The detection of subclinical synovitis by ultrasound in oligoarticular juvenile idiopathic arthritis: a pilot study

Objectives. Adult studies have demonstrated that ultrasonography (US) is more sensitive at detecting synovitis than clinical examination. The detection of subclinical disease has implications for deciding which patients receive more aggressive therapy from the outset. This study aimed to determine whether children with clinically diagnosed oligoarticular juvenile idiopathic arthritis (JIA) had US-detectable subclinical synovitis. Methods. This was a cross-sectional pilot study conducted in a tertiary paediatric rheumatology clinic. Seventeen children with a median age of 10 years (range 3-13 years) and with oligoarticular disease of duration <12 months (median 5 months) were recruited. All subjects were DMARD and oral/i.v. corticosteroid naive. A core set of 40 joints was clinically examined for synovitis and then scanned by a rheumatologist trained in joint US and blinded to all clinical data, at the same appointment. Results. In total, 680 joints were examined both clinically and by US. Twenty-three joints were found to have clinical synovitis, and of these only 17 had synovitis confirmed by US. A further 15 joints were found to have synovitis on US examination alone. Overall, subclinical synovitis was detected in 6/17 children, mostly in the hands and feet. One child was reclassified as having polyarticular disease. Conclusions. This pilot study has highlighted a discrepancy between clinical examination and ultrasound when assessing the joints of children with JIA. US is a feasible tool for examining multiple joints and identifying subclinical synovitis, particularly when considering the small joints of the hands and feet.