Ultrasound may contribute to differential diagnosis of acute erosive arthritis
Ultrasound (US) may provide valuable information for the differential diagnosis of acute erosive arthritis, with a recent study showing that subcutaneous tissue changes and periosteal vascularity are more common in acute osteomyelitis (OM), whereas periosteal tophaceous material distinguishes gouty arthritis from acute OM and rheumatoid arthritis (RA).
Researchers determined the specific ultrasonographic features of acute arthritis with periarticular bone erosions in seven patients with acute OM (mean age, 60.6 years), 18 with RA flares (mean age, 53.6 years) and eight with GA attacks (mean age, 72.3 years). All patients presented with acute monoarthritis or oligoarthritis.
Three rheumatologists blinded to the diagnosis assessed the US images. The median scores of their evaluation of the subcutaneous tissue, periosteum and synovium were compared.
Patients in the acute OM group had the highest mean grade of subcutaneous oedema, with grade 2 oedema being significantly more common than in the RA and GA groups (p=0.003 and p=0.026, respectively).
Furthermore, subcutaneous power Doppler signal was more prevalent in patients with acute OM than in those with RA and GA (p<0.001 and p=0.041, respectively). Periosteal vascularity was also more frequently detected in acute OM (vs RA, p=0.003; vs GA, p=0.041), although the interrater reliability was poor.
Meanwhile, the tophaceous material in GA was distinctive from OM (p=0.010) and RA (p<0.001).
The researchers stressed that the US diagnosis of acute erosive arthritis related to OM, RA or GA should be based on a complete evaluation of the subcutaneous tissue and periosteal tissue besides synovium.