Muscle strength will be measured by hydraulic hand dynamometer Jamar (Kinetec company) at M0, M6, M12 then every year and also at each change of treatment. Physical performances will be evaluated by a 6-minute walking test, 10 meters walking speed and "Timed up-and-go test" stool test, which combines both coordination mechanisms, proprioception and muscular strength of lower limbs than M0, M6, M12 and then every year and also with each change of treatment.