TY - JOUR A1 - Sellmer, Andreas A1 - Stangl, Hubert A1 - Beyer, Mandy A1 - Grünstein, Elisabeth A1 - Leonhardt, Michel A1 - Pongratz, Herwig A1 - Eichhorn, Emerich A1 - Elz, Sigurd A1 - Striegl, Birgit A1 - Jenei-Lanzl, Zsuzsa A1 - Dove, Stefan A1 - Straub, Rainer H. A1 - Krämer, Oliver H. A1 - Mahboobi, Siavosh T1 - Marbostat-100 Defines a New Class of Potent and Selective Antiinflammatory and Antirheumatic Histone Deacetylase 6 Inhibitors JF - Journal of medicinal chemistry N2 - Epigenetic modifiers of the histone deacetylase (HDAC) family contribute to autoimmunity, cancer, HIV infection, inflammation, and neurodegeneration. Hence, histone deacetylase inhibitors (HDACi), which alter protein acetylation, gene expression patterns, and cell fate decisions, represent promising new drugs for the therapy of these diseases. Whereas pan-HDACi inhibit all 11 Zn2+-dependent histone deacetylases (HDACs) and cause a broad spectrum of side effects, specific inhibitors of histone deacetylase 6 (HDAC6i) are supposed to have less side effects. We present the synthesis and biological evaluation of Marbostats, novel HDAC6i that contain the hydroxamic acid moiety linked to tetrahydro-β-carboline derivatives. Our lead compound Marbostat-100 is a more potent and more selective HDAC6i than previously established well-characterized compounds in vitro as well as in cells. Moreover, Marbostat-100 is well tolerated by mice and effective against collagen type II induced arthritis. Thus, Marbostat-100 represents a most selective known HDAC6i and the possibility for clinical evaluation of a HDAC isoform-specific drug. KW - Animals KW - anti-Inflammatory agent KW - chemical synthesis KW - pharmacology KW - therapeutic use KW - toxicity Y1 - 2018 U6 - https://doi.org/10.1021/acs.jmedchem.7b01593 VL - 61 IS - 8 SP - 3454 EP - 3477 PB - ACS Publications ER - TY - GEN A1 - Baldaranov, Dobri A1 - Kilic, Mustafa A1 - Pflug, Kenny A1 - Theiss, Stephan A1 - Leis, Alexander A1 - Pemmerl, Josef A1 - Pels, Hendrik A1 - Boy, Sandra A1 - Bogdahn, Ulrich A1 - Schlachetzki, Felix T1 - Prehospital stroke education in paramedics T2 - European Journal of Neurology N2 - Background and aims: Rapid pre-hospital identification of stroke symptoms result in therapy directed admission to dedicated stroke units. Widespread application of stroke scales reveal high sensitivity but low specificity, especially in non-academic first aid personal. In our previous work we show that prehospital stroke diagnostics based on neurolo-gical examination and transcranial color-coded Duplex so-nography (TCCS) is feasible and results in high sensitivity and specificity for middle cerebral artery / distal internal carotid artery occlusion. The aim of our ongoing study is to design and evaluate a dedicated stroke educational program for paramedics including transcranial ultrasound. This is a prerequisite for a telemedical decision support system in the absence of stroke experienced emergency doctors. Methods: We currently educate 6 paramedics in advanced stroke neurology and also transcranial ultrasound examina-tion during a course of 2 months. The web-based curricu-lum was designed in two parts. The first was theoretical and the second will be the real-life training under neurological supervision. For final assessment of the theoretical know-ledge a control group will be implemented without specific stroke expertise. The stroke-educated paramedics will have to assist stroke investigation, perform pre-hospital TCCS and enter the date in a mobile telestroke pad. The data set will be send to an in-hospital stroke physician. We will as-sess the mean time to reach the diagnostic assessment, its sensitivity and specificity and the patient outcome after 30 days. Results: Our study is ongoing Conclusion: The study just reach the 2 part and we will be glad to present our data on the meeting EAN 2015. Disclosure: Nothing to disclose Y1 - 2015 VL - 22 IS - Suppl. 1 SP - 800 PB - Wiley ER - TY - JOUR A1 - Widbiller, Matthias A1 - Keim, Lukas A1 - Schlichting, Ralf A1 - Striegl, Birgit A1 - Hiller, Karl-Anton A1 - Jungbauer, Rebecca A1 - Buchalla, Wolfgang A1 - Galler, Kerstin M. T1 - Debris Removal by Activation of Endodontic Irrigants in Complex Root Canal Systems BT - A Standardized In-Vitro-Study JF - Applied Sciences N2 - Aim of the study was to develop a standardized model system to investigate endodontic irrigation techniques and assess the efficiency of different activation methods on the removal of hard tissue debris in complex root canal systems. Mesial roots of mandibular molars were firstly scanned by micro-computed tomography (µCT) and allocated to three groups of irrigant activation: sonic activation (EDDY, VDW, Munich, Germany), laser activation (AutoSWEEPS, FOTONA, Ljubljana, Slovenia) and conventional needle irrigation (control). Roots were fixed in individual 3D-printed holders to facilitate root canal enlargement under constant irrigation with NaOCl (5%). To enable standardized quantification of remaining debris, BaSO4-enriched dentine powder was compacted into the canals, followed by another µCT-scan. The final irrigation was performed using 17% ethylenediaminetetraacetic acid (EDTA) and 5% sodium hypochlorite (NaOCl) with the respective activation method, and the volume of remaining artificial debris was quantified after a final µCT-scan. The newly developed model system allowed for reliable, reproducible and standardized assessment of irrigation methods. Activation of the irrigant proved to be significantly more effective than conventional needle irrigation regarding the removal of debris, which persisted particularly in the apical third of the root canal in the control group. The efficiency of irrigation was significantly enhanced with laser- and sonic-based activation, especially in the apical third. Y1 - 2021 U6 - https://doi.org/10.3390/app11167331 VL - 11 IS - 16 SP - 1 EP - 14 PB - MDPI CY - Basel ER - TY - JOUR A1 - Huber, Michaela A1 - Schlosser, Daniela A1 - Stenzel, Susanne A1 - Maier, Johannes A1 - Pattappa, Girish A1 - Kujat, Richard A1 - Striegl, Birgit A1 - Docheva, Denitsa T1 - Quantitative Analysis of Surface Contouring with Pulsed Bipolar Radiofrequency on Thin Chondromalacic Cartilage JF - BioMed Research International N2 - The purpose of this study was to evaluate the quality of surface contouring of chondromalacic cartilage by bipolar radio frequency energy using different treatment patterns in an animal model, as well as examining the impact of the treatment onto chondrocyte viability by two different methods. Our experiments were conducted on 36 fresh osteochondral sections from the tibia plateau of slaughtered 6-month-old pigs, where the thickness of the cartilage is similar to that of human wrist cartilage. An area of 1 cm(2) was first treated with emery paper to simulate the chondromalacic cartilage. Then, the treatment with RFE followed in 6 different patterns. The osteochondral sections were assessed for cellular viability (live/dead assay, caspase (cell apoptosis marker) staining, and quantitative analysed images obtained by fluorescent microscopy). For a quantitative characterization of none or treated cartilage surfaces, various roughness parameters were measured using confocal laser scanning microscopy (Olympus LEXT OLS 4000 3D). To describe the roughness, the Root-Mean-Square parameter (Sq) was calculated. A smoothing effect of the cartilage surface was detectable upon each pattern of RFE treatment. The Sq for native cartilage was Sq=3.8 +/- 1.1 mu m. The best smoothing pattern was seen for two RFE passes and a 2-second pulsed mode (B2p2) with an Sq=27.3 +/- 4.9 mu m. However, with increased smoothing, an augmentation in chondrocyte death up to 95% was detected. Using bipolar RFE treatment in arthroscopy for small joints like the wrist or MCP joints should be used with caution. In the case of chondroplasty, there is a high chance to destroy the joint cartilage. KW - CHONDROCYTE DEATH KW - energy KW - HUMAN ARTICULAR-CARTILAGE KW - MONOPOLAR KW - THERMAL CHONDROPLASTY Y1 - 2020 U6 - https://doi.org/10.1155/2020/1242086 SP - 1 EP - 8 PB - HINDAWI ER - TY - JOUR A1 - Schroeder, Florian A1 - Polzer, Stanislav A1 - Slažanský, Martin A1 - Man, Vojtěch A1 - Skácel, Pavel T1 - Predictive capabilities of various constitutive models for arterial tissue JF - Journal of the Mechanical Behavior of Biomedical Materials N2 - Introduction Aim of this study is to validate some constitutive models by assessing their capabilities in describing and predicting uniaxial and biaxial behavior of porcine aortic tissue. Methods 14 samples from porcine aortas were used to perform 2 uniaxial and 5 biaxial tensile tests. Transversal strains were furthermore stored for uniaxial data. The experimental data were fitted by four constitutive models: Holzapfel-Gasser-Ogden model (HGO), model based on generalized structure tensor (GST), Four-Fiber-Family model (FFF) and Microfiber model. Fitting was performed to uniaxial and biaxial data sets separately and descriptive capabilities of the models were compared. Their predictive capabilities were assessed in two ways. Firstly each model was fitted to biaxial data and its accuracy (in term of R2 and NRMSE) in prediction of both uniaxial responses was evaluated. Then this procedure was performed conversely: each model was fitted to both uniaxial tests and its accuracy in prediction of 5 biaxial responses was observed. Results Descriptive capabilities of all models were excellent. In predicting uniaxial response from biaxial data, microfiber model was the most accurate while the other models showed also reasonable accuracy. Microfiber and FFF models were capable to reasonably predict biaxial responses from uniaxial data while HGO and GST models failed completely in this task. Conclusions HGO and GST models are not capable to predict biaxial arterial wall behavior while FFF model is the most robust of the investigated constitutive models. Knowledge of transversal strains in uniaxial tests improves robustness of constitutive models. KW - Arterial biomechanics KW - Constitutive modeling KW - Mechanical testing KW - Uniaxial – biaxial tension Y1 - 2018 U6 - https://doi.org/10.1016/j.jmbbm.2017.11.035 VL - 78 IS - February SP - 369 EP - 380 PB - Elsevier ER - TY - CHAP A1 - Geith, Markus A. A1 - Sommer, Gerhard A1 - Schratzenstaller, Thomas A1 - Holzapfel, Gerhard A. T1 - First Approaches in Quantifying Acute Vascular Damage due to Stenting T2 - 23rd Congress of the European Society of Biomechanics, July 2-5,2017, Seville, Spain KW - Stent KW - Implantation KW - Gefäßverletzung Y1 - 2017 ER - TY - JOUR A1 - Geith, Markus A. A1 - Eckmann, Jakob D. A1 - Haspinger, Daniel Ch. A1 - Agrafiotis, Emmanouil A1 - Maier, Dominik A1 - Szabo, Patrick A1 - Sommer, Gerhard A1 - Schratzenstaller, Thomas A1 - Holzapfel, Gerhard A. T1 - Experimental and mathematical characterization of coronary polyamide-12 balloon catheter membranes JF - PLoS One N2 - The experimental quantification and modeling of the multiaxial mechanical response of polymer membranes of coronary balloon catheters have not yet been carried out. Due to the lack of insights, it is not shown whether isotropic material models can describe the material response of balloon catheter membranes expanded with nominal or higher, supra-nominal pressures. Therefore, for the first time, specimens of commercial polyamide-12 balloon catheters membranes were investigated during uniaxial and biaxial loading scenarios. Furthermore, the influence of kinematic effects on the material response was observed by comparing results from quasi-static and dynamic biaxial extension tests. Novel clamping techniques are described, which allow to test even tiny specimens taken from the balloon membranes. The results of this study reveal the semi-compliant, nonlinear, and viscoelastic character of polyamide-12 balloon catheter membranes. Above nominal pressure, the membranes show a pronounced anisotropic mechanical behavior with a stiffer response in the circumferential direction. The anisotropic feature intensifies with an increasing strain-rate. A modified polynomial model was applied to represent the realistic mechanical response of the balloon catheter membranes during dynamic biaxial extension tests. This study also includes a compact set of constitutive model parameters for the use of the proposed model in future finite element analyses to perform more accurate simulations of expanding balloon catheters. KW - Catheters KW - Anisotropy KW - Polymers KW - Viscoelasticity KW - Coronary stenting KW - Finite element analysis KW - Deformation KW - Adhesives Y1 - 2020 U6 - https://doi.org/10.1371/journal.pone.0234340 VL - 15 IS - 6 SP - 1 EP - 22 PB - PLOS ER - TY - JOUR A1 - Geith, Markus A. A1 - Swidergal, Krzysztof A1 - Hochholdinger, Bernd A1 - Schratzenstaller, Thomas A1 - Wagner, Marcus A1 - Holzapfel, Gerhard A. T1 - On the importance of modeling balloon folding, pleating, and stent crimping: An FE study comparing experimental inflation tests JF - International Journal for Numerical Methods in Biomedical Engineering N2 - Finite element (FE)–based studies of preoperative processes such as folding,pleating, and stent crimping with a comparison with experimental inflation tests are not yet available. Therefore, a novel workflow is presented in which residual stresses of balloon folding and pleating, as well as stent crimping, and the geometries of all contact partners were ultimately implemented in an FE code to simulate stent expansion by using an implicit solver. The numerical results demonstrate that the incorporation of residual stresses and strains experienced during the production step significantly increased the accuracy of the subsequent simulations, especially of the stent expansion model. During the preoperative processes, stresses inside the membrane and the stent material also reached a rather high level. Hence, there can be no presumption that balloon catheters or stents are undamaged before the actual surgery. The implementation of the realistic geometry, in particular the balloon tapers, and the blades of the process devices improved the simulation of the expansion mech-anisms, such as dogboning, concave bending, or overexpansion of stent cells. This study shows that implicit solvers are able to precisely simulate the mentioned preoperative processes and the stent expansion procedure without a preceding manipulation of the simulation time or physical mass. KW - Catheter KW - Coronary KW - Crimping KW - Finite element KW - Stent KW - Stent KW - Implantation KW - Simulation KW - Finite-Elemente-Methode Y1 - 2019 U6 - https://doi.org/10.1002/cnm.3249 N1 - This study was funded by the Bavarian Research Foundation within the project “PIZ‐225‐18” VL - 35 IS - 11 PB - Wiley 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 - 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 - JOUR A1 - Prantl, Lukas A1 - Eigenberger, Andreas A1 - Reinhard, Ruben A1 - Siegmund, Andreas A1 - Heumann, Kerstin A1 - Felthaus, Oliver T1 - Cell-Enriched Lipotransfer (CELT) Improves Tissue Regeneration and Rejuvenation without Substantial Manipulation of the Adipose Tissue Graft JF - Cells N2 - The good availability and the large content of adult stem cells in adipose tissue has made it one of the most interesting tissues in regenerative medicine. Although lipofilling is one of the most frequent procedures in plastic surgery, the method still struggles with high absorption rates and volume losses of up to 70%. Therefore, many efforts have been made to optimize liposuction and to process the harvested tissue in order to increase fat graft retention. Because of their immunomodulatory properties, their cytokine secretory activity, and their differentiation potential, enrichment with adipose tissue-derived stem cells was identified as a promising tool to promote transplant survival. Here, we review the important parameters for lipofilling optimization. Finally, we present a new method for the enrichment of lipoaspirate with adipose tissue-derived stem cells and discuss the parameters that contribute to fat graft survival. Y1 - 2022 U6 - https://doi.org/10.3390/cells11193159 VL - 11 IS - 19 SP - 1 EP - 11 PB - MDPI 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 - JOUR A1 - Hausleiter, Jörg A1 - Kastrati, Adnan A1 - Wessely, Rainer A1 - Dibra, Alban A1 - Mehilli, Julinda A1 - Schratzenstaller, Thomas A1 - Graf, Isolde A1 - Renke-Gluszko, Magdalena A1 - Behnisch, Boris A1 - Dirschinger, Josef A1 - Wintermantel, Erich A1 - Schömig, Albert T1 - Prevention of restenosis by a novel drug-eluting stent system with a dose-adjustable, polymer-free, on-site stent coating JF - European Heart Journal - Clinical research N2 - Aims Drug-eluting stents (DES) represent a major advance in interventional cardiology. Along with the success shown, current DES also present limitations related to the presence of polymer-coating, fixed drug, and dose used. With the ISAR (Individualized Drug-Eluting Stent System to Abrogate Restenosis) project, a DES system has been developed that permits individualized choice of the drug and dose to use for the given patient. The objective of this prospective dose finding study was to assess the feasibility, safety, and efficacy of a polymer-free on-site stent coating with increasing rapamycin doses. Methods and results In this dose finding study, 602 patients were sequentially enrolled in four groups: microporous bare metal stent (BMS), DES stents coated with a 0.5, 1.0, and 2.0% rapamycin solution. The angiographic in-segment restenosis rate at follow-up angiography was the primary study endpoint. In-segment restenosis was significantly reduced from 25.9% with BMS to 18.9, 17.2, and 14.7% with 0.5, 1.0, and 2.0% rapamycin-eluting stents, respectively (P=0.024). Similarly, the need for target lesion revascularization at 1 year follow-up was reduced from 21.5% with BMS to 16.4, 12.6, and 8.8% with 0.5, 1.0, and 2.0% rapamycin-eluting stents, respectively (P=0.006). Conclusion The placement of polymer-free stents coated on-site with rapamycin is feasible and safe. Furthermore, a dose-dependent efficacy in restenosis prevention is achievable with this new DES concept. KW - Restenosis KW - Stents KW - Randomized KW - Rapamycin KW - Polymer Y1 - 2005 U6 - https://doi.org/10.1093/eurheartj/ehi405 VL - 26 IS - 15 SP - 1475 EP - 1481 ER - TY - GEN A1 - Singh, Max Diamond T1 - MDR Implementation Status and Lessons Learned from the Past Months: A Notified Body Perspective T2 - Cambridge Healthtech Institute's 2nd Annual Medical Device Clinical Trial Design and Operations: Trial Design and Technology to Optimize Medical Device Trials, Orlando, Florida + Virtual, 02.-03.03.2021 Y1 - PB - Cambridge Innovation Institute ER - TY - GEN A1 - Singh, Max Diamond T1 - MDR implementation status & lessons learned BT - MDR-Audtis – Best Practive & Learning, Tuttlingen, 10.02.2021 Y1 - 2021 ER - TY - JOUR A1 - Singh, Max Diamond A1 - Russ, Jochen A1 - Terzidis, Orestis T1 - The Impact of the ObamaCare Excise Tax on Innovation and Entrepreneurship – Early Empirical Findings JF - International Journal of Innovation Science N2 - This study addresses aspects of governmental influence on innovation by analyzing the impact of the ObamaCare excise tax on the medical device industry. We initially give an overview of common approaches to measuring innovativeness and entrepreneurship, empirically assess whether existing metrics are suitable for investigating the innovation performance of the U.S. medical device industry, and define a new measure (firm innovation activity) for entrepreneurship. Then we perform a quantitative analysis to explore the impact of the tax. We analyze more than 60,000 product clearances from 1996 to 2013, using the FDA database. We find a significant relationship between product counts and revenues for one segment. Contrary to the present criticism of the excise tax, we find hardly any noteworthy response in either firm innovation activity or number of products launched in the year after the tax was introduced. The 2013 reduction of new product submissions is well within the limits of typical annual fluctuations observed in previous years. This provides a first indication that the excise tax act did not have a strong impact on innovative activities through the present. Y1 - 2015 U6 - https://doi.org/10.1260/1757-2223.7.2.75 VL - 7 IS - 2 SP - 75 EP - 90 PB - Emerald ER - TY - GEN A1 - Singh, Max Diamond T1 - European Union MDRs impact on device manufacturers: Reprocessing of surgical invasive devices, critical timeliness and technical documentation requirements under MDR BT - [Vortrag gehalten am 26.03.2019] T2 - The validation of sterile medical devices: sterilization, packaging, biocompatibility, toxicology and reprocessing, Amsterdam, 26.03. - 28.03.2019 [Veranstalter: Nelson Labs ; Sterigenics] Y1 - 2019 ER - TY - GEN A1 - Singh, Max Diamond T1 - Challenges to innovate in the medical device industry under the light of the new EU MDR : a notified body perspective BT - Keynote Presentation. - Amsterdam, 21.-22.11.2019 // [Veranstalter: Samtek Group] T2 - Intelligent medical devices - the next disruptor in healthcare ; challenges and oppoertunieties: technical, clinical, regulatory and health economics/market access Y1 - 2019 ER - TY - GEN A1 - Singh, Max Diamond T1 - Zusätzliche Anforderungen an Produktdaten und technische Dokumentation durch die MDR T2 - Medizintechnik Kongress 2018: Effizienz in der Medizinprodukteentwicklung vor dem Hintergrund von MDR und IVDR ; Frankfurt am Main, 08.11.2018, [Veranstalter: Velten Consulting & ILC Consulting] Y1 - 2018 ER - TY - GEN A1 - Singh, Max Diamond T1 - EU-MDR from a Notified Body Perspective - aktuelle Situation hinsichtlich der Anforderungen zum Lieferantenmanagement BT - Tuttlingen, Technology Mountains / Medical Mountains, 2019 Y1 - 2019 ER - TY - GEN A1 - Singh, Max Diamond T1 - EU Medical Device Regulation: Top Challenges of Orthopedic Manufacturers T2 - OMTEC 2019 : 15th Annual Orthopedic Manufacturing & Technology Exposition and Conference, Chicago, 11.6.2019 Y1 - 2019 ER - TY - GEN A1 - Singh, Max Diamond T1 - Conformity Assessment Procedure MDR BT - [Vortrag gehalten am 24.02.2020] T2 - MDR Training: Person Responsible for Regulatory Compliance Course, 24.-25.02.2020, Tel Aviv, Obelis Academy Y1 - 2020 ER - TY - GEN A1 - Singh, Max Diamond T1 - Managing Innovation from the Notified Body Perspective - Understanding the 3 C’s of EU Regulations to Ensure Product Compliance: Changes, Challenges and Contributions T2 - 3rd annual european medical device and diagnostic product development and management meeting, 12-13 February 2019, Brussels Y1 - 2019 ER - TY - GEN A1 - Singh, Max Diamond T1 - Notified body feedback: PSUR Forms. Post Market Surveillance & Vigilance BT - [Vortrag gehalten am 24.06.2020] T2 - MedTech Summit 2020: EU MDR & IVDR: the end is in sight, Dublin/virtual, 20.-26.06.2020 Y1 - 2020 ER - TY - GEN A1 - Singh, Max Diamond T1 - MDR - Die neuen rechtlichen Bedingungen für Händler und Hersteller: aus der Sicht einer benannten Stelle T2 - MEGRA Jahrestagung. - Wien, 18.05.2020 [Veranstalter: Mitteleuropäische Gesellschaft für Regulatory Affairs] Y1 - 2020 ER - TY - GEN A1 - Singh, Max Diamond T1 - Innovation challenges for orthopedic device manufacturers under the new EU MDR BT - a notified body perspective T2 - ORS (Orthopaedic Research Society) Annual Meeting. - Phoenix, Arizona, 08. - 11.02.2020 Y1 - 2020 ER - TY - GEN A1 - Singh, Max Diamond T1 - KARL STORZ Navigation Panel Unit - Navigation for ENT surgery T2 - FESS 2010 : International Workshop on FESS ; Lectures & Live Surgery. - Royal Pearl Hospital, Tiruchirappalli (Indien), 10.-11.04.2010 Y1 - 2010 ER - TY - GEN A1 - Singh, Max Diamond T1 - Medical Device Regulation BT - Kurzer Überblick zur Zulassung von Medizinprodukten T2 - Forum MedTech Pharma: Start-ups in der Medizintechnik: Besonderheiten und Fallbeispiele, München, 17.7.2019 Y1 - 2019 ER - TY - GEN A1 - Singh, Max Diamond T1 - Market Access for Devices under MDD and MDR: Obligations for Manufacturers T2 - OSMA - Orthopedic Surgical Manufacturers Association, Winter Educational Program - virtual Y1 - 2021 ER - TY - GEN A1 - Singh, Max Diamond T1 - Innovationsmanagement BT - Sitzung des Ulmer Arbeitskreises Innovationsmanagement, Ulm, 03.11.2011 Y1 - 2011 ER - TY - GEN A1 - Singh, Max Diamond T1 - General Overview of the Medical Device Regulation T2 - MDR-Roadshow - TÜV SÜD MHS, India Y1 - 2020 ER - TY - GEN A1 - Singh, Max Diamond T1 - Stakeholder view on Post Market Surveillance under the EU MDR: Timelines, Compliance and Requirements ; Post Market Surveillance & Vigilance BT - [Vortrag gehalten am: 23.6.2020] T2 - MedTech summit 2020: EU MDR & IVDR: the end ist in sight, 22.-26.06.2020, Dublin/virtual Y1 - 2020 ER - TY - GEN A1 - Singh, Max Diamond T1 - Quality in Medical Device Innovation for Start-ups, SME, and large enterprises through the new Medical Device Regulation T2 - 3rd European QA Conference, Dublin, 06. - 08.11.2019 Y1 - 2019 ER - TY - GEN A1 - Singh, Max Diamond T1 - Technical Documentation MDR / IVDR, including the Declaration of Conformity BT - [Vortrag gehalten am 24.02.2020] T2 - MDR Training: Person Responsible for Regulatory Compliance, 24.-25.02.2020, Tel Aviv, Obelis Academy Y1 - 2020 ER - TY - GEN A1 - Singh, Max Diamond T1 - Notified Body Viewpoint : Preparing for MDR/IVDR T2 - MDR/IVDR - Status Report from Stakeholders. Where are we now in November 2018? - Bern, 22.11.2018 - [Veranstalter: RAPS : Regulatory Affairs Professionals Society] Y1 - 2018 ER - TY - GEN A1 - Singh, Max Diamond T1 - Reclassification of Orthopedic Devices per the Medical Device Regulation T2 - OSMA Winter Educational Program, St. Petersburg/USA, 2019. - [Veranstalter: Orthopedic Surgical Manufacturers Association (OSMA)] Y1 - 2019 ER - TY - GEN A1 - Singh, Max Diamond T1 - Strategies to Navigate to the EU MDR and Clinical Requirements T2 - Regulatory Affairs Professionals Society (RAPS): Session 1 - Tampa, Florida 2019 Y1 - 2019 ER - TY - GEN A1 - Singh, Max Diamond T1 - Herausforderungen der Medizinprodukteindustrie bei der Internationalisierung T2 - Studienwoche an der HNU (Hochschule Neu-Ulm) 2020 Y1 - 2020 ER - TY - GEN A1 - Singh, Max Diamond T1 - Technical Aspects for Navigated Sinus Surgery T2 - 4th Workshop on Endoscopic Surgery of the Maxillary Sinus and Navigation, Tübingen University Hospital, 2009 Y1 - 2009 ER - TY - GEN A1 - Singh, Max Diamond T1 - Overview of the Medical Device Regulation (MDR) BT - MDR-Roadshow TÜV SÜD MHS, San Diego & Minneapolis, 2018 Y1 - 2018 ER - TY - JOUR A1 - Singh, Max Diamond T1 - Orthopedic Medical Devices Under The Scope of The EU MDR JF - MedTech Outlook Y1 - 2019 UR - https://embedded-solutions.medicaltechoutlook.com/cxoinsight/orthopedic-medical-devices-under-the-scope-of-the-eu-mdr-nwid-921.html ER - TY - GEN A1 - Singh, Max Diamond A1 - Schlagintweit, S. A1 - Reischle, G. T1 - Additive-Manufactured Orthopedic Implants Under MDR Y1 - 2020 UR - https://www.odtmag.com/contents/view_online-exclusives/2020-08-11/additive-manufactured-orthopedic-implants-under-mdr/ IS - 08.11.20 ER - TY - GEN A1 - Singh, Max Diamond T1 - Joint NB-Position Paper on Spinal Classification per the MDR Y1 - 2019 UR - https://www.team-nb.org/wp-content/uploads/2019/01/Joint-NB-Spinal-Classification-Decision-Tree_final.pdf ER - TY - THES A1 - Singh, Max Diamond T1 - Aspects of the Dynamics of Spine Surgery Technologies: Assessing the Reality of Innovation and Entrepreneurship in the U.S. Medical Device Industry Y1 - 2016 PB - Karlsruhe Institute of Technology CY - Karlsruhe ER - TY - CHAP A1 - Raptis, Georgios ED - Wetter, Thomas T1 - Privacy and Data Protection: Mission Impossible? T2 - Consumer Health Informatics N2 - Medical confidentiality is very important because it builds the fundament of trust between doctors and patients. In modern health services data protection is essential. But there are also other important security objectives, such as integrity and authenticity of medical data and health services, as their breach can potentially lead to life threatening conditions. State of the art security mechanisms are necessary to protect medical data and services and prevent attacks known as “hacking”. They should include in particular cryptography, as you can usually rely on mathematics, more than in software security and access control mechanisms. As patients normally cannot assess the security of a service, security audits or certifications of health services should be provided to generate trust and confidence. KW - Gesundheitswesen KW - Medizinische Versorgung KW - Datenschutz KW - Datensicherung Y1 - 2016 SN - 978-3-319-19589-6 U6 - https://doi.org/10.1007/978-3-319-19590-2 SP - 273 EP - 280 PB - Springer International Publishing ER - TY - JOUR A1 - Raptis, Georgios T1 - Technischer Datenschutz in der telemedizinischen Versorgung JF - Der Krankenhaus-JUSTITIAR N2 - Die fortschreitende Digitalisierung des Gesundheitswesens ebnet auch den Weg einer stärkeren Verbreitung der telemedizinischen Versorgung in Deutschland. Die Politik erleichtert diesen Weg, z.B. mit dem eHealth-Gesetz oder mit der Lockerung des "Fernbehandlungsverbots" durch den Deutschen Ärztetag. Dabei wird schon aus der Definition (siehe z.B. die unten stehende Definition der AG Telemedizin) klar, dass Telemedizin keine neue medizinische Disziplin begründet. Bei Telemedizin handelt es sich nur um ein technisches Werkzeug in Kombination mit geeigneten klinischen Prozessen, damit bestehende medizinische Expertise unter Einsatz von Informations- und Kommunikationstechnologien räumliche Entfernungen oder einen zeitlichen Versatz überbrücken kann. Patientinnen und Patienten können also behandelt werden, auch wenn sie vom Arzt räumlich entfernt sind. KW - Telemedizin KW - Datenschutz Y1 - 2018 VL - 7 IS - 4 SP - 105 EP - 107 ER - TY - JOUR A1 - Raptis, Georgios T1 - Windows 10 und Datenschutz in der Arztpraxis JF - Bayerisches Ärzteblatt KW - Windows 10 KW - Datenschutz KW - Arztpraxis Y1 - 2016 UR - https://www.bayerisches-aerzteblatt.de/fileadmin/aerzteblatt/ausgaben/2016/07/komplettpdf/Baebl7_8_2016_Komplettausgabe.pdf IS - 7/8 SP - 364 ER - TY - CHAP A1 - Raptis, Georgios ED - Marschner, Uwe ED - Clasbrummel, Bernhard ED - Dehm, Johannes T1 - Gewährleistung der IT-Sicherheit bei vernetzten Implantaten T2 - Biomedizinische Technik: Vernetzte und intelligente Implantate KW - Implantat KW - Vernetzung KW - Datenschutz KW - Datensicherung KW - Personenbezogene Daten Y1 - 2020 SN - 978-3-11-034927-6 SP - 182 EP - 192 PB - Walter de Gruyter ER - TY - JOUR A1 - Hornberger, Helga A1 - Striegl, Birgit A1 - Trahanofsky, M. A1 - Kneissl, F. A1 - Kronseder, Matthias T1 - Degradation and bioactivity studies of Mg membranes for dental surgery JF - Materials Letter X N2 - Bioresorbable materials are under investigation due to their promising properties for applications as implant material. This study is about the degradation and bioactivity behaviour of magnesium foils, which allegorize dental membranes. The degradation behaviour including pitting corrosion during immersion tests can be precisely observed using micro-computed tomography. Using the bioactivity test according to Kokubo, it is shown that magnesium has strong Ca-phosphate layer formation correlated with high degradation. Therefore, magnesium foils appear to hold a great potential for bone implant application. KW - Magnesium KW - Dental membrane KW - Bioactivity KW - Corrosion rate Y1 - 2019 U6 - https://doi.org/10.1016/j.mlblux.2019.100007 VL - 2 IS - June SP - 1 EP - 5 PB - Elsevier 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 - JOUR A1 - Renkawitz, Tobias A1 - Weber, Markus A1 - Springorum, H.-R. A1 - Sendtner, E. A1 - Woerner, Michael A1 - Ulm, K. A1 - Weber, Tim A1 - Grifka, Joachim T1 - Impingement-free range of motion, cup coverage and early clinical results between femur first navigation and conventional total hip arthroplasty: a randomised controlled trial JF - Journal of Bone & Joint Surgery N2 - We report the kinematic and early clinical results of a patient- and observer-blinded randomised controlled trial in which CT scans were used to compare potential impingement-free range of movement (ROM) and acetabular component cover between patients treated with either the navigated 'femur-first' total hip arthroplasty (THA) method (n = 66; male/female 29/37, mean age 62.5 years; 50 to 74) or conventional THA (n = 69; male/female 35/34, mean age 62.9 years; 50 to 75). The Hip Osteoarthritis Outcome Score, the Harris hip score, the Euro-Qol-5D and the Mancuso THA patient expectations score were assessed at six weeks, six months and one year after surgery. A total of 48 of the patients (84%) in the navigated 'femur-first' group and 43 (65%) in the conventional group reached all the desirable potential ROM boundaries without prosthetic impingement for activities of daily living (ADL) in flexion, extension, abduction, adduction and rotation (p = 0.016). Acetabular component cover and surface contact with the host bone were > 87% in both groups. There was a significant difference between the navigated and the conventional groups' Harris hip scores six weeks after surgery (p = 0.010). There were no significant differences with respect to any clinical outcome at six months and one year of follow-up. The navigated 'femur-first' technique improves the potential ROM for ADL without prosthetic impingement, although there was no observed clinical difference between the two treatment groups. KW - combined anteversion KW - computer-assisted orthopaedic surgery KW - THA KW - Hüftgelenkprothese KW - Operationstechnik KW - Computerunterstütztes Verfahren KW - Beweglichkeit Y1 - 2015 U6 - https://doi.org/10.1302/0301-620X.97B7.34729 VL - 97-B SP - 890 EP - 898 ER - TY - JOUR A1 - Weber, Markus A1 - Weber, Tim A. A1 - Woerner, Michael A1 - Craiovan, Benjamin A1 - Worlicek, Michael A1 - Winkler, Sebastian A1 - Grifka, Joachim A1 - Renkawitz, Tobias T1 - The impact of standard combined anteversion definitions on gait and clinical outcome within one year after total hip arthroplasty JF - International Orthopaedics N2 - Different target areas within the concept of combined cup and stem anteversion have been published for total hip arthroplasty (THA). We asked whether component positioning according to eight standard combined anteversion rules is associated with (1) more physiological gait patterns, (2) higher improvement of gait variables and (3) better clinical outcome after THA.In a prospective clinical study, 60 patients received cementless THA through an anterolateral MIS approach in a lateral decubitus position. Six weeks postoperatively, implant position was analysed using 3D-CT by an independent external institute. Preoperatively, six and 12 months postoperatively range of motion, normalized walking speed and hip flexion symmetry index were measured using 3D motion-capture gait analysis. Patient-related outcome measures (HHS, HOOS, EQ-5D) were obtained by an observer blinded to 3D-CT results. Eight combined anteversion definitions and Lewinnek's "safe zone" were evaluated regarding their impact on gait patterns and clinical outcome.Combined cup and stem anteversion according to standard combined anteversion definitions as well as cup placement within Lewinnek's "safe zone" did not influence range of motion, normalized walking speed and/or hip flexion symmetry index six and 12 months after THA. Similarly, increase of gait parameters within the first year after THA was comparable between all eight combined anteversion rules. Clinical outcome measures like HHS, HOOS and EQ-5D did not show any benefit for either of the combined anteversion definitions.Standard combined cup and stem anteversion rules do not improve postoperative outcome as measured by gait analysis and clinical scores within one year after THA. KW - Total hip athroplasty KW - Combined anteversion KW - Outcome KW - Gait analysis KW - Hüftgelenkprothese KW - Bewegungsanalyse KW - Gehen KW - Funktionelle Anatomie Y1 - 2015 U6 - https://doi.org/10.1007/s00264-015-2777-8 VL - 39 IS - 12 SP - 2323 EP - 2333 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 - 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 - 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 -