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Applications of shape memory alloys for neurology and neuromuscular rehabilitation.

Pittaccio S, Garavaglia L, Ceriotti C, Passaretti F - J Funct Biomater (2015)

Bottom Line: Our group has applied SMA in the field of neuromuscular rehabilitation, designing some new devices based on the mentioned SMA properties: in particular, a new type of orthosis for spastic limb repositioning, which allows residual voluntary movement of the impaired limb and has no predetermined final target position, but follows and supports muscular elongation in a dynamic and compliant way.Two different SMA-based applications in the field of neuroscience are then presented, a guide and a limb mobiliser specially designed to be compatible with diagnostic instrumentations that impose rigid constraints in terms of electromagnetic compatibility and noise distortion.Finally, the paper discusses possible uses of these materials in the treatment of movement disorders, such as dystonia or hyperkinesia, where their dynamic characteristics can be advantageous.

View Article: PubMed Central - PubMed

Affiliation: National Research Council of Italy, Institute for Energetics and Interphases (CNR-IENI), C.so Promessi Sposi, 29-23900 Lecco, Italy. s.pittaccio@ieni.cnr.it.

ABSTRACT
Shape memory alloys (SMAs) are a very promising class of metallic materials that display interesting nonlinear properties, such as pseudoelasticity (PE), shape memory effect (SME) and damping capacity, due to high mechanical hysteresis and internal friction. Our group has applied SMA in the field of neuromuscular rehabilitation, designing some new devices based on the mentioned SMA properties: in particular, a new type of orthosis for spastic limb repositioning, which allows residual voluntary movement of the impaired limb and has no predetermined final target position, but follows and supports muscular elongation in a dynamic and compliant way. Considering patients in the sub-acute phase after a neurological lesion, and possibly bedridden, the paper presents a mobiliser for the ankle joint, which is designed exploiting the SME to provide passive exercise to the paretic lower limb. Two different SMA-based applications in the field of neuroscience are then presented, a guide and a limb mobiliser specially designed to be compatible with diagnostic instrumentations that impose rigid constraints in terms of electromagnetic compatibility and noise distortion. Finally, the paper discusses possible uses of these materials in the treatment of movement disorders, such as dystonia or hyperkinesia, where their dynamic characteristics can be advantageous.

No MeSH data available.


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Two views of the EMG-controlled SMA device for assisted ankle exercise.
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jfb-06-00328-f002: Two views of the EMG-controlled SMA device for assisted ankle exercise.

Mentions: In order to bridge the gap between the period of time when patients, being paretic, cannot do any active exercise and the later phase in which voluntary control is partially recovered and work-out is recommended, electromyography (EMG) or some other biosignal can be employed to trigger activation of the orthosis. An example of this is described in [23], where a proof-of-concept is provided, with trials on the tibiotarsal joint of healthy volunteers. By setting two adjustable threshold values, it was possible to discriminate between rest, minimal voluntary contraction of the anterior tibialis (TA) muscle and a regular contraction leading to ankle dorsiflexion. Now, if a patient starts regaining some voluntary control of muscular contraction, but this action is not recognized because the contraction is too weak to give rise to a perceivable movement, it could be argued that opportunities for commencing active exercise early might go missed. On the other hand, if minimal contractions are picked up through EMG sensors, these events can be used to trigger passive mobilization by a suitable device. In a way, patients’ involvement would be halfway between active and passive, because movement initiation could be exercised directly by the patient, while the proprioceptive feedback and the reward for that effort would be provided by the device in the form of aided motion. By gradually adjusting threshold values session after session, the therapist could set increasing targets for the patient, ultimately paving the way to active work-out (Figure 2).


Applications of shape memory alloys for neurology and neuromuscular rehabilitation.

Pittaccio S, Garavaglia L, Ceriotti C, Passaretti F - J Funct Biomater (2015)

Two views of the EMG-controlled SMA device for assisted ankle exercise.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493515&req=5

jfb-06-00328-f002: Two views of the EMG-controlled SMA device for assisted ankle exercise.
Mentions: In order to bridge the gap between the period of time when patients, being paretic, cannot do any active exercise and the later phase in which voluntary control is partially recovered and work-out is recommended, electromyography (EMG) or some other biosignal can be employed to trigger activation of the orthosis. An example of this is described in [23], where a proof-of-concept is provided, with trials on the tibiotarsal joint of healthy volunteers. By setting two adjustable threshold values, it was possible to discriminate between rest, minimal voluntary contraction of the anterior tibialis (TA) muscle and a regular contraction leading to ankle dorsiflexion. Now, if a patient starts regaining some voluntary control of muscular contraction, but this action is not recognized because the contraction is too weak to give rise to a perceivable movement, it could be argued that opportunities for commencing active exercise early might go missed. On the other hand, if minimal contractions are picked up through EMG sensors, these events can be used to trigger passive mobilization by a suitable device. In a way, patients’ involvement would be halfway between active and passive, because movement initiation could be exercised directly by the patient, while the proprioceptive feedback and the reward for that effort would be provided by the device in the form of aided motion. By gradually adjusting threshold values session after session, the therapist could set increasing targets for the patient, ultimately paving the way to active work-out (Figure 2).

Bottom Line: Our group has applied SMA in the field of neuromuscular rehabilitation, designing some new devices based on the mentioned SMA properties: in particular, a new type of orthosis for spastic limb repositioning, which allows residual voluntary movement of the impaired limb and has no predetermined final target position, but follows and supports muscular elongation in a dynamic and compliant way.Two different SMA-based applications in the field of neuroscience are then presented, a guide and a limb mobiliser specially designed to be compatible with diagnostic instrumentations that impose rigid constraints in terms of electromagnetic compatibility and noise distortion.Finally, the paper discusses possible uses of these materials in the treatment of movement disorders, such as dystonia or hyperkinesia, where their dynamic characteristics can be advantageous.

View Article: PubMed Central - PubMed

Affiliation: National Research Council of Italy, Institute for Energetics and Interphases (CNR-IENI), C.so Promessi Sposi, 29-23900 Lecco, Italy. s.pittaccio@ieni.cnr.it.

ABSTRACT
Shape memory alloys (SMAs) are a very promising class of metallic materials that display interesting nonlinear properties, such as pseudoelasticity (PE), shape memory effect (SME) and damping capacity, due to high mechanical hysteresis and internal friction. Our group has applied SMA in the field of neuromuscular rehabilitation, designing some new devices based on the mentioned SMA properties: in particular, a new type of orthosis for spastic limb repositioning, which allows residual voluntary movement of the impaired limb and has no predetermined final target position, but follows and supports muscular elongation in a dynamic and compliant way. Considering patients in the sub-acute phase after a neurological lesion, and possibly bedridden, the paper presents a mobiliser for the ankle joint, which is designed exploiting the SME to provide passive exercise to the paretic lower limb. Two different SMA-based applications in the field of neuroscience are then presented, a guide and a limb mobiliser specially designed to be compatible with diagnostic instrumentations that impose rigid constraints in terms of electromagnetic compatibility and noise distortion. Finally, the paper discusses possible uses of these materials in the treatment of movement disorders, such as dystonia or hyperkinesia, where their dynamic characteristics can be advantageous.

No MeSH data available.


Related in: MedlinePlus