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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.


Related in: MedlinePlus

(a) Examples of pseudoelastic orthoses; (b) pseudoelastic hinge prototypes; (c) a drawing of the hinge assembly with the SMA spring (dark grey).
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jfb-06-00328-f003: (a) Examples of pseudoelastic orthoses; (b) pseudoelastic hinge prototypes; (c) a drawing of the hinge assembly with the SMA spring (dark grey).

Mentions: In order to implement these concepts, our group devised a set of hinges [26] that can be used to create compliant orthoses. Inside the hinges are placed two springs made of NiTi, shaped as a capital letter omega (Ω) (Figure 3). This particular shape allows the material to be loaded along its entire length, prevents localized stress concentrations and, ultimately, failures. The spring action is based on pseudoelasticity. The nonlinearity and hysteretic behavior of NiTi-based alloys indeed endow these orthoses with convenient characteristics for this application and solve some inherent problems of dynamic splints with purely elastic elements. In fact, in classic elastic tension or torque elements, the spring-back forces change with elongation; assuming that those elements are preloaded in such a manner as to guide repositioning towards a desired posture, the corrective force applied to the limb will be high at the beginning of the process and will gradually decrease the closer the joint angle gets to the target. Clockwork springs could be used to counter this effect, but they tend to be either weak or bulky. On the contrary, the nonlinear behavior of pseudoelastic SMA, due to the presence of long plateaux at quasi-constant stress, makes it possible to administer a continual therapeutic action even in proximity of the goal and in general for much wider deformation/elongation ranges.


Applications of shape memory alloys for neurology and neuromuscular rehabilitation.

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

(a) Examples of pseudoelastic orthoses; (b) pseudoelastic hinge prototypes; (c) a drawing of the hinge assembly with the SMA spring (dark grey).
© Copyright Policy
Related In: Results  -  Collection

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

jfb-06-00328-f003: (a) Examples of pseudoelastic orthoses; (b) pseudoelastic hinge prototypes; (c) a drawing of the hinge assembly with the SMA spring (dark grey).
Mentions: In order to implement these concepts, our group devised a set of hinges [26] that can be used to create compliant orthoses. Inside the hinges are placed two springs made of NiTi, shaped as a capital letter omega (Ω) (Figure 3). This particular shape allows the material to be loaded along its entire length, prevents localized stress concentrations and, ultimately, failures. The spring action is based on pseudoelasticity. The nonlinearity and hysteretic behavior of NiTi-based alloys indeed endow these orthoses with convenient characteristics for this application and solve some inherent problems of dynamic splints with purely elastic elements. In fact, in classic elastic tension or torque elements, the spring-back forces change with elongation; assuming that those elements are preloaded in such a manner as to guide repositioning towards a desired posture, the corrective force applied to the limb will be high at the beginning of the process and will gradually decrease the closer the joint angle gets to the target. Clockwork springs could be used to counter this effect, but they tend to be either weak or bulky. On the contrary, the nonlinear behavior of pseudoelastic SMA, due to the presence of long plateaux at quasi-constant stress, makes it possible to administer a continual therapeutic action even in proximity of the goal and in general for much wider deformation/elongation ranges.

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