Objectives:
To assess the importance of ultrasound (US) examination of joints in hands and feet in patients with early arthritis and perform comparative analysis of the diagnostic value of US examination for 8, 12 and 52 selected joints.

Material and methods:
123 patients (87 women, 36 men) with arthritis lasting less than 12 months, naive to disease-modifying anti-rheumatic drugs and glucocorticosteroids. Necessary differential diagnostics was performed for each patient. After the preliminary analysis, 72 patients met the classification criteria for rheumatoid arthritis (RA) according to ACR/EULAR of 2010, and undifferentiated arthritis (UA) was diagnosed in 51 patients. UA patients were followed up after 6 and 12 months, and verification of the initial diagnosis yielded the following groups of patients: patients meeting classification criteria for RA, patients with maintained diagnosis of UA, patients in remission, and patients with other diagnoses. Ultrasound examination was performed considering the volume of joint effusion (JE), synovial membrane hypertrophy (GS), and synovial membrane hyperaemia assessed by power Doppler (PD). Results were assessed using the semi-qualitative scale. Coefficients being the sum of US scores for the assessment of JE, GS and PD for 52 and 12 joints in hands and feet, and 8 joints in hands were determined for the purpose of the study.

Results:
In patients meeting classification criteria for RA during the initial assessment the US examination yielded significantly higher PD-52I, PD-12I and PD-8I coefficients. In UA patients who were diagnosed with RA after 12 months, the GS-8I coefficient was significantly higher.

Conclusions:
Ultrasonography is a valuable tool in diagnostics of early arthritis. The GS assessment has prognostic value for UA patients. The assessment of 8 or 12 selected joints is often sufficient for the diagnostics of patients with early arthritis.