Ultrasonography for detecting enthesitis in juvenile idiopathic arthritis

Objective

Enthesitis is a major feature of juvenile idiopathic arthritis (JIA) but is difficult to diagnose clinically. Our objective was to compare the accuracy of ultrasonography with power Doppler (US‐PD) versus clinical examination for diagnosing enthesitis in patients with JIA and healthy controls.

Methods

Twenty‐six consecutive patients with JIA and 41 healthy volunteers underwent standardized clinical and US‐PD examinations of 5 entheseal sites (proximal and distal quadricepital tendon insertions, Achilles tendon, and plantar fascia). US‐PD reproducibility was evaluated. US‐PD enthesitis was defined as a PD signal at the enthesis insertion. Bursitis, erosions, and cartilage vascularization were recorded.

Results

In the JIA group, 27 (12.5%) of the entheseal sites exhibited clinical enthesitis (distal patellar ligament in 45% of cases) and 20 (9.4%) exhibited US‐PD enthesitis (distal patellar tendon in 30%), including 10 clinically normal sites (50%). US‐PD enthesitis was found in several patients with oligoarthritis or polyarthritis. Clinical enthesitis (P < 0.0001) and HLA–B27–positive (P = 0.05) status were significantly associated with US‐PD enthesitis. Erosion and bursitis, but not tendon thickening, were associated with US‐PD enthesitis. US‐PD enthesitis was not found at any of the 410 entheseal sites in controls; grade 1 cartilage vascularization was noted at 6% of the control sites.

Conclusion

Enthesitis is a rare phenomenon in JIA. Clinically silent enthesitis is detected by US‐PD and can be found in JIA categories other than enthesitis‐related arthritis. Tendon thickening and cartilage vascularization can be detected in healthy controls. These findings may have implications for patient classification of the use of US‐PD.