Function, Locomotion, Measurement and Inflammation

FoLoMI is a pilot study in which the investigators will seek to determine if gait spatio-temporal and kinematic parameters can explain the evolution of a functional score, the Bath Ankylosing Spondylitis Functional Index (BASFI), at 18 months. The secondary objectives are: (1) to study the relationship between gait parameters measured at T0 and the BASFI at T0, (2) to study the relationship between gait parameters at T0 and the BASDAI at T0, (3) to assess general state of health of the patients and its evolution by appreciating: level of physical activity, state of fatigue, diurnal sleepiness and quality of life, and (4) to compare spatio-temporal gait parameters between patients and healthy controls.