A below-knee orthosis comprises a footplate, which is carried by a connecting element projecting therefrom, the upper end part of which has a releasable coupling that can be coupled to an upper part of a patient's lower leg, a longitudinal section of the connecting element being formed of a spring element, which extends in a curved path at a radial distance from a fulcrum of the spring element, and said fulcrum being placed to be essentially aligned with the patient's ankle-joint axis.