A knee brace for the treatment of osteoarthritis comprising an upper half-shell (12) and a lower half-shell (13), joined by an articulated rod (14), as well as a pressure plate (17) for the lateral support against the knee on the opposite side with respect to the articulated rod (14), also comprises a strap system comprising an upper and lower transverse front adjustment strap (19, 20), adjustable in length, connected at opposite ends to the respective half-shells (12, 13) and to the pressure plate (17), as well as a unique rear tightening strap (21), adjustable in length and provided with a pulley tensioning device (23), arranged on the rear side of the knee brace (10) according to two diagonals that, starting from the upper (12) and lower (13) half-shells, respectively, converge to an articulated slot (116) of the pressure plate (17), wherein the straps are connected to the half-shells (12, 13) and to the pressure plate (17) exclusively in an articulated manner through constraining elements (16).
