Background/Purpose: Ankle involvement is frequent in rheumatoid arthritis (RA), with at least 90% of patients affected anytime during the disease course though ankle involvement may often be subclinical. Imaging, especially ultrasound (US), plays a fundamental role in ankle assessment, given that it assesses both joint and peri-articular soft tissue inflammation. Considering that ankle involvement in RA is underrecognized we decided to investigate the prevalence and characteristics of subclinical ankle involvement in patients with RA by US.

Methods: Sixty-two RA patients without clinical history of ankle involvement and 60 healthy age and sex-matched controls were included. Both RA patients and healthy controls underwent clinical examination including a 28 joint assessment and a comprehensive ankle assessment to exclude tendon or joint involvement. Age, gender, disease duration, visual analogue scale (VAS) for pain and global activity, body mass index (BMI), Disease Activity Score for 28 joints (DAS28), rheumatoid factor (RF), anti-CCP antibodies, erythrocyte sedimentation rate (ESR) and C-Reactive Protein (CRP), were also recorded.

All participants underwent US examination, which was performed by experienced sonographers using both greyscale and power Doppler (PD) technique. Ankles were scanned at the anterior, medial and lateral views, in transverse and longitudinal scans recording the following US pathological findings: exudative or proliferative tenosynovitis/synovitis, presence of peritendinous, intratendinous or intra-articular PD and tendinous ruptures. All US scanning techniques and definitions were used as proposed by the EULAR working group for musculoskeletal ultrasound and OMERACT ultrasound task force.

Results: Sixty-two patients with RA were included (40 female) and 60 healthy sex and age-matched controls. Subclinical ankle involvement was found in 25 of 62 RA patients (40.3%). In 13 ankles (4 intra-articular, 6.45%, and 9 peri-articular, 14.5%) a positive PD was found. In the control group, ankle involvement was seen in 10 (16.6%) patients, with a statistically significant difference (p=0.03) with respect to the study group. No PD was found in this group (p=0.03).  Tibio-talar joint proliferative synovitis with positive PD signal, and proliferative tenosynovitis of the tibialis anterior, tibialis posterior and peroneous longus were more frequently seen in the RA group (p=0.002). No correlation between DAS28 and ankle US findings was seen (r=0.13), though DAS28 and the total number of joints with positive PD showed a tendency for positive correlation (r=0.270). No correlation was found between BMI, RF or ACPA with any US finding (r=0.136).

Conclusion: Our results indicate that both grayscale US and PD findings suggestive of subclinical ankle involvement were more frequently found in RA patients. The use of US should be strongly recommended to avoid underestimating ankle involvement in RA patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/subclinical-ankle-involvement-in-rheumatoid-arthritis-a-multicentre-ultrasound-study/