Purpose:

• Assessment of ultrasound MASEI index in axial spondyloarthritis and in healthy subjects, athletes or not
• Comparison of the ultrasound semiology of enthesitis in the 3 populations
• Comparison of the MASEI scores in the 3 populations

Inclusion Criteria:

• - Axial spondyloarthritis according to the ASAS classification criteria
• 18-45 years old
• Athletes are defined by sport activities greater than or equal to 6 hours per week
• Non athletes are defined by sport activities lesser than or equal to 1 hour per week

Exclusion Criteria:

• - History of heel or ankle surgery
• Recent corticosteroid infiltration of the heel or the ankle