TY - JOUR A1 - Belyaeva, Inna A. A1 - Kramarenko, Elena Yu A1 - Stepanov, Gennady V. A1 - Sorokin, Vladislav V. A1 - Stadler, Dominik A1 - Shamonin (Chamonine), Mikhail T1 - Transient magnetorheological response of magnetoactive elastomers to step and pyramid excitations JF - SOFT MATTER N2 - Transient rheological response of magnetoactive elastomers is experimentally studied using dynamic torsion at a fixed oscillation frequency in temporally stepwise changing magnetic fields and oscillation amplitudes. For step magnetic-field excitations, at least three exponential functions are required to reasonably describe the time behavior of the storage shear modulus over long time scales (>10(3) s). The deduced characteristic time constants of the corresponding rearrangement processes of the filler network differ approximately by one order of magnitude: tau(1) less than or similar to 10(1) s, tau(2) similar to 10(2) s, and tau(3) similar to 10(3) s. The sudden imposition of the external magnetic field activates a very fast rearrangement process with the characteristic time under 10 s, which cannot be determined more precisely due to the measurement conditions. Even more peculiar transient behavior has been observed during pyramid excitations, when either the external magnetic field was first stepwise increased and then decreased in a staircase manner at a fixed strain amplitude gamma or the strain amplitude gamma was first stepwise increased and then decreased in a staircase manner at a fixed magnetic field. In particular, the so-called "cross-over effect'' has been identified in both dynamical loading programs. This cross-over effect seems to be promoted by the application of the external magnetic field. The experimental results are discussed in the context of the specific rearrangement of the magnetic filler network under the simultaneous action of the external magnetic field and shear deformation. Striking similarities of the observed phenomena to the structural relaxation processes in glassy materials and to the jamming transition of granular materials are pointed out. The obtained results are important for fundamental understanding of material behavior in magnetic fields as well as for the development of devices on the basis of magnetoactive elastomeric materials. KW - AMPLITUDE KW - BEHAVIOR KW - DEPENDENCE KW - FLUID KW - HOMOGENEOUS MAGNETIC-FIELD KW - NORMAL FORCE KW - OSCILLATORY SHEAR KW - TIME KW - VISCOELASTIC PROPERTIES Y1 - 2016 U6 - https://doi.org/10.1039/c5sm02690c VL - 12 IS - 11 SP - 2901 EP - 2913 PB - ROYAL SOC CHEMISTRY ER - TY - CHAP A1 - Dendorfer, Sebastian A1 - Feldotto, Benedikt A1 - Walch, Blasius A1 - Koch, Patrick A1 - Knoll, Alois T1 - Co-Development of an Infant Prototype in Hardware and Simulation based on CT Imaging Data T2 - IEEE International Conference on Cyborg and Bionic Systems (CBS), 2019, Munich N2 - 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. KW - Biomechanische Analyse KW - Robotik KW - Computertomographie KW - 3D-Druck Y1 - 2019 UR - http://mediatum.ub.tum.de/doc/1520042/985669104579.pdf ER - TY - JOUR A1 - Weber, Tim A. A1 - Dendorfer, Sebastian A1 - Bulstra, Sjoerd K. A1 - Grifka, Joachim A1 - Verkerke, Gijsbertus Jacob A1 - Renkawitz, Tobias T1 - 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 JF - Gait & Posture N2 - 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. KW - Biomechanics KW - Combined anteversion KW - Computer-assisted surgery KW - Femur first KW - Gait analysis Y1 - 2016 U6 - https://doi.org/10.1016/j.gaitpost.2016.06.035 VL - vol. 49 SP - 418 EP - 425 ER - TY - JOUR A1 - Renkawitz, Tobias A1 - Weber, Tim A. A1 - Dullien, Silvia A1 - Woerner, Michael A1 - Dendorfer, Sebastian A1 - Grifka, Joachim A1 - Weber, Markus T1 - Leg length and offset differences above 5 mm after total hip arthroplasty are associated with altered gait kinematics JF - Gait & Posture N2 - We aimed to investigate the relationship between postoperative leg length/offset (LL/OS) reconstruction and gait performance after total hip arthroplasty (THA). In the course of a prospective randomized controlled trial, 60 patients with unilateral hip arthrosis received cementless THA through a minimally-invasive anterolateral surgical approach. One year post-operatively, LL and global OS restoration were analyzed and compared to the contralateral hip on AP pelvic radiographs. The combined postoperative limb length/OS reconstruction of the operated hip was categorized as restored (within 5 mm) or non-restored (more than 5 mm reduction or more than 5 mm increment). The acetabular component inclination, anteversion and femoral component anteversion were evaluated using CT scans of the pelvis and the femur. 3D gait analysis of the lower extremity and patient related outcome measures (HHS, HOOS, EQ-5D) were obtained pre-operatively, six months and twelve months post-operatively by an observer blinded to radiographic results. Component position of cup and stem was comparable between the restored and non-restored group. Combined LL and OS restoration within 5 mm resulted in higher Froude number (p < 0.001), normalized walking speed (p < 0.001) and hip range-of-motion (ROM) (p = 0.004) during gait twelve months postoperatively, whereas gait symmetry was comparable regardless of LL and OS reconstruction at both examinations. Clinical scores did not show any relevant association between the accuracy of LL or OS reconstruction and gait six/twelve months after THA. In summary, postoperative LL/OS discrepancies larger than 5 mm relate to unphysiological gait kinematics within the first year after THA. DRKS00000739, German Clinical Trials Register. KW - THA KW - Leg length KW - Offset KW - Gait analysis KW - Biomechanics Y1 - 2016 U6 - https://doi.org/10.1016/j.gaitpost.2016.07.011 VL - vol. 49 SP - 196 EP - 201 ER - TY - JOUR A1 - Ignasiak, Dominika A1 - Dendorfer, Sebastian A1 - Ferguson, Stephen J. T1 - Thoracolumbar spine model with articulated ribcage for the prediction of dynamic spinal loading JF - Journal of Biomechanics N2 - Musculoskeletal modeling offers an invaluable insight into the spine biomechanics. A better understanding of thoracic spine kinetics is essential for understanding disease processes and developing new prevention and treatment methods. Current models of the thoracic region are not designed for segmental load estimation, or do not include the complex construct of the ribcage, despite its potentially important role in load transmission. In this paper, we describe a numerical musculoskeletal model of the thoracolumbar spine with articulated ribcage, modeled as a system of individual vertebral segments, elastic elements and thoracic muscles, based on a previously established lumbar spine model and data from the literature. The inverse dynamics simulations of the model allow the prediction of spinal loading as well as costal joints kinetics and kinematics. The intradiscal pressure predicted by the model correlated well (R2=0.89) with reported intradiscal pressure measurements, providing a first validation of the model. The inclusion of the ribcage did not affect segmental force predictions when the thoracic spine did not perform motion. During thoracic motion tasks, the ribcage had an important influence on the predicted compressive forces and muscle activation patterns. The compressive forces were reduced by up to 32%, or distributed more evenly between thoracic vertebrae, when compared to the predictions of the model without ribcage, for mild thoracic flexion and hyperextension tasks, respectively. The presented musculoskeletal model provides a tool for investigating thoracic spine loading and load sharing between vertebral column and ribcage during dynamic activities. Further validation for specific applications is still necessary. KW - Inverse dynamics KW - Musculoskeletal model KW - Thoracolumbar spine KW - Brustwirbelsäule KW - Brustkorb KW - Biomechanik KW - Mechanische Belastung KW - Prognose Y1 - 2016 U6 - https://doi.org/10.1016/j.jbiomech.2015.10.010 VL - vol. 49 IS - 6 SP - 959 EP - 966 PB - Elsevier Science ER - TY - JOUR A1 - Hölscher, Thomas A1 - Weber, Tim A. A1 - Lazarev, Igor A1 - Englert, Carsten A1 - Dendorfer, Sebastian T1 - The influence of rotator cuff tears on glenohumeral stability during abduction tasks JF - Journal of Orthopaedic Research N2 - One of the main goals in reconstructing rotator cuff tears is the restoration of glenohumeral joint stability, which is subsequently of utmost importance in order to prevent degenerative damage such as superior labral anterior posterior (SLAP) lesion, arthrosis, and malfunction. The goal of the current study was to facilitate musculoskeletal models in order to estimate glenohumeral instability introduced by muscle weakness due to cuff lesions. Inverse dynamics simulations were used to compute joint reaction forces for several static abduction tasks with different muscle weakness. Results were compared with the existing literature in order to ensure the model validity. Further arm positions taken from activities of daily living, requiring the rotator cuff muscles were modeled and their contribution to joint kinetics computed. Weakness of the superior rotator cuff muscles (supraspinatus; infraspinatus) leads to a deviation of the joint reaction force to the cranial dorsal rim of the glenoid. Massive rotator cuff defects showed higher potential for glenohumeral instability in contrast to single muscle ruptures. The teres minor muscle seems to substitute lost joint torque during several simulated muscle tears to maintain joint stability. Joint instability increases with cuff tear size. Weakness of the upper part of the rotator cuff leads to a joint reaction force closer to the upper glenoid rim. This indicates the comorbidity of cuff tears with SLAP lesions. The teres minor is crucial for maintaining joint stability in case of massive cuff defects and should be uprated in clinical decision-making. KW - Abduction tasks KW - Glenohumeral stability KW - Musculoskeletal Modeling KW - Muscle weakness KW - Rotator cuff tears KW - Rotatorenmanschettenriss KW - Schultergelenk KW - Stabilität Y1 - 2016 U6 - https://doi.org/10.1002/jor.23161 VL - 34 IS - 9 SP - 1628 EP - 1635 ER - TY - CHAP A1 - Auer, Simon A1 - Kubowitsch, Simone A1 - Krutsch, Werner A1 - Renkawitz, Tobias A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Effect of mental demand on knee forces in professional youth soccer players T2 - ISBS Proceedings Archive N2 - 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. KW - Kniegelenk KW - Körperliche Belastung KW - Stress KW - Computersimulation Y1 - 2020 UR - https://commons.nmu.edu/isbs/vol38/iss1/28 VL - 38 IS - 1, Art. 28 ER - TY - JOUR A1 - Dendorfer, Sebastian T1 - Älterwerden muss auch mal wehtun! JF - Gesunde Hochschule, OTH Regensburg, 4.7.2016 Y1 - 2016 ER - TY - JOUR A1 - Putzer, Michael A1 - Auer, Stefan A1 - Malpica, William A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - A numerical study to determine the effect of ligament stiffness on kinematics of the lumbar spine during flexion JF - BMC Musculoskeletal Disorders N2 - 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. KW - Lumbar spine KW - Ligament stiffness KW - Musculoskeletal Modeling KW - Biomechanics Y1 - 2016 U6 - https://doi.org/10.1186/s12891-016-0942-x VL - 17 IS - 95 ER - TY - JOUR A1 - Aurbach, Maximilian A1 - Špička, Jan A1 - Süß, Franz A1 - Vychytil, J. A1 - Havelková, Leonard A1 - Ryba, T. A1 - Dendorfer, Sebastian T1 - Torus obstacle method as a wrapping approach of the deltoid muscle group for humeral abduction in musculoskeletal simulation JF - Journal of Biomechanics N2 - Musculoskeletal models of the shoulder complex are valuable research aids to investigate tears of the supraspinatus and the resulting mechanical impact during abduction of the humerus. One of the major contributors to this motion is the deltoid muscle group and for this, an accurate modeling of the lines of action is indispensable. The aim of this work was to utilize a torus obstacle wrapping approach for the deltoids of an existing shoulder model and assess the feasibility of the approach during humeral abduction. The shoulder model from the AnyBody™ modeling system was used as a platform. The size of the tori is based on a magnetic resonance imaging (MRI) approach and several kinematic couplings are implemented to determine the trajectories of the tori during abduction. To assess the model behavior, the moment arms of the virtual muscle elements and the resultant glenohumeral joint reaction force (GHJF) were compared with reference data from the literature during abduction of the humerus in the range 20°–120°. The root mean square error for the anterior, lateral and posterior part between the simulated muscle elements and reference data from the literature was 3.9, 1.7 and 5.8 mm, respectively. The largest deviation occurred on the outer elements of the muscle groups, with 12.6, 10.4 and 20.5 mm, respectively. During abduction, there is no overlapping of the muscle elements and these are in continuous contact with the torus obstacles, thus enabling a continuous force transmission. This results in a rising trend of the resultant GHJF. The torus obstacle approach as a wrapping method for the deltoid muscles provides a guided muscle pathing by simultaneously approximating the curvature of the deltoid muscle. The results from the comparison of the simulated moment arms and the resultant GHJF are in accordance with those in the literature in the range 20°–120° of abduction. Although this study shows the strength of the torus obstacle as a wrapping approach, the method of fitting the tori according to MRI data was not suitable. A cadaver study is recommended to better validate and mathematically describe the torus approach. KW - Muscoloskeletal model KW - AnyBody Modeling System KW - MRI KW - Shoulder joint complex KW - Muscle trajectory KW - Torus KW - Wrapping Y1 - 2020 U6 - https://doi.org/10.1016/j.jbiomech.2020.109864 VL - 109 IS - August PB - Elsevier ER - TY - JOUR A1 - Aurbach, Maximilian A1 - Spicka, Jan A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Evaluation of musculoskeletal modelling parameters of the shoulder complex during humeral abduction above 90° JF - Journal of Biomechanics N2 - 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. KW - Shoulder joint KW - Musculoskeletal modelling KW - EMG KW - Glenohumeral joint reaction force KW - Muscle model KW - Schultergelenk KW - Bewegungsapparat KW - Biomechanik KW - Simulation Y1 - 2020 U6 - https://doi.org/10.1016/j.jbiomech.2020.109817 VL - 106 IS - June PB - Elsevier ER - TY - JOUR A1 - Schmitz, Paul A1 - Neumann, Christoph Cornelius A1 - Neumann, Carsten A1 - Nerlich, Michael A1 - Dendorfer, Sebastian T1 - Biomechanical analysis of iliac crest loading following cortico-cancellous bone harvesting JF - Journal of Orthopaedic Surgery and Research N2 - 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. KW - Bone harvesting KW - Autologous bone graft KW - Iliac crest KW - Fatigue fracture KW - Pelvis KW - ASIS KW - FEA KW - Biomechanical investigation KW - Beckenkammknochen KW - Knochenentnahme KW - Spongiosa KW - Biomechanische Analyse Y1 - 2018 U6 - https://doi.org/10.1186/s13018-018-0822-1 VL - 13 IS - 108 SP - 1 EP - 8 PB - Springer Nature ER - TY - CHAP A1 - Horner, Marc A1 - Dendorfer, Sebastian A1 - Kiis, Arne A1 - Lawrenchuk, Mike A1 - Verma, Gunjan T1 - A Patient based simulation workflow for orthopedic device design and analysis T2 - SBC Ortho Workshop, June 2011 Y1 - 2011 ER - TY - CHAP A1 - Dendorfer, Sebastian T1 - The effect of multifidus muscles atrophy following disc herniation on disc loading T2 - Deutsche Gesellschaft für Biomechanik, Murnau, 2011 Y1 - 2011 ER - TY - GEN A1 - Melzner, Maximilian A1 - Ismail, Khaled A1 - Rušavý, Zdeněk A1 - Kališ, Vladimír A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Musculoskeletal Lower Back Load of Accoucheurs During Delivery T2 - 26th Congress of the European Society of Biomechanics, July 11-14, 2021, Milan, Italy N2 - 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. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-20208 CY - Milan ER - TY - CHAP A1 - Aurbach, Maximilian A1 - Jungtäubl, Dominik A1 - Spicka, Jan A1 - Dendorfer, Sebastian T1 - EMG-based validation of musculoskeletal models considering crosstalk T2 - World Congress Biomechanics, 28-30 June 2018, Dublin N2 - 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. Y1 - 2018 U6 - https://doi.org/10.1109/BIOMDLORE.2018.8467211 ER - TY - VIDEO A1 - Auer, Simon A1 - Reinker, Lukas A1 - Süß, Franz A1 - Kubowitsch, Simone A1 - Krutsch, Werner A1 - Weber, Markus A1 - Renkawitz, Tobias A1 - Dendorfer, Sebastian T1 - Webcast: Effect of mental demand on leg loading in highly dynamic motion N2 - 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. KW - Webcast KW - AnyBody KW - Stress KW - Football KW - Speedcourt Y1 - 2020 UR - https://www.youtube.com/watch?v=uSc_9XlnkaA ER - TY - GEN A1 - Englert, Carsten A1 - Dendorfer, Sebastian T1 - Einfluss der Rotatorenmanschette auf die glenohumerale Stabilität T2 - 20. Intensivkurs Schulterendoprothetik Marburg KW - Biomechanik Y1 - 2022 CY - Marburg ER - TY - GEN A1 - Dendorfer, Sebastian T1 - The influence of modeling parameters in the AnyBody Modeling System on muscle and joint loading in the shoulder T2 - International Shoulder Group Meeting Y1 - 2021 VL - 05 ER - TY - GEN A1 - Dendorfer, Sebastian T1 - Biomechanische Aspekte bei Sportverletzungen T2 - OT World Leipzig, Internationale Fachmesse und Weltkongress für Orthopädie und Rehatechnik, 10.-13. Mai 2022 Y1 - 2022 ER - TY - GEN A1 - Dendorfer, Sebastian T1 - KI-basierte mechanische Modelle für Prävention, Diagnostik und Rehabilitation T2 - Serien-Webmeeting zu AI - KI-basierte Bildanalyse zur computer-unterstützten Frakturerkennung, 09.11.22 Y1 - 2022 ER - TY - VIDEO A1 - Melzner, Maximilian A1 - Engelhardt, Lucas T1 - AnyBody Webcast - A new musculoskeletal AnyBody™ detailed hand model Y1 - 2020 UR - https://www.youtube.com/watch?v=E4xnbjRJYm8&t=631s ER - TY - GEN A1 - Eger, Maximilian A1 - Bergstraesser, Marcel A1 - Dendorfer, Sebastian A1 - Lenich, Andreas A1 - Pfeifer, Christian T1 - Influence of radial head prosthetic design on humeroradial stability: Validation of a test rig therefore T2 - DOKU2022, Deutscher Kongress für Orthopädie und Unfallchirurgie, 25.-28. 10.2022, Berlin KW - radial head prostheses KW - humeroradial stability KW - radial head arthroplasty KW - subluxation Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0183-22dkou6115 PB - German Medical Science GMS Publishing House CY - Düsseldorf ER - TY - CHAP A1 - Putzer, Michael A1 - Penzkofer, Rainer A1 - Ehrlich, Ingo A1 - Rasmussen, John A1 - Gebbeken, Norbert A1 - Dendorfer, Sebastian T1 - Musculoskeletal simulations to investigate the influence of vertebral geometrical parameters on lumbar spine loading T2 - 7th World Congress of Biomechanics, Boston, United States, 04/07/14 -11/07/14 Y1 - 2014 ER - TY - JOUR A1 - Weber, Markus A1 - Merle, Christian A1 - Nawabi, Danyal H. A1 - Dendorfer, Sebastian A1 - Grifka, Joachim A1 - Renkawitz, Tobias T1 - Inaccurate offset restoration in total hip arthroplasty results in reduced range of motion JF - Scientific Reports N2 - 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. KW - Adaptive clinical trial KW - Bone imaging Y1 - 2020 U6 - https://doi.org/10.1038/s41598-020-70059-1 VL - 10 IS - 13208 SP - 9 PB - Nature ER - TY - GEN A1 - Melzner, Maximilian A1 - Dendorfer, Sebastian T1 - Biomechanik und muskuloskeletale Simulation T2 - Jahreskongress des ISPO Deutschland e.V., 2./3. Juni 2022, Hedelberg Y1 - 2022 ER - TY - GEN A1 - Melzner, Maximilian A1 - Pfeifer, Christian A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Muskuloskeletal analysis of elbow stability for common injury patterns T2 - 27th Congress of the European Society of Biomechanics, 26 - 29 June 2022, Porto, Portugal Y1 - 2022 UR - https://drive.google.com/uc?id=1RBguxyHZE-Wr2y6ktOWK06_3lQg2M9Rb&export=download&confirm=t SP - 654 ER - TY - CHAP A1 - Galibarov, Pavel E. A1 - Al-Munajjed, Amir Andreas A1 - Dendorfer, Sebastian A1 - Christensen, Soeren Toerholm A1 - Rasmussen, John T1 - The effect of varying the stiffness of spinal fusion devices on the adjacent levels using multibody dynamics simulation T2 - Orthopaedic Proceedings N2 - 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. Y1 - 2011 VL - 94-B IS - SUPP_XL01 Sep 2012 SP - 2 ER - TY - CHAP A1 - Galibarov, Pavel E. A1 - Dendorfer, Sebastian A1 - Christensen, Soeren Toerholm T1 - On modelling spine curvature dependent on muscular and external forces in multibody dynamics system T2 - International Society of Biomechanics (ISB), 13th congress, 2011, Brussels, Belgium N2 - 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. Y1 - 2011 UR - https://paperpile.com/shared/63VCBY/download/2608c6d1-adef-0330-86f8-7996e623c627 SP - 2 ER - TY - CHAP A1 - Rasmussen, John A1 - Bichler, R. A1 - Christensen, Soeren Toerholm A1 - Wirix-Speetjens, Roel A1 - Dendorfer, Sebastian A1 - Renkawitz, Tobias T1 - Subject-specific Musculoskeletal Simulation of Hip Dislocation Risk in Activities of Daily Living T2 - Proceedings of the 2011 ORS Annual Meeting, Long Beach, CA. Y1 - 2011 UR - http://www.ors.org/Transactions/57/0306.pdf IS - Paper No. 306 ER - TY - CHAP A1 - Robie, Bruce A1 - Dendorfer, Sebastian A1 - Rasmussen, John A1 - Christensen, Soeren Toerholm T1 - Axial Rotation Requires Greatest Load in Multifidus Muscle – Potential Association with Low Back Pain? T2 - Annual Meeting of the AANS/CNS Section on Disorders of the Spine and Peripheral Nerves, 2011, Phoenix, Arizona Y1 - 2011 UR - https://paperpile.com/shared/o0LQEG ER - TY - CHAP A1 - Galibarov, Pavel E. A1 - Dendorfer, Sebastian A1 - Rasmussen, John T1 - Two Computational Models of the Lumbar Spine: BT - Comparison and Validation T2 - Proceedings of the 2011 ORS Annual Meeting, Long Beach, CA, vol. Marie Curie Initial Training Network "SpineFX" Y1 - 2011 UR - http://www.ors.org/Transactions/57/0786.pdf ER - TY - CHAP A1 - Jungtäubl, Dominik A1 - Schmitz, Paul A1 - Gross, Simon A1 - Dendorfer, Sebastian ED - Badnjevic, Almir T1 - FEA of the transiliacal internal fixator as an osteosynthesis of pelvic ring fractures T2 - CMBEBIH 2017, Proceedings of the International Conference on Medical and Biological Engineering 2017 N2 - 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. KW - Finite element analysis KW - Musculoskeletal simulation KW - Internal fixator KW - Pelvic ring fracture KW - Beckenbruch KW - Operationstechnik KW - Finite-Elemente-Methode KW - Biomechanik KW - Simulation Y1 - 2017 SN - 978-981-10-4165-5 U6 - https://doi.org/10.1007/978-981-10-4166-2_32 SP - 212 EP - 217 PB - Springer CY - Singapore ER - TY - JOUR A1 - Benditz, Achim A1 - Auer, Simon A1 - Spörrer, J.F. A1 - Wolkerstorfer, S. A1 - Grifka, Joachim A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Regarding loads after spinal fusion, every level should be seen separately: a musculoskeletal analysis JF - European Spine Journal N2 - 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. KW - AnyBody Modeling System KW - Musculoskeletal analysis KW - Sagittal balance KW - Spinal fusion KW - Spine biomechanics KW - Biomechanische Analyse KW - Wirbelsäulenversteifung KW - Vergleichende Anatomie Y1 - 2018 U6 - https://doi.org/10.1007/s00586-018-5476-5 VL - 27 IS - 8 SP - 1905 EP - 1910 PB - Springer-Verlag ER - TY - JOUR A1 - Scheer, Clara A1 - Kubowitsch, Simone A1 - Dendorfer, Sebastian A1 - Jansen, Petra T1 - Happy Enough to Relax? How Positive and Negative Emotions Activate Different Muscular Regions in the Back - an Explorative Study JF - Frontiers in Psychology N2 - 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. KW - electromyography KW - muscle activity KW - emotion KW - sadness KW - happiness KW - embodiment Y1 - 2021 U6 - https://doi.org/10.3389/fpsyg.2021.511746 SN - 1664-1078 VL - Volume 12 IS - May 2021 PB - Frontiers Media ER - TY - CHAP A1 - Dendorfer, Sebastian A1 - Kubowitsch, Simone A1 - Süß, Franz T1 - How to determine the effect of working conditions on the human body T2 - 11th International Scientific Conference on Production Engineering DEVELOPMENT AND MODERNIZATION OF PRODUCTION (RIM 2017), Sarajevo, Bosnia and Herzegovina N2 - 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. KW - Arbeitsbedingungen KW - Körper KW - Mensch Y1 - 2017 UR - https://tfb.ba/repozitorij/2/RIM/RIM2017/01A-Sebastian%20Dendorfer,%20Simone%20Kubowitsch,%20Franz%20S%C3%BC%C3%9F-HOW%20TO%20DETERMINE%20THE%20EFFECT%20OF%20WORKING%20CONDITIONS%20ON%20THE%20HUMAN%20BODY.pdf ER - TY - CHAP A1 - Weber, Tim A. A1 - Dendorfer, Sebastian A1 - Dullien, Silvia A1 - Grifka, Joachim A1 - Verkerke, Gijsbertus Jacob A1 - Renkawitz, Tobias T1 - Measuring functional outcome after total hip replacement with subject-specific hip joint loading T2 - Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine N2 - 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. KW - total hip replacement KW - subject-specific musculoskeletal modeling KW - functional outcome KW - force pathways KW - force angles KW - critical hip joint loading KW - rim loading KW - cup loading KW - Hüftgelenkprothese KW - Biomechanik KW - Lastverteilung KW - Ganganalyse KW - Simulation Y1 - 2012 U6 - https://doi.org/10.1177/0954411912447728 VL - 226 IS - 12 SP - 939 EP - 946 ER - TY - JOUR A1 - Weber, Tim A1 - Al-Munajjed, Amir Andreas A1 - Verkerke, Gijsbertus Jacob A1 - Dendorfer, Sebastian A1 - Renkawitz, Tobias T1 - Influence of minimally invasive total hip replacement on hip reaction forces and their orientations JF - Journal of Orthopaedic Research N2 - 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. KW - THA KW - THR KW - Biomechanics KW - Conventional surgery KW - Early recovery KW - Hüftgelenkprothese KW - Minimal-invasive Chirurgie KW - Biomechanik Y1 - 2014 U6 - https://doi.org/10.1002/jor.22710 VL - 32 IS - 12 SP - 1680 EP - 1687 ER - TY - JOUR A1 - Penzkofer, Rainer A1 - Barnsteiner, K. A1 - Dendorfer, Sebastian T1 - The influence of age, shoe type and kicking direction on the severity of head trauma JF - Journal of Forensic Biomechanics N2 - In the last few years, increasingly kicks to the head were observed as a criminal offense. This study examined the influence of age, shoe type and kicking direction on the severity of head trauma. Male test persons were divided into two groups “Old” and “Young”. Both groups were equipped with light sneakers and combat boots. A standard laboratory crash dummy was used to simulate the victim’s body. First, the dummy’s head, free floating above the ground, was kicked vertically. Second, the dummy’s head was kicked horizontally. Established injury criteria were used to quantify the injury risk. No influence concerning the type of foot wear and no difference between the groups “Old” and “Young” could be found. For all analyses, kicking vertically generally lead to a higher risk for the subject compared to kicking horizontally. In this study, only the integral effect of the kicks could be analyzed. A detailed injury pattern cannot directly be derived from the data. Nevertheless, the presented data show the massive potential of injuries associated with head kicks. KW - Head trauma KW - Biomechanics KW - Kicks KW - Kopfverletzung KW - Schädel-Hirn-Trauma KW - Einflussgröße Y1 - 2014 UR - https://www.longdom.org/open-access/the-influence-of-age-shoe-type-and-kicking-direction-on-the-severity-of-head-trauma-2090-2697-1000116.pdf U6 - https://doi.org/10.4172/2090-2697.1000116 VL - 5 IS - 1 ER - TY - JOUR A1 - Dendorfer, Sebastian A1 - Weber, Tim A1 - Kennedy, O. T1 - Musculoskeletal modeling for hip replacement outcome analyses and other applications JF - The Journal of the American Academy of Orthopaedic Surgeons KW - Hüftgelenkprothese KW - Bewegungsapparat KW - Simulation Y1 - 2014 U6 - https://doi.org/10.5435/JAAOS-22-04-268 VL - 22 IS - 4 SP - 268 EP - 269 ER - TY - JOUR A1 - Lazarev, I.A. A1 - Ryabokon, P.V. A1 - Haller, M. A1 - Dendorfer, Sebastian T1 - Effect of the fractured calcaneus's peripheral fragment displacement on the triceps surae function JF - ЖУРНАЛ «ТРАВМА» Ukrainian Trauma Journal Y1 - 2015 VL - 2, TOM 16 ER - TY - CHAP A1 - Aurbach, Maximilian A1 - Wagner, Kilian A1 - Süß, Franz A1 - Dendorfer, Sebastian ED - Badnjevic, Almir T1 - Implementation and Validation of Human Kinematics Measured Using IMUs for Musculoskeletal Simulations by the Evaluation of Joint Reaction Forces T2 - CMBEBIH 2017, Proceedings of the International Conference on Medical and Biological Engineering 2017, Sarajevo, Bosnia and Herzegovina N2 - 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. KW - Inertial Measurement Units KW - Multibody Simulation KW - Musculoskeletal Simulation KW - AnyBody KW - Motion Capture KW - Bewegungsapparat KW - Biomechanik KW - Motion Capturing KW - Mehrkörpersimulation KW - Ground Reaction Force Prediction KW - Gait KW - IMU KW - Joint Reaction Forces Y1 - 2017 U6 - https://doi.org/10.1007/978-981-10-4166-2_31 VL - Vol. 62 SP - 205 EP - 211 PB - Springer CY - Singapore ER - TY - JOUR A1 - De Pieri, Enrico A1 - Atzori, Federica A1 - Ferguson, Stephen J. A1 - Dendorfer, Sebastian A1 - Leunig, Michael A1 - Aepli, Martin T1 - Contact force path in total hip arthroplasty: effect of cup medialisation in a whole-body simulation JF - HIP International N2 - 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. KW - Cup medialisation KW - femoral offset KW - hip contact force KW - total hip anthroplasty KW - total hip replacement KW - Hüftgelenkprothese KW - Kontaktkraft KW - Biomechanische Analyse KW - Simulation Y1 - 2020 U6 - https://doi.org/10.1177/1120700020917321 VL - 31 IS - 5 SP - 624 EP - 631 PB - Sage ER - TY - JOUR A1 - Renkawitz, Tobias A1 - Dendorfer, Sebastian T1 - Orthopedic navigation technology and biomechanical evaluation for total hip replacement JF - Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine KW - Hüftgelenkprothese KW - Orthopädische Chirurgie KW - Computerunterstütztes Verfahren KW - Biomechanische Analyse Y1 - 2012 U6 - https://doi.org/10.1177/0954411912458746 VL - 226 IS - 12 SP - 897 EP - 898 ER - TY - CHAP A1 - Weber, Tim A1 - Stezowski, P. A1 - Dullien, Silvia A1 - Dendorfer, Sebastian T1 - Eine biomechanische Bewertung verschiedener Belastungsszenarios nach der Implantierung einer Hüft-Totalendoprothese T2 - 89. Jahrestagung der Vereinigung der Bayerischen Chirurgen e.V., 25. - 27. Juli 2012, Regensburg T2 - A biomechanical evaluation of different load scenarios after implantation of a total hip replacement Y1 - 2012 ER - TY - CHAP A1 - Weber, Tim A1 - Dendorfer, Sebastian A1 - Renkawitz, Tobias A1 - Dullien, Silvia A1 - Grifka, Joachim T1 - Clinical gait analysis combined with musculoskeletal modelling – coding a new generation of evaluation instruments T2 - Deutsche Gesellschaft für Biomechanik, Murnau, 2011 Y1 - 2011 ER - TY - CHAP A1 - Pilling, A. A1 - Süß, Franz A1 - Kubowitsch, Simone A1 - Dendorfer, Sebastian T1 - Experimental workflow for determining psychological stress from physiological biosignals T2 - Jahrestagung der BIOMEDIZINISCHEN TECHNIK und Dreiländertagung der MEDIZINISCHEN PHYSIK, Dresden, Germany, 2017 Y1 - 2017 ER - TY - JOUR A1 - Zellner, Johannes A1 - Hierl, Katja A1 - Mueller, Michael A1 - Pfeifer, Christian A1 - Berner, Arne A1 - Dienstknecht, Thomas A1 - Krutsch, Werner A1 - Geis, Sebastian A1 - Gehmert, Sebastian A1 - Kujat, Richard A1 - Dendorfer, Sebastian A1 - Prantl, Lukas A1 - Nerlich, Michael A1 - Angele, Peter ED - Gilbert, Jeremy T1 - Stem cell-based tissue-engineering for treatment of meniscal tears in the avascular zone JF - Journal of Biomedical Materials Research Part B Applied Biomaterials N2 - 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. KW - biomechanics KW - meniscus KW - scaffolds KW - stem cells KW - tissue engineering KW - Meniskusschaden KW - Tissue Engineering KW - Mesenchymzelle KW - Hyaluronsäure Y1 - 2013 U6 - https://doi.org/10.1002/jbm.b.32922 VL - 101 IS - 7 SP - 1133 EP - 1142 ER - TY - CHAP A1 - Weber, Tim A1 - Dendorfer, Sebastian A1 - Grifka, Joachim A1 - Weber, Markus A1 - Wörner, Michael A1 - Dullien, Silvia A1 - Verkerke, Gijsbertus Jacob A1 - Renkawitz, Tobias T1 - Verbessert die computerassistierte Femur First Operationstechnik für die Hüftendoprothetik den muskuloskelettalen Lastfall auf das Hüftgelenk? T2 - DKOU 2015, Deutscher Kongress für Orthopädie und Unfallchirurgie 2015 Y1 - 2015 UR - https://www.researchgate.net/publication/283259007_Verbessert_die_computerassistierte_Femur_First_Operationstechnik_fur_die_Huftendoprothetik_den_muskuloskelettalen_Lastfall_auf_das_Huftgelenk ER - TY - CHAP A1 - Weber, Tim A1 - Renkawitz, Tobias A1 - Grifka, Joachim A1 - Bulstra, Sjoerd K. A1 - Verkerke, Gijsbertus Jacob A1 - Dendorfer, Sebastian T1 - The musculoskeletal load scenario of computer-assisted Femur-First THR up to one year after surgery T2 - VI International Conference on Computational Bioengineering, Barcelona, Sept. 2015 Y1 - 2015 UR - https://www.researchgate.net/publication/281745827_The_musculoskeletal_load_scenario_of_computer-assisted_Femur-First_THR_up_to_one_year_after_surgery ER - TY - CHAP A1 - Gross, Simon A1 - Süß, Franz A1 - Verkerke, Gijsbertus Jacob A1 - Dendorfer, Sebastian T1 - Simulating fatigue in musculoskeletal models using surface electromyography, ECCOMAS Congress, Crete, Greece, 201 T2 - ECCOMAS Congress, Crete, Greece, 2016 Y1 - 2016 ER - TY - CHAP A1 - Süß, Franz A1 - Kubowitsch, Simone A1 - Verkerke, Gijsbertus Jacob A1 - Dendorfer, Sebastian T1 - The influence of stress on spinal loading T2 - ESEM webconference, Dez. 2017 Y1 - 2016 ER - TY - CHAP A1 - Dendorfer, Sebastian A1 - Kubowitsch, Simone T1 - The interaction of mental stress and biomechanics T2 - Health Technology Triangle, Weiden, 2016 Y1 - 2016 ER - TY - CHAP A1 - Al-Munajjed, Amir Andreas A1 - Nolte, Daniel A1 - Rasmussen, John A1 - Dendorfer, Sebastian T1 - Force distribution in the foot during braking – a musculoskeletal approach T2 - Human Modeling Symposium 2014, Munich, Germany N2 - 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. Y1 - 2014 UR - https://www.researchgate.net/publication/281229902_Force_distribution_in_the_foot_during_braking_-a_musculoskeletal_approach ER - TY - JOUR A1 - Völlner, Florian A1 - Weber, Tim A. A1 - Weber, Markus A1 - Renkawitz, Tobias A1 - Dendorfer, Sebastian A1 - Grifka, Joachim A1 - Craiovan, Benjamin T1 - A simple method for determining ligament stiffness during total knee arthroplasty in vivo JF - Scientific Reports N2 - 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. KW - Biomechanische Analyse KW - Kniegelenkband KW - Steifigkeit Y1 - 2019 U6 - https://doi.org/10.1038/s41598-019-41732-x VL - 9 SP - 1 EP - 8 PB - Nature ER - TY - CHAP A1 - Weber, Tim A1 - Dendorfer, Sebastian A1 - Bulstra, Sjoerd K. A1 - Verkerke, Gijsbertus Jacob A1 - Renkawitz, Tobias T1 - Biomechanical Outcome after computer-assisted vs. Conventional THR T2 - ANSYS Conference & 32th CADFEM Users' Meeting 2014, 04.-06. Juni, Nürnberg Y1 - 2014 UR - https://www.researchgate.net/publication/264547774_Biomechanical_outcome_after_computer-assisted_vs_conventional_THR ER - TY - CHAP A1 - Dendorfer, Sebastian T1 - Virtuelle Menschmodelle – von der Bewegung zur Belastung T2 - Medbo Bezirksklinikum Regensburg, April 2016 Y1 - 2016 ER - TY - CHAP A1 - Dendorfer, Sebastian T1 - Biomechanik des Alterns T2 - Kolpingfortbildung Lambach, April 2016 Y1 - 2016 ER - TY - CHAP A1 - Gross, Simon A1 - Verkerke, Gijsbertus Jacob A1 - Dendorfer, Sebastian T1 - Combined Experimental and Numerical Approach to Investigate Changes in Muscle Recruitment Pattern of the Back Muscles during Exhausting Exercise T2 - World Congress Biomechanics Dublin, 2018 N2 - 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. Y1 - 2018 ER - TY - JOUR A1 - Auer, Simon A1 - Kurbowitsch, Simone A1 - Süß, Franz A1 - Renkawitz, Tobias A1 - Krutsch, Werner A1 - Dendorfer, Sebastian T1 - Mental stress reduces performance and changes musculoskeletal loading in football-related movements JF - Science and Medicine in Football N2 - 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. KW - Biomechanics KW - muscle injury KW - attention KW - musculoskeletal simulation Y1 - 2020 U6 - https://doi.org/10.1080/24733938.2020.1860253 VL - 5 IS - 4 SP - 323 EP - 329 PB - Taylor & Francis ER - TY - JOUR A1 - Putzer, Michael A1 - Ehrlich, Ingo A1 - Rasmussen, John A1 - Gebbeken, Norbert A1 - Dendorfer, Sebastian T1 - Sensitivity of lumbar spine loading to anatomical parameters JF - Journal of Biomechanics N2 - 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. KW - Musculoskeletal simulation KW - Lumbar spine KW - Parameter study KW - Vertebra KW - Wirbelsäule KW - Belastung KW - Simulation Y1 - 2015 U6 - https://doi.org/10.1016/j.jbiomech.2015.11.003 VL - 49 IS - 6 SP - 953 EP - 958 PB - Elsevier Science ER - TY - JOUR A1 - Dendorfer, Sebastian A1 - Hammer, Joachim A1 - Lenich, Andreas T1 - Characterisation and testing of biomaterials JF - Technology and Health Care KW - Testing biomaterials KW - Characterisation testing KW - Biomaterial KW - Test Y1 - 2011 U6 - https://doi.org/10.3233/THC-2011-0644 VL - 19 IS - 5 SP - 357 EP - 371 ER - TY - CHAP A1 - Putzer, Michael A1 - Galibarov, Pavel E. A1 - Dendorfer, Sebastian T1 - Influence of vertebral parameters on lumbar spine loading T2 - Pre-meeting SpineFX, Eurospine 2013, Liverpool, UK Y1 - 2013 ER - TY - CHAP A1 - Dendorfer, Sebastian A1 - Penzkofer, Rainer T1 - Experimentelle Untersuchung der Belastungen im Kopf beim Treten T2 - Fachsymposium "Treten gegen den Kopf", April 2013, Nürnberg Y1 - 2013 ER - TY - CHAP A1 - Dendorfer, Sebastian T1 - Einführung in die Mechanik T2 - Biomechanik Workshop, Klinikum Bad Abbach, Nov. 2013 Y1 - 2013 ER - TY - CHAP A1 - Dendorfer, Sebastian T1 - Innovationen in der Medizintechnik T2 - Oberpfalztag Weiherhammer, Nov. 2013 Y1 - 2013 ER - TY - JOUR A1 - Hoenicka, M. A1 - Lehle, Karla A1 - Jacobs, V. R. A1 - Dendorfer, Sebastian A1 - Kostorz, A. A1 - Schmid, F. X. A1 - Birnbaum, D. E. T1 - Mechanical and seeding properties of human umbilical vein – a potential scaffold for a tissue-engineered vessel graft JF - The Thoracic and Cardiovascular Surgeon N2 - 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. KW - Nabelvene KW - Tissue Engineering Y1 - 2007 U6 - https://doi.org/10.1055/s-2007-967592 VL - 55 IS - S 1 SP - P_37 PB - Thieme ER - TY - JOUR A1 - Englert, Carsten A1 - Angele, Peter A1 - Fierlbeck, J. A1 - Dendorfer, Sebastian A1 - Schubert, T. A1 - Müller, R. A1 - Lienhard, S. A1 - Zellner, J. A1 - Nerlich, Michael A1 - Neumann, Carsten T1 - Conductive bone substitute material with variable antibiotic delivery JF - Der Unfallchirurg N2 - 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. KW - Knochenersatz KW - Leitfähgkeit KW - Antibiotika KW - Biomechanik KW - Bone substitute materials KW - Osteoconductive KW - Osteomyelitis KW - Multiresistant KW - Biomechanics Y1 - 2007 U6 - https://doi.org/10.1007/s00113-007-1229-3 VL - 110 IS - 5 SP - 408 EP - 413 PB - Springer ER - TY - JOUR A1 - Dendorfer, Sebastian A1 - Maier, Hans Jürgen A1 - Hammer, Josef T1 - Fatigue damage in cancellous bone: an experimental approach from continuum to micro scale JF - Journal of the Mechanical Behavior of Biomedical Materials N2 - 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. KW - Knochen KW - Spongiosa KW - Ermüdungsbruch KW - Fatigue KW - Cancellous bone KW - Deformation behaviour KW - Damage KW - Measurement and testing KW - Mechanical behaviour Y1 - 2009 U6 - https://doi.org/10.1016/j.jmbbm.2008.03.003 VL - 2 IS - 1 SP - 113 EP - 119 ER - TY - CHAP A1 - Jungtäubl, Dominik A1 - Aurbach, Maximilian A1 - Melzner, Maximilian A1 - Spicka, Jan A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - EMG-Based Validation of Musculoskeletal Models Considering Crosstalk T2 - International Conference BIOMDLORE, June 28 - 30 2018, Białystok, Poland N2 - 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. KW - musculoskeletal modeling KW - validation KW - surface electromyography KW - crosstalk Y1 - 2018 U6 - https://doi.org/10.1109/BIOMDLORE.2018.8467211 ER - TY - GEN A1 - Melzner, Maximilian A1 - Pfeifer, Christian A1 - Alt, V. A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Änderung der Gelenkreaktionskraft bei Schädigung des medialen Bandapparates im Ellenbogen T2 - Zeitschrift fur Orthopadie und Unfallchirurgie KW - Muskuloskelettale Simulation KW - Ellenbogenstabilität Y1 - 2020 U6 - https://doi.org/10.1055/s-0040-1717270 N1 - Poster VL - 158 IS - S01 PB - Thieme ER - TY - CHAP A1 - Dendorfer, Sebastian A1 - Hammer, Joachim A1 - Lenich, Andreas ED - Lee, T. Clive ED - Niederer, Peter F. T1 - Characterisation and testing of biomaterials T2 - Basic Engineering for Medics and Biologists: An ESEM Primer KW - Biomaterial KW - Werkstoff KW - Test Y1 - 2010 SN - 978-1607505266 IS - Chapter IV.4. PB - Non Basic Stock Line ER - TY - CHAP A1 - Süß, Franz A1 - Kubowitsch, Simone A1 - Verkerke, Gijsbertus Jacob A1 - Dendorfer, Sebastian T1 - The influence of mental stress on spinal disc loading and muscle activity T2 - 23th Congress of the European Society of Biomechanics, Sevilla, Spain, 2017 Y1 - 2017 ER - TY - CHAP A1 - Melzner, Maximilian A1 - Engelhardt, Lucas A1 - Havelkova, Leonard A1 - Simon, Ulrich A1 - Dendorfer, Sebastian T1 - A new musculoskeletal AnyBody detailed hand model validated by electromyography T2 - 16th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering (CMBBE) 2019, New York City, USA N2 - 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. Y1 - 2019 UR - https://www.researchgate.net/publication/336944957_A_NEW_MUSCULOSKELETAL_ANYBODY_DETAILED_HAND_MODEL_VALIDATED_BY_ELECTROMYOGRAPHY ER - TY - GEN A1 - Auer, Simon A1 - Niebler, Michael A1 - Eiglsperger, Josef A1 - Kubowitsch, Simone A1 - Renkawitz, Tobias A1 - Achenbach, Leonard A1 - Krutsch, Werner A1 - Dendorfer, Sebastian T1 - Cognitive stress increases muscle forces in dynamic football specific movements T2 - European Society of Biomechanics meeting 2019, Vienna, Austria Y1 - 2019 UR - https://owncloud.tuwien.ac.at/index.php/s/dovqqcj02VeZHze ER - TY - CHAP A1 - Süß, Franz A1 - Kubowitsch, Simone A1 - Rasmussen, John A1 - Verkerke, Gijsbertus Jacob A1 - Dendorfer, Sebastian T1 - The influence of cognitive stress on muscle activation and spinal disc load T2 - European Society of Biomechanics meeting 2019, Vienna, Austria Y1 - 2019 UR - https://owncloud.tuwien.ac.at/index.php/s/dovqqcj02VeZHze ER - TY - GEN A1 - Melzner, Maximilian A1 - Engelhardt, Leonard A1 - Süß, Friedrich A1 - Dendorfer, Sebastian T1 - Sensitivity evaluation of a musculoskeletal hand model using Latin hypercube sampling T2 - ESMAC 2020 Abstracts Y1 - 2020 U6 - https://doi.org/10.1016/j.gaitpost.2020.08.008 VL - 81 IS - Suppl. 1 PB - Elsevier ER - TY - CHAP A1 - Gross, Simon A1 - Verkerke, Gijsbertus Jacob A1 - Dendorfer, Sebastian T1 - Investigation of external load dependent static and dynamic muscle fatigue T2 - 23th Congress of the European Society of Biomechanics, Sevilla, Spain, 2017 Y1 - 2017 ER - TY - CHAP A1 - Kubowitsch, Simone A1 - Süß, Franz A1 - Jansen, Petra A1 - Dendorfer, Sebastian T1 - Comparison of dynamic muscular imbalances in back pain patients and healthy controls T2 - World Congress Biomechanics Dublin, 2018 Y1 - 2018 ER - TY - CHAP A1 - Seefried, C. A1 - Aurbach, Maximilian A1 - Wyss, C. A1 - Dendorfer, Sebastian T1 - Achilles tendon lengthening alters stresses in the growth plate T2 - International Conference BIOMDLORE, June 28 - 30 2018, Białystok, Poland Y1 - 2018 ER - TY - CHAP A1 - Kubowitsch, Simone A1 - Süß, Franz A1 - Jansen, Petra A1 - Dendorfer, Sebastian T1 - Muscular imbalances during experimentally induced stress T2 - 23th Congress of the European Society of Biomechanics, Sevilla, Spain, 2017 Y1 - 2017 ER - TY - GEN A1 - Engelhardt, Lucas A1 - Melzner, Maximilian A1 - Havelkova, Linda A1 - Fiala, Pavel A1 - Rybarova, Martina A1 - Christen, Patrik A1 - Dendorfer, Sebastian A1 - Simon, Ulrich T1 - A new musculoskeletal AnyBody detailed hand model T2 - European Society of Biomechanics meeting 2019, Vienna, Austria N2 - 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. Y1 - 2019 UR - https://owncloud.tuwien.ac.at/index.php/s/dovqqcj02VeZHze ER - TY - JOUR A1 - Weber, Tim A1 - Dullien, Silvia A1 - Grifka, Joachim A1 - Renkawitz, Tobias A1 - Dendorfer, Sebastian T1 - Validation of a Motion Capture Laboratory and a new marker-placement protcol for clinical applications JF - Gait & Posture Y1 - 2013 U6 - https://doi.org/10.1016/j.gaitpost.2013.07.229 VL - 38 IS - Suppl. 1 SP - 113 EP - 114 ER - TY - GEN A1 - Aurbach, Maximilian A1 - Spicka, Jan A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Musculoskeletal modelling of the shoulder – effects on muscle recruitment and joint reaction force T2 - European Society of Biomechanics meeting 2019, Vienna, Austria Y1 - 2019 UR - https://owncloud.tuwien.ac.at/index.php/s/dovqqcj02VeZHze ER - TY - CHAP A1 - Weber, Tim A1 - Dullien, Silvia A1 - Putzer, Michael A1 - Dendorfer, Sebastian A1 - Renkawitz, Tobias T1 - Biomechanical outcome after computer-assisted vs. conventional THR – study concept and preliminary gait analysis results T2 - GAMMA Workshop, Hannover, 2012 Y1 - 2012 ER - TY - GEN A1 - Kubowitsch, Simone A1 - Süß, Franz A1 - Jansen, Petra A1 - Dendorfer, Sebastian T1 - Effect of dual tasking on muscular imbalances T2 - European Society of Biomechanics meeting 2019, Vienna, Austria Y1 - 2019 UR - https://owncloud.tuwien.ac.at/index.php/s/dovqqcj02VeZHze ER - TY - GEN A1 - Aurbach, Maximilian A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - The impact of the hill type muscle model on the glenohumeral joint reaction force T2 - 16th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering (CMBBE) 2019, New York City, USA Y1 - 2019 ER - TY - GEN A1 - Dendorfer, Sebastian T1 - Virtuelle Modelle der oberen Extremität T2 - 22. Interdisziplinäres Symposium Medizin-Physiotherapie-Sportwissenschaften, 22.-23.11.2019, Regensburg, Germany Y1 - 2019 ER - TY - GEN A1 - Dendorfer, Sebastian T1 - The influence of mental stress on the musculoskeletal system Y1 - 2020 ER - TY - CHAP A1 - Weber, Tim A1 - Renkawitz, Tobias A1 - Bulstra, Sjoerd K. A1 - Grifka, Joachim A1 - Verkerke, Gijsbertus Jacob A1 - Dendorfer, Sebastian T1 - Biomechanics of computer-assisted vs. conventional THR after one year follow up T2 - XXV Congress of the International Society of Biomechanics, Glasgow, UK, 12th-16th July 2015 Y1 - 2015 ER - TY - CHAP A1 - Ignasiak, Dominika A1 - Dendorfer, Sebastian A1 - Ferguson, Stephen J. T1 - Thoracolumbar spine model with articulated rigcage for the prediction of dynamic spinal loading T2 - International Workshop on Spine Loading and Deformation: From Loading to Recovery, 2-4 July 2015, Julius Wolff Institute, Charité-Universitatsmedizin Berlin, Germany Y1 - 2015 ER - TY - CHAP A1 - Weber, Tim A1 - Dendorfer, Sebastian A1 - Bulstra, Sjoerd K. A1 - Grifka, Joachim A1 - Verkerke, Gijsbertus Jacob A1 - Renkawitz, Tim T1 - Navigated Femur First Total Hip Arthroplasty leads to improved Biomechanical Outcome after surgery T2 - ORS annual meeting, Las Vegas, USA, 2015 Y1 - 2015 ER - TY - CHAP A1 - Billing, A. A1 - Götz, J. A1 - Weber, Tim A1 - Dendorfer, Sebastian T1 - Positionsanalyse von winkelstabilen Plattenosteosynthesesystemen zur Versorgung von Metatarsalfrakturen mit Hilfe von patientenspezifischen biomechanischen Modellen T2 - Vereinigung Süddeutscher Orthopäden und Unfallchirurgen Jahrestagung 2015, Baden-Baden, Germany Y1 - 2015 ER - TY - CHAP A1 - Weber, Tim A1 - Stezowski, P. A1 - Dullien, Silvia A1 - Putzer, Michael A1 - Dendorfer, Sebastian T1 - Eine biomechanische Bewertung verschiedener Belastungsszenarien nach Implantierung einer Hüft-Totalendoprothese T2 - GAMMA Workshop, Hannover, 2012 Y1 - 2012 ER - TY - CHAP A1 - Süß, Franz A1 - Kubowitsch, Simone A1 - Verkerke, Gijsbertus Jacob A1 - Dendorfer, Sebastian T1 - Investigation of cognitive stress induced changes in spinal disc forces due to altered kinematics and muscle activity T2 - World Congress Biomechanics, Dublin, 2018 Y1 - 2018 ER - TY - CHAP A1 - Spreiter, G. A1 - Galibarov, Pavel E. A1 - Dendorfer, Sebastian A1 - Ferguson, Stephen J. T1 - Influence of kyphosis on spinal loading T2 - 10th International Symposium Computer Methods in Biomechanics and Biomedical Engineering (CMBBE) Meeting, 11. - 14. April 2012, Berlin Y1 - 2012 ER - TY - CHAP A1 - Putzer, Michael A1 - Dendorfer, Sebastian T1 - Sensitivity of lumbar spine loading to anatomical parameters T2 - International Workshop on Spine Loading and Deformation: From Loading to Recovery, 2-4 July 2015, Julius Wolff Institute, Charité-Universitatsmedizin Berlin, Germany Y1 - 2015 ER - TY - CHAP A1 - Kubowitsch, Simone A1 - Dendorfer, Sebastian T1 - Psychologie und Biomechanik – Integrierte Betrachtung von Muskelrekrutierung BT - Erkenntnisse und Ableitungen für Biofeedback T2 - Jahrestagung der Deutschen Gesellschaft für Biofeedback e. V., Regensburg, 2018 Y1 - 2018 ER - TY - GEN A1 - Auer, Simon A1 - Reinker, Lukas A1 - Dendorfer, Sebastian T1 - Evaluation of muscle recruitment and muscle models in musculoskeletal simulation of dynamic motion T2 - 26th Congress of the European Society of Biomechanics, July 11-14, 2021, Milan, Italy N2 - 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. KW - esb KW - biomechanics KW - muscle recruitment Y1 - 2021 UR - https://esbiomech.org/conference/archive/2021milan/Contribution_1719.pdf CY - Milan ER - TY - JOUR A1 - Visscher, Rosa A1 - Wyss, C. A1 - Singh, Navrag B. A1 - Taylor, William R. A1 - Dendorfer, Sebastian A1 - Rutz, E. A1 - Brunner, Reinald T1 - Influence of TAL-TATS surgery on energy production of Tricepts Surae - A musculoskeletal modeling evaluation JF - Gait & Posture Y1 - 2020 U6 - https://doi.org/10.1016/j.gaitpost.2020.08.090 VL - 81 IS - Suppl. 1 SP - 381 EP - 382 PB - Elsevier ER - TY - CHAP A1 - Penzkofer, Rainer A1 - Grechenig, S. A1 - Kujat, Richard A1 - Angele, Peter A1 - Dendorfer, Sebastian T1 - Biomechanical comparison of the dorsal femur condyles and the iliac crest in terms of failure behavior T2 - XXV Congress of the International Society of Biomechanics, Glasgow, UK, 12th-16th July 2015 Y1 - 2015 ER - TY - CHAP A1 - Striegl, B. A1 - Kujat, Richard A1 - Dendorfer, Sebastian T1 - Quantitative analysis of cartilage surface by confocal laser scanning microscopy T2 - Biomedizinische Technik Y1 - 2014 U6 - https://doi.org/10.1515/bmt-2014-4012 VL - 59 IS - s1-A SP - 24 ER - TY - CHAP A1 - Weber, Tim A1 - Dendorfer, Sebastian A1 - Bulstra, Sjoerd K. A1 - Verkerke, Gijsbertus Jacob A1 - Renkawitz, Tobias T1 - Musculoskeletal modeling for orthopedic surgery – Applications and chances T2 - Orthopedics meets Engineering, Regensburg, 2015 Y1 - 2015 ER - TY - CHAP A1 - Putzer, Michael A1 - Weber, Tim A1 - Dendorfer, Sebastian T1 - Design studies on hip prosthesis using patient specific data T2 - Simpleware Users meeting, November 9th 2011, Bristol, UK Y1 - 2011 ER - TY - CHAP A1 - Süß, Franz A1 - Putzer, Michael A1 - Dendorfer, Sebastian T1 - Numerische und experimentelle Untersuchungen an der Wirbelsäule T2 - Forschungssymposium Bad Abbach, Germany, 2015 Y1 - 2015 ER - TY - CHAP A1 - Dendorfer, Sebastian T1 - Mechanobiology – Impact on regeneration and degradation T2 - Translations in Regenerative Medicine, TIRM and FIFA Symposium, Regensburg, 2015 Y1 - 2015 ER - TY - CHAP A1 - Englert, Carsten A1 - Müller, F. A1 - Dendorfer, Sebastian T1 - Einfluss der Muskelkräfte, des Bewegungsausmaßes und der Bruchform auf die Kraftübertragung des Implantat-Knochenverbundes am Beispiel der Claviculafraktur im mittleren Drittel T2 - 17. Jahreskongress der Deutschen Vereinigung für Schulter- und Ellenbogenchirurgie (DVSE), Rosenheim 2010 N2 - 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. Y1 - 2010 ER - TY - JOUR A1 - Auer, Simon A1 - Krutsch, Werner A1 - Renkawitz, Tobias A1 - Kubowitsch, Simone A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Kognitiver Stress führt zu unphysiologisch erhöhten Kniebelastungen im Profifußball JF - Sports Orthopaedics and Traumatology Y1 - 2020 U6 - https://doi.org/10.1016/j.orthtr.2020.04.122 VL - 36 IS - 2 SP - 202 EP - 203 PB - Elsevier ER - TY - CHAP A1 - Andersen, Michael Skipper A1 - de Zee, Mark A1 - Dendorfer, Sebastian A1 - MacWilliams, Bruce A1 - Rasmussen, John T1 - Validation of a detailed lower extremity model based on the Klein Horsman data set T2 - Proceedings of the 12th International Symposium on Computer Simulation in Biomechanics (ISB 2009), July 2nd - 4th 2009, Cape Town, South Africa Y1 - 2009 SP - 27 EP - 28 ER - TY - CHAP A1 - Dendorfer, Sebastian A1 - Rasmussen, John A1 - Christensen, Soeren Toerholm A1 - Robie, Bruce T1 - The Effect of Spinal Disc Herniation on Multifidus Muscles T2 - 56th Orthopaedic Research Society Meeting, New Orleans, USA, 2010 Y1 - 2010 UR - https://www.ors.org/Transactions/56/1487.pdf ER - TY - GEN A1 - Suess, Franz A1 - Melzner, Maximilian A1 - Dendorfer, Sebastian T1 - Towards Ergonomic working - machine learning algorithms and musculoskeletal modeling T2 - RIM 2021, 13th International Scientific Conference on Manufacturing Engineering, 29 Sept. - 1 Oct 2021, Sarajevo, Bosnia and Herzegovina Y1 - 2021 ER - TY - CHAP A1 - Hammer, Joachim A1 - Dendorfer, Sebastian T1 - Cyclic loading and microstructure of cancellous bone T2 - Journal of Biomechanics Y1 - 2008 U6 - https://doi.org/10.1016/S0021-9290(08)70409-3 VL - 41 IS - Suppl. 1, July 2008 SP - S410 ER - TY - CHAP A1 - Robie, Bruce A1 - Rasmussen, John A1 - Christensen, Soeren Toerholm A1 - Dendorfer, Sebastian T1 - Herniation Induces 55% Increase in Load of Key Stabilizing Muscle – Impact on Herniation Treatment Devices? T2 - Spine Arthoplasty Society Meeting, New Orleans, 2010 Y1 - 2010 ER - TY - CHAP A1 - Dendorfer, Sebastian T1 - How much iron to pump? The determination of muscle forces for activities of daily living T2 - DGU, Berlin, 2008 Y1 - 2008 ER - TY - CHAP A1 - Dendorfer, Sebastian T1 - Biomechanical evaluation and optimisation of countermeasure exercises T2 - ESA/ESTEC Bedrest Strategy Workshop, Noordwijk, NL, 2009 Y1 - 2009 ER - TY - CHAP A1 - Dendorfer, Sebastian A1 - Carbes, S. A1 - Rasmussen, John T1 - The influence of muscle forces on biomechanical fracture fixation simulations – from in-vivo forces to tissue strains T2 - World Congress on Medical Physics and Biomedical Engineering, 7 - 12, 2009, Munich Y1 - 2009 ER - TY - CHAP A1 - Dendorfer, Sebastian A1 - Rasmussen, John T1 - The influence of in-vivo muscle forces on the stress distribution in a vertebral body during activities of daily living T2 - Eurospine Warsaw, Poland 2009 Y1 - 2009 ER - TY - CHAP A1 - Dendorfer, Sebastian A1 - Englert, Carsten T1 - Forces on a clavicles midshaft fracture and influence of fracture type T2 - AO Symposium, Regensburg, 2009 Y1 - 2009 ER - TY - GEN A1 - Kögler, Michael A1 - Ismail, Khaled M. A1 - Rusavy, Zdenek A1 - Kalis, Vladimir A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Influence of bed height and stance on accoucheurs lower back and glenohumeral load during simulated childbirth T2 - 31st meeting of Czech Urogynaecological Society, Prague, 2022 Y1 - 2022 ER - TY - JOUR A1 - Dendorfer, Sebastian A1 - Melzner, Maximilian T1 - Rückenschmerzen bei Geburtshelfer:innen. Die Haltung macht's. JF - Deutsche Hebammen-Zeitschrift N2 - Für Mutter und Kind konnte das Risiko der Geburt durch die Weiterentwicklung der Medizin drastisch reduziert werden. Doch wie ist es um das Wohl derer bestellt, die die Gebärende unterstützen? Eine Studie der Ostbayerischen Technischen Hochschule Regensburg hat sich mit den muskuloskelettalen Beschwerden von Geburtshelfer:innen auseinandergesetzt Y1 - 2022 UR - https://ip.staudeverlag.de/de/profiles/c3962f735915-elwin-staude-verlag-kiosk-bc/editions/dhz-11-2022/pages/page/32 SN - 0012-026X VL - 74 IS - 11 SP - 60 EP - 62 PB - Staude CY - Hannover ER - TY - JOUR A1 - Lazarev, I. A. A1 - Riabokon, P. V. A1 - Haller, M. A1 - Dendorfer, Sebastian T1 - Effect of the Displacement of Calcaneal Bone Peripheral Fragment in its Fracture on the Function of the Three-Headed Calf Muscle JF - TRAUMA N2 - In the structure of musculoskeletal injuries, calcaneal fractures account for up to 4 % of all skeletal fractures and up to 60 % of hindfoot fractures. The effect of the displacement of the peripheral fragment of the calcaneus on the calf muscles’s reaction forces at the time of the adoption of the simplified squatting position was investigated by modeling in AnyBody Modeling System 6.0 software. M.gastrocnemius (lateralis et medialis) in the initial phase of motion in all variants of the peripheral fragment displacement did not develop sufficient muscular effort in comparison to the intact calcaneus. M.soleus medialis et lateralis showed significant increase in muscle activity rates in the initial phase of motion (41.87 ± 1.90 H and 52.07 ± 2.10 H) before reaching its maximum values, as compared with those of the intact calcaneus. In the final phase of the movement, upon muscle reaches its maximum length, muscular strength indicators of the m.soleus returned to their original values or were significantly below them. The decline in muscle strength was due to shortening of the moment arm or muscle excursion in case of convergence of muscle attachment points. When the peripheral fragment is displaced, due to putting down the heel to the surface of the support in terms of anatomical muscle lengthening, it takes extra effort to achieve rest length and its maximum power. In all types of the displacement of the peripheral fragment, the function of three-headed calf muscle is disturbed with involvement of additional muscular effort and energy expenditure. This fact should motivate the surgeon on the need for accurate repositioning of bone fragments in calcaneal fractures with the displacement of the peripheral fragment. Y1 - 2016 U6 - https://doi.org/10.22141/1608-1706.2.16.2015.80247 VL - 16 IS - 2 SP - 20 EP - 24 PB - Zaslavsky ER - TY - JOUR A1 - Dendorfer, Sebastian A1 - Maier, Hans Jürgen A1 - Taylor, David A1 - Hammer, Joachim T1 - Anisotropy of the fatigue behaviour of cancellous bone JF - Journal of Biomechanics N2 - 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. KW - Ermüdung KW - Knochen KW - Spongiosa KW - Anisotropie Y1 - 2008 U6 - https://doi.org/10.1016/j.jbiomech.2007.09.037 VL - 41 IS - 3 SP - 636 EP - 641 ER - TY - GEN A1 - Auer, Simon A1 - Krutsch, Werner A1 - Renkawitz, Tobias A1 - Kubowitsch, Simone A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Effect of mental demand on leg loading in highly dynamic motion T2 - AnyBody online Webinar, Oct 2020 N2 - 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. Y1 - 2020 ER - TY - RPRT A1 - Putzer, Michael A1 - Rasmussen, John A1 - Ehrlich, Ingo A1 - Gebbeken, Norbert A1 - Dendorfer, Sebastian ED - Baier, Wolfgang T1 - Muskuloskelettale Simulation zur Untersuchung des Einflusses geometrischer Parameter der Wirbelkörper auf die Belastung der Lendenwirbelsäule T2 - Forschungsbericht 2013 / Ostbayerische Technische Hochschule Regensburg Y1 - 2013 UR - https://doi.org/10.35096/othr/pub-799 SP - 60 EP - 61 CY - Regensburg ER - TY - CHAP A1 - Muehling, M. A1 - Englert, Carsten A1 - Dendorfer, Sebastian T1 - Influence of biceps tenotomy and tenodesis on post-operative shoulder strength T2 - Jahrestagung der Deutschen Gesellschaft für Biomechanik, March 2017, Hannover, Germany Y1 - 2017 ER - TY - JOUR A1 - Dillinger, Andrea Elisabeth A1 - Mayer, Matthias A1 - Schneider, Magdalena A1 - Weber, Gregor R. A1 - Goeppner, Corinna A1 - Tamm, Ernst R. A1 - Shamonin (Chamonine), Mikhail A1 - Monkman, Gareth J. A1 - Fuchshofer, Rudolf T1 - Reactive changes in optic nerve astrocytes are mediated by CTGF, TGF beta 2 and increasing substratum stiffness JF - Investigative ophthalmology & visual science N2 - Purpose: Patients with primary open-angle glaucoma (POAG) show a stiffer peripapillary sclera, reactive astrocytes and a remodeled lamina cribrosa (LC). The changes are thought to be mediated by TGFβ2 and its downstream mediator CTGF. Recently we developed a murine glaucoma model by overexpressing CTGF in the anterior eye (βb1CTGF). In this study we investigated the glial lamina region of βb1CTGF mice, and the changes of astrocytes in response to CTGF and TGFβ2 as well as increasing substratum stiffness. Methods: Tangential sections of the glial LC of 2-month-old βb1CTGF mice and their wild-type littermates (WT) were stained with phalloidin and antibodies against GFAP, CTGF and fibronectin (FN). Murine optic nerve (ON) astrocytes from CD1 mice were isolated, cultured and characterized by GFAP staining. The astrocytes were treated with TGFβ2 (1ng/ml) and CTGF (50ng/ml and 100ng/ml). In addition, the cells were seeded on PDMS substrata with different stiffness (10, 30 and 60 kPa). Treated cells were analyzed by Western blotting, real-time RT-PCR and immunohistochemistry. Wound healing assays were performed to analyze migration rate following growth factor treatment. Results: βb1CTGF mice showed a massive increase in CTGF and GFAP in the glial LC when compared with WT mice. Moreover, an increase in FN staining and phalloidin-labeled actin was observed in the peripapillary sclera. Murine ON astrocytes reacted on increased substrate stiffness by increasing the synthesis of GFAP, vimentin and CTGF. Treatment of the cells with TGFβ2 and CTGF led to an enhanced migration rate. In addition, treatment resulted in an increased expression and synthesis of ECM proteins, including FN, tropoelastin, collagen type I and III. The in vitro findings correlated with those seen in the glaucoma mouse model. Conclusions: We conclude that changes in the ECM of LC and peripapillary sclera alter their biomechanical properties and thereby induce reactive changes in resident astrocytes. The reactive changes induced by higher stiffness of their surrounding ECM give rise to a self-amplifying process that includes increased TGFβ2/CTGF signaling and leads to synthesis of ECM and cytoskeletal proteins, a process that in turn augments the stiffness at the optic nerve head (ONH). Such a scenario may finally result in a vicious circle as the causative mechanism for ONH deformation in POAG. Y1 - 2015 VL - 56 IS - 7 PB - ASSOC RESEARCH VISION OPHTHALMOLOGY INC ER - TY - JOUR A1 - Lauer, Norina T1 - Interprofessionelle Zusammenarbeit im klinischen Setting JF - Logos. Die Fachzeitschrift für Logopädie und Sprachtherapie N2 - Interprofessionelle Zusammenarbeit ist ein entscheidender Faktor für eine erfolgreiche Gesundheitsversorgung. Gerade im klinischen Setting kommen täglich mehrere Professionen zusammen, deren Aufgabengebiete aneinander angrenzen oder sich überschneiden. Pflegefachkräfte und ÄrztInnen stellen hierbei in der Regel die größten Berufsgruppen dar. In einer qualitativen Interviewstudie wurde im Rahmen eines Projekts zum forschenden Lernen der Frage nachgegangen, von welchen Erfahrungen diese beiden Berufsgruppen über den Austausch mit LogopädInnen bzw. SprachtherapeutInnen in ihrem eigenen klinischen Umfeld im Hinblick auf Förderfaktoren und Barrieren für Interprofessionalität berichten können. Neun Pflegefachkräfte und sechs ÄrztInnen von sechs stationären Einrichtungen nahmen an den Interviews teil. Die Auswertung erfolgte mittels der qualitativen Inhaltsanalyse. In den Ergebnissen werden subjektive Sichtweisen auf die koordinierte Zusammenarbeit der unterschiedlichen Berufsgruppen deutlich. Es zeigt sich, dass eine positive und wertschätzende Kommunikationskultur eine wichtige Rolle bei der interprofessionellen Versorgung spielt und die Logopädie/Sprachtherapie als Mitglied im sog. ‚Knotenpunkt-Team‘ geschätzt wird. Davon ausgehend werden Verbesserungspotenziale für den interprofessionellen Austausch diskutiert, die sich auf übergeordnete Rahmenbedingungen, strukturelle Aspekte, persönliche Faktoren und Ausbildungsbedingungen beziehen, sowie Vorschläge für weitere Forschung angesprochen. KW - Kooperation KW - Gesundheit KW - Interprofessionalität KW - qualitative Forschung Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-56068 SN - 0944-405X VL - 30 IS - 4 SP - 266 EP - 276 PB - ProLog, Therapie- und Lernmittel GmbH CY - Köln ER - TY - JOUR A1 - Lenich, Andreas A1 - Bachmeier, S. A1 - Dendorfer, Sebastian A1 - Mayr, E. A1 - Nerlich, Michael A1 - Füchtmeier, Bernd T1 - Development of a test system to analyze different hip fracture osteosyntheses under simulated walking JF - Biomedizinische Technik. Biomedical engineering N2 - 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. KW - biomechanical implant test KW - dynamic multiplanar loading KW - hip fractureg KW - implant migration KW - patient specific loading KW - Hüftgelenk KW - Knochenbruch KW - Osteosynthese KW - Bewegungsanalyse KW - Simulation Y1 - 2012 U6 - https://doi.org/10.1515/bmt-2011-0999 VL - 57 IS - 2 SP - 113 EP - 119 ER - TY - JOUR A1 - Weber, Tim A. A1 - Dendorfer, Sebastian A1 - Grifka, Joachim A1 - Verkerke, Gijsbertus Jacob A1 - Renkawitz, Tobias ED - Takagi, Michiaki T1 - Does Computer-Assisted Femur First THR Improve Musculoskeletal Loading Conditions? JF - BioMed Research International N2 - 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. KW - Hüftgelenkprothese KW - Operationstechnik KW - Computerunterstütztes Verfahren KW - Bewegungsapparat KW - Mechanische Belastung Y1 - 2015 U6 - https://doi.org/10.1155/2015/625317 VL - 2015 SP - ID 625317 ER - TY - JOUR A1 - Pfeifer, Christian A1 - Müller, Michael A1 - Prantl, Lukas A1 - Berner, Arne A1 - Dendorfer, Sebastian A1 - Englert, Carsten T1 - Cartilage labelling for mechanical testing in T-peel configuration JF - International Orthopaedics N2 - 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. KW - Bovine cartilage KW - Cartilage samples KW - Indian ink KW - T-peel configuration KW - Method labeling KW - Knorpel KW - Rind KW - Kennzeichnung KW - Tinte KW - Biomechanik KW - Prüfung Y1 - 2012 U6 - https://doi.org/10.1007/s00264-011-1468-3 VL - 36 IS - 7 SP - 1493 EP - 1499 PB - Springer ER - TY - JOUR A1 - Wong, Christian A1 - Rasmussen, John A1 - Simonsen, Erik B. A1 - Hansen, Lone A1 - de Zee, Mark A1 - Dendorfer, Sebastian T1 - The Influence of Muscle Forces on the Stress Distribution in the Lumbar Spine JF - The Open Spine Journal N2 - Introduction: Previous studies of bone stresses in the human lumbar spine have relied on simplified models when modeling the spinal musculature, even though muscle forces are likely major contributors to the stresses in the vertebral bones. Detailed musculoskeletal spine models have recently become available and show good correlation with experimental findings. A combined inverse dynamics and finite element analysis study was conducted in the lumbar spine to investigate the effects of muscle forces on a detailed musculoskeletal finite element model of the 4th lumbar vertebral body. Materials and Methodology: The muscle forces were computed with a detailed and validated inverse dynamics musculoskeletal spine model in a lifting situation, and were then applied to an orthotropic finite element model of the 4th lumbar vertebra. The results were compared with those from a simplified load case without muscles. Results: In general the von Mises stress was larger by 30%, and even higher when looking at the von Mises stress distribution in the superio-anterior and central part of the vertebral body and in the pedicles. Conclusion: The application of spine muscles to a finite element model showed markedly larger von Mises stress responses in the central and anterior part of the vertebral body, which can be tolerated in the young and healthy spine, but it would increase the risk of compression fractures in the elderly, osteoporotic spine. KW - Lumbar spine KW - Muscle influence KW - Inverse dynamics KW - Finite element analysis KW - Lendenwirbelsäule KW - Muskelkraft KW - Belastung KW - Finite-Elemente-Methode Y1 - 2011 U6 - https://doi.org/10.2174/1876532701103010021 VL - 3 IS - 1 SP - 21 EP - 26 ER - TY - CHAP A1 - Dendorfer, Sebastian A1 - Maier, Hans Jürgen A1 - Hammer, Josef T1 - How do age and anisotropy affect the fatigue behaviour of cancellous bone? T2 - Medicine Meets Engineering N2 - 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. KW - Knochenbruch KW - Spongiosa KW - Alter KW - Anisotropie Y1 - 2008 SP - 68 EP - 74 PB - IOS Press ER - TY - GEN A1 - Auer, Simon A1 - Reinker, Lukas A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Comparing calculated and measured muscle activity of thigh muscles in dynamic motion. T2 - 27th Congress of the European Society of Biomechanics, 26 - 29 June 2022, Porto, Portugal Y1 - 2022 UR - https://drive.google.com/uc?id=1RBguxyHZE-Wr2y6ktOWK06_3lQg2M9Rb&export=download&confirm=t SP - 640 ER - TY - JOUR A1 - Reinker, Lukas A1 - Bläsing, Dominic A1 - Bierl, Rudolf A1 - Ulbricht, Sabina A1 - Dendorfer, Sebastian T1 - Correlation of Acceleration Curves in Gravitational Direction for Different Body Segments during High-Impact Jumping Exercises JF - sensors N2 - Osteoporosis is a common disease of old age. However, in many cases, it can be very well prevented and counteracted with physical activity, especially high-impact exercises. Wearables have the potential to provide data that can help with continuous monitoring of patients during therapy phases or preventive exercise programs in everyday life. This study aimed to determine the accuracy and reliability of measured acceleration data at different body positions compared to accelerations at the pelvis during different jumping exercises. Accelerations at the hips have been investigated in previous studies with regard to osteoporosis prevention. Data were collected using an IMU-based motion capture system (Xsens) consisting of 17 sensors. Forty-nine subjects were included in this study. The analysis shows the correlation between impacts and the corresponding drop height, which are dependent on the respective exercise. Very high correlations (0.83–0.94) were found between accelerations at the pelvis and the other measured segments at the upper body. The foot sensors provided very weak correlations (0.20–0.27). Accelerations measured at the pelvis during jumping exercises can be tracked very well on the upper body and upper extremities, including locations where smart devices are typically worn, which gives possibilities for remote and continuous monitoring of programs. KW - osteoporosis KW - inertial measurement units KW - wearable motion-tracking sensors KW - high-impact exercisess Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-58217 N1 - Corresponding author: Lukas Reinker N1 - This work was supported by the Bavarian Academic Forum [BayWISS-Verbundkolleg Gesundheit] and the DHZK fond for behavioral cardiovascular diseases [Behaviorale kardiovaskuläre Erkrankungen; grand number: 81Z0400105]. VL - 23 IS - 4 PB - MDPI CY - Basel ER - TY - JOUR A1 - Morag, Sarah A1 - Kieninger, Martin A1 - Eissnert, Christoph A1 - Auer, Simon A1 - Dendorfer, Sebastian A1 - Popp, Daniel A1 - Hoffmann, Johannes A1 - Kieninger, Bärbel T1 - Comparison of different techniques for prehospital cervical spine immobilization: Biomechanical measurements with a wireless motion capture system JF - PLOS ONE Y1 - 2023 U6 - https://doi.org/10.1371/journal.pone.0292300 VL - 18 IS - 11 SP - 1 EP - 14 PB - PLOS CY - San Francisco, California ER - TY - GEN A1 - Dendorfer, Sebastian T1 - Patientenindividuelle biomechanisch optimierte Rehabilitation T2 - Primär- und Revisionsendoprothetik des Kniegelenks. Trends und zukünftige Herausforderungen. Regensburg 2023 Y1 - 2023 ER - TY - JOUR A1 - Reinker, Lukas A1 - Dendorfer, Sebastian T1 - Evaluation of acceleration patterns during high-impact jumping exercises JF - Gait & Posture Y1 - 2023 U6 - https://doi.org/10.1016/j.gaitpost.2022.11.051 VL - 100 IS - Supplement 1, March SP - 93 EP - 94 PB - Elsevier CY - Amsterdam [u.a.] ER - TY - JOUR A1 - Melzner, Maximilian A1 - Ismail, Khaled A1 - Rušavy, Zdenek A1 - Kališ, Vladimír A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Musculoskeletal lower back load of accoucheurs during childbirth – A pilot and feasibility study JF - European Journal of Obstetrics & Gynecology and Reproductive Biology N2 - 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. KW - lower back load KW - Accoucheur KW - Musculoskeletal simulation Y1 - 2021 U6 - https://doi.org/10.1016/j.ejogrb.2021.07.042 IS - 264 SP - 306 EP - 313 PB - Elsevier ER - TY - JOUR A1 - Engelhardt, Lucas A1 - Melzner, Maximilian A1 - Havelkova, Linda A1 - Fiala, Pavel A1 - Christen, Patrik A1 - Dendorfer, Sebastian A1 - Simon, Ulrich T1 - A new musculoskeletal AnyBodyTM detailed hand model JF - Computer Methods in Biomechanics and Biomedical Engineering N2 - 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. KW - Musculoskeletal KW - hand KW - AnyBody KW - inverse dynamics KW - moment arm Y1 - 2020 U6 - https://doi.org/10.1080/10255842.2020.1851367 VL - 24 IS - 7 SP - 777 EP - 787 PB - Taylor & Francis ER - TY - GEN A1 - Saffert, Anne-Sophia A1 - Melzner, Maximilian A1 - Dendorfer, Sebastian T1 - Biomechanical Analysis of the Right Elevated Glenohumeral Joint in Violinists during Legato-Playing T2 - Biomdlore 2021: 21-23 October 2021 Vilnius/Trakai, Lithuania N2 - 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. Y1 - 2021 U6 - https://doi.org/10.3233/THC-219001 N1 - Veröffentlicht in: Technology and Health Care, vol. 30, no. 1 (Selected Papers From the 13th International Conference BIOMDLORE 2021), pp. 177-186, 2022 ER - TY - JOUR A1 - Auer, Simon A1 - Schiebl, Jonas A1 - Iversen, Kristoffer A1 - Subhash Chander, Divyaksh A1 - Damsgaard, Michael A1 - Dendorfer, Sebastian T1 - Biomechanical assessment of the design and efficiency of occupational exoskeletons with the AnyBody Modeling System JF - Zeitschrift für Arbeitswissenschaften N2 - Exoskeletons were invented over 100 years ago but have only become popular in the last two decades, especially in the working industry as they can decrease work-related loads significantly. The most often used exoskeletons are for the lower back and shoulder since these are commonly affected body regions. All devices have in common that their purpose is to reduce internal loads of vulnerable body regions. Nevertheless, there is still little understanding on how biomechanical loading in the human body changes when exoskeletons are used. Therefore, further analyses are needed. A promising candidate for these are musculoskeletal models, which are based on an inverse dynamics approach and can calculate external parameters such as ground reaction forces or other interaction forces as well as internal parameters such as joint reaction forces or muscle activities. The various examples in the literature show that these models are increasingly used for assessing the biomechanical effects of exoskeletons on the human body. Furthermore, musculoskeletal models can calculate biomechanical loadings of humans with and without exoskeletons for all kinds of applications and allow an evaluation of their purpose. Practical Relevance: This article highlights the possibilities of musculoskeletal models for assessing the design and efficiency of occupational exoskeletons. Several practical use cases are described along with distinct descriptions of common implications of musculoskeletal and exoskeleton modeling. KW - Biomechanics KW - Ergonomics KW - Motion capture KW - Inverse dynamics Y1 - 2022 U6 - https://doi.org/10.1007/s41449-022-00336-4 N1 - Corresponding author: Sebastian Dendorfer VL - 76 IS - 4 SP - 440 EP - 449 PB - Springer Nature ER - TY - JOUR A1 - Weber, Markus A1 - Suess, Franz A1 - Jerabek, Seth A1 - Meyer, Matthias A1 - Grifka, Joachim A1 - Renkawitz, Tobias A1 - Dendorfer, Sebastian T1 - Kinematic pelvic tilt during gait alters functional cup position in total hip arthroplasty JF - Journal of Orthopaedic Research N2 - 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. KW - component position KW - gait analysis KW - kinematics KW - pelvic tilt KW - total hip arthroplasty KW - Hüftgelenkprothese KW - Haltungsfehler KW - Hüftgelenkpfanne Y1 - 2021 U6 - https://doi.org/10.1002/jor.25106 SN - 1554-527X VL - 40 IS - 4 SP - 846 EP - 853 PB - Wiley ER - TY - JOUR A1 - Melzner, Maximilian A1 - Suess, Franz A1 - Dendorfer, Sebastian T1 - The impact of anatomical uncertainties on the predictions of a musculoskeletal hand model – a sensitivity study JF - Computer Methods in Biomechanics and Biomedical Engineering N2 - 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. KW - Biomechanik KW - Simulation Y1 - 2021 U6 - https://doi.org/10.1080/10255842.2021.1940974 SN - 1476-8259 N1 - Corresponding author: Maximilian Melzner VL - 25 IS - 2 SP - 156 EP - 164 PB - Taylor & Francis ER - TY - JOUR A1 - Auer, Simon A1 - Kubowitsch, Simone A1 - Dendorfer, Sebastian T1 - Kombinierter Einfluss von psychologischen und biomechanischen Faktoren auf die muskulären Belastungen beim Fußballspielen JF - Die Orthopädie N2 - When mental stress and musculoskeletal loading interact, the risk for injury increases due to altered body kinematics and increased muscle tension. These changes can be detected with musculoskeletal models, and mental loading and stress must be analyzed at emotional, cognitive, and behavioral levels. To investigate these kinematic and loading changes under stress, competitive athletes were subjected to mental stress during highly dynamic movements, and musculoskeletal models were used to analyze the biomechanical loading. It was shown that under mental stress, independent of the subjective perception, a strong change in muscle forces can occur. Accordingly, competitive athletes should undergo screenings to assess individual movement patterns and promote general stress resilience. N2 - Für Fußballer:innen stellen muskuläre Verletzungen der unteren Extremitäten ein großes Problem dar. Ein Beispiel hierfür liefert die Nationalmannschaftsstürmerin Alexandra Popp, die aufgrund muskulärer Probleme das EM-Finale 2022 in Wembley kurzfristig verpasste. Oftmals stehen gerade hohe Anspannungssituationen in zeitlichem Zusammenhang mit Verletzungen, der Einfluss der psychischen Beanspruchung auf die biomechanischen Belastungen wird jedoch meist nur wenig beachtet. KW - Biologische Modelle KW - Biomechanik KW - Leistungssportler KW - Bewegung KW - Resilienz, psychologische KW - Biological models KW - Biomechanics KW - Elite athletes KW - Movement KW - Resilience, psychological Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-65113 N1 - Corresponding author: Sebastian Dendorfer VL - 52 IS - 11 SP - 1 EP - 6 PB - Springer ER - TY - JOUR A1 - Melzner, Maximilian A1 - Pfeiffer, Christian A1 - Suess, Franz A1 - Dendorfer, Sebastian T1 - Musculoskeletal simulation of elbow stability for common injury patterns JF - Journal of Orthopaedic Research N2 - Elbow stability is derived from a combination of muscular, ligamentous, and bony structures. After an elbow trauma the stability of the joint is an important decision criterion for the subsequent treatment. The decision regarding non-operative/operative care depends mostly on subjective assessments of medical experts. Therefore, the aim of this study is to use musculoskeletal simulations as an objective assessment tool to investigate the extent to which failure of different stabilizers affects the elbow stability and how these observations correspond to the assessment from clinical practice. A musculoskeletal elbow simulation model was developed for this aim. To investigate the stability of the elbow, varus/valgus moments were applied under 0°, 45°and 90° flexion while the respective cubital angle was analyzed. This was performed for nine different injury scenarios, which were also evaluated for stability by clinical experts. With the results, it can be determined by which injury pattern and under which flexion angle the elbow stability is impaired regarding varus/valgus moments. The scenario with a complete failure of the medial and lateral ligaments and a fracture of the radial head was identified as having the greatest instability. The study presented a numerical determination of elbow stability against varus/valgus moments regarding clinical injury patterns, as well as a comparison of the numerical outcome with experience gained in clinical practice. The numerical predictions agree well with the assessments of the clinical specialists. Thus, the results from musculoskeletal simulation can make an important contribution to a more objective assessment of the elbow stability. KW - AnyBody KW - musculoskeletal simulation KW - elbow stability Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-54819 SN - 1554-527X N1 - Corresponding author: Maximilian Melzner VL - 41 IS - 6 SP - 1356 EP - 1364 PB - Wiley ER - TY - JOUR A1 - Melzner, Maximilian A1 - Engelhardt, Lucas A1 - Simon, Ulrich A1 - Dendorfer, Sebastian T1 - Electromyography-Based Validation of a Musculoskeletal Hand Model JF - Journal of Biomechanical Engineering N2 - 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. KW - Elektromyographie KW - Biomechanik KW - Simulation KW - Electromyography KW - Muscle KW - Musculoskeletal system KW - Signals KW - Simulation Y1 - 2021 U6 - https://doi.org/10.1115/1.4052115 VL - 144 IS - 2 PB - American Society of Mechanical Engineers, ASME ER - TY - JOUR A1 - Saffert, Anne-Sophie A1 - Melzner, Maximilian A1 - Dendorfer, Sebastian T1 - Biomechanical analysis of the right elevated glenohumeral joint in violinists during legato-playing JF - Technology and Health Care N2 - 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. KW - Biomechanische Analyse KW - Schultergelenk KW - Verletzung KW - Violinspiel KW - biomechanics KW - violin KW - shoulder elevation KW - shoulder joint force KW - musculoskeletal disease Y1 - 2022 U6 - https://doi.org/10.3233/THC-219001 N1 - Corresponding author: Anne-Sophie Saffert VL - 30 IS - 1 SP - 177 EP - 186 PB - IOS Press ER - TY - JOUR A1 - Förstl, Nikolas A1 - Süß, Franz A1 - Englert, Carsten A1 - Dendorfer, Sebastian T1 - Design of a reverse shoulder implant to measure shoulder stiffness during implant component positioning JF - Medical Engineering & Physics N2 - To avoid dislocation of the shoulder joint after reverse total shoulder arthroplasty, it is important to achieve sufficient shoulder stability when placing the implant components during surgery. One parameter for assessing shoulder stability can be shoulder stiffness. The aim of this research was to develop a temporary reverse shoulder implant prototype that would allow intraoperative measurement of shoulder stiffness while varying the position of the implant components. Joint angle and torque measurement techniques were developed to determine shoulder stiffness. Hall sensors were used to measure the joint angles by converting the magnetic flux densities into angles. The accuracy of the joint angle measurements was tested using a test bench. Torques were determined by using thin-film pressure sensors. Various mechanical mechanisms for variable positioning of the implant components were integrated into the prototype. The results of the joint angle measurements showed measurement errors of less than 5° in a deflection range of ±15° adduction/abduction combined with ±45° flexion/extension. The proposed design provides a first approach for intra-operative assessment of shoulder stiffness. The findings can be used as a technological basis for further developments. Y1 - 2023 U6 - https://doi.org/10.1016/j.medengphy.2023.104059 N1 - Corresponding author: Sebstian Dendorfer VL - 121 PB - Elsevier ET - Journal Pre-proof ER - TY - CHAP A1 - Suess, Franz A1 - Melzner, Maximilian A1 - Dendorfer, Sebastian T1 - Towards ergonomics working - machine learning algorithms and musculoskeletal modeling T2 - IOP Conference Series: Materials Science and Engineering N2 - 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. Y1 - 2021 U6 - https://doi.org/10.1088/1757-899X/1208/1/012001 SN - 1757-899X N1 - Corresponding author: Sebastian Dendorfer VL - 1208 PB - IOP Publishing ER - TY - JOUR A1 - Dendorfer, Sebastian A1 - Gschoßman, Lukas T1 - Hightech in der Rehabiliation JF - BVOU Infobrief: Hightech in Orthopädie und Unfallchirurgie N2 - Aufgrund der steigenden Lebenserwartung und dem damit einhergehenden demographischen Wandel wird der Bedarf an Rehabilitations-Behandlungen in absehbarer Zukunft stark ansteigen. Ein Beispiel für diesen Trend ist die physiotherapeutische Behandlung nach Erhalt einer Knie-Totalendoprothese (Knie-TEP). So gehen Modellrechnungen basierend auf dem Bevölkerungswachstum und der bisherigen Prävalenz von Knie-TEPs davon aus, dass die Anzahl an durchgeführten Eingriffen in einkommensstarken Ländern wie Deutschland weiter zunehmen wird. Weiterhin stoßen traditionelle Rehabilitationsverfahren, gerade in strukturschwachen Regionen, schon heute an ihre Grenzen. Deutlich zu sehen war das während den Hochphasen der aktuellen Covid-19-Pandemie, als der Kontakt zwischen Therapeut*in und Patient*in flächendeckend eingeschränkt war. Eine erhöhte Nachfrage nach neuartigen Reha-Angeboten ist die logische Konsequenz. Innovative Konzepte sind daher dringend notwendig, um die daraus resultierenden technischen, sozialen und ökonomischen Herausforderungen zu bewältigen. Y1 - 2023 UR - https://www.bvou.net/infobrief-1-23/ SN - 2747-5913 IS - 1 SP - 9 EP - 11 PB - BVOU – Berufsverband für Orthopädie und Unfallchirurgie e.V. CY - Berlin ER - TY - JOUR A1 - Brébant, Vanessa A1 - Weiherer, Maximilian A1 - Noisser, Vivien A1 - Seitz, Stephan A1 - Prantl, Lukas A1 - Eigenberger, Andreas T1 - Implants Versus Lipograft: Analysis of Long-Term Results Following Congenital Breast Asymmetry Correction JF - Aesthetic Plastic Surgery N2 - Aims Congenital breast asymmetry represents a particular challenge to the classic techniques of plastic surgery given the young age of patients at presentation. This study reviews and compares the long-term results of traditional breast augmentation using silicone implants and the more innovative technique of lipografting. Methods To achieve this, we not only captured subjective parameters such as satisfaction with outcome and symmetry, but also objective parameters including breast vol-ume and anthropometric measurements. The objective examination was performed manually and by using the Vectra H2 photogrammetry scanning system. Results Differences between patients undergoing either implant augmentation or lipograft were revealed not to be significant with respect to patient satisfaction with surgical outcome (p= 0.55) and symmetry (p= 0.69). Furthermore, a breast symmetry of 93 % was reported in both groups. Likewise, no statistically significant volume difference between the left and right breasts was observed in both groups (p\0.41). However, lipograft patients needed on average 2.9 procedures to achieve the desired result, compared with 1.3 for implant augmentation. In contrast, patients treated with implant augmentation may require anumber of implant changes during their lifetime. Conclusion Both methods may be considered for patients presenting with congenital breast asymmetry. KW - Congenital Breast Asymmetry KW - 3D volumetry KW - Autologous fat injections KW - Three-dimensional imaging KW - Lipograft Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-32404 VL - 46 SP - 2228 EP - 2236 PB - Springer Nature ER - TY - GEN A1 - Krefting, Dagmar A1 - Zaunseder, Sebastian A1 - Säring, Dennis A1 - Wittenberg, Thomas A1 - Palm, Christoph A1 - Schiecke, Karin A1 - Krenkel, Lars A1 - Hennemuth, Anja A1 - Schnell, Susanne A1 - Spicher, Nicolai T1 - Blutdruck, Hämodynamik und Gefäßzustand: Innovative Erfassung und Bewertung – Schwerpunkt bildbasierte Verfahren T2 - 66. Jahrestagung der Deutschen Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie e. V. (GMDS), 12. Jahreskongress der Technologie- und Methodenplattform für die vernetzte medizinische Forschung e. V. (TMF), 26. - 30.09.2021, online N2 - Einleitung: Blutdruck gilt als sogenannter Vitalparameter als einer der grundlegenden Indikatoren für den Gesundheitszustand einer Person. Sowohl zu niedriger als auch zu hoher Blutdruck kann lebensbedrohend sein, letzerer ist darüber hinaus ein Risikofaktor insbesondere für Herz-Kreislauferkrankungen, die trotz wichtiger Fortschritte in der Behandlung immer noch die häufigste Todesursache in Deutschland darstellen. Die Hämodynamik, also die raumzeitliche Dynamik des Blutflusses, und der Gefäßzustand sind eng verbunden mit dem Blutdruck und ebenfalls von hoher klinischer Relevanz, u.a. zur Identifikation von Durchblutungsstörungen und ungünstigen Druckverteilungen der Gefäßwand. Innovationen in der Messtechnik als auch in der Datenanalyse bieten heute neue Möglichkeiten der Erfassung und Bewertung von Blutdruck, Hämodynamik und Gefäßzustand [1], [2], [3], [4]. Methodik: In einer gemeinsamen Workshopserie der AG Medizinische Bild- und Signalverarbeitung der GMDS und des Fachausschusses Biosignale der DGBMT werden wir neue Ansätze und Lösungen für Mess- und Analyseverfahren zu Blutdruck und -fluss sowie zum Gefäßzustand vorstellen und diskutieren. Dabei stehen im ersten Workshop auf der GMDS Jahrestagung Bildbasierte Verfahren im Zentrum, während der zweite Workshop auf der DGBMT Jahrestagung den Fokus auf Biosignalbasierten Verfahren legt. Es werden aktuelle Forschungsergebnisse vorgestellt und diskutiert. Es sind jeweils mehrere Vorträge geplant mit ausreichend Zeit zur Diskussion. Folgende Vorträge sind geplant (Arbeitstitel): Sebastian Zaunseder: Videobasierte Erfassung des Blutdrucks Anja Hennemuth: A Visualization Toolkit for the Analysis of Aortic Anatomy and Pressure Distribution Lars Krenkel: Numerische Analyse der Rupturwahrscheinlichkeit zerebraler Aneurysmata Susanne Schnell: Messung des Blutflusses und hämodynamischer Parameter mit 4D flow MRI: Möglichkeiten und Herausforderungen Ergebnisse: Ziel des Workshops ist die Identifikation von innovativen Ansätzen und neuen Methoden zur qualitativen und quantitativen Bestimmung von hämodynamischen Parametern sowie deren kritische Bewertung durch die Community für die Eignung in der klinischen Entscheidungsunterstützung. Diskussion: Der Workshop leistet inhaltlich einen Beitrag zu zentralen Aspekten für die Herz-Kreislauf-Medizin. Er bringt dabei Expertise aus verschiedenen Bereichen zusammen und schlägt die Brücke zwischen Kardiologie, Medizininformatik und Medizintechnik. Schlussfolgerung: Innovative Technologien aus Medizintechnik und Informatik ermöglichen zunehmend einfache und raumzeitlich aufgelöste Erfassung und Bewertung wichtiger Informationen zur Unterstützung von Diagnose und Therapieverfolgung. [1] Zaunseder S, Trumpp A, Wedekind D, Malberg H. Cardiovascular assessment by imaging photoplethysmography - a review. Biomed Tech (Berl). 2018 Oct 25;63(5):617–34. [2] Huellebrand M, Messroghli D, Tautz L, Kuehne T, Hennemuth A. An extensible software platform for interdisciplinary cardiovascular imaging research. Comput Methods Programs Biomed. 2020 Feb;184:105277. [3] Schmitter S, Adriany G, Waks M, Moeller S, Aristova M, Vali A, et al. Bilateral Multiband 4D Flow MRI of the Carotid Arteries at 7T. Magn Reson Med. 2020 Oct;84(4):1947–60. [4] Birkenmaier C, and Krenkel, L. Flow in Artificial Lungs. In: New Results in Numerical and Experimental Fluid Mechanics XIII. Contributions to the 22nd STAB/DGLR Symposium. Springer; 2021. KW - Bildbasierte Verfahren KW - Blutdruck KW - Hämodynamik KW - Blutgefäß KW - Bildgebendes Verfahren Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0183-21gmds0167 ER - TY - JOUR A1 - Schaeffer, Leon A1 - Herrmann, David A1 - Schratzenstaller, Thomas A1 - Dendorfer, Sebastian A1 - Böhm, Valter T1 - Preliminary theoretical considerations on the stiffness characteristics of a tensegrity joint for the use in dynamic orthoses JF - Journal of Medical Robotics Research N2 - Early motion therapy plays an important role for effective long-term healing of joint injuries. In many cases, conventional dynamic orthoses fail to address the intricate movement possibilities of the underlying joints, limited by their simplistic joint representations, often represented by revolute joints, enabling rotations by only one axis. In this paper, a two-dimensional compliant tensegrity joint for use in biomedical applications is investigated. It consists of two compressed members and five compliant tensioned members. Relative movement possibilities are realized by the intrinsic compliance of the structure. In the development of these systems, the first step is the determination of the static stable equilibrium. This analysis is conducted in this paper by considering the potential energy approach or by using the geometric nonlinear finite element method. The mechanical behavior of the structure is assessed with a specific emphasis on its mechanical compliance. The primary objective of this study is the investigation of the influence of structural parameters on the overall stiffness and movability of the structure. The results underscore the significant effect of member parameters on the stiffness and movability of the compliant tensegrity joint, particularly under varying load magnitudes. These findings provide insights for optimizing the joint’s performance, contributing to its potential application in advanced orthotic and exoskeleton devices. KW - mechanical compliance KW - flexibility ellipsis KW - form-finding KW - tensegrity joint Y1 - 2023 U6 - https://doi.org/10.1142/S2424905X23400081 PB - World Scientific ER - TY - GEN A1 - Dendorfer, Sebastian T1 - Muskuloskelettale Simulation - Implikationen für die Hüftendoprothetik T2 - Primär- und Revisionsendoprothetik des Hüftgelenks Trends und zukünftige Herausforderungen, 11.-12.11.2022, OTH Ostbayerische Technische Hochschule, Regensburg Y1 - 2022 ER -