Dynamic orthosis for drop foot, with a vertical flat, rigid bar (1 ) anchored to a collar (2) of a patients leg (3), and whose lower free end is integral to a bearing (4) which is to take position in front of the internal malleoulus (30) of the user and to constitute the joint of a cantilevered arm (5) whose free end is integral to a bracket (8) for the foot, and whose motion required for lifting the foot during the deambulation is obtained by the force Fs generated by a magnetic spring (9) with the interposition of a rod (94) the required lifting force Fs being produced by more pairs of magnets (92) vertically lined up and with the same polarity being juxtaposed to allow using their mutual repulsive force. The loading phase of the spring (9) corresponds to the pressure of the foot onto the ground and, therefore, to the maximum moment onto the malleoulus exerted by the compression of the magnets upon the movement thereof close to each other. On the other hand, the next release phase of the spring, that is, the spontaneous movement of the magnets away from each other - which takes place upon the detachment of the foot from the ground - that is, when the moment onto the malleoulus is minimum, is cause for a clockwise rotation of the arm (5) and, consequently, the lifting of the bracket (8) along with the foot.La présente invention concerne une orthèse dynamique pour pied tombant, dotée dune barre rigide, plate et verticale (1) ancrée sur un bracelet (2) dune jambe (3) de patient, et dont lextrémité libre inférieure est solidaire dun support (4) qui doit prendre position devant la malléole interne (30) de lutilisateur et constituer larticulation dun bras en porte-à-faux (5) dont lextrémité libre est solidaire dun support (8) destiné au pied, et dont le mouvement requis pour lever le pied au cours de la déambulation est obtenu grâce à la force Fs générée par un ressort magnétique (9) avec lintercalation dune tige (94) la force de levée requise Fs étant produite par daut
