Foot and ankle arthritis in rheumatoid arthritis: prevalence and clinical correlation with disease activity

Foot and ankle arthritis (FAA) in Rheumatoid Arthritis (RA) patients is an under-recognized clinical problem. Patients may have FAA in a disease remission state as most of the disease severity calculation consider 28 joints excluding FAA. Our objective was to estimate the prevalence of FAA, and to determine its correlation with disease activity and other clinical variables.

A cross-sectional study was conducted from 2022 to 2023 among 201 RA patients, meeting 2010 ACR/EULAR criteria. Clinical assessment, joint examination (including foot and ankle), laboratory parameters, and disease activity scores (CDAI, DAS28, SDAI) were recorded.

Among the 201 RA participants, 65.0% were female, 75.1% had advanced disease, and 25.4% had comorbidity. The mean age was 44.7 ± 11.48 years. FAA was reported in 46.8% of patients, with more frequent ankle involvement (30.3%) than MTP joints (14.4%). However, 35.3% had FAA in the past. FAA was significantly associated with higher ESR (p < 0.01), pain scores (VAS) [ p = 0.001], conventional disease modifying drugs (csDMARDs) [p = 0.009] and higher swollen joint count/tender joint count (p < 0.05). FAA correlated significantly with higher disease activity scores (CDAI, SDAI, DAS28; p < 0.001). No significant association was found with age, comorbidities, BMI, disease duration, serology, or steroid use.

The prevalence of FAA is high in RA and strongly associated with increased disease activity despite being excluded from standard indices. These findings highlight the need to incorporate foot and ankle assessments into routine RA evaluations. Key Points •FAA is commonly affected in RA and may be considered when assessing disease activity. •FAA showed a significant association with higher disease activity, even though it is excluded from disease activity score.