The purpose of this study is to evaluate the interest of enthesis sonography for the diagnosis of spondylarthritis, in patients with uncertain diagnosis consulting for clinical symptoms suggestive of spondylarthritis

Spondylarthritis (SPA) are the second most frequent inflammatory rheumatic disorders and, because it starts early in life and has a chronic progressive course, the impact of this disease on health resources and patient's life quality can be important. Because the characteritic signs of SPA, like radiological evidence of sacro-iliitis, appear late in time, the lag time between the onset first signs of SPA for the patient and the confirmed diagnosis can be very long (up to 8 years). Previous studies proved that patients who are affected by SPA are showing abnormal vascularization of peripheral enthesis more frequently than patients affected by other rheumatic diseases. Ultrasonography in B mode combined with power Doppler (PDUS) is a non invasive and highly sensitive toll which can detect enthesitis and abnormal vsacularization even for the patients who are not showing yet the evidence of SPA's symptomatology. Using PDUS as a early diagnosis tool could lead to the improvement of diagnostic procedures and therapeutic management of SpA and reduce the cost of diagnosis for patient and health insurances.

Inclusion Criteria:

• patients < 50 years old, consulting for spinal inflammatory symptoms > 3 months duration
• patients consulting for arthritis or tenderness joints > 3 months duration
• patients < 50 years old consulting for enthesitis or dactylitis > 3 months duration
• patients with uveitis and HLA-B27 positivity
• relatives of SpA patients consulting for symptoms suggestive of SpA

Exclusion Criteria:

• patient with confirmed diagnosis of rheumatic disease (included SpA)
• patient protected by law (patient <18 years old, pregnant woman)
• patient who can't atempt the RMI
• patient who will have difficulties to complete the two years of follow-up

Patients with a symptomatology which can lead to a SPA diagnosis but with no confirmed diagnosis yet for any rheumatic didease.