A blocking device (20) for fastening orthoses used in the orthopedic-rehabilitation sector to parts of the body of a person comprises a casing (21) housing a cable (40) wound on a reel (23) by the rotation of a knob (27) restrained to the casing (21) during the winding stage and partially releasable from the casing by pushing and/or pulling the knob, in order to operate with respect to a ratchet-type non-return system, wherein the ratchet-type non-return system consists of elastic tabs (32) which are part of the casing (21), and an inner toothed edge (31) of the knob (27). The knob (27) is restrained in a rotating direction and unrestrained in an axial direction with respect to the reel (23) by a pin (25) with a shaped head (25′), whereby the restraint between the knob (27) and the reel is achieved by a shaped axial opening (30) in the knob, which reflects the shape of the head (25′) of the pin (25), wherein maintaining the knob (27) in the gripping/release positions is ensured by the concave profiles (33) present on the shaped head (25′) of the pin (25) and convex surfaces (34) present in the opening (30) of the knob (27), thereby allowing the knob to be moved from a gripping condition with the ratchet-type non-return system in the tightening and blocking stage to a release condition in the opening stage while maintaining control of the cable (40) wound on the reel.
