Frequent discordance between clinical and musculoskeletal ultrasound examinations of foot disease in juvenile idiopathic arthritis observed in the multidisciplinary setting

OBJECTIVE To evaluate the levels of agreement from independent clinical examination (CE) by a pediatric rheumatologist and podiatrist and an ultrasound (US) examination of articular and periarticular foot disease in juvenile idiopathic arthritis (JIA). METHODS Thirty patients with JIA and a history of foot disease underwent CE and US examination of 24 foot joints, 10 tendons, and 6 periarticular soft tissues. Each site was examined independently by a rheumatologist and a podiatrist for synovitis and tenderness/swelling. The same sites were examined independently by a sonographer for effusion, synovial hypertrophy, power Doppler (PD) signal, tenosynovitis, or abnormal tendon thickening. Agreement was estimated using Cohen's unweighted kappa with corresponding 95% confidence intervals. RESULTS Seven hundred twenty joints, 300 tendons, and 180 soft tissue sites were examined. Clinically detected synovitis, tenderness, and swelling were recorded in 42 (5.8%), 78 (10.8%), and 73 joints (10.1%), respectively. US-detected effusions, synovial hypertrophy, and PD signal were recorded in 88 (12.2%), 47 (6.5%), and 12 joints (1.7%), respectively. Subclinical foot disease was found in 52 joints (7.2%), 5 tendons (1.6%), and 4 soft tissue sites (2.2%). Agreement was consistently less than moderate (κ = <0.4) for each clinical and US interaction. CONCLUSION This study uniquely demonstrated an interprofessional evaluation of foot disease in JIA. Interobserver agreement was less than acceptable for CE versus US, and subclinical foot disease is common in joints and periarticular soft tissues. US may be a useful tool to aid CE of the foot in JIA patients.