@misc{BroserFalterŁawrowskietal., author = {Broser, Christian and Falter, Thomas and Ławrowski, Robert Damian and Altenbuchner, Amelie and V{\"o}gele, Daniel and Koss, Claus and Schlampp, Matthias and Dunnweber, Jan and Steffens, Oliver and Heckner, Markus and Jaritz, Sabine and Schiegl, Thomas and Corsten, Sabine and Lauer, Norina and Guertler, Katherine and Koenig, Eric and Haug, Sonja and Huber, Dominik and Birkenmaier, Clemens and Krenkel, Lars and Wagner, Thomas and Justus, Xenia and Saßmannshausen, Sean Patrick and Kleine, Nadine and Weber, Karsten and Braun, Carina N. and Giacoppo, Giuliano and Heinrich, Michael and Just, Tobias and Schreck, Thomas and Schnabl, Andreas and Gilmore, Amador T{\´e}ran and Roeslin, Samuel and Schmid, Sandra and Wellnitz, Felix and Malz, Sebastian and Maurial, Andreas and Hauser, Florian and Mottok, J{\"u}rgen and Klettke, Meike and Scherzinger, Stefanie and St{\"o}rl, Uta and Heckner, Markus and Bazo, Alexander and Wolff, Christian and Kopper, Andreas and Westner, Markus and Pongratz, Christian and Ehrlich, Ingo and Briem, Ulrich and Hederer, Sebastian and Wagner, Marcus and Schillinger, Moritz and G{\"o}rlach, Julien and Hierl, Stefan and Siegl, Marco and Langer, Christoph and Hausladen, Matthias and Schreiner, Rupert and Haslbeck, Matthias and Kreuzer, Reinhard and Br{\"u}ckl, Oliver and Dawoud, Belal and Rabl, Hans-Peter and Gamisch, Bernd and Schmidt, Ottfried and Heberl, Michael and G{\"a}nsbauer, Bianca and Bick, Werner and Ellermeier, Andreas and Monkman, Gareth J. and Prem, Nina and Sindersberger, Dirk and Tschurtschenthaler, Karl and Aurbach, Maximilian and Dendorfer, Sebastian and Betz, Michael A. and Szecsey, Tamara and Mauerer, Wolfgang and Murr, Florian}, title = {Forschung 2018}, editor = {Baier, Wolfgang}, address = {Regensburg}, organization = {Ostbayerische Technische Hochschule Regensburg}, isbn = {978-3-9818209-5-9}, doi = {10.35096/othr/pub-1382}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-13826}, pages = {98}, subject = {Forschung}, language = {de} } @article{SchmitzNeumannNeumannetal., author = {Schmitz, Paul and Neumann, Christoph Cornelius and Neumann, Carsten and Nerlich, Michael and Dendorfer, Sebastian}, title = {Biomechanical analysis of iliac crest loading following cortico-cancellous bone harvesting}, series = {Journal of Orthopaedic Surgery and Research}, volume = {13}, journal = {Journal of Orthopaedic Surgery and Research}, number = {108}, publisher = {Springer Nature}, doi = {10.1186/s13018-018-0822-1}, pages = {1 -- 8}, abstract = {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.}, subject = {Beckenkammknochen}, language = {en} } @inproceedings{AurbachJungtaeublSpickaetal., author = {Aurbach, Maximilian and Jungt{\"a}ubl, Dominik and Spicka, Jan and Dendorfer, Sebastian}, title = {EMG-based validation of musculoskeletal models considering crosstalk}, series = {World Congress Biomechanics, 28-30 June 2018, Dublin}, booktitle = {World Congress Biomechanics, 28-30 June 2018, Dublin}, doi = {10.1109/BIOMDLORE.2018.8467211}, abstract = {BACKGROUND: Validation and verification of multibody musculoskeletal models sEMG is a difficult process because of the reliability of sEMG data and the complex relationship of muscle force and sEMG. OBJECTIVE: This work aims at comparing experimentally recorded and simulated muscle activities considering a numerical model for crosstalk. METHODS: For providing an experimentally derived reference data set, subjects were performing elevations of the arm, where the activities of the contemplated muscle groups were measured by sEMG sensors. Computed muscle activities were further processed and transformed into an artificial electromyographical signal, which includes a numerical crosstalk model. In order to determine whether the crosstalk model provides a better agreement with the measured muscle activities, the Pearson correlation coefficient has been computed as a qualitative way of assessing the curve progression of the data sets. RESULTS: The results show an improvement in the correlation coefficient between the experimental data and the simulated muscle activities when taking crosstalk into account. CONCLUSIONS: Although the correlation coefficient increased when the crosstalk model was utilized, it is questionable if the discretization of both, the crosstalk and the musculoskeletal model, is accurate enough.}, language = {en} } @article{BenditzAuerSpoerreretal., author = {Benditz, Achim and Auer, Simon and Sp{\"o}rrer, J.F. and Wolkerstorfer, S. and Grifka, Joachim and S{\"u}ß, Franz and Dendorfer, Sebastian}, title = {Regarding loads after spinal fusion, every level should be seen separately: a musculoskeletal analysis}, series = {European Spine Journal}, volume = {27}, journal = {European Spine Journal}, number = {8}, publisher = {Springer-Verlag}, doi = {10.1007/s00586-018-5476-5}, pages = {1905 -- 1910}, abstract = {The number of spinal fusion surgeries is steadily increasing and biomechanical consequences are still in debate. The aim of this study is to provide biomechanical insights into the sagittal balance of the spine and to compare spinal load before and after spinal fusion. METHOD: The joint reaction forces of 52 patients were analyzed in proximo-distal and antero-posterior direction from the levels T12-L1 to L5-S1 using musculoskeletal simulations. RESULTS: In 104 simulations, pre-surgical forces were equal to post-surgical. The levels L4-L5 and T12-L1, however, showed increased spinal forces compression forces with higher sagittal displacement. Improved restauration of sagittal balance was accompanied by lower spinal load. AP shear stress, interestingly decreased with sagittal imbalance. CONCLUSION: Imbalanced spines have a risk of increased compression forces at Th12-L1. L4-L5 always has increased spinal loads. These slides can be retrieved under Electronic Supplementary Material.}, subject = {Biomechanische Analyse}, language = {en} } @inproceedings{GrossVerkerkeDendorfer, author = {Gross, Simon and Verkerke, Gijsbertus Jacob and Dendorfer, Sebastian}, title = {Combined Experimental and Numerical Approach to Investigate Changes in Muscle Recruitment Pattern of the Back Muscles during Exhausting Exercise}, series = {World Congress Biomechanics Dublin, 2018}, booktitle = {World Congress Biomechanics Dublin, 2018}, abstract = {In recent years, musculoskeletal computation has become a widely used tool to investigate joint and muscle forces within the human body. However, the issue of muscle fatigue is not considered adequately in most models and is a challenging task. One aspect that needs to be examined is the interaction of muscles during an exhausting task. Therefore, an experimental study was designed to analyze the changes of back muscle recruitment pattern during such exercises. In this study 38 subjects (27 male, 11 female, height = 177±8.5 cm, weight = 74.0±13.6 kg) participated. Each subject had to perform three static and three dynamic exhausting exercises where the back muscles were loaded with subject specific forces using a dynamometer adapter especially designed for the trunk muscles. To collect the muscle activity, twelve surface electromyography sensors were applied on the back, and four on the abdominal muscles. Muscle activity and fatigue were analyzed by calculating the maximum voluntary contraction normalized signal and the median frequency. At first the fatigue of m. erector spinae and m. multifidi was analyzed, since these muscles carry the main load during the exercises. Subsequently the activity of the m. trapezius, m. rectus abdominis and m. obliquus externus were investigated to determine recruitment patterns. To gain more detailed information of these patterns a numerical model was built using the AnyBody Modeling System™. Analyzing the measurements, we can observe an increasing muscle activity during isokinetic exercises while the force is constant. Since the activity in the simulation is defined as the current force output divided by the strength of the muscle, the strength parameter was scaled down based on the measured data, assuming a linear force - activity correlation, and using a numerical algorithm considering the influence of cross talk. The results show, that changes in recruitment pattern can be divided into three major subgroups. Prior to total exhaustion, some of the subjects show additional activation of muscles in the trapezius region, while other subjects show an additional activation of abdominal muscles, increasing the intra-abdominal pressure which supports the spine. In the third group an activation in both regions can be observed. The numerical simulations show an increasing activity of abdominal muscles as well as muscles in the upper back. Especially the m. latissimus dorsi shows a significantly higher activity. The results lead to the conclusion that prior to total exhaustion, additional muscles are recruited to support the main muscles. It was shown that abdominal muscles are activated to support back muscles by pressurizing the trunk cavity to delay total exhaustion as long as possible. In conclusion, the results show that changes in muscle recruitment pattern need to be considered when introducing muscle fatigue to musculoskeletal models.}, language = {en} } @inproceedings{JungtaeublAurbachMelzneretal., author = {Jungt{\"a}ubl, Dominik and Aurbach, Maximilian and Melzner, Maximilian and Spicka, Jan and S{\"u}ß, Franz and Dendorfer, Sebastian}, title = {EMG-Based Validation of Musculoskeletal Models Considering Crosstalk}, series = {International Conference BIOMDLORE, June 28 - 30 2018, Białystok, Poland}, booktitle = {International Conference BIOMDLORE, June 28 - 30 2018, Białystok, Poland}, doi = {10.1109/BIOMDLORE.2018.8467211}, abstract = {BACKGROUND: Validation and verification of multibody musculoskeletal models sEMG is a difficult process because of the reliability of sEMG data and the complex relationship of muscle force and sEMG. OBJECTIVE: This work aims at comparing experimentally recorded and simulated muscle activities considering a numerical model for crosstalk. METHODS: For providing an experimentally derived reference data set, subjects were performing elevations of the arm, where the activities of the contemplated muscle groups were measured by sEMG sensors. Computed muscle activities were further processed and transformed into an artificial electromyographical signal, which includes a numerical crosstalk model. In order to determine whether the crosstalk model provides a better agreement with the measured muscle activities, the Pearson correlation coefficient has been computed as a qualitative way of assessing the curve progression of the data sets. RESULTS: The results show an improvement in the correlation coefficient between the experimental data and the simulated muscle activities when taking crosstalk into account. CONCLUSIONS: Although the correlation coefficient increased when the crosstalk model was utilized, it is questionable if the discretization of both, the crosstalk and the musculoskeletal model, is accurate enough.}, language = {en} } @inproceedings{KubowitschSuessJansenetal., author = {Kubowitsch, Simone and S{\"u}ß, Franz and Jansen, Petra and Dendorfer, Sebastian}, title = {Comparison of dynamic muscular imbalances in back pain patients and healthy controls}, series = {World Congress Biomechanics Dublin, 2018}, booktitle = {World Congress Biomechanics Dublin, 2018}, language = {en} } @inproceedings{SeefriedAurbachWyssetal., author = {Seefried, C. and Aurbach, Maximilian and Wyss, C. and Dendorfer, Sebastian}, title = {Achilles tendon lengthening alters stresses in the growth plate}, series = {International Conference BIOMDLORE, June 28 - 30 2018, Białystok, Poland}, booktitle = {International Conference BIOMDLORE, June 28 - 30 2018, Białystok, Poland}, language = {en} } @inproceedings{SuessKubowitschVerkerkeetal., author = {S{\"u}ß, Franz and Kubowitsch, Simone and Verkerke, Gijsbertus Jacob and Dendorfer, Sebastian}, title = {Investigation of cognitive stress induced changes in spinal disc forces due to altered kinematics and muscle activity}, series = {World Congress Biomechanics, Dublin, 2018}, booktitle = {World Congress Biomechanics, Dublin, 2018}, language = {en} } @inproceedings{KubowitschDendorfer, author = {Kubowitsch, Simone and Dendorfer, Sebastian}, title = {Psychologie und Biomechanik - Integrierte Betrachtung von Muskelrekrutierung}, series = {Jahrestagung der Deutschen Gesellschaft f{\"u}r Biofeedback e. V., Regensburg, 2018}, booktitle = {Jahrestagung der Deutschen Gesellschaft f{\"u}r Biofeedback e. V., Regensburg, 2018}, language = {de} }