Background Fortunately, management of RA at the early stage has become possible thanks to both the emergence of new biotherapies and the strategy treat to target. Musculoskeletal ultrasound (US) is a potent tool for the detection of synovitis, effusion and bone erosion in RA.

Objectives The aim of this study was to assess the contribution of US in diagnosing RA at the early stage of the disease.

Methods A cross-sectional study was performed during 2 years. Patients with a history of inflammatory joint pain for ≥6 weeks and ≤2 years with synovitis of at least one joint were enrolled in this study. All patients underwent clinical assessement, laboratory tests and plain radiography of hands and feet.US was assessed within one week of clinical examination. Synovitis and erosion were defined according to the OMERACT.

Results One hundred patients were included in this study with an average age of 51,8±14,6 years-old. Female outnumbered male with a sex ratio of 3,8. The mean duration of the disease was 10,9±7,4 months. When admitted to our department and after clinical examination it was found that 31% of patients presented polyarthritis, 4% had oligoarthritis and 7% suffered from monoarthritis.

US findings: US was found to be more sensitive than clinical examination to detect synovitis. Among the 2200 joints assessed by US, a synovitis was detected in 81% patients, an intra-articular effusion in 36% patients and PD signals in 51% patients. Also, flexor tenosynovitis were present in 55% patients and extensor tenosynovitis in 59% patients. Erosions were more detected in plain radiography (70%) than in US (41%). Clinical parameters (VAS, duration of morning stiffness, number of night awakens, TJC) were not correlated with most US findings. Nevertheless, correlation was detected for US effusion (r=0,250, p=0,028) and for US Doppler (r=0,289, p=0,011) with SJC. PDUS examination correlated with CRP results (r=0,302, p=0,023) but not with ESR results. A significant, positive correlation was observed between erosions in X-rays or US assessment (r=0,342, p=0,002). The US detected synovitis in 25% of patients who had no swollen joint at the clinical examination when admitted to our department and had detected erosions in 9% of patients having negative plain X rays.

Conclusions Ultrasound appears as a sensitive tool to detect subclinical synovitis (25%) and infra- radiological erosions (9%). It helps us to make an early diagnosis and start appropriate treatment before the onset of irreversible joint destruction.

Disclosure of Interest None declared