Biornechanical design of a shape memory alloy spring for the activation of a flaccid hand rehabilitation device

Hand rehabilitation techniques are very widespread in the clinical practice, as they are strongly indicated in the treatment of several different neuromuscular diseases. For instance, the distal upper extremities are very often affected by stroke events. Considering the social impact of stroke alone (700,000 new/recurrent cases a year in the US, with a cost of $56.8 billion in 2005, and more than a million American adults complaining various degrees of disability resulting from stroke) it is easy to appreciate the importance of developing new strategies in this field. After stroke, a rehabilitation program should be performed as soon as the patient's conditions are sufficiently good. This is required in order to prevent complications, minimise impairment (e.g. contractures) and maximise functional recovery. AHA/ASAendorsed guidelines for 2005, besides stressing the need for a multidisciplinary approach in post-stroke care, also indicate that a strong difference in the final treatment outcomes derives from the sheer time spent on physical rehabilitation. Whereas a clinical institution is currently able to provide exercise 5 hours a day, 7 days a week to hospitalised patients, the same patient will receive only 1 hour treatment a day, 3 days a week from a single therapist after discharge. Since it often happens that short-term rehabilitation does not correspond to long-term benefits, it is stated that therapy should be extended after discharge to obtain a lasting improvement.