@article{MelznerEngelhardtSimonetal., author = {Melzner, Maximilian and Engelhardt, Lucas and Simon, Ulrich and Dendorfer, Sebastian}, title = {Electromyography-Based Validation of a Musculoskeletal Hand Model}, series = {Journal of Biomechanical Engineering}, volume = {144}, journal = {Journal of Biomechanical Engineering}, number = {2}, publisher = {American Society of Mechanical Engineers, ASME}, doi = {10.1115/1.4052115}, pages = {8}, abstract = {Regarding the prevention of injuries and rehabilitation of the human hand, musculoskeletal simulations using an inverse dynamics approach allow for insights of the muscle recruitment and thus acting forces on the hand. Currently, several hand models from various research groups are in use, which are mainly validated by the comparison of numerical and anatomical moment arms. In contrast to this validation and model-building technique by cadaver studies, the aim of this study is to further validate a recently published hand model [1] by analyzing numerically calculated muscle activities in comparison to experimentally measured electromyographical signals of the muscles. Therefore, the electromyographical signals of 10 hand muscles of five test subjects performing seven different hand movements were measured. The kinematics of these tasks were used as input for the hand model, and the numerical muscle activities were computed. To analyze the relationship between simulated and measured activities, the time difference of the muscle on- and off-set points was calculated, which resulted in a mean on- and off-set time difference of 0.58 s between the experimental data and the model. The largest differences were detected for movements that mainly addressed the wrist. One major issue comparing simulated and measured muscle activities of the hand is cross-talk. Nevertheless, the results show that the hand model fits the experiment quite accurately despite some limitations and is a further step toward patient-specific modeling of the upper extremity.}, subject = {Elektromyographie}, language = {en} } @article{AuerKurbowitschSuessetal., author = {Auer, Simon and Kurbowitsch, Simone and S{\"u}ß, Franz and Renkawitz, Tobias and Krutsch, Werner and Dendorfer, Sebastian}, title = {Mental stress reduces performance and changes musculoskeletal loading in football-related movements}, series = {Science and Medicine in Football}, volume = {5}, journal = {Science and Medicine in Football}, number = {4}, publisher = {Taylor \& Francis}, doi = {10.1080/24733938.2020.1860253}, pages = {323 -- 329}, abstract = {Purpose: Football players have a high risk of leg muscle injuries, especially when exposed to mental stress. Hence, this study investigated the musculoskeletal response of elite youth football players during highly dynamic movements under stress. The hypothesis is that mental stress reduces performance and changes the muscular forces exerted. Materials \& methods: Twelve elite youth football players were subjected to mental stress while performing sports-specific change-of-direction movements. A modified version of the d2 attention test was used as stressor. The kinetics are computed using inverse dynamics. Running times and exerted forces of injury-prone muscles were analysed. Results: The stressor runs were rated more mentally demanding by the players (p = 0.006, rs = 0.37) with unchanged physical demand (p = 0.777, rs = 0.45). This resulted in 10\% longer running times under stress (p < 0.001, d = -1.62). The musculoskeletal analysis revealed higher peak muscle forces under mental stress for some players but not for others. Discussion: The study shows that motion capture combined with musculoskeletal computation is suitable to analyse the effects of stress on athletes in highly dynamic movements. For the first time in football medicine, our data quantifies an association between mental stress with reduced football players' performance and changes in muscle force.}, language = {en} } @article{EngelhardtMelznerHavelkovaetal., author = {Engelhardt, Lucas and Melzner, Maximilian and Havelkova, Linda and Fiala, Pavel and Christen, Patrik and Dendorfer, Sebastian and Simon, Ulrich}, title = {A new musculoskeletal AnyBodyTM detailed hand model}, series = {Computer Methods in Biomechanics and Biomedical Engineering}, volume = {24}, journal = {Computer Methods in Biomechanics and Biomedical Engineering}, number = {7}, publisher = {Taylor \& Francis}, doi = {10.1080/10255842.2020.1851367}, pages = {777 -- 787}, abstract = {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.}, language = {en} } @article{SaffertMelznerDendorfer, author = {Saffert, Anne-Sophie and Melzner, Maximilian and Dendorfer, Sebastian}, title = {Biomechanical analysis of the right elevated glenohumeral joint in violinists during legato-playing}, series = {Technology and Health Care}, volume = {30}, journal = {Technology and Health Care}, number = {1}, publisher = {IOS Press}, doi = {10.3233/THC-219001}, pages = {177 -- 186}, abstract = {BACKGROUND: Many statistics reveal that violin players suffer most often from musculoskeletal disorders compared to musicians of other instrument groups. A common phenomenon, especially observed in violin beginners, is the tendency to elevate the right shoulder during playing the violin. This can probably lead to serious disorders in long-term practice with repetitive movements. OBJECTIVE: For this reason, this study investigated the relationship between the right shoulder elevation and the force in the right glenohumeral joint during violin playing. It was hypothesized that the forces in the right glenohumeral joint are higher during playing with the right shoulder raised compared to playing in normal posture. METHODS: Motion capture data from four experienced violinists was recorded and processed by means of musculoskeletal simulation to get the force and elevation angle while playing with raised shoulder and in normal position. RESULTS: The results indicate that the absolute values of the resulting force, as well as the forces in the mediolateral, inferosuperior, and anteroposterior directions, are higher in playing the violin with the shoulder raised than in a normal posture. CONCLUSIONS: Elevating the right shoulder while playing the violin may pose a potential problem.}, subject = {Biomechanische Analyse}, language = {en} } @article{AuerSuessDendorfer, author = {Auer, Simon and S{\"u}ß, Franz and Dendorfer, Sebastian}, title = {Using markerless motion capture and musculoskeletal models: An evaluation of joint kinematics}, series = {Technology and Health Care}, journal = {Technology and Health Care}, publisher = {IOS Press}, issn = {0928-7329}, doi = {10.3233/THC-240202}, pages = {1 -- 10}, abstract = {BACKGROUND: This study presents a comprehensive comparison between a marker-based motion capture system (MMC) and a video-based motion capture system (VMC) in the context of kinematic analysis using musculoskeletal models. OBJECTIVE: Focusing on joint angles, the study aimed to evaluate the accuracy of VMC as a viable alternative for biomechanical research. METHODS: Eighteen healthy subjects performed isolated movements with 17 joint degrees of freedom, and their kinematic data were collected using both an MMC and a VMC setup. The kinematic data were entered into the AnyBody Modelling System, which enables the calculation of joint angles. The mean absolute error (MAE) was calculated to quantify the deviations between the two systems. RESULTS: The results showed good agreement between VMC and MMC at several joint angles. In particular, the shoulder, hip and knee joints showed small deviations in kinematics with MAE values of 4.8∘, 6.8∘ and 3.5∘, respectively. However, the study revealed problems in tracking hand and elbow movements, resulting in higher MAE values of 13.7∘ and 27.7∘. Deviations were also higher for head and thoracic movements. CONCLUSION: Overall, VMC showed promising results for lower body and shoulder kinematics. However, the tracking of the wrist and pelvis still needs to be refined. The research results provide a basis for further investigations that promote the fusion of VMC and musculoskeletal models.}, language = {en} } @misc{Dendorfer, author = {Dendorfer, Sebastian}, title = {The influence of modeling parameters in the AnyBody Modeling System on muscle and joint loading in the shoulder}, series = {International Shoulder Group Meeting}, volume = {05}, journal = {International Shoulder Group Meeting}, language = {en} } @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{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{SuessKubowitschVerkerkeetal., author = {S{\"u}ß, Franz and Kubowitsch, Simone and Verkerke, Gijsbertus Jacob and Dendorfer, Sebastian}, title = {The influence of mental stress on spinal disc loading and muscle activity}, series = {23th Congress of the European Society of Biomechanics, Sevilla, Spain, 2017}, booktitle = {23th Congress of the European Society of Biomechanics, Sevilla, Spain, 2017}, language = {en} } @inproceedings{PillingSuessKubowitschetal., author = {Pilling, A. and S{\"u}ß, Franz and Kubowitsch, Simone and Dendorfer, Sebastian}, title = {Experimental workflow for determining psychological stress from physiological biosignals}, series = {Jahrestagung der BIOMEDIZINISCHEN TECHNIK und Dreil{\"a}ndertagung der MEDIZINISCHEN PHYSIK, Dresden, Germany, 2017}, booktitle = {Jahrestagung der BIOMEDIZINISCHEN TECHNIK und Dreil{\"a}ndertagung der MEDIZINISCHEN PHYSIK, Dresden, Germany, 2017}, language = {en} } @inproceedings{GrossVerkerkeDendorfer, author = {Gross, Simon and Verkerke, Gijsbertus Jacob and Dendorfer, Sebastian}, title = {Investigation of external load dependent static and dynamic muscle fatigue}, series = {23th Congress of the European Society of Biomechanics, Sevilla, Spain, 2017}, booktitle = {23th Congress of the European Society of Biomechanics, Sevilla, Spain, 2017}, language = {en} } @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} } @misc{Dendorfer, author = {Dendorfer, Sebastian}, title = {The influence of mental stress on the musculoskeletal system}, language = {en} } @inproceedings{WeberRenkawitzGrifkaetal., author = {Weber, Tim and Renkawitz, Tobias and Grifka, Joachim and Bulstra, Sjoerd K. and Verkerke, Gijsbertus Jacob and Dendorfer, Sebastian}, title = {The musculoskeletal load scenario of computer-assisted Femur-First THR up to one year after surgery}, series = {VI International Conference on Computational Bioengineering, Barcelona, Sept. 2015}, booktitle = {VI International Conference on Computational Bioengineering, Barcelona, Sept. 2015}, language = {en} } @inproceedings{GrossSuessVerkerkeetal., author = {Gross, Simon and S{\"u}ß, Franz and Verkerke, Gijsbertus Jacob and Dendorfer, Sebastian}, title = {Simulating fatigue in musculoskeletal models using surface electromyography, ECCOMAS Congress, Crete, Greece, 201}, series = {ECCOMAS Congress, Crete, Greece, 2016}, booktitle = {ECCOMAS Congress, Crete, Greece, 2016}, language = {en} } @inproceedings{KubowitschSuessJansenetal., author = {Kubowitsch, Simone and S{\"u}ß, Franz and Jansen, Petra and Dendorfer, Sebastian}, title = {Muscular imbalances during experimentally induced stress}, series = {23th Congress of the European Society of Biomechanics, Sevilla, Spain, 2017}, booktitle = {23th Congress of the European Society of Biomechanics, Sevilla, Spain, 2017}, language = {en} } @inproceedings{SuessKubowitschVerkerkeetal., author = {S{\"u}ß, Franz and Kubowitsch, Simone and Verkerke, Gijsbertus Jacob and Dendorfer, Sebastian}, title = {The influence of stress on spinal loading}, series = {ESEM webconference, Dez. 2017}, booktitle = {ESEM webconference, Dez. 2017}, language = {en} } @inproceedings{DendorferKubowitsch, author = {Dendorfer, Sebastian and Kubowitsch, Simone}, title = {The interaction of mental stress and biomechanics}, series = {Health Technology Triangle, Weiden, 2016}, booktitle = {Health Technology Triangle, Weiden, 2016}, language = {en} } @inproceedings{WeberRenkawitzBulstraetal., author = {Weber, Tim and Renkawitz, Tobias and Bulstra, Sjoerd K. and Grifka, Joachim and Verkerke, Gijsbertus Jacob and Dendorfer, Sebastian}, title = {Biomechanics of computer-assisted vs. conventional THR after one year follow up}, series = {XXV Congress of the International Society of Biomechanics, Glasgow, UK, 12th-16th July 2015}, booktitle = {XXV Congress of the International Society of Biomechanics, Glasgow, UK, 12th-16th July 2015}, language = {en} } @inproceedings{IgnasiakDendorferFerguson, author = {Ignasiak, Dominika and Dendorfer, Sebastian and Ferguson, Stephen J.}, title = {Thoracolumbar spine model with articulated rigcage for the prediction of dynamic spinal loading}, series = {International Workshop on Spine Loading and Deformation: From Loading to Recovery, 2-4 July 2015, Julius Wolff Institute, Charit{\´e}-Universitatsmedizin Berlin, Germany}, booktitle = {International Workshop on Spine Loading and Deformation: From Loading to Recovery, 2-4 July 2015, Julius Wolff Institute, Charit{\´e}-Universitatsmedizin Berlin, Germany}, language = {en} } @inproceedings{WeberDendorferBulstraetal., author = {Weber, Tim and Dendorfer, Sebastian and Bulstra, Sjoerd K. and Grifka, Joachim and Verkerke, Gijsbertus Jacob and Renkawitz, Tim}, title = {Navigated Femur First Total Hip Arthroplasty leads to improved Biomechanical Outcome after surgery}, series = {ORS annual meeting, Las Vegas, USA, 2015}, booktitle = {ORS annual meeting, Las Vegas, USA, 2015}, language = {en} } @inproceedings{PenzkoferGrechenigKujatetal., author = {Penzkofer, Rainer and Grechenig, S. and Kujat, Richard and Angele, Peter and Dendorfer, Sebastian}, title = {Biomechanical comparison of the dorsal femur condyles and the iliac crest in terms of failure behavior}, series = {XXV Congress of the International Society of Biomechanics, Glasgow, UK, 12th-16th July 2015}, booktitle = {XXV Congress of the International Society of Biomechanics, Glasgow, UK, 12th-16th July 2015}, language = {en} } @inproceedings{WeberDendorferBulstraetal., author = {Weber, Tim and Dendorfer, Sebastian and Bulstra, Sjoerd K. and Verkerke, Gijsbertus Jacob and Renkawitz, Tobias}, title = {Musculoskeletal modeling for orthopedic surgery - Applications and chances}, series = {Orthopedics meets Engineering, Regensburg, 2015}, booktitle = {Orthopedics meets Engineering, Regensburg, 2015}, language = {en} } @inproceedings{PutzerDendorfer, author = {Putzer, Michael and Dendorfer, Sebastian}, title = {Sensitivity of lumbar spine loading to anatomical parameters}, series = {International Workshop on Spine Loading and Deformation: From Loading to Recovery, 2-4 July 2015, Julius Wolff Institute, Charit{\´e}-Universitatsmedizin Berlin, Germany}, booktitle = {International Workshop on Spine Loading and Deformation: From Loading to Recovery, 2-4 July 2015, Julius Wolff Institute, Charit{\´e}-Universitatsmedizin Berlin, Germany}, language = {en} } @inproceedings{Dendorfer, author = {Dendorfer, Sebastian}, title = {Mechanobiology - Impact on regeneration and degradation}, series = {Translations in Regenerative Medicine, TIRM and FIFA Symposium, Regensburg, 2015}, booktitle = {Translations in Regenerative Medicine, TIRM and FIFA Symposium, Regensburg, 2015}, language = {en} } @inproceedings{AlMunajjedNolteRasmussenetal., author = {Al-Munajjed, Amir Andreas and Nolte, Daniel and Rasmussen, John and Dendorfer, Sebastian}, title = {Force distribution in the foot during braking - a musculoskeletal approach}, series = {Human Modeling Symposium 2014, Munich, Germany}, booktitle = {Human Modeling Symposium 2014, Munich, Germany}, abstract = {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.}, language = {en} } @inproceedings{WeberDendorferBulstraetal., author = {Weber, Tim and Dendorfer, Sebastian and Bulstra, Sjoerd K. and Verkerke, Gijsbertus Jacob and Renkawitz, Tobias}, title = {Biomechanical Outcome after computer-assisted vs. Conventional THR}, series = {ANSYS Conference \& 32th CADFEM Users' Meeting 2014, 04.-06. Juni, N{\"u}rnberg}, booktitle = {ANSYS Conference \& 32th CADFEM Users' Meeting 2014, 04.-06. Juni, N{\"u}rnberg}, language = {en} } @inproceedings{StrieglKujatDendorfer, author = {Striegl, B. and Kujat, Richard and Dendorfer, Sebastian}, title = {Quantitative analysis of cartilage surface by confocal laser scanning microscopy}, series = {Biomedizinische Technik}, volume = {59}, booktitle = {Biomedizinische Technik}, number = {s1-A}, doi = {10.1515/bmt-2014-4012}, pages = {24}, language = {en} } @inproceedings{PutzerGalibarovDendorfer, author = {Putzer, Michael and Galibarov, Pavel E. and Dendorfer, Sebastian}, title = {Influence of vertebral parameters on lumbar spine loading}, series = {Pre-meeting SpineFX, Eurospine 2013, Liverpool, UK}, booktitle = {Pre-meeting SpineFX, Eurospine 2013, Liverpool, UK}, language = {en} } @article{WeberDullienGrifkaetal., author = {Weber, Tim and Dullien, Silvia and Grifka, Joachim and Renkawitz, Tobias and Dendorfer, Sebastian}, title = {Validation of a Motion Capture Laboratory and a new marker-placement protcol for clinical applications}, series = {Gait \& Posture}, volume = {38}, journal = {Gait \& Posture}, number = {Suppl. 1}, doi = {10.1016/j.gaitpost.2013.07.229}, pages = {113 -- 114}, language = {en} } @inproceedings{WeberDullienPutzeretal., author = {Weber, Tim and Dullien, Silvia and Putzer, Michael and Dendorfer, Sebastian and Renkawitz, Tobias}, title = {Biomechanical outcome after computer-assisted vs. conventional THR - study concept and preliminary gait analysis results}, series = {GAMMA Workshop, Hannover, 2012}, booktitle = {GAMMA Workshop, Hannover, 2012}, language = {en} } @inproceedings{WeberDendorferRenkawitzetal., author = {Weber, Tim and Dendorfer, Sebastian and Renkawitz, Tobias and Dullien, Silvia and Grifka, Joachim}, title = {Clinical gait analysis combined with musculoskeletal modelling - coding a new generation of evaluation instruments}, series = {Deutsche Gesellschaft f{\"u}r Biomechanik, Murnau, 2011}, booktitle = {Deutsche Gesellschaft f{\"u}r Biomechanik, Murnau, 2011}, language = {en} } @inproceedings{SpreiterGalibarovDendorferetal., author = {Spreiter, G. and Galibarov, Pavel E. and Dendorfer, Sebastian and Ferguson, Stephen J.}, title = {Influence of kyphosis on spinal loading}, series = {10th International Symposium Computer Methods in Biomechanics and Biomedical Engineering (CMBBE) Meeting, 11. - 14. April 2012, Berlin}, booktitle = {10th International Symposium Computer Methods in Biomechanics and Biomedical Engineering (CMBBE) Meeting, 11. - 14. April 2012, Berlin}, language = {en} } @inproceedings{PutzerWeberDendorfer, author = {Putzer, Michael and Weber, Tim and Dendorfer, Sebastian}, title = {Design studies on hip prosthesis using patient specific data}, series = {Simpleware Users meeting, November 9th 2011, Bristol, UK}, booktitle = {Simpleware Users meeting, November 9th 2011, Bristol, UK}, language = {en} } @inproceedings{Dendorfer, author = {Dendorfer, Sebastian}, title = {The effect of multifidus muscles atrophy following disc herniation on disc loading}, series = {Deutsche Gesellschaft f{\"u}r Biomechanik, Murnau, 2011}, booktitle = {Deutsche Gesellschaft f{\"u}r Biomechanik, Murnau, 2011}, language = {en} } @inproceedings{GalibarovAlMunajjedDendorferetal., author = {Galibarov, Pavel E. and Al-Munajjed, Amir Andreas and Dendorfer, Sebastian and Christensen, Soeren Toerholm and Rasmussen, John}, title = {The effect of varying the stiffness of spinal fusion devices on the adjacent levels using multibody dynamics simulation}, series = {Orthopaedic Proceedings}, volume = {94-B}, booktitle = {Orthopaedic Proceedings}, number = {SUPP_XL01 Sep 2012}, pages = {2}, abstract = {INTRODUCTION Several clinical studies demonstrated long-term adjacent-level effects after implantation of spinal fusion devices[1]. These effects have been reported as adjacent joint degeneration and the development of new symptoms correlating with adjacent segment degeneration[2] and the trend has therefore gone to motion preservation devices; however, these effects have not been understood very well and have not been investigated thoroughly[3]. The aim of this study is to investigate the effect of varying the stiffness of spinal fusion devices on the adjacent vertebral levels. Disc forces, moments and facet joint forces were analyzed. METHODS The AnyBody Modeling System was used to compute the in-vivo muscle and joint reaction forces of a musculoskeletal model. The full body model used in this study consists of 188 muscle fascicles in the lumbar spine and more than 1000 individual muscle branches in total. The model has been proposed by de Zee et al.[3], validated by Rasmussen et al.[4] and by Galibarov et al.[5]. The new model[5] determines the individual motions between vertebrae based on the equilibrium between forces acting on the vertebrae from muscles and joints and the passive stiffness in disks and ligaments, figure 1a. An adult of 1.75 m and 75 kg with a spinal implant in L4L5 was modeled. This model was subjected to a flexion-extension motion using different elastic moduli to analyze and compare to a non-implanted scenario. The analyzed variables were vertebral motion, the disc reaction forces and moments, as well as facet joint forces in the treated and the adjacent levels: L2L3, L3L4, L4L5 and L5-Sacrum. RESULTS When introducing a spinal fusion device in the L4L5 joint the reaction forces and moments decreased in this joint with stiffer devices leading to lower joint loads. However, in the adjacent joints, L3L4 and L5Sacrum, an increase was observed when implanting stiffer devices. Similar trends could be found for the L2L3 joint. The loads in the facet joints showed the same trends. While introducing a spinal fusion device reduced the facet joint forces in the treated joint, the loads in the adjacent facet joints were increased according to the stiffness of the implanted device, figure 1b. DISCUSSION While the treated disc joint showed reduced motion and loads, the adjacent levels demonstrated a significant increase. In particular, the increased facet joint forces in the adjacent levels can lead to adjacent level facet pain or accelerated facet joint degeneration. Introducing a device resulted in preventing facet contact and therefore facet joint loads, even using the device with the lowest stiffness. CONCLUSION The presented model shows that clinical complications such as facet joint degeneration in adjacent levels after implantation of spinal fusion device are consistent with the change in the mechanical-stimulus distribution in the system.}, language = {en} } @inproceedings{GalibarovDendorferChristensen, author = {Galibarov, Pavel E. and Dendorfer, Sebastian and Christensen, Soeren Toerholm}, title = {On modelling spine curvature dependent on muscular and external forces in multibody dynamics system}, series = {International Society of Biomechanics (ISB), 13th congress, 2011, Brussels, Belgium}, booktitle = {International Society of Biomechanics (ISB), 13th congress, 2011, Brussels, Belgium}, pages = {2}, abstract = {This paper presents a computational approach for investigating effect of muscular and external forces on curvature of the lumbar spine. Multibody dynamics system is used to compute the lumbar spine curvature using a force-dependent kinematics facility, e.g. this method allows releasing some degrees of freedom in order to be computed based on the current load configuration.}, language = {en} } @inproceedings{RasmussenBichlerChristensenetal., author = {Rasmussen, John and Bichler, R. and Christensen, Soeren Toerholm and Wirix-Speetjens, Roel and Dendorfer, Sebastian and Renkawitz, Tobias}, title = {Subject-specific Musculoskeletal Simulation of Hip Dislocation Risk in Activities of Daily Living}, series = {Proceedings of the 2011 ORS Annual Meeting, Long Beach, CA.}, booktitle = {Proceedings of the 2011 ORS Annual Meeting, Long Beach, CA.}, number = {Paper No. 306}, language = {en} } @inproceedings{RobieDendorferRasmussenetal., author = {Robie, Bruce and Dendorfer, Sebastian and Rasmussen, John and Christensen, Soeren Toerholm}, title = {Axial Rotation Requires Greatest Load in Multifidus Muscle - Potential Association with Low Back Pain?}, series = {Annual Meeting of the AANS/CNS Section on Disorders of the Spine and Peripheral Nerves, 2011, Phoenix, Arizona}, booktitle = {Annual Meeting of the AANS/CNS Section on Disorders of the Spine and Peripheral Nerves, 2011, Phoenix, Arizona}, language = {en} } @inproceedings{DendorferRasmussenChristensenetal., author = {Dendorfer, Sebastian and Rasmussen, John and Christensen, Soeren Toerholm and Robie, Bruce}, title = {The Effect of Spinal Disc Herniation on Multifidus Muscles}, series = {56th Orthopaedic Research Society Meeting, New Orleans, USA, 2010}, booktitle = {56th Orthopaedic Research Society Meeting, New Orleans, USA, 2010}, language = {en} } @inproceedings{GalibarovDendorferRasmussen, author = {Galibarov, Pavel E. and Dendorfer, Sebastian and Rasmussen, John}, title = {Two Computational Models of the Lumbar Spine:}, series = {Proceedings of the 2011 ORS Annual Meeting, Long Beach, CA, vol. Marie Curie Initial Training Network "SpineFX"}, booktitle = {Proceedings of the 2011 ORS Annual Meeting, Long Beach, CA, vol. Marie Curie Initial Training Network "SpineFX"}, language = {en} } @inproceedings{HornerDendorferKiisetal., author = {Horner, Marc and Dendorfer, Sebastian and Kiis, Arne and Lawrenchuk, Mike and Verma, Gunjan}, title = {A Patient based simulation workflow for orthopedic device design and analysis}, series = {SBC Ortho Workshop, June 2011}, booktitle = {SBC Ortho Workshop, June 2011}, language = {en} } @inproceedings{AndersendeZeeDendorferetal., author = {Andersen, Michael Skipper and de Zee, Mark and Dendorfer, Sebastian and MacWilliams, Bruce and Rasmussen, John}, title = {Validation of a detailed lower extremity model based on the Klein Horsman data set}, series = {Proceedings of the 12th International Symposium on Computer Simulation in Biomechanics (ISB 2009), July 2nd - 4th 2009, Cape Town, South Africa}, booktitle = {Proceedings of the 12th International Symposium on Computer Simulation in Biomechanics (ISB 2009), July 2nd - 4th 2009, Cape Town, South Africa}, pages = {27 -- 28}, language = {en} } @inproceedings{RobieRasmussenChristensenetal., author = {Robie, Bruce and Rasmussen, John and Christensen, Soeren Toerholm and Dendorfer, Sebastian}, title = {Herniation Induces 55\% Increase in Load of Key Stabilizing Muscle - Impact on Herniation Treatment Devices?}, series = {Spine Arthoplasty Society Meeting, New Orleans, 2010}, booktitle = {Spine Arthoplasty Society Meeting, New Orleans, 2010}, language = {en} } @inproceedings{DendorferCarbesRasmussen, author = {Dendorfer, Sebastian and Carbes, S. and Rasmussen, John}, title = {The influence of muscle forces on biomechanical fracture fixation simulations - from in-vivo forces to tissue strains}, series = {World Congress on Medical Physics and Biomedical Engineering, 7 - 12, 2009, Munich}, booktitle = {World Congress on Medical Physics and Biomedical Engineering, 7 - 12, 2009, Munich}, language = {en} } @inproceedings{DendorferRasmussen, author = {Dendorfer, Sebastian and Rasmussen, John}, title = {The influence of in-vivo muscle forces on the stress distribution in a vertebral body during activities of daily living}, series = {Eurospine Warsaw, Poland 2009}, booktitle = {Eurospine Warsaw, Poland 2009}, language = {en} } @inproceedings{Dendorfer, author = {Dendorfer, Sebastian}, title = {How much iron to pump? The determination of muscle forces for activities of daily living}, series = {DGU, Berlin, 2008}, booktitle = {DGU, Berlin, 2008}, language = {en} } @misc{GschossmannDendorfer, author = {Gschoßmann, Lukas and Dendorfer, Sebastian}, title = {Personalized Rehabilitation after Total Knee Arthroplasty}, series = {32nd Annual Meeting of the European Orthopaedic Research Society (EORS 2024), 18 - 20 September 2024, Aalborg}, journal = {32nd Annual Meeting of the European Orthopaedic Research Society (EORS 2024), 18 - 20 September 2024, Aalborg}, language = {en} }