Abstract: The present invention generally relates to an orthopedic exerciser and its actuating mechanism which, more specifically, are used for therapy, post-surgery rehabilitation or healing of a knee, of a joint, or the muscles of a leg or any other body member. Such exercisers usually allow a combination of exercises that help in the recovery of the joint, but to minimize the chances of further injuring the body part and therefore increase the recovery process, the exerciser must submit the body part to a controlled level of force. The orthopedic exerciser of the present invention includes an actuating mechanism cooperating with a resistance assembly which provides resistance and/or assistance along different directions of movement of the actuating mechanism.