TY - CHAP A1 - Taylor, William R. A1 - Fröhlich, Annika A1 - Buttgereit, Frank A1 - Ehrig, Rainald A1 - Witaschek, Tom A1 - Duda, Georg ED - Kersting, Uwe ED - Morlock, Michael ED - Jirova-Enzmann, Daniela ED - Dremstrup, Kim T1 - Metacarpophalangeal joint stiffness is reduced in patients affected by rheumatoid arthritis after glucocorticoid medication T2 - Proceedings of the ESM-2012, Aalborg Y1 - 2012 SP - 39 PB - Department of Health Science and Technology, Aalborg University ER - TY - CHAP A1 - Kornaropoulos, Evgenios I. A1 - Taylor, William R. A1 - Duda, Georg A1 - Ehrig, Rainald A1 - Heller, Markus O. T1 - Frontal plane lower limb alignment using functionally determined joint centers and axes T2 - International Conference on Computational Bioengineering Y1 - 2009 ER - TY - CHAP A1 - Kornaropoulos, Evgenios I. A1 - Taylor, William R. A1 - Duda, Georg A1 - Ehrig, Rainald A1 - Heller, Markus O. T1 - An imageless method to quantify the Mechanical Femoral-Tibial Angle (MFTA) using functionally defined joint centers and axes. T2 - 6th Annual meeting of the German Society for Biomechanics (DGfB) Y1 - 2009 ER - TY - CHAP A1 - Krämer, Martin A1 - Maggioni, Marta A1 - Tycowicz, Christoph von A1 - Brisson, Nick A1 - Zachow, Stefan A1 - Duda, Georg A1 - Reichenbach, Jürgen T1 - Ultra-short echo-time (UTE) imaging of the knee with curved surface reconstruction-based extraction of the patellar tendon T2 - ISMRM (International Society for Magnetic Resonance in Medicine), 26th Annual Meeting 2018, Paris, France N2 - Due to very short T2 relaxation times, imaging of tendons is typically performed using ultra-short echo-time (UTE) acquisition techniques. In this work, we combined an echo-train shifted multi-echo 3D UTE imaging sequence with a 3D curved surface reconstruction to virtually extract the patellar tendon from an acquired 3D UTE dataset. Based on the analysis of the acquired multi-echo data, a T2* relaxation time parameter map was calculated and interpolated to the curved surface of the patellar tendon. Y1 - 2018 ER - TY - JOUR A1 - Alves, Sónia A1 - Ehrig, Rainald A1 - Raffalt, Peter C. A1 - Bender, Alwina A1 - Duda, Georg A1 - Agres, Alison N. T1 - Quantifying Asymmetry in Gait: A Weighted Universal Symmetry Index to Evaluate 3D Ground Reaction Forces JF - Frontiers in Bioengineering and Biotechnology N2 - Though gait asymmetry is used as a metric of functional recovery in clinical rehabilitation, there is no consensus on an ideal method for its evaluation. Various methods have been proposed but are limited in scope, as they can often use only positive signals or discrete values extracted from time-scale data as input. By defining five symmetry axioms, a framework for benchmarking existing methods was established and a new method was described here for the first time: the weighted universal symmetry index (wUSI), which overcomes limitations of other methods. Both existing methods and the wUSI were mathematically compared to each other and in respect to their ability to fulfill the proposed symmetry axioms. Eligible methods that fulfilled these axioms were then applied using both discrete and continuous approaches to ground reaction force (GRF) data collected from healthy gait, both with and without artificially induced asymmetry using a single instrumented elbow crutch. The wUSI with a continuous approach was the only symmetry method capable of determining GRF asymmetries in different walking conditions in all three planes of motion. When used with a continuous approach, the wUSI method was able to detect asymmetries while avoiding artificial inflation, a common problem reported in other methods. In conclusion, the wUSI is proposed as a universal method to quantify three-dimensional GRF asymmetries, which may also be expanded to other biomechanical signals. Y1 - 2020 ER - TY - JOUR A1 - Willie, Bettina M. A1 - Pap, Thomas A1 - Perka, Carsten A1 - Schmidt, Carsten Oliver A1 - Eckstein, Felix A1 - Arampatzis, Adamantios A1 - Hege, Hans-Christian A1 - Madry, Henning A1 - Vortkamp, Andrea A1 - Duda, Georg T1 - OVERLOAD of joints and its role in osteoarthritis - Towards understanding and preventing progression of primary osteoarthritis JF - Zeitschrift für Rheumatologie N2 - Intact joints are necessary for skeletal function and mobility in daily life. A healthy musculoskeletal system is the basis for a functional cardiovascular system as well as an intact immune system. Locomotion, physiotherapy, and various forms of patient activity are essential clinical therapies used in the treatment of neurodegeneration, stroke, diabetes, and cancer. Mobility is substantially impaired with degeneration of joints and, in advanced stages, nighttime pain and sleep disturbance are particularly cumbersome. Osteoarthritis (OA) is also known as degenerative joint disease. OA involves structural and compositional changes in the articular cartilage, as well as in the calcified cartilage, subchondral cortical bone, subchondral cancellous bone, meniscus, joint capsular tissue, and synovium; which eventually lead to degeneration of these tissues comprising synovial joints. Y1 - 2015 U6 - https://doi.org/10.1007/s00393-014-1561-2 VL - 76 IS - Suppl. 1 SP - 1 EP - 4 ER - TY - JOUR A1 - Krämer, Martin A1 - Maggioni, Marta A1 - Brisson, Nicholas A1 - Zachow, Stefan A1 - Teichgräber, Ulf A1 - Duda, Georg A1 - Reichenbach, Jürgen T1 - T1 and T2* mapping of the human quadriceps and patellar tendons using ultra-short echo-time (UTE) imaging and bivariate relaxation parameter-based volumetric visualization JF - Magnetic Resonance Imaging N2 - Quantification of magnetic resonance (MR)-based relaxation parameters of tendons and ligaments is challenging due to their very short transverse relaxation times, requiring application of ultra-short echo-time (UTE) imaging sequences. We quantify both T1 and T2⁎ in the quadriceps and patellar tendons of healthy volunteers at a field strength of 3 T and visualize the results based on 3D segmentation by using bivariate histogram analysis. We applied a 3D ultra-short echo-time imaging sequence with either variable repetition times (VTR) or variable flip angles (VFA) for T1 quantification in combination with multi-echo acquisition for extracting T2⁎. The values of both relaxation parameters were subsequently binned for bivariate histogram analysis and corresponding cluster identification, which were subsequently visualized. Based on manually-drawn regions of interest in the tendons on the relaxation parameter maps, T1 and T2⁎ boundaries were selected in the bivariate histogram to segment the quadriceps and patellar tendons and visualize the relaxation times by 3D volumetric rendering. Segmentation of bone marrow, fat, muscle and tendons was successfully performed based on the bivariate histogram analysis. Based on the segmentation results mean T2⁎ relaxation times, over the entire tendon volumes averaged over all subjects, were 1.8 ms ± 0.1 ms and 1.4 ms ± 0.2 ms for the patellar and quadriceps tendons, respectively. The mean T1 value of the patellar tendon, averaged over all subjects, was 527 ms ± 42 ms and 476 ms ± 40 ms for the VFA and VTR acquisitions, respectively. The quadriceps tendon had higher mean T1 values of 662 ms ± 97 ms (VFA method) and 637 ms ± 40 ms (VTR method) compared to the patellar tendon. 3D volumetric visualization of the relaxation times revealed that T1 values are not constant over the volume of both tendons, but vary locally. This work provided additional data to build upon the scarce literature available on relaxation times in the quadriceps and patellar tendons. We were able to segment both tendons and to visualize the relaxation parameter distributions over the entire tendon volumes. Y1 - 2019 U6 - https://doi.org/10.1016/j.mri.2019.07.015 VL - 63 IS - 11 SP - 29 EP - 36 ER - TY - JOUR A1 - Trepczynski, Adam A1 - Kneifel, Paul A1 - Heyland, Mark A1 - Leskovar, Marko A1 - Moewis, Philippe A1 - Damm, Philipp A1 - Taylor, William R. A1 - Zachow, Stefan A1 - Duda, Georg N. T1 - Impact of the external knee flexion moment on patello-femoral loading derived from in vivo loads and kinematics JF - Frontiers in Bioengineering and Biotechnology N2 - Introduction: Anterior knee pain and other patello-femoral (PF) complications frequently limit the success of total knee arthroplasty as the final treatment of end stage osteoarthritis. However, knowledge about the in-vivo loading conditions at the PF joint remains limited, as no direct measurements are available. We hypothesised that the external knee flexion moment (EFM) is highly predictive of the PF contact forces during activities with substantial flexion of the loaded knee. Materials and methods: Six patients (65–80 years, 67–101 kg) with total knee arthroplasty (TKA) performed two activities of daily living: sit-stand-sit and squat. Tibio-femoral (TF) contact forces were measured in vivo using instrumented tibial components, while synchronously internal TF and PF kinematics were captured with mobile fluoroscopy. The measurements were used to compute PF contact forces using patient specific musculoskeletal models. The relationship between the EFM and the PF contact force was quantified using linear regression. Results: Mean peak TF contact forces of 1.97–3.24 times body weight (BW) were found while peak PF forces reached 1.75 to 3.29 times body weight (BW). The peak EFM ranged from 3.2 to 5.9 %BW times body height, and was a good predictor of the PF contact force (R2 = 0.95 and 0.88 for sit-stand-sit and squat, respectively). Discussion: The novel combination of in vivo TF contact forces and internal patellar kinematics enabled a reliable assessment of PF contact forces. The results of the regression analysis suggest that PF forces can be estimated based solely on the EFM from quantitative gait analysis. Our study also demonstrates the relevance of PF contact forces, which reach magnitudes similar to TF forces during activities of daily living. Y1 - 2024 U6 - https://doi.org/10.3389/fbioe.2024.1473951 SN - 2296-4185 VL - 12/2024 PB - Frontiers Media SA ER - TY - JOUR A1 - Heller, Markus O. A1 - Matziolis, Georg A1 - König, Christian A1 - Taylor, William R. A1 - Hinterwimmer, S. A1 - Graichen, H. A1 - Hege, Hans-Christian A1 - Bergmann, G. A1 - Perka, Carsten A1 - Duda, G. N. T1 - Muskuloskelettale Biomechanik des Kniegelenks - Grundlagen für die präoperative Planung von Umstellung und Gelenkersatz JF - Der Orthopäde Y1 - 2007 U6 - https://doi.org/10.1007/s00132-007-1115-2 VL - 36 IS - 7 SP - 628 EP - 634 ER - TY - CHAP A1 - Lamecker, Hans A1 - Wenckebach, Thomas A1 - Hege, Hans-Christian A1 - N. Duda, Georg A1 - Heller, Markus T1 - Atlas-basierte 3D-Rekonstruktion des Beckens aus 2D-Projektionsbildern T2 - Bildverarbeitung für die Medizin 2006: Algorithmen - Systeme - Anwendungen Y1 - 2006 U6 - https://doi.org/10.1007/3-540-32137-3_6 SP - 26 EP - 30 PB - Springer Berlin Heidelberg ER - TY - JOUR A1 - Ziegler, Günter M. A1 - Hege, Hans-Christian A1 - Duda, Georg T1 - Neue Bilder für die Medizin? JF - DFN-Mitteilungen Y1 - 2005 VL - 13(3) SP - 163 EP - 167 ER -