A knee orthosis provides varying levels of support to a patient during a stance phase and a swing phase of a gait cycle. The orthosis comprises an upper auxiliary support, a lower auxiliary support, an actuator, a sensor configured to detect a plurality of leg movements during the gait cycle and to output a plurality of detection signals corresponding to the detected leg movements, and a processor configured to determine whether the knee is in the stance phase or the swing phase of the gait cycle, to control the actuator to apply pressure on the lower auxiliary support when the knee is in the stance phase, and to release pressure when the knee is in the swing phase.
