A hinged connecting device comprising a damping mechanism intended to counter a predetermined resistance at least during bending of the prosthesis (1), by replacing the muscle groups usually used for this purpose. The damping mechanism (200) is capable of being switched between a first operating mode (M1), selected by default, in which the value of the resistance corresponds to a first maximum value (Vmax), and a second operating mode (M2), that can be actuated only in a hyperextension position (P0) of the prosthesis (1), in which the resistance value corresponds to a second minimum value (Vmin); and the hinged connecting device (2) moreover comprises a fully mechanical locking system (3), arranged in order to allow the second operating mode (M2) to be activated only when the inclination of the tibial part (102) exceeds a first predetermined oriented angle (X1) relative to the vertical.