Dynamic orthotics for dyskinesia and dystonia in the young: materials, designs and pilot clinical trials.

Background. Movement disorders are neurological diseases affecting different age groups. They worsen patients' quality of life preventing the possibility of carrying out daily activities independently, and disturbing their social relationships especially in childhood. Drugs and surgery are among the most widely-employed means of controlling the symptoms of those disorders, but not often give the expected relief; an alternative solution is offered by orthoses that possess dynamic characteristics and can deliver a functionally-customised therapy. Methods. We have designed functionally-customised devices exploiting the characteristics of a class of metallic materials, shape memory alloys (SMA), that possess some unconventional properties such as a nonlinear viscoelastic behaviour, wide hysteresis and internal friction, useful for controlling pathological limb motion and fighting ill-postures, while preserving the ability to carry out voluntary tasks. Three paediatric patients with dystonic and dyskinetic cerebral palsy were enrolled so far. The mechanical properties of the SMA were set and adjusted to address the clinical requests and individual patient's needs. Ad hoc protocols were devised to measure patients clinical status and biometric characteristics; an optoelectronic system and EMG were used to obtain quantitative information about upper-limb anatomy, kinematics and muscular activation to be employed as a basis for the personalised fabrication of the splints. Measurements on an age-matched healthy group were used as a reference for the motion tasks performed by patients. Results. The first observations suggest that wearing the personalised SMA-based dynamic orthosis, patients manage to carry out standardised motor tasks like reaching for objects or bringing food to one's mouth in a more direct way, with less stray motion. Conclusions Preliminary results support the hypothesis that splints with nonlinear mechanical characteristics can provide posture control and stabilisation during the execution of upper-limb tasks. Clinical trials are continuing..