Staging and follow-up of rheumatoid arthritis of the knee. Comparison of sonography, thermography, and clinical assessment.

Twenty patients with longstanding polyarticular rheumatoid arthritis (including knee involvement) were selected for this study. The severity of the knee synovitis was assessed before and during treatment (with intra-articular corticosteroid injections) using clinical scores, sonography, and thermography. In all patients, the inflammation regressed during treatment. During follow-up, the quantity of synovial fluid, as measured sonographically 10 days after the start of therapy, correlated best with the clinical status. Maximal regression of synovial thickening was noted on delayed sonograms performed three months after treatment. Thermographic peak temperature showed good correlation with the clinical status, but the thermographic index was unreliable.