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Bo K Foreman - One of the best experts on this subject based on the ideXlab platform.

  • contribution of ankle Foot Orthosis moment in regulating ankle and knee motions during gait in individuals post stroke
    Clinical Biomechanics, 2017
    Co-Authors: Toshiki Kobayashi, Michael S Orendurff, Madeline L Singer, Bo K Foreman
    Abstract:

    Abstract Background Ankle-Foot Orthosis moment resisting plantarflexion has systematic effects on ankle and knee joint motion in individuals post-stroke. However, it is not known how much ankle-Foot Orthosis moment is generated to regulate their motion. The aim of this study was to quantify the contribution of an articulated ankle-Foot Orthosis moment to regulate ankle and knee joint motion during gait in individuals post-stroke. Methods Gait data were collected from 10 individuals post-stroke using a Bertec split-belt instrumented treadmill and a Vicon 3-dimensional motion analysis system. Each participant wore an articulated ankle-Foot Orthosis whose moment resisting plantarflexion was adjustable at four levels. Ankle-Foot Orthosis moment while walking was calculated under the four levels based on angle-moment relationship of the ankle-Foot Orthosis around the ankle joint measured by bench testing. The ankle-Foot Orthosis moment and the joint angular position (ankle and knee) relationship in a gait cycle was plotted to quantify the ankle-Foot Orthosis moment needed to regulate the joint motion. Findings Ankle and knee joint motion were regulated according to the amount of ankle-Foot Orthosis moment during gait. The ankle-Foot Orthosis maintained the ankle angular position in dorsiflexion and knee angular position in flexion throughout a gait cycle when it generated moment from − 0.029 (0.011) to − 0.062 (0.019) Nm/kg (moment resisting plantarflexion was defined as negative). Interpretations Quantifying the contribution of ankle-Foot Orthosis moment needed to regulate lower limb joints within a specific range of motion could provide valuable criteria to design an ankle-Foot Orthosis for individuals post-stroke.

  • reduction of genu recurvatum through adjustment of plantarflexion resistance of an articulated ankle Foot Orthosis in individuals post stroke
    Clinical Biomechanics, 2016
    Co-Authors: Toshiki Kobayashi, Michael S Orendurff, Madeline L Singer, Wayne K Daly, Bo K Foreman
    Abstract:

    Abstract Background Genu recurvatum (knee hyperextension) is a common issue for individuals post-stroke. Ankle-Foot orthoses are used to improve genu recurvatum, but evidence is limited concerning their effectiveness. Therefore, the aim of this study was to investigate the effect of changing the plantarflexion resistance of an articulated ankle-Foot Orthosis on genu recurvatum in patients post-stroke. Methods Gait analysis was performed on 6 individuals post-stroke with genu recurvatum using an articulated ankle-Foot Orthosis whose plantarflexion resistance was adjustable at four levels. Gait data were collected using a Bertec split-belt instrumented treadmill in a 3-dimensional motion analysis laboratory. Gait parameters were extracted and plotted for each subject under the four plantarflexion resistance conditions of the ankle-Foot Orthosis. Gait parameters included: a) peak ankle plantarflexion angle, b) peak ankle dorsiflexion moment, c) peak knee extension angle and d) peak knee flexion moment. A non-parametric Friedman test was performed followed by a post-hoc Wilcoxon Signed-Rank test for statistical analyses. Findings All the gait parameters demonstrated statistically significant differences among the four resistance conditions of the AFO. Increasing the amount of plantarflexion resistance of the ankle-Foot Orthosis generally reduced genu recurvatum in all subjects. However, individual analyses showed that the responses to the changes in the plantarflexion resistance of the AFO were not necessarily linear, and appear unique to each subject. Interpretations The plantarflexion resistance of an articulated AFO should be adjusted to improve genu recurvatum in patients post-stroke. Future studies should investigate what clinical factors would influence the individual differences.

  • direct measurement of plantarflexion resistive moments and angular positions of an articulated ankle Foot Orthosis while walking in individuals post stroke a preliminary study
    Journal of Rehabilitation and Assistive Technologies Engineering, 2016
    Co-Authors: Toshiki Kobayashi, Michael S Orendurff, Madeline L Singer, Wayne K Daly, Lucas S. Lincoln, Fan Gao, Bo K Foreman
    Abstract:

    The plantarflexion resistive moments of an articulated ankle-Foot Orthosis play an important role in improving gait in individuals post stroke. However, the evidence regarding their magnitude required from the articulated ankle-Foot Orthosis to improve walking is still limited. Therefore, the primary aim of this study was to directly measure the plantarflexion resistive moments and the joint angular positions while walking using a prototype instrumented articulated ankle-Foot Orthosis in five individuals post stroke. The secondary aim was to investigate their moment-angle relationship by changing its preset plantarflexion stiffness. Each subject was fitted with the instrumented articulated ankle-Foot Orthosis and walked on a treadmill under four different preset plantarflexion stiffness conditions (0.35 N·m/°, 0.51 N·m/°, 0.87 N·m/°, and 1.27 N·m/°). For each subject, the plantarflexion resistive moments and the joint angular positions of five continuous gait cycles were extracted and averaged for each condition. Data were plotted and presented as case series. Both plantarflexion resistive moments and joint angular positions of the ankle-Foot Orthosis changed according to the preset plantarflexion stiffness in all subjects. Using the instrumented articulated ankle-Foot Orthosis could potentially advance the understanding of the biomechanics of an ankle-Foot Orthosis, as well as contribute to more evidence-based orthotic care of patients.

  • the effect of changing plantarflexion resistive moment of an articulated ankle Foot Orthosis on ankle and knee joint angles and moments while walking in patients post stroke
    Clinical Biomechanics, 2015
    Co-Authors: Toshiki Kobayashi, Michael S Orendurff, Madeline L Singer, Wayne K Daly, Bo K Foreman
    Abstract:

    Abstract Background The adjustment of plantarflexion resistive moment of an articulated ankle–Foot Orthosis is considered important in patients post stroke, but the evidence is still limited. Therefore, the aim of this study was to investigate the effect of changing the plantarflexion resistive moment of an articulated ankle–Foot Orthosis on ankle and knee joint angles and moments in patients post stroke. Methods Gait analysis was performed on 10 subjects post stroke under four different plantarflexion resistive moment conditions using a newly designed articulated ankle–Foot Orthosis. Data were recorded using a Bertec split-belt instrumented treadmill in a 3-dimensional motion analysis laboratory. Findings The ankle and knee sagittal joint angles and moments were significantly affected by the amount of plantarflexion resistive moment of the ankle–Foot Orthosis. Increasing the plantarflexion resistive moment of the ankle–Foot Orthosis induced significant decreases both in the peak ankle plantarflexion angle (P  Interpretation These results suggest an important link between the kinematic/kinetic parameters of the lower-limb joints and the plantarflexion resistive moment of an articulated ankle–Foot Orthosis. A future study should be performed to clarify their relationship further so that the practitioners may be able to use these parameters as objective data to determine an optimal plantarflexion resistive moment of an articulated ankle–Foot Orthosis for improved orthotic care in individual patients.

  • the effect of ankle Foot Orthosis plantarflexion stiffness on ankle and knee joint kinematics and kinetics during first and second rockers of gait in individuals with stroke
    Clinical Biomechanics, 2014
    Co-Authors: Madeline L Singer, Michael S Orendurff, Lucas S. Lincoln, Toshiki Kobayashi, Bo K Foreman
    Abstract:

    Abstract Background Stiffness of an ankle–Foot Orthosis plays an important role in improving gait in patients with a history of stroke. To address this, the aim of this case series study was to determine the effect of increasing plantarflexion stiffness of an ankle–Foot Orthosis on the sagittal ankle and knee joint angle and moment during the first and second rockers of gait. Methods Gait data were collected in 5 subjects with stroke at a self-selected walking speed under two plantarflexion stiffness conditions (0.4 Nm/° and 1.3 Nm/°) using a stiffness-adjustable experimental ankle–Foot Orthosis on a Bertec split-belt fully instrumented treadmill in a 3-dimensional motion analysis laboratory. Findings By increasing the plantarflexion stiffness of the ankle–Foot Orthosis, peak plantarflexion angle of the ankle was reduced and peak dorsiflexion moment was generally increased in the first rocker as hypothesized. Two subjects demonstrated increases in both peak knee flexion angle and peak knee extension moment in the second rocker as hypothesized. The two subjects exhibited minimum contractility during active plantarflexion, while the other three subjects could actively plantarflex their ankle joint. Interpretation It was suggested that those with the decreased ability to actively plantarflex their ankle could not overcome excessive plantarflexion stiffness at initial contact of gait, and as a result exhibited compensation strategies at the knee joint. Providing excessively stiff ankle–Foot orthoses might put added stress on the extensor muscles of the knee joint, potentially creating fatigue and future pathologies in some patients with stroke.

Toshiki Kobayashi - One of the best experts on this subject based on the ideXlab platform.

  • The effects of an articulated ankle-Foot Orthosis with resistance-adjustable joints on lower limb joint kinematics and kinetics during gait in individuals post-stroke.
    Clinical Biomechanics, 2018
    Co-Authors: Toshiki Kobayashi, Michael S Orendurff, Lucas S. Lincoln, Grace Hunt, Nicholas Lecursi, K. Bo Foreman
    Abstract:

    Abstract Background Resistance is a key mechanical property of an ankle-Foot Orthosis that affects gait in individuals post-stroke. Triple Action® joints allow independent adjustment of plantarflexion resistance and dorsiflexion resistance of an ankle-Foot Orthosis. Therefore, the aim of this study was to investigate the effects of incremental changes in dorsiflexion and plantarflexion resistance of an articulated ankle-Foot Orthosis with the Triple Action joints on lower limb joint kinematics and kinetics in individuals post-stroke during gait. Methods Gait analysis was performed on 10 individuals who were post-stroke under eight resistance settings (four plantarflexion and four dorsiflexion resistances) using the articulated ankle-Foot Orthosis. Kinematic and kinetic data of the lower limb joints were recorded while walking using a three-dimensional Vicon motion capture system and a Bertec split-belt instrumented treadmill. Findings Repeated measures analysis of variance revealed that adjustment of plantarflexion resistance had significant main effects on the ankle (P  Interpretation This study demonstrated that the adjustments of resistance in the ankle-Foot Orthosis with the Triple Action joints influenced ankle and knee kinematics in individuals post-stroke. Further work is necessary to investigate the long-term effects of the articulated ankle-Foot orthoses on their gait.

  • contribution of ankle Foot Orthosis moment in regulating ankle and knee motions during gait in individuals post stroke
    Clinical Biomechanics, 2017
    Co-Authors: Toshiki Kobayashi, Michael S Orendurff, Madeline L Singer, Bo K Foreman
    Abstract:

    Abstract Background Ankle-Foot Orthosis moment resisting plantarflexion has systematic effects on ankle and knee joint motion in individuals post-stroke. However, it is not known how much ankle-Foot Orthosis moment is generated to regulate their motion. The aim of this study was to quantify the contribution of an articulated ankle-Foot Orthosis moment to regulate ankle and knee joint motion during gait in individuals post-stroke. Methods Gait data were collected from 10 individuals post-stroke using a Bertec split-belt instrumented treadmill and a Vicon 3-dimensional motion analysis system. Each participant wore an articulated ankle-Foot Orthosis whose moment resisting plantarflexion was adjustable at four levels. Ankle-Foot Orthosis moment while walking was calculated under the four levels based on angle-moment relationship of the ankle-Foot Orthosis around the ankle joint measured by bench testing. The ankle-Foot Orthosis moment and the joint angular position (ankle and knee) relationship in a gait cycle was plotted to quantify the ankle-Foot Orthosis moment needed to regulate the joint motion. Findings Ankle and knee joint motion were regulated according to the amount of ankle-Foot Orthosis moment during gait. The ankle-Foot Orthosis maintained the ankle angular position in dorsiflexion and knee angular position in flexion throughout a gait cycle when it generated moment from − 0.029 (0.011) to − 0.062 (0.019) Nm/kg (moment resisting plantarflexion was defined as negative). Interpretations Quantifying the contribution of ankle-Foot Orthosis moment needed to regulate lower limb joints within a specific range of motion could provide valuable criteria to design an ankle-Foot Orthosis for individuals post-stroke.

  • reduction of genu recurvatum through adjustment of plantarflexion resistance of an articulated ankle Foot Orthosis in individuals post stroke
    Clinical Biomechanics, 2016
    Co-Authors: Toshiki Kobayashi, Michael S Orendurff, Madeline L Singer, Wayne K Daly, Bo K Foreman
    Abstract:

    Abstract Background Genu recurvatum (knee hyperextension) is a common issue for individuals post-stroke. Ankle-Foot orthoses are used to improve genu recurvatum, but evidence is limited concerning their effectiveness. Therefore, the aim of this study was to investigate the effect of changing the plantarflexion resistance of an articulated ankle-Foot Orthosis on genu recurvatum in patients post-stroke. Methods Gait analysis was performed on 6 individuals post-stroke with genu recurvatum using an articulated ankle-Foot Orthosis whose plantarflexion resistance was adjustable at four levels. Gait data were collected using a Bertec split-belt instrumented treadmill in a 3-dimensional motion analysis laboratory. Gait parameters were extracted and plotted for each subject under the four plantarflexion resistance conditions of the ankle-Foot Orthosis. Gait parameters included: a) peak ankle plantarflexion angle, b) peak ankle dorsiflexion moment, c) peak knee extension angle and d) peak knee flexion moment. A non-parametric Friedman test was performed followed by a post-hoc Wilcoxon Signed-Rank test for statistical analyses. Findings All the gait parameters demonstrated statistically significant differences among the four resistance conditions of the AFO. Increasing the amount of plantarflexion resistance of the ankle-Foot Orthosis generally reduced genu recurvatum in all subjects. However, individual analyses showed that the responses to the changes in the plantarflexion resistance of the AFO were not necessarily linear, and appear unique to each subject. Interpretations The plantarflexion resistance of an articulated AFO should be adjusted to improve genu recurvatum in patients post-stroke. Future studies should investigate what clinical factors would influence the individual differences.

  • direct measurement of plantarflexion resistive moments and angular positions of an articulated ankle Foot Orthosis while walking in individuals post stroke a preliminary study
    Journal of Rehabilitation and Assistive Technologies Engineering, 2016
    Co-Authors: Toshiki Kobayashi, Michael S Orendurff, Madeline L Singer, Wayne K Daly, Lucas S. Lincoln, Fan Gao, Bo K Foreman
    Abstract:

    The plantarflexion resistive moments of an articulated ankle-Foot Orthosis play an important role in improving gait in individuals post stroke. However, the evidence regarding their magnitude required from the articulated ankle-Foot Orthosis to improve walking is still limited. Therefore, the primary aim of this study was to directly measure the plantarflexion resistive moments and the joint angular positions while walking using a prototype instrumented articulated ankle-Foot Orthosis in five individuals post stroke. The secondary aim was to investigate their moment-angle relationship by changing its preset plantarflexion stiffness. Each subject was fitted with the instrumented articulated ankle-Foot Orthosis and walked on a treadmill under four different preset plantarflexion stiffness conditions (0.35 N·m/°, 0.51 N·m/°, 0.87 N·m/°, and 1.27 N·m/°). For each subject, the plantarflexion resistive moments and the joint angular positions of five continuous gait cycles were extracted and averaged for each condition. Data were plotted and presented as case series. Both plantarflexion resistive moments and joint angular positions of the ankle-Foot Orthosis changed according to the preset plantarflexion stiffness in all subjects. Using the instrumented articulated ankle-Foot Orthosis could potentially advance the understanding of the biomechanics of an ankle-Foot Orthosis, as well as contribute to more evidence-based orthotic care of patients.

  • the effect of changing plantarflexion resistive moment of an articulated ankle Foot Orthosis on ankle and knee joint angles and moments while walking in patients post stroke
    Clinical Biomechanics, 2015
    Co-Authors: Toshiki Kobayashi, Michael S Orendurff, Madeline L Singer, Wayne K Daly, Bo K Foreman
    Abstract:

    Abstract Background The adjustment of plantarflexion resistive moment of an articulated ankle–Foot Orthosis is considered important in patients post stroke, but the evidence is still limited. Therefore, the aim of this study was to investigate the effect of changing the plantarflexion resistive moment of an articulated ankle–Foot Orthosis on ankle and knee joint angles and moments in patients post stroke. Methods Gait analysis was performed on 10 subjects post stroke under four different plantarflexion resistive moment conditions using a newly designed articulated ankle–Foot Orthosis. Data were recorded using a Bertec split-belt instrumented treadmill in a 3-dimensional motion analysis laboratory. Findings The ankle and knee sagittal joint angles and moments were significantly affected by the amount of plantarflexion resistive moment of the ankle–Foot Orthosis. Increasing the plantarflexion resistive moment of the ankle–Foot Orthosis induced significant decreases both in the peak ankle plantarflexion angle (P  Interpretation These results suggest an important link between the kinematic/kinetic parameters of the lower-limb joints and the plantarflexion resistive moment of an articulated ankle–Foot Orthosis. A future study should be performed to clarify their relationship further so that the practitioners may be able to use these parameters as objective data to determine an optimal plantarflexion resistive moment of an articulated ankle–Foot Orthosis for improved orthotic care in individual patients.

Michael S Orendurff - One of the best experts on this subject based on the ideXlab platform.

  • The effects of an articulated ankle-Foot Orthosis with resistance-adjustable joints on lower limb joint kinematics and kinetics during gait in individuals post-stroke.
    Clinical Biomechanics, 2018
    Co-Authors: Toshiki Kobayashi, Michael S Orendurff, Lucas S. Lincoln, Grace Hunt, Nicholas Lecursi, K. Bo Foreman
    Abstract:

    Abstract Background Resistance is a key mechanical property of an ankle-Foot Orthosis that affects gait in individuals post-stroke. Triple Action® joints allow independent adjustment of plantarflexion resistance and dorsiflexion resistance of an ankle-Foot Orthosis. Therefore, the aim of this study was to investigate the effects of incremental changes in dorsiflexion and plantarflexion resistance of an articulated ankle-Foot Orthosis with the Triple Action joints on lower limb joint kinematics and kinetics in individuals post-stroke during gait. Methods Gait analysis was performed on 10 individuals who were post-stroke under eight resistance settings (four plantarflexion and four dorsiflexion resistances) using the articulated ankle-Foot Orthosis. Kinematic and kinetic data of the lower limb joints were recorded while walking using a three-dimensional Vicon motion capture system and a Bertec split-belt instrumented treadmill. Findings Repeated measures analysis of variance revealed that adjustment of plantarflexion resistance had significant main effects on the ankle (P  Interpretation This study demonstrated that the adjustments of resistance in the ankle-Foot Orthosis with the Triple Action joints influenced ankle and knee kinematics in individuals post-stroke. Further work is necessary to investigate the long-term effects of the articulated ankle-Foot orthoses on their gait.

  • contribution of ankle Foot Orthosis moment in regulating ankle and knee motions during gait in individuals post stroke
    Clinical Biomechanics, 2017
    Co-Authors: Toshiki Kobayashi, Michael S Orendurff, Madeline L Singer, Bo K Foreman
    Abstract:

    Abstract Background Ankle-Foot Orthosis moment resisting plantarflexion has systematic effects on ankle and knee joint motion in individuals post-stroke. However, it is not known how much ankle-Foot Orthosis moment is generated to regulate their motion. The aim of this study was to quantify the contribution of an articulated ankle-Foot Orthosis moment to regulate ankle and knee joint motion during gait in individuals post-stroke. Methods Gait data were collected from 10 individuals post-stroke using a Bertec split-belt instrumented treadmill and a Vicon 3-dimensional motion analysis system. Each participant wore an articulated ankle-Foot Orthosis whose moment resisting plantarflexion was adjustable at four levels. Ankle-Foot Orthosis moment while walking was calculated under the four levels based on angle-moment relationship of the ankle-Foot Orthosis around the ankle joint measured by bench testing. The ankle-Foot Orthosis moment and the joint angular position (ankle and knee) relationship in a gait cycle was plotted to quantify the ankle-Foot Orthosis moment needed to regulate the joint motion. Findings Ankle and knee joint motion were regulated according to the amount of ankle-Foot Orthosis moment during gait. The ankle-Foot Orthosis maintained the ankle angular position in dorsiflexion and knee angular position in flexion throughout a gait cycle when it generated moment from − 0.029 (0.011) to − 0.062 (0.019) Nm/kg (moment resisting plantarflexion was defined as negative). Interpretations Quantifying the contribution of ankle-Foot Orthosis moment needed to regulate lower limb joints within a specific range of motion could provide valuable criteria to design an ankle-Foot Orthosis for individuals post-stroke.

  • reduction of genu recurvatum through adjustment of plantarflexion resistance of an articulated ankle Foot Orthosis in individuals post stroke
    Clinical Biomechanics, 2016
    Co-Authors: Toshiki Kobayashi, Michael S Orendurff, Madeline L Singer, Wayne K Daly, Bo K Foreman
    Abstract:

    Abstract Background Genu recurvatum (knee hyperextension) is a common issue for individuals post-stroke. Ankle-Foot orthoses are used to improve genu recurvatum, but evidence is limited concerning their effectiveness. Therefore, the aim of this study was to investigate the effect of changing the plantarflexion resistance of an articulated ankle-Foot Orthosis on genu recurvatum in patients post-stroke. Methods Gait analysis was performed on 6 individuals post-stroke with genu recurvatum using an articulated ankle-Foot Orthosis whose plantarflexion resistance was adjustable at four levels. Gait data were collected using a Bertec split-belt instrumented treadmill in a 3-dimensional motion analysis laboratory. Gait parameters were extracted and plotted for each subject under the four plantarflexion resistance conditions of the ankle-Foot Orthosis. Gait parameters included: a) peak ankle plantarflexion angle, b) peak ankle dorsiflexion moment, c) peak knee extension angle and d) peak knee flexion moment. A non-parametric Friedman test was performed followed by a post-hoc Wilcoxon Signed-Rank test for statistical analyses. Findings All the gait parameters demonstrated statistically significant differences among the four resistance conditions of the AFO. Increasing the amount of plantarflexion resistance of the ankle-Foot Orthosis generally reduced genu recurvatum in all subjects. However, individual analyses showed that the responses to the changes in the plantarflexion resistance of the AFO were not necessarily linear, and appear unique to each subject. Interpretations The plantarflexion resistance of an articulated AFO should be adjusted to improve genu recurvatum in patients post-stroke. Future studies should investigate what clinical factors would influence the individual differences.

  • direct measurement of plantarflexion resistive moments and angular positions of an articulated ankle Foot Orthosis while walking in individuals post stroke a preliminary study
    Journal of Rehabilitation and Assistive Technologies Engineering, 2016
    Co-Authors: Toshiki Kobayashi, Michael S Orendurff, Madeline L Singer, Wayne K Daly, Lucas S. Lincoln, Fan Gao, Bo K Foreman
    Abstract:

    The plantarflexion resistive moments of an articulated ankle-Foot Orthosis play an important role in improving gait in individuals post stroke. However, the evidence regarding their magnitude required from the articulated ankle-Foot Orthosis to improve walking is still limited. Therefore, the primary aim of this study was to directly measure the plantarflexion resistive moments and the joint angular positions while walking using a prototype instrumented articulated ankle-Foot Orthosis in five individuals post stroke. The secondary aim was to investigate their moment-angle relationship by changing its preset plantarflexion stiffness. Each subject was fitted with the instrumented articulated ankle-Foot Orthosis and walked on a treadmill under four different preset plantarflexion stiffness conditions (0.35 N·m/°, 0.51 N·m/°, 0.87 N·m/°, and 1.27 N·m/°). For each subject, the plantarflexion resistive moments and the joint angular positions of five continuous gait cycles were extracted and averaged for each condition. Data were plotted and presented as case series. Both plantarflexion resistive moments and joint angular positions of the ankle-Foot Orthosis changed according to the preset plantarflexion stiffness in all subjects. Using the instrumented articulated ankle-Foot Orthosis could potentially advance the understanding of the biomechanics of an ankle-Foot Orthosis, as well as contribute to more evidence-based orthotic care of patients.

  • the effect of changing plantarflexion resistive moment of an articulated ankle Foot Orthosis on ankle and knee joint angles and moments while walking in patients post stroke
    Clinical Biomechanics, 2015
    Co-Authors: Toshiki Kobayashi, Michael S Orendurff, Madeline L Singer, Wayne K Daly, Bo K Foreman
    Abstract:

    Abstract Background The adjustment of plantarflexion resistive moment of an articulated ankle–Foot Orthosis is considered important in patients post stroke, but the evidence is still limited. Therefore, the aim of this study was to investigate the effect of changing the plantarflexion resistive moment of an articulated ankle–Foot Orthosis on ankle and knee joint angles and moments in patients post stroke. Methods Gait analysis was performed on 10 subjects post stroke under four different plantarflexion resistive moment conditions using a newly designed articulated ankle–Foot Orthosis. Data were recorded using a Bertec split-belt instrumented treadmill in a 3-dimensional motion analysis laboratory. Findings The ankle and knee sagittal joint angles and moments were significantly affected by the amount of plantarflexion resistive moment of the ankle–Foot Orthosis. Increasing the plantarflexion resistive moment of the ankle–Foot Orthosis induced significant decreases both in the peak ankle plantarflexion angle (P  Interpretation These results suggest an important link between the kinematic/kinetic parameters of the lower-limb joints and the plantarflexion resistive moment of an articulated ankle–Foot Orthosis. A future study should be performed to clarify their relationship further so that the practitioners may be able to use these parameters as objective data to determine an optimal plantarflexion resistive moment of an articulated ankle–Foot Orthosis for improved orthotic care in individual patients.

Madeline L Singer - One of the best experts on this subject based on the ideXlab platform.

  • contribution of ankle Foot Orthosis moment in regulating ankle and knee motions during gait in individuals post stroke
    Clinical Biomechanics, 2017
    Co-Authors: Toshiki Kobayashi, Michael S Orendurff, Madeline L Singer, Bo K Foreman
    Abstract:

    Abstract Background Ankle-Foot Orthosis moment resisting plantarflexion has systematic effects on ankle and knee joint motion in individuals post-stroke. However, it is not known how much ankle-Foot Orthosis moment is generated to regulate their motion. The aim of this study was to quantify the contribution of an articulated ankle-Foot Orthosis moment to regulate ankle and knee joint motion during gait in individuals post-stroke. Methods Gait data were collected from 10 individuals post-stroke using a Bertec split-belt instrumented treadmill and a Vicon 3-dimensional motion analysis system. Each participant wore an articulated ankle-Foot Orthosis whose moment resisting plantarflexion was adjustable at four levels. Ankle-Foot Orthosis moment while walking was calculated under the four levels based on angle-moment relationship of the ankle-Foot Orthosis around the ankle joint measured by bench testing. The ankle-Foot Orthosis moment and the joint angular position (ankle and knee) relationship in a gait cycle was plotted to quantify the ankle-Foot Orthosis moment needed to regulate the joint motion. Findings Ankle and knee joint motion were regulated according to the amount of ankle-Foot Orthosis moment during gait. The ankle-Foot Orthosis maintained the ankle angular position in dorsiflexion and knee angular position in flexion throughout a gait cycle when it generated moment from − 0.029 (0.011) to − 0.062 (0.019) Nm/kg (moment resisting plantarflexion was defined as negative). Interpretations Quantifying the contribution of ankle-Foot Orthosis moment needed to regulate lower limb joints within a specific range of motion could provide valuable criteria to design an ankle-Foot Orthosis for individuals post-stroke.

  • reduction of genu recurvatum through adjustment of plantarflexion resistance of an articulated ankle Foot Orthosis in individuals post stroke
    Clinical Biomechanics, 2016
    Co-Authors: Toshiki Kobayashi, Michael S Orendurff, Madeline L Singer, Wayne K Daly, Bo K Foreman
    Abstract:

    Abstract Background Genu recurvatum (knee hyperextension) is a common issue for individuals post-stroke. Ankle-Foot orthoses are used to improve genu recurvatum, but evidence is limited concerning their effectiveness. Therefore, the aim of this study was to investigate the effect of changing the plantarflexion resistance of an articulated ankle-Foot Orthosis on genu recurvatum in patients post-stroke. Methods Gait analysis was performed on 6 individuals post-stroke with genu recurvatum using an articulated ankle-Foot Orthosis whose plantarflexion resistance was adjustable at four levels. Gait data were collected using a Bertec split-belt instrumented treadmill in a 3-dimensional motion analysis laboratory. Gait parameters were extracted and plotted for each subject under the four plantarflexion resistance conditions of the ankle-Foot Orthosis. Gait parameters included: a) peak ankle plantarflexion angle, b) peak ankle dorsiflexion moment, c) peak knee extension angle and d) peak knee flexion moment. A non-parametric Friedman test was performed followed by a post-hoc Wilcoxon Signed-Rank test for statistical analyses. Findings All the gait parameters demonstrated statistically significant differences among the four resistance conditions of the AFO. Increasing the amount of plantarflexion resistance of the ankle-Foot Orthosis generally reduced genu recurvatum in all subjects. However, individual analyses showed that the responses to the changes in the plantarflexion resistance of the AFO were not necessarily linear, and appear unique to each subject. Interpretations The plantarflexion resistance of an articulated AFO should be adjusted to improve genu recurvatum in patients post-stroke. Future studies should investigate what clinical factors would influence the individual differences.

  • direct measurement of plantarflexion resistive moments and angular positions of an articulated ankle Foot Orthosis while walking in individuals post stroke a preliminary study
    Journal of Rehabilitation and Assistive Technologies Engineering, 2016
    Co-Authors: Toshiki Kobayashi, Michael S Orendurff, Madeline L Singer, Wayne K Daly, Lucas S. Lincoln, Fan Gao, Bo K Foreman
    Abstract:

    The plantarflexion resistive moments of an articulated ankle-Foot Orthosis play an important role in improving gait in individuals post stroke. However, the evidence regarding their magnitude required from the articulated ankle-Foot Orthosis to improve walking is still limited. Therefore, the primary aim of this study was to directly measure the plantarflexion resistive moments and the joint angular positions while walking using a prototype instrumented articulated ankle-Foot Orthosis in five individuals post stroke. The secondary aim was to investigate their moment-angle relationship by changing its preset plantarflexion stiffness. Each subject was fitted with the instrumented articulated ankle-Foot Orthosis and walked on a treadmill under four different preset plantarflexion stiffness conditions (0.35 N·m/°, 0.51 N·m/°, 0.87 N·m/°, and 1.27 N·m/°). For each subject, the plantarflexion resistive moments and the joint angular positions of five continuous gait cycles were extracted and averaged for each condition. Data were plotted and presented as case series. Both plantarflexion resistive moments and joint angular positions of the ankle-Foot Orthosis changed according to the preset plantarflexion stiffness in all subjects. Using the instrumented articulated ankle-Foot Orthosis could potentially advance the understanding of the biomechanics of an ankle-Foot Orthosis, as well as contribute to more evidence-based orthotic care of patients.

  • the effect of changing plantarflexion resistive moment of an articulated ankle Foot Orthosis on ankle and knee joint angles and moments while walking in patients post stroke
    Clinical Biomechanics, 2015
    Co-Authors: Toshiki Kobayashi, Michael S Orendurff, Madeline L Singer, Wayne K Daly, Bo K Foreman
    Abstract:

    Abstract Background The adjustment of plantarflexion resistive moment of an articulated ankle–Foot Orthosis is considered important in patients post stroke, but the evidence is still limited. Therefore, the aim of this study was to investigate the effect of changing the plantarflexion resistive moment of an articulated ankle–Foot Orthosis on ankle and knee joint angles and moments in patients post stroke. Methods Gait analysis was performed on 10 subjects post stroke under four different plantarflexion resistive moment conditions using a newly designed articulated ankle–Foot Orthosis. Data were recorded using a Bertec split-belt instrumented treadmill in a 3-dimensional motion analysis laboratory. Findings The ankle and knee sagittal joint angles and moments were significantly affected by the amount of plantarflexion resistive moment of the ankle–Foot Orthosis. Increasing the plantarflexion resistive moment of the ankle–Foot Orthosis induced significant decreases both in the peak ankle plantarflexion angle (P  Interpretation These results suggest an important link between the kinematic/kinetic parameters of the lower-limb joints and the plantarflexion resistive moment of an articulated ankle–Foot Orthosis. A future study should be performed to clarify their relationship further so that the practitioners may be able to use these parameters as objective data to determine an optimal plantarflexion resistive moment of an articulated ankle–Foot Orthosis for improved orthotic care in individual patients.

  • the effect of ankle Foot Orthosis plantarflexion stiffness on ankle and knee joint kinematics and kinetics during first and second rockers of gait in individuals with stroke
    Clinical Biomechanics, 2014
    Co-Authors: Madeline L Singer, Michael S Orendurff, Lucas S. Lincoln, Toshiki Kobayashi, Bo K Foreman
    Abstract:

    Abstract Background Stiffness of an ankle–Foot Orthosis plays an important role in improving gait in patients with a history of stroke. To address this, the aim of this case series study was to determine the effect of increasing plantarflexion stiffness of an ankle–Foot Orthosis on the sagittal ankle and knee joint angle and moment during the first and second rockers of gait. Methods Gait data were collected in 5 subjects with stroke at a self-selected walking speed under two plantarflexion stiffness conditions (0.4 Nm/° and 1.3 Nm/°) using a stiffness-adjustable experimental ankle–Foot Orthosis on a Bertec split-belt fully instrumented treadmill in a 3-dimensional motion analysis laboratory. Findings By increasing the plantarflexion stiffness of the ankle–Foot Orthosis, peak plantarflexion angle of the ankle was reduced and peak dorsiflexion moment was generally increased in the first rocker as hypothesized. Two subjects demonstrated increases in both peak knee flexion angle and peak knee extension moment in the second rocker as hypothesized. The two subjects exhibited minimum contractility during active plantarflexion, while the other three subjects could actively plantarflex their ankle joint. Interpretation It was suggested that those with the decreased ability to actively plantarflex their ankle could not overcome excessive plantarflexion stiffness at initial contact of gait, and as a result exhibited compensation strategies at the knee joint. Providing excessively stiff ankle–Foot orthoses might put added stress on the extensor muscles of the knee joint, potentially creating fatigue and future pathologies in some patients with stroke.

Daniel P Ferris - One of the best experts on this subject based on the ideXlab platform.

  • A pneumatically powered knee-ankle-Foot Orthosis (KAFO) with myoelectric activation and inhibition
    Journal of NeuroEngineering and Rehabilitation, 2009
    Co-Authors: Gregory S Sawicki, Daniel P Ferris
    Abstract:

    Background The goal of this study was to test the mechanical performance of a prototype knee-ankle-Foot Orthosis (KAFO) powered by artificial pneumatic muscles during human walking. We had previously built a powered ankle-Foot Orthosis (AFO) and used it effectively in studies on human motor adaptation, locomotion energetics, and gait rehabilitation. Extending the previous AFO to a KAFO presented additional challenges related to the force-length properties of the artificial pneumatic muscles and the presence of multiple antagonistic artificial pneumatic muscle pairs. Methods Three healthy males were fitted with custom KAFOs equipped with artificial pneumatic muscles to power ankle plantar flexion/dorsiflexion and knee extension/flexion. Subjects walked over ground at 1.25 m/s under four conditions without extensive practice: 1) without wearing the Orthosis, 2) wearing the Orthosis with artificial muscles turned off, 3) wearing the Orthosis activated under direct proportional myoelectric control, and 4) wearing the Orthosis activated under proportional myoelectric control with flexor inhibition produced by leg extensor muscle activation. We collected joint kinematics, ground reaction forces, electromyography, and Orthosis kinetics. Results The KAFO produced ~22%–33% of the peak knee flexor moment, ~15%–33% of the peak extensor moment, ~42%–46% of the peak plantar flexor moment, and ~83%–129% of the peak dorsiflexor moment during normal walking. With flexor inhibition produced by leg extensor muscle activation, ankle (Pearson r-value = 0.74 ± 0.04) and knee ( r = 0.95 ± 0.04) joint kinematic profiles were more similar to the without Orthosis condition compared to when there was no flexor inhibition (r = 0.49 ± 0.13 for ankle, p = 0.05, and r = 0.90 ± 0.03 for knee, p = 0.17). Conclusion The proportional myoelectric control with flexor inhibition allowed for a more normal gait than direct proportional myoelectric control. The current Orthosis design provided knee torques smaller than the ankle torques due to the trade-off in torque and range of motion that occurs with artificial pneumatic muscles. Future KAFO designs could incorporate cams, gears, or different actuators to transmit greater torque to the knee.

  • an improved powered ankle Foot Orthosis using proportional myoelectric control
    Gait & Posture, 2006
    Co-Authors: Daniel P Ferris, Gregory S Sawicki, Keith E. Gordon, Ammanath Peethambaran
    Abstract:

    We constructed a powered ankle–Foot Orthosis for human walking with a novel myoelectric controller. The Orthosis included a carbon fiber and polypropylene shell, a metal hinge joint, and two artificial pneumatic muscles. Soleus electromyography (EMG) activated the artificial plantar flexor and inhibited the artificial dorsiflexor. Tibialis anterior EMG activated the artificial dorsiflexor. We collected kinematic, kinetic, and electromyographic data for a naive healthy subject walking with the Orthosis. The current design improves upon a previous prototype by being easier to don and doff and simpler to use. The novel controller allows naive wearers to quickly adapt to the Orthosis without artificial muscle co-contraction. The Orthosis may be helpful in studying human walking biomechanics and assisting patients during gait rehabilitation after neurological injury. # 2005 Elsevier B.V. All rights reserved.

  • an improved powered ankle Foot Orthosis using proportional myoelectric control
    Gait & Posture, 2006
    Co-Authors: Daniel P Ferris, Gregory S Sawicki, Keith E. Gordon, Ammanath Peethambaran
    Abstract:

    We constructed a powered ankle-Foot Orthosis for human walking with a novel myoelectric controller. The Orthosis included a carbon fiber and polypropylene shell, a metal hinge joint, and two artificial pneumatic muscles. Soleus electromyography (EMG) activated the artificial plantar flexor and inhibited the artificial dorsiflexor. Tibialis anterior EMG activated the artificial dorsiflexor. We collected kinematic, kinetic, and electromyographic data for a naive healthy subject walking with the Orthosis. The current design improves upon a previous prototype by being easier to don and doff and simpler to use. The novel controller allows naive wearers to quickly adapt to the Orthosis without artificial muscle co-contraction. The Orthosis may be helpful in studying human walking biomechanics and assisting patients during gait rehabilitation after neurological injury.

  • neuromechanical adaptation to hopping with an elastic ankle Foot Orthosis
    Journal of Applied Physiology, 2006
    Co-Authors: Daniel P Ferris, Zaineb A Bohra, Jamie R Lukos, Catherine R Kinnaird
    Abstract:

    When humans hop or run on different surfaces, they adjust their effective leg stiffness to offset changes in surface stiffness. As a result, the overall stiffness of the leg-surface series combination remains independent of surface stiffness. The purpose of this study was to determine whether humans make a similar adjustment when springs are placed in parallel with the leg via a lower limb Orthosis. We studied seven human subjects hopping in place on one leg while wearing an ankle-Foot Orthosis. We used an ankle-Foot Orthosis because the ankle joint is primarily responsible for leg stiffness during hopping. A spring was added to the ankle-Foot Orthosis so that it increased Orthosis stiffness by providing plantar flexor torque during ankle dorsiflexion. We hypothesized that subjects would decrease their biological ankle stiffness when the spring was added to the Orthosis, keeping total ankle stiffness constant. We collected kinematic, kinetic, and electromyographic data during hopping with and without the spring on the Orthosis. We found that total ankle stiffness and leg stiffness did not change across the two Orthosis conditions (ANOVA, P > 0.05). This was possible because subjects decreased their biological ankle stiffness to offset the Orthosis spring stiffness (P < 0.0001). The reduction in biological ankle stiffness was accompanied by decreases in soleus, medial gastrocnemius, and lateral gastrocnemius muscle activation (P < 0.0002). These results suggest that an elastic exoskeleton might improve human running performance by reducing muscle recruitment.

  • mechanical performance of artificial pneumatic muscles to power an ankle Foot Orthosis
    Journal of Biomechanics, 2006
    Co-Authors: Keith E. Gordon, Gregory S Sawicki, Daniel P Ferris
    Abstract:

    We developed a powered ankle-Foot Orthosis that uses artificial pneumatic muscles to produce active plantar flexor torque. The purpose of this study was to quantify the mechanical performance of the Orthosis during human walking. Three subjects walked at a range of speeds wearing ankle-Foot orthoses with either one or two artificial muscles working in parallel. The Orthosis produced similar total peak plantar flexor torque and network across speeds independent of the number of muscles used. The Orthosis generated approximately 57% of the peak ankle plantar flexor torque during stance and performed approximately 70% of the positive plantar flexor work done during normal walking. Artificial muscle bandwidth and force-length properties were the two primary factors limiting torque production. The lack of peak force and work differences between single and double muscle conditions can be explained by force-length properties. Subjects altered their ankle kinematics between conditions resulting in changes in artificial muscle length. In the double muscle condition greater plantar flexion yielded shorter artificial muscles lengths and decreased muscle forces. This finding emphasizes the importance of human testing in the design and development of robotic exoskeleton devices for assisting human movement. The results of this study outline the mechanical performance limitations of an ankle-Foot Orthosis powered by artificial pneumatic muscles. This Orthosis could be valuable for gait rehabilitation and for studies investigating neuromechanical control of human walking.