Background: Ultrasonography (US) is a useful tool for imaging, which can be used for assessment of joints and per articular structures in all rheumatologic disorders. Ankle and foot sonography requires a linear high-frequency transducer; a 7.5 to 15 MHz probe is commonly used. The aim of this study was to evaluate ankle joint affection in active Rheumatoid arthritis and its value in assessment of disease activity by using US, and its correlation to disease duration, sex and age.

Methods: A total of 63 patients with Rheumatoid arthritis according to the 2010 ACR/EULAR classification criteria. 20 age and sex matched control volunteers were included. Evaluation of disease activirty by DAS-28. US examination of both ankles were done for patients and controls. High frequency US with 12 MHZ linear probe was used.

Results: Our results show that ankle synovitis was found significantly higher among RA patients (18.3%) compared to controls (2.5%); p value = 0.013. although tenosynovitis and erosions were higher among cases (27% and 8.7%; respectively) than controls (15% and 0%; respectively); the differences were non-significant. We found that ankle affection as seen by US was significantly related to the activity of RA. Patients with higher DAS-28 score were more like to have ankle affection and also to have bilateral ankle affection; both with significant differences.

Conclusion: It can be stated that ankle evaluation by US should be considered more in RA assessment, and further studies should be done to uncover the under-etsimation of ankle involvement in RA patients.