A system for the adjustment and tautening of the fixing straps of an orthosis (20), this orthosis (20) comprising articulated couplings (21, 22) with controllable angular excursion, one of which can move closer to or farther away from the centre of the joint along an axis parallel to the rotation axis of the articulated coupling, and in which each of the articulated couplings (21, 22) acts as a support for respective pairs of bars (39, 42 and 23, 24) and comprises respective platforms (25, 41), facing inwards, consisting of a cushion pad for the condylar sectors of the joint, and in which bars constrained to the articulated couplings form lateral support sectors which are attached to and fixed on the joint by means of straps (26, 27) in turn attached to feedthrough loops being positioned on guides (29) sliding on respective bars (23, 24), allowing the loops (38), to be moved from a proximal to a distal position along the bar to which the guide is attached.
