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Ankle voluntary movement enhancement following robotic-assisted locomotor training in spinal cord injury.

Varoqui D, Niu X, Mirbagheri MM - J Neuroeng Rehabil (2014)

Bottom Line: To better understand the mechanisms underlying these improvements, we studied the effects of Lokomat training on impaired ankle voluntary movement, known to be an important limiting factor in gait for iSCI patients.After the Lokomat training, the active range of motion, the maximal velocity, and the movement smoothness were significantly improved in the voluntary movement.Correlation tests indicated a significant relationship between ankle voluntary movement performance and the walking clinical assessments.

View Article: PubMed Central - HTML - PubMed

Affiliation: Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, USA. mehdi@northwestern.edu.

ABSTRACT

Background: In incomplete spinal cord injury (iSCI), sensorimotor impairments result in severe limitations to ambulation. To improve walking capacity, physical therapies using robotic-assisted locomotor devices, such as the Lokomat, have been developed. Following locomotor training, an improvement in gait capabilities-characterized by increases in the over-ground walking speed and endurance-is generally observed in patients. To better understand the mechanisms underlying these improvements, we studied the effects of Lokomat training on impaired ankle voluntary movement, known to be an important limiting factor in gait for iSCI patients.

Methods: Fifteen chronic iSCI subjects performed twelve 1-hour sessions of Lokomat training over the course of a month. The voluntary movement was qualified by measuring active range of motion, maximal velocity peak and trajectory smoothness for the spastic ankle during a movement from full plantar-flexion (PF) to full dorsi-flexion (DF) at the patient's maximum speed. Dorsi- and plantar-flexor muscle strength was quantified by isometric maximal voluntary contraction (MVC). Clinical assessments were also performed using the Timed Up and Go (TUG), the 10-meter walk (10MWT) and the 6-minute walk (6MWT) tests. All evaluations were performed both before and after the training and were compared to a control group of fifteen iSCI patients.

Results: After the Lokomat training, the active range of motion, the maximal velocity, and the movement smoothness were significantly improved in the voluntary movement. Patients also exhibited an improvement in the MVC for their ankle dorsi- and plantar-flexor muscles. In terms of functional activity, we observed an enhancement in the mobility (TUG) and the over-ground gait velocity (10MWT) with training. Correlation tests indicated a significant relationship between ankle voluntary movement performance and the walking clinical assessments.

Conclusions: The improvements of the kinematic and kinetic parameters of the ankle voluntary movement, and their correlation with the functional assessments, support the therapeutic effect of robotic-assisted locomotor training on motor impairment in chronic iSCI.

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Experimental setup. Experimental apparatus used to evaluate ankle voluntary dorsi-flexion movement and isometric maximal voluntary contractions.
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Figure 1: Experimental setup. Experimental apparatus used to evaluate ankle voluntary dorsi-flexion movement and isometric maximal voluntary contractions.

Mentions: The voluntary movement capacity and muscle strength of the ankle were evaluated at the same two time intervals as the clinical assessments (i.e., baseline and 1-month). For this purpose, participants were seated in an experimental chair with the thigh strapped to the chair base (Figure 1). The ankle was secured to a rigid “footrest” which was in turn attached to the rotational axis of a servomotor, allowing for DF and PF of the ankle. The seat and footrest were adjusted such that the ankle and knee joints were flexed at 90° (ankle) and 130° (knee). A rotary encoder recorded angular position, while a 6-axis torque transducer recorded torque; this transducer was aligned such that the torque was measured about the ankle axis of rotation. Position and torque data were sampled at 1 kHz by a 16 bit A/D converter, and anti-alias filtered on-line at 200 Hz. A 90° angle between the calf and foot was considered as the neutral position for the ankle and defined as zero degrees; DF was considered positive by convention.


Ankle voluntary movement enhancement following robotic-assisted locomotor training in spinal cord injury.

Varoqui D, Niu X, Mirbagheri MM - J Neuroeng Rehabil (2014)

Experimental setup. Experimental apparatus used to evaluate ankle voluntary dorsi-flexion movement and isometric maximal voluntary contractions.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3974744&req=5

Figure 1: Experimental setup. Experimental apparatus used to evaluate ankle voluntary dorsi-flexion movement and isometric maximal voluntary contractions.
Mentions: The voluntary movement capacity and muscle strength of the ankle were evaluated at the same two time intervals as the clinical assessments (i.e., baseline and 1-month). For this purpose, participants were seated in an experimental chair with the thigh strapped to the chair base (Figure 1). The ankle was secured to a rigid “footrest” which was in turn attached to the rotational axis of a servomotor, allowing for DF and PF of the ankle. The seat and footrest were adjusted such that the ankle and knee joints were flexed at 90° (ankle) and 130° (knee). A rotary encoder recorded angular position, while a 6-axis torque transducer recorded torque; this transducer was aligned such that the torque was measured about the ankle axis of rotation. Position and torque data were sampled at 1 kHz by a 16 bit A/D converter, and anti-alias filtered on-line at 200 Hz. A 90° angle between the calf and foot was considered as the neutral position for the ankle and defined as zero degrees; DF was considered positive by convention.

Bottom Line: To better understand the mechanisms underlying these improvements, we studied the effects of Lokomat training on impaired ankle voluntary movement, known to be an important limiting factor in gait for iSCI patients.After the Lokomat training, the active range of motion, the maximal velocity, and the movement smoothness were significantly improved in the voluntary movement.Correlation tests indicated a significant relationship between ankle voluntary movement performance and the walking clinical assessments.

View Article: PubMed Central - HTML - PubMed

Affiliation: Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, USA. mehdi@northwestern.edu.

ABSTRACT

Background: In incomplete spinal cord injury (iSCI), sensorimotor impairments result in severe limitations to ambulation. To improve walking capacity, physical therapies using robotic-assisted locomotor devices, such as the Lokomat, have been developed. Following locomotor training, an improvement in gait capabilities-characterized by increases in the over-ground walking speed and endurance-is generally observed in patients. To better understand the mechanisms underlying these improvements, we studied the effects of Lokomat training on impaired ankle voluntary movement, known to be an important limiting factor in gait for iSCI patients.

Methods: Fifteen chronic iSCI subjects performed twelve 1-hour sessions of Lokomat training over the course of a month. The voluntary movement was qualified by measuring active range of motion, maximal velocity peak and trajectory smoothness for the spastic ankle during a movement from full plantar-flexion (PF) to full dorsi-flexion (DF) at the patient's maximum speed. Dorsi- and plantar-flexor muscle strength was quantified by isometric maximal voluntary contraction (MVC). Clinical assessments were also performed using the Timed Up and Go (TUG), the 10-meter walk (10MWT) and the 6-minute walk (6MWT) tests. All evaluations were performed both before and after the training and were compared to a control group of fifteen iSCI patients.

Results: After the Lokomat training, the active range of motion, the maximal velocity, and the movement smoothness were significantly improved in the voluntary movement. Patients also exhibited an improvement in the MVC for their ankle dorsi- and plantar-flexor muscles. In terms of functional activity, we observed an enhancement in the mobility (TUG) and the over-ground gait velocity (10MWT) with training. Correlation tests indicated a significant relationship between ankle voluntary movement performance and the walking clinical assessments.

Conclusions: The improvements of the kinematic and kinetic parameters of the ankle voluntary movement, and their correlation with the functional assessments, support the therapeutic effect of robotic-assisted locomotor training on motor impairment in chronic iSCI.

Show MeSH
Related in: MedlinePlus