Osteoarthritis (OA) is the most common joint disease in the world, especially OA of the knee. Not only elderly persons are affected in less mobility or pain, but also younger people are. The ankle-foot-orthosis Agilium Freestep is a revolutionary way of treating knee-OA – it is worn in the shoe. The ground reaction force is dynamically led towards the knee, i.e. the measurable varus torque is reduced. The new Agilium Freestep means: re-think the common orthopedic treatment of knee-OA, because place of application and place of effect are different.