ObjectivesTo characterize abnormalities in the dorsal extensor tendons of the hand and determine the importance of these findings in rheumatoid arthritis. MethodsA retrospective cross-sectional study was done on 26 patients with rheumatoid arthritis who had sonography of their hands. B-mode and power Doppler joint activity were scored, and the extensor tendons were examined for B-mode changes and power Doppler signals. B-mode changes included anechoic fluid around tendons, hypoechoic tissue around tendons, paratendon tissue and tendon thickening, as well as vascularity around the tendon, for which peritendon power Doppler signals were recorded. ResultsForty-one hands and 205 joints were reviewed. Anechoic fluid around the tendons and peritendon power Doppler signals were observed in 41% and 39%, respectively; 44% and 28% of patients had B-mode and power Doppler scores in the upper tertile, respectively. For both B-mode and power Doppler scores, 3 categories or tertiles were created, 0 to 0.9, 1 to 1.9, and 2 to 3. We reported the percentage of patients with power Doppler and B-mode scores in this category. The severity of synovitis was associated with anechoic fluid around the tendons and peritendon power Doppler signals according to the Cochran-Mantel-Haenszel test. The common odds ratio was 3.52 (95% confidence interval, 1.45- 8.53) for anechoic fluid around the tendons and severe synovitis. The common odds ratio was 2.52 (95% confidence interval, 1.13-5.63) for peritendon power Doppler signals and severe synovitis. ConclusionsFindings at the dorsal extensor tendons were anechoic fluid around tendons, hypoechoic tissue around tendons, peritendon power Doppler signals, and tendon thickening. Patients with anechoic fluid and power Doppler signals were found to have more severe disease activity at the joints based on B-mode and power Doppler scores.