Browsing by Author "Han, Seong-won"

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    5th Rocky Mountain Muscle Symposium
    (Faculty of Kinesiology, 2023-05-19) Joumaa, Venus; Hessel, Anthony; Nishikawa, Kiisa; Millard, Matthew; Han, Seong-won; Bell, Kaylyn; Leonard, Tim; Kaya, Motoshi; Corr, David; Swank, Douglas; Corvelyn, Marlies; Sahani, Ridhi; Mazara, Nicole; Moo, Eng Kuan; Granzier, Henk; Oldshue, Ashley; Adkins, Amy; Loya, Amy; Boldt, Kevin; Desloovere, Kaat; Fukutani, Atsuki; Martino, Giovanni; De Beukelaer, Nathalie; Horslen, Brian; Agen, Anouk; Costamanga, Domiziana; Swank, Doug; Holt, Natalie
    Proceedings from the 4th Rocky Mountain Muscle Symposium, Canmore Nordic Centre, June 19-21, 2023.
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    Changes in Patellofemoral Joint Mechanics in the Presence of Quadriceps Muscle Imbalance
    (2020-08-24) Han, Seong-won; Herzog, Walter; Edwards, William Brent; Wiley, James Preston
    The purpose of this thesis was to quantify the mechanical effects of quadriceps muscle weakness and imbalance on patellofemoral joint kinematics and kinetics, and to determine the independent action of individual quadriceps muscles on the patellofemoral joint. The rabbit knee joint was used for approaching this purpose and a novel experimental technique was developed allowing for controlled activation of the individual muscles of the quadriceps group, thereby permitting simulation of any experimental joint loading scenario of interest. The primary outcome measures were the 3-dimensional patellar kinematics, and the patellofemoral joint contact pressure distribution as a function of quadriceps force, muscle weakness, and muscle imbalance. The key findings were: (i) that pressure distribution in the patellofemoral joint changed when simulating muscle imbalance and vastus medialis (VM) weakness; (ii) that patellar tracking depended greatly on knee extensor force/torque; and (iii) that the VM shifts, rotates, and tilts the patella medially throughout the range of motion. We conclude from these results that VM weakness changes the mechanics in the rabbit patellofemoral joint, and that, due to the anatomical similarity of the rabbit patellofemoral joint with other animals’ joints, including those of humans, the results may have important clinical implications. Furthermore, even though muscle imbalance induced by VM weakness altered patellar tracking, these new paths of the patella did not go beyond the range of tracking paths observed when knee extensor torques were changed from zero (passive) to maximal, thus, they may be considered within the normal range.
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    Contribution of individual quadriceps muscles to knee joint mechanics
    (2019-03) Han, Seong-won; Sawatsky, Andrew; Fontana, Heiliane de Brito; Herzog, Walter
    Many attempts have been made to determine the contribution of individual muscles in an agonistic group to the mechanics of joints. However, previous approaches had the limitations that muscles often could not be controlled in a precise manner, that individual muscles in an agonistic group could not be activated individually, and that individual muscle contributions could not be measured in an actively contracting agonistic group. Here, we introduce a surgical approach that allows for controlled activation of individual muscles of an agonistic group. The approach is illustrated for the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) of the rabbit quadriceps femoris group. We provide exemplar results for potential applications of the approach, such as measuring the pressure distribution in the patellofemoral joint, and the torque–angle relationship of VL, VM and RF when activated individually and when the three muscles are activated simultaneously.
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    Effect of Vastus Medialis Loss on Rabbit Patellofemoral Joint Contact Pressure Distribution
    (2020-08) Han, Seong-won; Sawatsky, Andrew; Jinha, Azim; Herzog, Walter
    Vastus medialis (VM) weakness is thought to alter patellar tracking, thereby changing the loading of the patellofemoral joint (PFJ), resulting in patellofemoral pain. However, it is challenging to measure VM force and weakness in human studies, nor is it possible to measure the associated mechanical changes in the PFJ. To obtain fundamental insight into VM weakness and its effects on PFJ mechanics, the authors determined PFJ loading in the presence of experimentally simulated VM weakness. Skeletally mature New Zealand White rabbits were used (n = 6), and the vastus lateralis, VM, and rectus femoris were stimulated individually through 3 custom-built nerve cuff electrodes. Muscle torque and PFJ pressure distribution were measured while activating all muscles simultaneously, or when the vastus lateralis and rectus femoris were activated, while VM was not, to simulate a quadriceps muscle strength imbalance. For a given muscular joint torque, peak pressures were greater and joint contact areas were smaller when simulating VM weakness compared with the condition where all muscles were activated simultaneously. The results in the rabbit model support that VM weakness results in altered PFJ loading, which may cause patellofemoral pain, often associated with a strength imbalance of the knee extensor muscle group.
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    Proceedings of the 4th Rocky Mountain Muscle Symposium
    (2019-07-27) Joumaa, Venus; Hessel, Anthony; Nishikawa, Kiisa; Millard, Matthew; Han, Seong-won; Bell, Kaylyn; Leonard, Tim; Corr, David; Swank, Douglas; Corvelyn, Marlies; Sahani, Ridhi; Mazara, Nicole; Moo, Eng Kuan; Lieber, Rick; Kaya, Motoshi; Granzier, Henk; Oldshue, Ashley; Adkins, Amy; Loya, Amy; Boldt, Kevin; Desloovere, Kaat; Fukutani, Atsuki; Martino, Giovanni; De Beukelaer, Nathalie; Horslen, Brian; Agten, Anouk; Costamagna, Domiziana; Lee, Sabrina; Schwaner, Marie Janneke; Abbott, Emily; Binder-Markey, Benjamin; Siebert, Tobias; Lin, David; Fontana, Heiliane de Brito; Daley, Monica; Hahn, Daniel; Evangelidis, Pavlos; Knaus, Katherine; Smith, Ian; Deloovere, Kat; Kawakami, Yasuo; Hodson-Tole, Emma; Oliveira, Liliam; Ichinose, Hoshizora; Tillin, Neale; Raiteri, Brent; Seiberl, Wolfgang; Vaz, Marco; Cruz-Montecinos, Carlos; Griffiths, Robert; MacIntosh, Brian; Lourdes Rios, Jacqueline; Bossuyt, Fransiska
    Proceedings from the 4th Rocky Mountain Muscle Symposium, Canmore Nordic Centre, July 27-29, 2019