Ergonomic assessment of an active orthosis for the rehabilitation of flexion and extension of Wrist

Muscular stiffness and limb rigidity are two main consequences of Parkinson’s disease. These motor symptoms may be present in distinct parts of the body, influencing functional tasks executed by hands. To aid people suffering from these motor symptoms, we developed an active wrist orthosis whose purpose is to enable increase the flexion and extension range of motion of the wrist joint. We identified five relevant ergonomic variables that should be considered when using the orthosis in the clinical practice: (i) device stability, (ii) forearm position; (iii) muscular strength; (iv) amplitude of motion; and (v) mass of the device. These variables were identified based on the observation of movements while users executed the flexion and extension of the wrist with and without the device. In this research, we present a description of the developed orthosis and an evaluation of the ergonomic variables (i), (ii) and (iii). An enhanced support structure has been used with the orthosis and shown to lead to a stability improvement. Electromyographic analysis showed that the use of the orthosis does not introduce undue muscular load on the user at distinct angular positions of the forearm