Correlation between clinical and ultrasound assessment of the knee in children with mono-articular or pauci-articular juvenile rheumatoid arthritis

Background. Ultrasonography of the knee is a non-invasive, readily available and low-cost tool for demonstrating peri-articular tissues. Objective. To correlate clinical features with US findings in the detection, quantification and follow-up of inflammatory signs of the knee in children with pauci-articular juvenile rheumatoid arthritis (JRA). Materials and methods. US of both knees was performed in 49 patients on the same day as the clinical examination. All joints were classified into two groups by clinical criteria: group A (active disease) or group B (quiescent disease). Thirteen patients underwent one or more follow-up examinations. US was performed with a small-parts, 7.5-MHz, electronic linear probe by using a technique previously reported. Quantitative assessment of any effusion and synovial thickening was evaluated at the level of the suprapatellar bursa. Wilcoxon and Spear man tests were employed to compare US findings between the two groups and to correlate clinical and US findings within each group, respectively. Results. US demonstrated significant increase of effusion and synovial thickening in group A joints. US enabled visualisation of clinically undetected popliteal cysts in three patients. Correlation between clinical and US findings was significant in group A and positive, though not significant, in group B. Conclusions. US seems to be a sensitive and reliable method for the assessment and monitoring of knee joint involvement in pauci-articular JRA.