Sonographic Findings in Gouty Arthritis: Diagnostic Value and Association with Disease Duration

The objective of this work was to evaluate the sonographic features of gouty arthritis and correlate findings with disease duration. The study was conducted on 100 patients in ambulatory care aged ≥40 y. Inclusion criteria included mono- or oligo-arthritis with effusion of the knee or the first metatarsophalangeal (MTP) joint and no known history of gout. A complete medical history was obtained with emphasis on the known risk factors or causes of gouty arthritis. A 12-MHz Medison linear probe was used for ultrasonography (US). Synovial fluid analysis with polarizing light microscopy was performed on all patients. Ninety-eight knee joints and 33 first MTP joints were examined. Gouty arthritis was found by US in four forms: (i) floating echogenic foci in effusion fluid or Baker cysts, (ii) deposits on the cartilage surface (double contour sign), (iii) erosions and (iv) mature tophus/tophi. These were found in 78.9%, 42.3%, 39.4% and 28.2% of patients, respectively. The overall sensitivity and specificity of US in detecting gout (as defined by the clinical gold standard, i.e., detection of urate crystals by polarizing light microscopy) were 85.9% and 86.7%, respectively. Detection of echogenic foci in effusion fluid was associated with the shortest duration of symptoms (median duration 2 y) followed by double contour sign (3.5 y), erosions (4 y) and tophus (12.5 y). Sonographic findings in gout can be assigned a temporal pattern, with echogenic foci being associated with the shortest and full tophus formation with the longest disease duration.