Ultrasound detected synovitis, tenosynovitis and erosions in hand and wrist joints: a comparative study between rheumatoid and psoriatic arthritis

OBJECTIVES: Musculoskeletal ultrasound (MSUS) has been introduced as a valuable simple imaging tool for arthritis. The objective was to assess the role of ultrasound (US) in the differential diagnosis between rheumatoid arthritis (RA) and psoriatic arthritis (PsA) at the wrist and hand joints and tendons. MATERIAL AND METHODS: Thirty-five patients (20 RA and 15 PsA) with symptomatic involvement of at least one of the hand and/or wrist joints for > 6 weeks were included. Bilateral wrists (distal radioulnar, radiocarpal and midcarpal joints), hands (1(st)–5(th) metacarpophalangeal [MCP], 2(n)d–5(th) proximal interphalangeal [PIP] and 1(st)–5(th) distal interphalangeal [DIP] joints), flexor tendons and extensor compartments at the level of the wrist joint were examined sonographically. Synovial hypertrophy, joint effusion, erosions and tenosynovitis were diagnosed according to Outcome Measures in Rheumatology definitions. The findings were correlated with clinical, laboratory and disease activity indices. RESULTS: Among 680 and 510 joints examined in RA and PsA respectively, certain US features such as synovitis and erosions at the DIP were exclusively detected in PsA (p < 0.001). Synovitis was frequently detected at the distal radioulnar joints (DRUJ) in RA in comparison to PsA patients (52.5% vs. 26.7% respectively, p = 0.029). Joint effusion was more frequently detected at radiocarpal and midcarpal joints in RA compared to PsA (p = 0.047, 0.039 respectively), whereas erosions were significantly more frequently detected at radiocarpal joints in RA versus PsA patients (45% vs. 20% respectively, p = 0.029). Tenosynovitis was significantly more frequently detected at the extensor tendons in RA and at the flexor tendons in PsA patients (p = 0.021, 0.022 respectively). CONCLUSIONS: There are significant differences in the musculoskeletal US findings of the hand and wrist that joints help to distinguish between RA and PsA.