A knee orthosis device provides medial, lateral, and rotational control of a knee joint. The novel knee orthosis device stabilizes an injured or surgically repaired, or a weakened knee joint having a neurological disability, which causes instability therein, by applying adjustable corrective and therapeutic forces, which operate to stabilize and protect the knee as well as to correct abnormal gait and to rehabilitate the knee joint and surrounding muscles above and below the knee by encouraging and recruiting said muscles to operate again more normally through the use of a dynamic swing assist mechanism. The knee orthosis also provides dynamically conformable thigh and shin cuff circumferential band systems in combination with a multitude of other elements that conform to the constant dimensional changes of the muscle groups that are surrounded by the knee orthosis device during ambulatory or athletic motion.