[Role of ultrasonography of the knee in the follow-up of juvenile rheumatoid arthritis].

Juvenile rheumatoid arthritis is a chronic disease, with the synovium as the target tissue. We made 594 US examinations of the knee in 240 children (mean age: 9 years) with juvenile rheumatoid arthritis. All patients underwent at least one US exam and 156 patients underwent many US examinations during 3 years' follow-up. In our series mean synovial thickness was 6 mm (range: 2.5-11 mm) while in normal subjects mean synovial thickness is 2.7 mm (range: 1-4.5 mm). The mean thickness of the suprapatellar bursa was 9 mm (range: 4-18 mm) versus 2.8 mm (range: 1-5 mm) in normal subjects. The mean length of the suprapatellar bursa was 27 mm (range: 13-44 mm) versus 14.3 mm (range: 8-23.5 mm) in normal children. Cartilage thickness was 3.3 mm (range: 1.2-5.8 mm) at the intercondylar notch, and 3 mm (range: 0.8-5.3 mm) at the femoral condyles. Cartilage thickness is 3.5 mm (range: 2-6 mm) at the intercondylar notch, and 3.2 mm (range: 1.8-5.4 mm) at the femoral condyles in normal subjects. The articular cartilage outline was blurred in 36% of patients with active knee involvement. A Baker cyst was found in 24 patients (10%). The mean volume was 3 ml (range: 1-40 ml). No tendinous alterations were observed. Changes in synovial membrane (synovial thickness), the presence of fluid in the suprapatellar bursa, and blurring of the articular cartilage outline showed statistically significant differences between juvenile rheumatoid arthritis patients with active knee involvement and subjects in clinical remission. On the contrary, articular cartilage thickening or thinning showed no statistically significant differences between juvenile rheumatoid arthritis patients with active knee involvement and subjects in clinical remission. In conclusion, US is a simple, rapid, inexpensive and accurate method for the staging and follow-up of joint inflammation in patients with juvenile rheumatoid arthritis of the knee.