; Schindler, Timo ; Ramsauer, Ralf ; Kiszka, Jan ; Kölbl, Andreas ; Lohmann, Daniel ; Mauerer, Wolfgang ; Maier, Johannes ; Scorna, Ulrike ; Palm, Christoph ; Soska, Alexander ; Mottok, Jürgen ; Ellermeier, Andreas ; Vögele, Daniel ; Hierl, Stefan ; Briem, Ulrich ; Buschmann, Knut ; Ehrlich, Ingo ; Pongratz, Christian ; Pielmeier, Benjamin ; Tyroller, Quirin ; Monkman, Gareth J. ; Gut, Franz ; Roth, Carina ; Hausler, Peter ; Bierl, Rudolf ; Prommesberger, Christian ; Ławrowski, Robert Damian ; Langer, Christoph ; Schreiner, Rupert ; Huang, Yifeng ; She, Juncong ; Ottl, Andreas ; Rieger, Walter ; Kraml, Agnes ; Poxleitner, Thomas ; Hofer, Simon ; Heisterkamp, Benjamin ; Lerch, Maximilian ; Sammer, Nike ; Golde, Olivia ; Wellnitz, Felix ; Schmid, Sandra ; Muntschick, Claudia ; Kusterle, Wolfgang ; Paric, Ivan ; Brückl, Oliver ; Haslbeck, Matthias ; Schmidt, Ottfried ; Schwanzer, Peter ; Rabl, Hans-Peter ; Sterner, Michael ; Bauer, Franz ; Steinmann, Sven ; Eckert, Fabian ; Hofrichter, Andreas
Effect of mental demand on knee forces in professional youth soccer players (2020)
Auer, Simon ; Kubowitsch, Simone ; Krutsch, Werner ; Renkawitz, Tobias ; Süß, Franz ; Dendorfer, Sebastian
Soccer is one of the most popular sports all around the world. It is an injurious type of sport with a focus on lower extremities and high psychological pressure during matches. The stressor is linked with injuries and an increased musculoskeletal loading. This study investigates the influence of cognitive stress on the load profile of the knee joint. Twelve professional youth soccer players performed highly dynamic runs with and without additional cognitive stress. The runs were analysed with a musculoskeletal simulation software. The data analysis shows no difference in knee joint reaction loading under additional mental stress compared to the baseline. Yet running times are significantly lower in the baseline. While there is no increase in the joint loads, the running times indicate an altered movement behaviour when the subjects are exposed to additional mental demand.
Musculoskeletal lower back load of accoucheurs during childbirth – A pilot and feasibility study (2021)
Melzner, Maximilian ; Ismail, Khaled ; Rušavy, Zdenek ; Kališ, Vladimír ; Süß, Franz ; Dendorfer, Sebastian
Introduction: Back problems represent one of the leading causes of accouchers' work-related musculoskeletal morbidities. The correct execution of birth-related maneuvers including manual perineal protection is crucial not only for the mother and child but also for obstetricians and midwives to reduce any strain on their musculoskeletal system. Therefore, the overall aim of this study was to test the feasibility of determining the effect of different accouchers' postures (standing and kneeling) on their musculoskeletal system. Methods: The biomechanical analysis is based on musculoskeletal simulations that included motion recordings of real deliveries as well as deliveries conducted on a birthing simulator. These simulations were then used to determine individual joints' loads. Results: In the kneeling posture, both a low intra-operator variability and a lower average maximum load of the lower back was observed. For the standing position the spine load was reduced by pivoting the elbow on the accouchers' thigh, which in turn was associated with a significantly greater load on the shoulder joint. Conclusion: The study demonstrated the feasibility of our technique to assess joints loads. It also provided initial data indicating that a posture that reduces spinal flexion and tilt, achieved in this study by the kneeling, can significantly reduce the strain on the practitioner's musculoskeletal system.
Happy Enough to Relax? How Positive and Negative Emotions Activate Different Muscular Regions in the Back - an Explorative Study (2021)
Scheer, Clara ; Kubowitsch, Simone ; Dendorfer, Sebastian ; Jansen, Petra
Embodiment theories have proposed a reciprocal relationship between emotional state and bodily reactions. Besides large body postures, recent studies have found emotions to affect rather subtle bodily expressions, such as slumped or upright sitting posture. This study investigated back muscle activity as an indication of an effect of positive and negative emotions on the sitting position. The electromyography (EMG) activity of six back muscles was recorded in 31 healthy subjects during exposure to positive and negative affective pictures. A resting period was used as a control condition. Increased muscle activity patterns in the back were found during the exposure to negative emotional stimuli, which was mainly measured in the lumbar and thorax regions. The positive emotion condition caused no elevated activity. The findings show that negative emotions lead to increased differential muscle activity in the back and thus corroborate those of previous research that emotion affects subtle bodily expressions.
Sensitivity of lumbar spine loading to anatomical parameters (2015)
Putzer, Michael ; Ehrlich, Ingo ; Rasmussen, John ; Gebbeken, Norbert ; Dendorfer, Sebastian
Musculoskeletal simulations of lumbar spine loading rely on a geometrical representation of the anatomy. However, this data has an inherent inaccuracy. This study evaluates the influence of defined geometrical parameters on lumbar spine loading utilising five parametrised musculoskeletal lumbar spine models for four different postures. The influence of the dimensions of vertebral body, disc, posterior parts of the vertebrae as well as the curvature of the lumbar spine was studied. Additionally, simulations with combinations of selected parameters were conducted. Changes in L4/L5 resultant joint force were used as outcome variable. Variations of the vertebral body height, disc height, transverse process width and the curvature of the lumbar spine were the most influential. These parameters can be easily acquired from X-rays and should be used to morph a musculoskeletal lumbar spine model for subject-specific approaches with respect to bone geometry. Furthermore, the model was very sensitive to uncommon configurations and therefore, it is advised that stiffness properties of discs and ligaments should be individualised.
The influence of modeling parameters in the AnyBody Modeling System on muscle and joint loading in the shoulder (2021)
Dendorfer, Sebastian
Kinematic pelvic tilt during gait alters functional cup position in total hip arthroplasty (2021)
Weber, Markus ; Suess, Franz ; Jerabek, Seth ; Meyer, Matthias ; Grifka, Joachim ; Renkawitz, Tobias ; Dendorfer, Sebastian
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.
Electromyography-Based Validation of a Musculoskeletal Hand Model (2021)
Melzner, Maximilian ; Engelhardt, Lucas ; Simon, Ulrich ; Dendorfer, Sebastian
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.
The impact of anatomical uncertainties on the predictions of a musculoskeletal hand model – a sensitivity study (2021)
Melzner, Maximilian ; Suess, Franz ; Dendorfer, Sebastian
Outputs of musculoskeletal models should be considered probabilistic rather than deterministic as they are affected by inaccuracies and estimations associated with the development of the model. One of these uncertainties being critical for modeling arises from the determination of the muscles' line of action and the physiological cross-sectional area. Therefore, the aim of this study was to evaluate the outcome sensitivity of model predictions from a musculoskeletal hand model in comparison to the uncertainty of these input parameters. For this purpose, the kinematics and muscle activities of different hand movements (abduction of the fingers, abduction of the thumb, and flexion of the thumb) were recorded. One thousand simulations were calculated for each movement using the Latin hypercube sampling method with a corresponding variation of the muscle origin/insertion points and the cross-sectional area. Comparing the standard hand to simulations incorporating uncertainties of input parameters shows no major deviations in on- and off-set time point of muscle activities. About 60% of simulations are located within a ± 30% interval around the standard model concerning joint reaction forces. The comparison with the variation of the input data leads to the conclusion that the standard hand model is able to provide not over-scattered outcomes and, therefore, can be considered relatively stable. These results are of practical importance to the personalization of a musculoskeletal model with subject-specific bone geometries and hence changed muscle line of action.
Biomechanical analysis of the right elevated glenohumeral joint in violinists during legato-playing (2022)
Saffert, Anne-Sophie ; Melzner, Maximilian ; Dendorfer, Sebastian
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.
Biomechanical Analysis of the Right Elevated Glenohumeral Joint in Violinists during Legato-Playing (2021)
Saffert, Anne-Sophia ; Melzner, Maximilian ; Dendorfer, Sebastian
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.
Musculoskeletal Lower Back Load of Accoucheurs During Delivery (2021)
Melzner, Maximilian ; Ismail, Khaled ; Rušavý, Zdeněk ; Kališ, Vladimír ; Süß, Franz ; Dendorfer, Sebastian
With the progress in modern medicine, it was possible to significantly reduce the risks of birth for mother and child. One aspect that has received less attention so far is the risk of injury to the accoucheurs (obstetricians and midwives) during the birth process. Indeed, studies indicate that 92% of midwives suffer from musculoskeletal disorders, with the lower back being the main cause of complaints (72%). The aim of this study was to investigate two commonly used postural techniques used by accoucheurs during childbirth and to analyze the resulting load on the lower back using the AnyBodyTM musculoskeletal simulation software.
Co-Development of an Infant Prototype in Hardware and Simulation based on CT Imaging Data (2019)
Dendorfer, Sebastian ; Feldotto, Benedikt ; Walch, Blasius ; Koch, Patrick ; Knoll, Alois
The development of biomimetic robots has gained research interest in the last years as it may both help under-standing processes of motion execution in biological systems as well as developping a novel generation of intelligent and energy efficient robots. However, exact model generation that builds up on observations and robot design is very time intensive. In this paper we present a novel pipeline for co-development of biomimetic hardware and simulation models based on biological Computer Tomography (CT) data. For this purpose we exploit State of the Art rapid prototyping technologies such as 3D Printing and the Neurorobotics Platform for musculoskeletal simulations in virtual environments. The co-development integrates both advantages of virtual and physical experimental models and is expected to increase development speed of controllers that can be tested on the simulated counterpart before application to a printed robot model. We demonstrate the pipeline by generating a one year old infant model as a musculoskeletal simulation model and a print-in-place 3D printed skeleton as a single movable part. Even though we hereonly introduce the initial body generation and only a first testsetup for a modular sensory and control framework, we can clearly spot advantages in terms of rapid model generation and highly biological related models. Engineering costs are reducedand models can be provided to a wide research community for controller testing in an early development phase.
Einfluss der Rotatorenmanschette auf die glenohumerale Stabilität (2022)
Englert, Carsten ; Dendorfer, Sebastian
Towards ergonomic working - machine learning algorithms and musculoskeletal modeling (2021)
Suess, Franz ; Melzner, Maximilian ; Dendorfer, Sebastian
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.
Biomechanische Aspekte bei Sportverletzungen (2022)
Dendorfer, Sebastian
Towards Ergonomic working - machine learning algorithms and muscloskeletal modeling (2021)
Suess, Franz ; Melzner, Maximilian ; Dendorfer, Sebastian
Towards ergonomics working - machine learning algorithms and musculoskeletal modeling (2021)
Suess, Franz ; Melzner, Maximilian ; Dendorfer, Sebastian
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.
Evaluation of muscle recruitment and muscle models in musculoskeletal simulation of dynamic motion (2021)
Auer, Simon ; Reinker, Lukas ; Dendorfer, Sebastian
Musculoskeletal simulation plays an increasingly important role in sports biomechanics. In the last years, the field of application widened from orthopaedics and ergonomics to sports [1]. A muscle recruitment algorithm with a quadratic objective function is usually used to calculate muscle activity in dynamic movements. The agreement of calculated and measured thigh muscle activity has already been investigated [2]. They found a strong agreement for sprinting and running, while the correlation decreased for side-cutting manoeuvres. Nevertheless, the influence of different muscle recruitment criteria on muscle activity in dynamic musculoskeletal simulations is currently unknown. Hence, this study aimed to analyse the effect of different muscle recruitment criteria and muscle models on the correlation of numerical and measured muscle activity in highly dynamic movements.
A new musculoskeletal AnyBody™ detailed hand model (2020)
Engelhardt, Lucas ; Melzner, Maximilian ; Havelkova, Linda ; Fiala, Pavel ; Christen, Patrik ; Dendorfer, Sebastian ; Simon, Ulrich
Musculoskeletal research questions regarding the prevention or rehabilitation of the hand can be addressed using inverse dynamics simulations when experiments are not possible. To date, no complete human hand model implemented in a holistic human body model has been fully developed. The aim of this work was to develop, implement, and validate a fully detailed hand model using the AnyBody Modelling System (AMS) (AnyBody, Aalborg, Denmark). To achieve this, a consistent multiple cadaver dataset, including all extrinsic and intrinsic muscles, served as a basis. Various obstacle methods were implemented to obtain with the correct alignment of the muscle paths together with the full range of motion of the fingers. These included tori, cylinders, and spherical ellipsoids. The origin points of the lumbrical muscles within the tendon of the flexor digitorum profundus added a unique feature to the model. Furthermore, the possibility of an entire patient-specific scaling based on the hand length and width were implemented in the model. For model validation, experimental datasets from the literature were used, which included the comparison of numerically calculated moment arms of the wrist, thumb, and index finger muscles. In general, the results displayed good comparability of the model and experimental data. However, the extrinsic muscles showed higher accordance than the intrinsic ones. Nevertheless, the results showed, that the proposed developed inverse dynamics hand model offers opportunities in a broad field of applications, where the muscles and joint forces of the forearm play a crucial role.
A simple method for determining ligament stiffness during total knee arthroplasty in vivo (2019)
Völlner, Florian ; Weber, Tim A. ; Weber, Markus ; Renkawitz, Tobias ; Dendorfer, Sebastian ; Grifka, Joachim ; Craiovan, Benjamin
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.
Achilles tendon lengthening alters stresses in the growth plate (2018)
Seefried, C. ; Aurbach, Maximilian ; Wyss, C. ; Dendorfer, Sebastian
A numerical study to determine the effect of ligament stiffness on kinematics of the lumbar spine during flexion (2016)
Putzer, Michael ; Auer, Stefan ; Malpica, William ; Süß, Franz ; Dendorfer, Sebastian
Background There is a wide range of mechanical properties of spinal ligaments documented in literature. Due to the fact that ligaments contribute in stabilizing the spine by limiting excessive intersegmental motion, those properties are of particular interest for the implementation in musculoskeletal models. The aim of this study was to investigate the effect of varying ligament stiffness on the kinematic behaviour of the lumbar spine. Methods A musculoskeletal model with a detailed lumbar spine was modified according to fluoroscopic recordings and corresponding data files of three different subjects. For flexion, inverse dynamics analysis with a variation of the ligament stiffness matrix were conducted. The influence of several degrees of ligament stiffness on the lumbar spine model were investigated by tracking ligament forces, disc forces and resulting moments generated by the ligaments. Additionally, the kinematics of the motion segments were evaluated. Results An increase of ligament stiffness resulted in an increase of ligament and disc forces, whereas the relative change of disc force increased at a higher rate at the L4/L5 level (19 %) than at the L3/L4 (10 %) level in a fully flexed posture. The same behaviour applied to measured moments with 67 % and 45 %. As a consequence, the motion deflected to the lower levels of the lumbar spine and the lower discs had to resist an increase in loading. Conclusions Higher values of ligament stiffness over all lumbar levels could lead to a shift of the loading and the motion between segments to the lower lumbar levels. This could lead to an increased risk for the lower lumbar parts.
A new musculoskeletal AnyBody detailed hand model validated by electromyography (2019)
Melzner, Maximilian ; Engelhardt, Lucas ; Havelkova, Leonard ; Simon, Ulrich ; Dendorfer, Sebastian
The AnyBody™ Modeling System (AMS) [1], is an universally used musculoskeletal simulation software using inverse dynamics. Until now, no complete human hand model is known in the AMS. Also considering other musculoskeletal software platforms, just one detailed entire hand model is recently published [2] but is only based on one subject. The aim of this work is to implement a full detailed hand model for the AMS including all extrinsic and intrinsic muscles using data by the UWB gained through an anatomical study of ten cadaver hands.
A new musculoskeletal AnyBody detailed hand model (2019)
Engelhardt, Lucas ; Melzner, Maximilian ; Havelkova, Linda ; Fiala, Pavel ; Rybarova, Martina ; Christen, Patrik ; Dendorfer, Sebastian ; Simon, Ulrich
The AnyBody™ Modeling System (AMS) [1], is an universally used musculoskeletal simulation software using inverse dynamics. Until now, no complete human hand model is known in the AMS. Also considering other musculoskeletal software platforms, just one detailed entire hand model is recently published [2] but is only based on one subject. The aim of this work is to implement a full detailed hand model for the AMS including all extrinsic and intrinsic muscles using data by the UWB gained through an anatomical study of ten cadaver hands.
A Patient based simulation workflow for orthopedic device design and analysis (2011)
Horner, Marc ; Dendorfer, Sebastian ; Kiis, Arne ; Lawrenchuk, Mike ; Verma, Gunjan
Influence of minimally invasive total hip replacement on hip reaction forces and their orientations (2014)
Weber, Tim ; Al-Munajjed, Amir Andreas ; Verkerke, Gijsbertus Jacob ; Dendorfer, Sebastian ; Renkawitz, Tobias
Minimally invasive surgery (MIS) is becoming increasingly popular. Supporters claim that the main advantages of MIS total hip replacement (THR) are less pain and a faster rehabilitation and recovery. Critics claim that safety and efficacy of MIS are yet to be determined. We focused on a biomechanical comparison between surgical standard and MIS approaches for THR during the early recovery of patients. A validated, parameterized musculoskeletal model was set to perform a squat of a 50th percentile healthy European male. A bilateral motion was chosen to investigate effects on the contralateral side. Surgical approaches were simulated by excluding the incised muscles from the computations. Resulting hip reaction forces and their symmetry and orientation were analyzed. MIS THR seemed less influential on the symmetry index of hip reaction forces between the operated and nonoperated leg when compared to the standard lateral approach. Hip reaction forces at peak loads of the standard transgluteal approach were 24% higher on the contralateral side when compared to MIS approaches. Our results suggest that MIS THR contributes to a greater symmetry of hip reaction forces in absolute value as well as force-orientation following THR.
Influence of TAL-TATS surgery on energy production of Tricepts Surae - A musculoskeletal modeling evaluation (2020)
Visscher, Rosa ; Wyss, C. ; Singh, Navrag B. ; Taylor, William R. ; Dendorfer, Sebastian ; Rutz, E. ; Brunner, Reinald
Influence of kyphosis on spinal loading (2012)
Spreiter, G. ; Galibarov, Pavel E. ; Dendorfer, Sebastian ; Ferguson, Stephen J.
Influence of biceps tenotomy and tenodesis on post-operative shoulder strength (2017)
Muehling, M. ; Englert, Carsten ; Dendorfer, Sebastian
Influence of vertebral parameters on lumbar spine loading (2013)
Putzer, Michael ; Galibarov, Pavel E. ; Dendorfer, Sebastian
Innovationen in der Medizintechnik (2013)
Dendorfer, Sebastian
Änderung der Gelenkreaktionskraft bei Schädigung des medialen Bandapparates im Ellenbogen (2020)
Melzner, Maximilian ; Pfeifer, Christian ; Alt, V. ; Süß, Franz ; Dendorfer, Sebastian
Älterwerden muss auch mal wehtun! (2016)
Dendorfer, Sebastian
Inaccurate offset restoration in total hip arthroplasty results in reduced range of motion (2020)
Weber, Markus ; Merle, Christian ; Nawabi, Danyal H. ; Dendorfer, Sebastian ; Grifka, Joachim ; Renkawitz, Tobias
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.
Evaluation of musculoskeletal modelling parameters of the shoulder complex during humeral abduction above 90° (2020)
Aurbach, Maximilian ; Spicka, Jan ; Süß, Franz ; Dendorfer, Sebastian
Based on electromyographic data and force measurements within the shoulder joint, there is an indication that muscle and resulting joint reaction forces keep increasing over an abduction angle of 90°. In inverse dynamics models, no single parameter could be attributed to simulate this force behaviour accordingly. The aim of this work is to implement kinematic, kinetic and muscle model modifications to an existing model of the shoulder (AnyBody™) and assess their single and combined effects during abduction up to 140° humeral elevation. The kinematics and the EMG activity of 10 test subjects were measured during humeral abduction. Six modifications were implemented in the model: alternative wrapping of the virtual deltoid muscle elements, utilization of a three element Hill model, strength scaling, motion capture driven clavicle elevation/protraction, translation of the GH joint in dependency of the acting forces and an alteration of the scapula/clavicle rhythm. From the six modifications, 16 different combinations were considered. Parameter combinations with the Hill model changed the resultant GH joint reaction force and led to an increase in force during abduction of the humerus above 90°. Under the premise of muscle activities and forces within the GH joint rising after 90° of humeral abduction, we propose that the Hill type muscle model is a crucial parameter for accurately modelling the shoulder. Furthermore, the outcome of this study indicates that the Hill model induces the co-contraction of the muscles of the shoulder without the need of an additional stability criterion for an inverse dynamics approach.
Comparing calculated and measured muscle activity of thigh muscles in dynamic motion. (2022)
Auer, Simon ; Reinker, Lukas ; Süß, Franz ; Dendorfer, Sebastian
Muskuloskeletal analysis of elbow stability for common injury patterns (2022)
Melzner, Maximilian ; Pfeifer, Christian ; Süß, Franz ; Dendorfer, Sebastian
Biomechanik und muskuloskeletale Simulation (2022)
Melzner, Maximlian ; Dendorfer, Sebastian
Experimental workflow for determining psychological stress from physiological biosignals (2017)
Pilling, A. ; Süß, Franz ; Kubowitsch, Simone ; Dendorfer, Sebastian
Experimentelle Untersuchung der Belastungen im Kopf beim Treten (2013)
Dendorfer, Sebastian ; Penzkofer, Rainer
FEA of the transiliacal internal fixator as an osteosynthesis of pelvic ring fractures (2017)
Jungtäubl, Dominik ; Schmitz, Paul ; Gross, Simon ; Dendorfer, Sebastian
Common Schanz screw systems can be used to stabilize pelvic ring fractures. In order to accommodate for different patient’s requirements, implants can be placed in cranio-caudal direction into the os ilium (T1), or into the supraacetabular bone canal, and thus, in dorso-ventral direction (T2). Whereas both techniques are currently used, no data of the biomechanical behavior is available up to this date. The aim of this study is to analyze, whether T2 shows biomechanical advantages with respect to tissue and implant stresses due to the enlarged bone-implant interface. Forces acting on the pelvis were analyzed using motion capture data of a gait cycle obtained by the utilization of a musculoskeletal simulation program. A three dimensional finite element (FE) model of the pelvis with grayscale-based material properties was generated. The muscle and joint reaction forces at toe-off were applied to the FE model and instable pelvis fractures were implemented. The osteosynthesis systems were positioned within the model in order to enable the comparison between the two different surgical techniques. Stresses and displacements were analyzed for bone tissue, fracture zone and implant. T2 lead to approx. 30% larger displacements in the fracture zone. Von-Mises stresses were larger for T2 in the implant (80 MPa vs. 227 MPa), whereas T1 leads to larger stresses in the bone tissue (200 MPa vs. 140 MPa). Both implantation techniques showed a good biomechanical behavior. Differences could be found with respect to tissue strains and deformations in the fracture zone. If bone quality or fracture healing are of concern, T2 or T1 should be used, respectively. However, both techniques seem to be applicable for cases with no special requirements. Further analyses aim to investigate the behavior under cyclic loading.
Fatigue damage in cancellous bone: an experimental approach from continuum to micro scale (2009)
Dendorfer, Sebastian ; Maier, Hans Jürgen ; Hammer, Josef
Repeated loadings may cause fatigue fractures in bony structures. Even if these failure types are known, data for trabecular bone exposed to cyclic loading are still insufficient as the majority of fatigue analyses on bone concentrate on cortical structures. Despite its highly anisotropic and inhomogeneous structure, trabecular bone is treated with continuum approaches in fatigue analyses. The underlying deformation and damage mechanism within trabecular specimens are not yet sufficiently investigated. In the present study different types of trabecular bone were loaded in monotonic and cyclic compression. In addition to the measurement of integral specimen deformations, optical deformation analysis was employed in order to obtain strain distributions at different scale levels, from the specimens' surface to the trabeculae level. These measurements allowed for the possibility of linking the macroscopic and microscopic mechanical behaviour of cancellous bone. Deformations were found to be highly inhomogeneous across the specimen. Furthermore strains were found to already localise at very low load levels and after few load cycles. Microcracks in individual trabeculae were induced in the very early stage of cyclic testing. The results provide evidence of the capability of the method to supply essential data on the failure behaviour of individual trabeculae in future studies.
Force distribution in the foot during braking – a musculoskeletal approach (2014)
Al-Munajjed, Amir Andreas ; Nolte, Daniel ; Rasmussen, John ; Dendorfer, Sebastian
High loads can appear in the individual joints of the human foot while the driver uses the pedals, in particular, during breaking. Measuring these internal forces is very difficult or almost impossible; therefore, advanced models are necessary to perform musculoskeletal simulations. The objective of this investigation was to see what loads are acting in the individual foot joints from the phalanges to calcaneus and talus during different brake scenarios. The Glasgow-Maastricht AnyBody Foot Model with 26 separate segments, connected by joints, ligaments and muscles was used inside the AnyBody Modeling System to compute individual mid foot joint loads. The amount, the direction of the force and additionally also the load insertion point was varied for several simulations. Figure 1: Seated musculoskeletal body model with applied brake force and forces for the lateral, intermediate and medial cuneiform-navicular joint for two different brake forces. The simulation showed that for the different brake scenarios, different muscles will be activated in the human and therefore different loads are apply in the fore-and mid-foot, respectively. The torso of the subject was assumed to be fixed in the seat. Further studies are ongoing to simulate the seat as an elastic element that allows different H-point locations according to the different loadings in the foot from the brake pedal using a new inverse dynamics analysis method called force-dependent kinematics.
Forces on a clavicles midshaft fracture and influence of fracture type (2009)
Dendorfer, Sebastian ; Englert, Carsten
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 (2016)
Weber, Tim A. ; Dendorfer, Sebastian ; Bulstra, Sjoerd K. ; Grifka, Joachim ; Verkerke, Gijsbertus Jacob ; Renkawitz, Tobias
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.
Herniation Induces 55% Increase in Load of Key Stabilizing Muscle – Impact on Herniation Treatment Devices? (2010)
Robie, Bruce ; Rasmussen, John ; Christensen, Soeren Toerholm ; Dendorfer, Sebastian
How do age and anisotropy affect the fatigue behaviour of cancellous bone? (2008)
Dendorfer, Sebastian ; Maier, Hans Jürgen ; Hammer, Josef
The fatigue behaviour of materials is of particular interest for the failure prediction of materials and structures exposed to cyclic loading. For trabecular bone structures only a few sets of lifetime data have been reported in the literature and structural measures are commonly not considered. The influence of load contributions not aligned with the main physiological axis remains unclear. Furthermore age effects on the fatigue behaviour are not well described. In the present study, different groups of human vertebral cancellous bone were exposed to cyclic compression. The inital modulus and therefore lifetimes were found to be highly dependent on age. The decrease in both with increasing age was much more pronounced in specimens which were not aligned with the main physiological axis. This implies that old bone is much more sensitive to (cyclic) failure loads in general but particularly to loads which are not coincident with the physiological main axis.
How to determine the effect of working conditions on the human body (2017)
Dendorfer, Sebastian ; Kubowitsch, Simone ; Süß, Franz
Work places and conditions strains the human body, both psychologically and biomechanically. In order to analyse working conditions and in the following to improve them, detailed knowledge about the effect of the different stressors on the body is needed. This manuscript discusses methods on how to evaluate biomechanical and mental loading and its effect on the musculoskeletal system. A possible workflow for the analysis is presented.
How much iron to pump? The determination of muscle forces for activities of daily living (2008)
Dendorfer, Sebastian
Implementation and Validation of Human Kinematics Measured Using IMUs for Musculoskeletal Simulations by the Evaluation of Joint Reaction Forces (2017)
Aurbach, Maximilian ; Wagner, Kilian ; Süß, Franz ; Dendorfer, Sebastian
The gold standard for the analysis of human kinematics and kinetics is a camera-based motion capture system in combination with force measurement platforms. Alternatively, inertial measurement units can be utilized to obtain human kinematics, while ground reaction forces are computed from full body dynamics. This setup represents a system independent from the spatial confinement of a gait laboratory. The aim of this study is the comparison of the two methods by the investigation of lower limb kinematics and the resulting joint reaction forces within the ankle-, knee- and hip joints. For this purpose, human motion during gait was captured simultaneously by both measurement techniques. 13 trials from 8 different test subjects were evaluated in total. IMU data was processed with a quaternion based Kalman Filter. The data sets were implemented into a musculoskeletal simulation program in order to drive a virtual human body model. Each sensor was aligned to the gravitational and magnetic field vectors of the earth. The angles of flexions, extensions and rotations were analyzed to determine kinematic differences. Joint reaction forces defined kinetic dissimilarities. The overall kinematic differences of both models yielded root mean square errors of 7.62°, 6.02°, 4.95°, 2.79°, 2.38° and 3.56° for ankle flexion, subtalar eversion, knee flexion, hip external rotation, hip abduction and hip flexion, respectively. The proximo-distal differences in force peaks between the models yielded overall for the ankle, 57.33 %Bodyweight(BW) ± 46.86 %BW (16.66 %(Maximum peak to peak) ± 13.62 %) for the knee 37.09 %BW ± 29.33 %BW (17.65 % ± 15.44 %) and 32.03 %BW ± 24.33 %BW (15.6 % ± 12.54 %) for the hip. The overall outcome of this work investigated an approach independent of the common setup of the gait laboratory, thus enabling a cheaper and more flexible technology as an alternative. However, kinematic and thus kinetic differences remain rather large. Future work aims to improve the contact criterion for the calculation of the ground reaction forces and the implementation of a full-body calibration algorithm for the IMU system in order to counteract magnetic field disturbances.
Investigation of cognitive stress induced changes in spinal disc forces due to altered kinematics and muscle activity (2018)
Süß, Franz ; Kubowitsch, Simone ; Verkerke, Gijsbertus Jacob ; Dendorfer, Sebastian
Investigation of external load dependent static and dynamic muscle fatigue (2017)
Gross, Simon ; Verkerke, Gijsbertus Jacob ; Dendorfer, Sebastian
Kognitiver Stress führt zu unphysiologisch erhöhten Kniebelastungen im Profifußball (2020)
Auer, Simon ; Krutsch, Werner ; Renkawitz, Tobias ; Kubowitsch, Simone ; Süß, Franz ; Dendorfer, Sebastian
Anisotropy of the fatigue behaviour of cancellous bone (2008)
Dendorfer, Sebastian ; Maier, Hans Jürgen ; Taylor, David ; Hammer, Joachim
The fatigue behaviour of materials is of particular interest for the failure prediction of materials and structures exposed to cyclic loading. For trabecular bone structures only a few sets of lifetime data have been reported in the literature and structural measures are commonly not considered. The influence of load contributions which are not aligned with the main physiological axis remains unclear. Furthermore site and species dependent relationships are not well described. In this study five different groups of trabecular bone, defined in terms of orientation, species and site were exposed to cyclic compression. In total, 108 fatigue tests were analysed. The lifetimes were found to decrease drastically when off-axis loads were applied. Additionally, species and site strongly affect fatigue lifetimes. Strains at failure were also found to be a function of orientation.
Axial Rotation Requires Greatest Load in Multifidus Muscle – Potential Association with Low Back Pain? (2011)
Robie, Bruce ; Dendorfer, Sebastian ; Rasmussen, John ; Christensen, Soeren Toerholm
Biomechanical analysis of iliac crest loading following cortico-cancellous bone harvesting (2018)
Schmitz, Paul ; Neumann, Christoph Cornelius ; Neumann, Carsten ; Nerlich, Michael ; Dendorfer, Sebastian
Background Iliac crest bone harvesting is a frequently performed surgical procedure widely used to treat bone defects. The objective of this study is to assess the biomechanical quantities related to risk for pelvic fracture after harvesting an autologous bone graft at the anterior iliac crest. Methods Finite element models with a simulated harvest site (sized 15 × 20 mm, 15 × 35 mm, 30 × 20 mm and 30 × 35 mm) in the iliac wing are created. The relevant loading case is when the ipsilateral leg is lifted off the ground. Musculoskeletal analysis is utilized to compute the muscle and joint forces involved in this motion. These forces are used as boundary conditions for the finite element analyses. Bone tissue stress is analyzed. Results Critical stress peaks are located between the anterior superior iliac spine (ASIS) and the anterior edge of the harvest site. Irrespective of the graft size, the iliac wing does not show any significant stress peaks with the harvest site being 20 to 25 mm posterior to the ASIS. The harvest area itself inhibits the distribution of the forces applied on the ASIS to extend to the posterior iliac wing. This leads to a lack of stress posterior to the harvest site. A balanced stress distribution with no stress peaks appears when the bone graft is taken below the iliac crest. Conclusion A harvest site located at least 20 to 25 mm posterior to the ASIS should be preferred to minimize the risk of iliac fatigue fracture.
Biomechanical Outcome after computer-assisted vs. Conventional THR (2014)
Weber, Tim ; Dendorfer, Sebastian ; Bulstra, Sjoerd K. ; Verkerke, Gijsbertus Jacob ; Renkawitz, Tobias
Biomechanical outcome after computer-assisted vs. conventional THR – study concept and preliminary gait analysis results (2012)
Weber, Tim ; Dullien, Silvia ; Putzer, Michael ; Dendorfer, Sebastian ; Renkawitz, Tobias
Biomechanical comparison of the dorsal femur condyles and the iliac crest in terms of failure behavior (2015)
Penzkofer, Rainer ; Grechenig, S. ; Kujat, Richard ; Angele, Peter ; Dendorfer, Sebastian
Biomechanical evaluation and optimisation of countermeasure exercises (2009)
Dendorfer, Sebastian
Biomechanics of computer-assisted vs. conventional THR after one year follow up (2015)
Weber, Tim ; Renkawitz, Tobias ; Bulstra, Sjoerd K. ; Grifka, Joachim ; Verkerke, Gijsbertus Jacob ; Dendorfer, Sebastian
Biomechanik des Alterns (2016)
Dendorfer, Sebastian
Cartilage labelling for mechanical testing in T-peel configuration (2012)
Pfeifer, Christian ; Müller, Michael ; Prantl, Lukas ; Berner, Arne ; Dendorfer, Sebastian ; Englert, Carsten
PURPOSE: The purpose of this study was to find a suitable method of labelling cartilage samples for the measurement of distraction distances in biomechanical testing. METHODS: Samples of bovine cartilage were labelled using five different methods: hydroquinone and silver nitrate (AgNO3), potassium permanganate (KMnO4) with sodium thiosulphate (Na2S2O3), India ink, heat, and laser energy. After the labelling, we analysed the cartilage samples with regard to cytotoxity by histochemical staining with ethidiumbromide homodimer (EthD-1) and calcein AM. Furthermore, we tested cartilages labelled with India ink and heat in a T-peel test configuration to analyse possible changes in the mechanical behaviour between marked and unlabelled samples. RESULTS: Only the labelling methods with Indian ink or a heated needle showed acceptable results in the cytotoxity test with regard to labelling persistence, accuracy, and the influence on consistency and viability of the chondrocytes. In the biomechanical T-peel configuration, heat-labelled samples collapsed significantly earlier than unlabelled samples. CONCLUSION: Labelling bovine cartilage samples with Indian ink in biomechanical testing is a reliable, accurate, inexpensive, and easy-to-perform method. This labelling method influenced neither the biomechanical behaviour nor the viability of the tissue compared to untreated bovine cartilage.
Characterisation and testing of biomaterials (2010)
Dendorfer, Sebastian ; Hammer, Joachim ; Lenich, Andreas
Characterisation and testing of biomaterials (2011)
Dendorfer, Sebastian ; Hammer, Joachim ; Lenich, Andreas
Combined Experimental and Numerical Approach to Investigate Changes in Muscle Recruitment Pattern of the Back Muscles during Exhausting Exercise (2018)
Gross, Simon ; Verkerke, Gijsbertus Jacob ; Dendorfer, Sebastian
In recent years, musculoskeletal computation has become a widely used tool to investigate joint and muscle forces within the human body. However, the issue of muscle fatigue is not considered adequately in most models and is a challenging task. One aspect that needs to be examined is the interaction of muscles during an exhausting task. Therefore, an experimental study was designed to analyze the changes of back muscle recruitment pattern during such exercises. In this study 38 subjects (27 male, 11 female, height = 177±8.5 cm, weight = 74.0±13.6 kg) participated. Each subject had to perform three static and three dynamic exhausting exercises where the back muscles were loaded with subject specific forces using a dynamometer adapter especially designed for the trunk muscles. To collect the muscle activity, twelve surface electromyography sensors were applied on the back, and four on the abdominal muscles. Muscle activity and fatigue were analyzed by calculating the maximum voluntary contraction normalized signal and the median frequency. At first the fatigue of m. erector spinae and m. multifidi was analyzed, since these muscles carry the main load during the exercises. Subsequently the activity of the m. trapezius, m. rectus abdominis and m. obliquus externus were investigated to determine recruitment patterns. To gain more detailed information of these patterns a numerical model was built using the AnyBody Modeling System™. Analyzing the measurements, we can observe an increasing muscle activity during isokinetic exercises while the force is constant. Since the activity in the simulation is defined as the current force output divided by the strength of the muscle, the strength parameter was scaled down based on the measured data, assuming a linear force – activity correlation, and using a numerical algorithm considering the influence of cross talk. The results show, that changes in recruitment pattern can be divided into three major subgroups. Prior to total exhaustion, some of the subjects show additional activation of muscles in the trapezius region, while other subjects show an additional activation of abdominal muscles, increasing the intra-abdominal pressure which supports the spine. In the third group an activation in both regions can be observed. The numerical simulations show an increasing activity of abdominal muscles as well as muscles in the upper back. Especially the m. latissimus dorsi shows a significantly higher activity. The results lead to the conclusion that prior to total exhaustion, additional muscles are recruited to support the main muscles. It was shown that abdominal muscles are activated to support back muscles by pressurizing the trunk cavity to delay total exhaustion as long as possible. In conclusion, the results show that changes in muscle recruitment pattern need to be considered when introducing muscle fatigue to musculoskeletal models.
Cognitive stress increases muscle forces in dynamic football specific movements (2019)
Auer, Simon ; Niebler, Michael ; Eiglsperger, Josef ; Kubowitsch, Simone ; Renkawitz, Tobias ; Achenbach, Leonard ; Krutsch, Werner ; Dendorfer, Sebastian
Clinical gait analysis combined with musculoskeletal modelling – coding a new generation of evaluation instruments (2011)
Weber, Tim ; Dendorfer, Sebastian ; Renkawitz, Tobias ; Dullien, Silvia ; Grifka, Joachim
Comparison of dynamic muscular imbalances in back pain patients and healthy controls (2018)
Kubowitsch, Simone ; Süß, Franz ; Jansen, Petra ; Dendorfer, Sebastian
Contact force path in total hip arthroplasty: effect of cup medialisation in a whole-body simulation (2020)
De Pieri, Enrico ; Atzori, Federica ; Ferguson, Stephen J. ; Dendorfer, Sebastian ; Leunig, Michael ; Aepli, Martin
Background: Cup medialisation down to the true acetabular floor in total hip arthroplasty with a compensatory femoral offset increase seems to be mechanically advantageous for the abductor muscles due to the relocation of the lever arms (body weight lever arm decreased, abductor lever arm increased). However, limited information is currently available about the effects of this reconstruction type at the head cup interface, compared to an anatomical reconstruction that maintains the natural lever arms. Through a whole-body simulation analysis, we compared medialised versus anatomical reconstruction in THA to analyse the effects on: (1) contact force magnitude at the head cup interface; (2) contact force path in the cup; and (3) abductor activity. Methods: Musculoskeletal simulations were performed to calculate the above-mentioned parameters using inverse dynamics analysis. The differences between the virtually implanted THAs were calculated to compare the medialised versus anatomical reconstruction. Results: Cup medialisation with compensatory femoral offset increase led to: (1) a reduction in contact force magnitude at the head cup interface up to 6.6%; (2) a similar contact force path in the cup in terms of sliding distance and aspect ratio; and (3) a reduction in abductor activity up to 17.2% (gluteus medius). Conclusions: In our opinion, these potential biomechanical gains do not generally justify a fully medialised reconstruction, especially in younger patients that are more likely to undergo revision surgery in their lifetime. Cup medialisation should be performed until sufficient press fit and bony coverage of a properly sized and oriented cup can be achieved.
Conductive bone substitute material with variable antibiotic delivery (2007)
Englert, Carsten ; Angele, Peter ; Fierlbeck, J. ; Dendorfer, Sebastian ; Schubert, T. ; Müller, R. ; Lienhard, S. ; Zellner, J. ; Nerlich, Michael ; Neumann, Carsten
A new bone substitute, consisting of hydroxylapatite and calcium sulphate, was prepared in two formulations and analysed for its mechanical strength and antibiotic elution.The bone substitute PerOssal has osteoconductive and degradable properties. The material has a built-in capillary structure, which results in an immediate fluid uptake. Antibiotics absorbed to the bone substitute resulted in a prolonged release rate. Mechanical strength was investigated by an unconfined compression test up to failure under both wet and dry conditions for both formulations of the bone substitute. Antibiotic release was analysed microbiologically for two antibiotics, vancomycin and gentamicin, over an elution period of 10 days using the agar diffusion method.The drug release analysis resulted in a prolonged release rate of both antibiotics over 10 days. In vitro the amount of gentamicin and vancomycin eluted at day 10. From one pellet still exceeded the minimal inhibitory concentration of most aetiologically important pathogens. Formulation two of the present bone substitute is significantly harder in both wet and dry conditions when compared to formulation one. Both formulations lose strength in the wet condition relative to their performance in the dry condition. However, formulation two is as hard under wet conditions as formulation one is when dry.PerOssal is a suitable new degradable osteoconductive bone substitute that can be loaded with antibiotic solutions, which are released in effective doses over 10 days. The mechanical strength of PerOssal is sufficient to support cancellous bone defects in non-weight-bearing areas or in combination with osteosynthesis.
Controlled central advancement of the midface after Le Fort III osteotomy by a 3-point skeletal anchorage (2011)
Roldán, J.C. ; Moralis, A. ; Dendorfer, Sebastian ; Witte, J. ; Reicheneder, C.
A 3-point skeletal anchorage with taping screws for distraction osteogenesis after a Le Fort III osteotomy was applied for the first time in a severely mentally impaired patient where intraoral devices had to be avoided. All 3-force application points included the center of resistance, which allowed an optimal control on the resulting moment. A novel device for skeletal long-term retention into the nasal dorsum prevented a relapse, whereas adjustment of the midface position was observed. Fusioned three-dimensional computed tomography analysis revealed real movements not accessible by a conventional cephalometry.
Cyclic loading and microstructure of cancellous bone (2008)
Hammer, Joachim ; Dendorfer, Sebastian
Development of a test system to analyze different hip fracture osteosyntheses under simulated walking (2012)
Lenich, Andreas ; Bachmeier, S. ; Dendorfer, Sebastian ; Mayr, E. ; Nerlich, Michael ; Füchtmeier, B.
The mechanical complications of osteosyntheses after hip fractures are previously investigated by mostly static or dynamic uniaxial loading test systems. However, the physiologic loading of the hip joint during a normal gait is a multiplanar, dynamic movement. Therefore, we constructed a system to test osteosyntheses for hip fractures under physiologic multiplanar loading representative of normal gait. To evaluate the testing system, 12 femora pairs were tested under 25,000 cycles with two standard osteosyntheses (Proximal Femoral Nail Antirotation/Gamma3 Nail). For angular movement, the varus collapse to cut out (∝CO) (∝CO=4.8°±2.1° for blade and ∝CO=7.8°±3.8° for screw) was the dominant failure mode, and only slight rotational angle shifts (∝Rot) (∝Rot=1.7°±0.4° for blade and ∝Rot=2.4°±0.3° for screw) of the femoral head around the implant axis were observed. Angular displacements in varus direction and rotation were higher in specimens reinforced with screws. Hence, the cut out model and the migration directions showed a distinction between helical blade and hip screw. However, there were no significant differences between the different implants. The new setup is able to create clinical failures and allows to give evidence about the anchorage stability of different implant types under dynamic gait motion pattern.
Design studies on hip prosthesis using patient specific data (2011)
Putzer, Michael ; Weber, Tim ; Dendorfer, Sebastian
Does Computer-Assisted Femur First THR Improve Musculoskeletal Loading Conditions? (2015)
Weber, Tim A. ; Dendorfer, Sebastian ; Grifka, Joachim ; Verkerke, Gijsbertus Jacob ; Renkawitz, Tobias
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.
Effect of mental demand on leg loading in highly dynamic motion (2020)
Auer, Simon ; Krutsch, Werner ; Renkawitz, Tobias ; Kubowitsch, Simone ; Süß, Franz ; Dendorfer, Sebastian
Football players have a high risk of leg muscle injuries, especially when exposed to mental stress. Injuries to muscles of the thigh are common in amateur and professional football, representing almost a third of all injuries. These injuries occur primarily in non-contact situations and from overuse. They can lead to a range of costs, including financial costs associated with treatment as well as those associated with long-term recovery, and absence from training and/or competition. Further, there is a high risk of injury recurrence and subsequent injury.
Effect of dual tasking on muscular imbalances (2019)
Kubowitsch, Simone ; Süß, Franz ; Jansen, Petra ; Dendorfer, Sebastian
Effect of the fractured calcaneus's peripheral fragment displacement on the triceps surae function (2015)
Lazarev, I.A. ; Ryabokon, P.V. ; Haller, M. ; Dendorfer, Sebastian
Einfluss der Muskelkräfte, des Bewegungsausmaßes und der Bruchform auf die Kraftübertragung des Implantat-Knochenverbundes am Beispiel der Claviculafraktur im mittleren Drittel (2010)
Englert, Carsten ; Müller, F. ; Dendorfer, Sebastian
Fragestellung Es soll in dieser Computersimulationsstudie untersucht werden, wie der Osteosyntheseverbund Platte mit Schrauben im Verbund mit einer im mittleren Drittel gebrochenen Clavicula durch das Bewegungsausmaß in vivo belastet ist. Was sind die grundlegenden Kräfte die auf Clavicula und Implantat wirken und welchen Einfl uss hat die Bruchform. Methodik Die Muskel- und Gelenkkräfte sowie die Belastung des Implantatverbundes wurden mit einer muskuloskelletalen Simulationssoftware (AnyBody Technology, V.4) berechnet. Hierfür wurden mit einem komplexen Model des menschlichen Körpers folgende Bewegungen analysiert: eine Flexion von 160° und Abduktion 160° mit einem Gewicht von 2 kg in der Hand. Aus CT-Patientendaten wurden zwei dreidimensionale Modelle des Clavicula-Implantat Verbundes gebildet, die sich in der Frakturform unterscheiden (Querfraktur und vertikale Fraktur). In beiden Modellen wurde eine Claviculaosteosynthese in superiorer Position mit einer 6 Loch LCP mit 2 Schrauben pro Hauptfragment verwendet. Die Materialeigenschaften wurden aus der Dichte des Materials sowie aus Literaturdaten verwendet. Die Muskel- und Gelenkkräfte aus der muskuloskelletalen Berechnung wurden auf das Finite Elemente Modell übertragen und die Spannungen und Dehnungen des Implantat-Knochenverbundes wurden berechnet. Ergebnisse Es zeigte sich, dass die simulierte in vivo Belastung stark abhängig vom Flexionswinkel ist. Das Implantat ist in der superioren Lage auf Biegung belastet, welche maximale Werte im Überschulterniveau erreicht. Die Bruchform mit anatomischer Reposition und Kontakt der Hauptfragmente zueinander führt zu einer deutlichen Entlastung des Osteosyntheseverbundes im Vergleich zu einer Bruchform mit vertikaler Fraktur. Schlussfolgerung Aus den Analysen ist eine Positionierung der Plattenosteosynthese für die im mittleren Drittel frakturierte Clavicula in anterior-superiorer Lage wünschenswert. Die anatomische Reposition entlastet den Osteosyntheseverbund und sollte möglichst erreicht werden. Die Nachbehandlung sollte ein Bewegungsausmaß für den Arm für 4 Wochen für einfache Bruchformen auf 70° Flexion und Abduktion limitieren und für komplexe Bruchformen diese Limitierung ausgedehnt werden.
EMG-based validation of musculoskeletal models considering crosstalk (2018)
Aurbach, Maximilian ; Jungtäubl, Dominik ; Spicka, Jan ; Dendorfer, Sebastian
BACKGROUND: Validation and verification of multibody musculoskeletal models sEMG is a difficult process because of the reliability of sEMG data and the complex relationship of muscle force and sEMG. OBJECTIVE: This work aims at comparing experimentally recorded and simulated muscle activities considering a numerical model for crosstalk. METHODS: For providing an experimentally derived reference data set, subjects were performing elevations of the arm, where the activities of the contemplated muscle groups were measured by sEMG sensors. Computed muscle activities were further processed and transformed into an artificial electromyographical signal, which includes a numerical crosstalk model. In order to determine whether the crosstalk model provides a better agreement with the measured muscle activities, the Pearson correlation coefficient has been computed as a qualitative way of assessing the curve progression of the data sets. RESULTS: The results show an improvement in the correlation coefficient between the experimental data and the simulated muscle activities when taking crosstalk into account. CONCLUSIONS: Although the correlation coefficient increased when the crosstalk model was utilized, it is questionable if the discretization of both, the crosstalk and the musculoskeletal model, is accurate enough.
Eine biomechanische Bewertung verschiedener Belastungsszenarios nach der Implantierung einer Hüft-Totalendoprothese (2012)
Weber, Tim ; Stezowski, P. ; Dullien, Silvia ; Dendorfer, Sebastian
Eine biomechanische Bewertung verschiedener Belastungsszenarien nach Implantierung einer Hüft-Totalendoprothese (2012)
Weber, Tim ; Stezowski, P. ; Dullien, Silvia ; Putzer, Michael ; Dendorfer, Sebastian
Einführung in die Mechanik (2013)
Dendorfer, Sebastian
EMG-Based Validation of Musculoskeletal Models Considering Crosstalk (2018)
Jungtäubl, Dominik ; Aurbach, Maximilian ; Melzner, Maximilian ; Spicka, Jan ; Süß, Franz ; Dendorfer, Sebastian
BACKGROUND: Validation and verification of multibody musculoskeletal models sEMG is a difficult process because of the reliability of sEMG data and the complex relationship of muscle force and sEMG. OBJECTIVE: This work aims at comparing experimentally recorded and simulated muscle activities considering a numerical model for crosstalk. METHODS: For providing an experimentally derived reference data set, subjects were performing elevations of the arm, where the activities of the contemplated muscle groups were measured by sEMG sensors. Computed muscle activities were further processed and transformed into an artificial electromyographical signal, which includes a numerical crosstalk model. In order to determine whether the crosstalk model provides a better agreement with the measured muscle activities, the Pearson correlation coefficient has been computed as a qualitative way of assessing the curve progression of the data sets. RESULTS: The results show an improvement in the correlation coefficient between the experimental data and the simulated muscle activities when taking crosstalk into account. CONCLUSIONS: Although the correlation coefficient increased when the crosstalk model was utilized, it is questionable if the discretization of both, the crosstalk and the musculoskeletal model, is accurate enough.
Muskuloskelettale Simulation zur Untersuchung des Einflusses geometrischer Parameter der Wirbelkörper auf die Belastung der Lendenwirbelsäule (2013)
Putzer, Michael ; Rasmussen, John ; Ehrlich, Ingo ; Gebbeken, Norbert ; Dendorfer, Sebastian
Musculoskeletal modelling of the shoulder – effects on muscle recruitment and joint reaction force (2019)
Aurbach, Maximilian ; Spicka, Jan ; Süß, Franz ; Dendorfer, Sebastian
Musculoskeletal simulations to investigate the influence of vertebral geometrical parameters on lumbar spine loading (2014)
Putzer, Michael ; Penzkofer, Rainer ; Ehrlich, Ingo ; Rasmussen, John ; Gebbeken, Norbert ; Dendorfer, Sebastian
Musculoskeletal modeling for hip replacement outcome analyses and other applications (2014)
Dendorfer, Sebastian ; Weber, Tim ; Kennedy, O.
Musculoskeletal modeling for orthopedic surgery – Applications and chances (2015)
Weber, Tim ; Dendorfer, Sebastian ; Bulstra, Sjoerd K. ; Verkerke, Gijsbertus Jacob ; Renkawitz, Tobias
Numerische und experimentelle Untersuchungen an der Wirbelsäule (2015)
Süß, Franz ; Putzer, Michael ; Dendorfer, Sebastian
Measuring functional outcome after total hip replacement with subject-specific hip joint loading (2012)
Weber, Tim A. ; Dendorfer, Sebastian ; Dullien, Silvia ; Grifka, Joachim ; Verkerke, Gijsbertus Jacob ; Renkawitz, Tobias
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.
Mechanical and seeding properties of human umbilical vein – a potential scaffold for a tissue-engineered vessel graft (2007)
Hoenicka, M. ; Lehle, K. ; Jacobs, V. R. ; Dendorfer, Sebastian ; Kostorz, A. ; Schmid, F. X. ; Birnbaum, D. E.
Objectives: The mechanical properties and seeding with endothelial cells were investigated in fresh and cryopreserved human umbilical vein. Methods: Human umbilical veins (HUV) were frozen in Euro-Collins/1M DMSO at –1°C/min and stored in liquid nitrogen. Stress-strain relationships of fresh and thawed veins were determined in an uniaxial tension-testing rig. HUV endothelial cells (HUVEC) were seeded onto denuded HUV under static conditions and grown for 3d. Luminal surfaces were analyzed by scanning electron microscopy. Calcein-stained cells were seeded hyperconfluently to determine the cell retention capacity of fresh and cryopreserved veins. Results: The stress-strain relationships of HUV followed a biphasic pattern typical for natural vessels. Neither the failure stress (2.71±0.36 vs. 3.25±0.97 N, n=3) nor the displacement required to achieve failure (9.73±0.9 vs. 7.43±2.07mm, n=3) were altered by cryopreservation. The burst pressure was estimated as approx. 1000mm Hg within the limitations of the uniaxial model. HUVEC seeded onto denuded HUV formed patches (at 9E3 cells per cm2) or an almost confluent endothelium (at 3E4 cells per cm2) within three days. The capacity to retain seeded HUVEC of denuded HUV was not altered by cryopreservation (1.15±0.08E5 vs. 1.26±0.14E5 cells per cm2, n=6). Conclusions: The burst pressure of HUV seems to be sufficiently high for the human arterial circulation and is not altered by cryopreservation. HUVEC can establish a confluent endothelium on denuded HUV. Therefore HUV appears to be a suitable storable scaffold for vascular tissue engineering.
Mechanobiology – Impact on regeneration and degradation (2015)
Dendorfer, Sebastian
  • 1 to 100

OPUS4 Logo

  • Contact
  • Imprint and Datasecure
  • Sitelinks