[Feasibility of the construction of a magnetorheological joint for a lower limb orthosis in valve configuration].

Ortheses are devices that assist in the function of the limbs, contributing with stability and support to the involved joints. KAFOs (knee-ankle-foot orthosis) are mainly indicated for people with muscular or neural diseases that affect the lower limbs. The actual designs of knee hinges for KAFOs compromise the stability and mobility of the limb. In this work, it was tested the feasibility of a design for a knee hinge for KAFO that should be able to modify its mechanical resistance depending on the gait phase. Orthotics biomechanical criteria and gait biomechanical requirements were considered. It was proposed an electromagnetic system in order to modify the hinge damping. In the future, the system will be interacting with a magnetorheological fluid (MR) which can change its rheological properties when a magnetic field is applied, thus, reaching different damping constants with the designed hinge. The diameter of the internal pipes required for the MR fluid to freely circulate within the orthosis was established. It was observed that the original design of the proposed orthotic hinge is feasible; however, some proposals are presented in order to achieve a better performance of the orthosis.