An assembly for active and resistive joint rehabilitation exercises enables a joint, such as a knee, to flex in a controlled, curvilinear motion, while enabling adjustable resistance. In this manner, the joint practices both resistive exercises and active exercises for strengthening, as well as redeveloping range of motions. A base member with stabilizing bars provides lateral support for the assembly. The base member has a recessed docking region. A bracket detachably attaches in the docking region and joins the rails to base member. In this manner, the rails can detachably release from the base member. A lever and a base handle enable assembly to be moved and tilted. A vehicle comprises wheels that ride the rails while the foot rests therein, so that joint extends and retracts the curvilinear motion. An adjustment member increases and decreases friction coefficient between the wheels and rails for adjustable resistance of curvilinear motions.