Analysis of foot structural damage in rheumatoid arthritis: clinical evaluation by validated measures and serological correlations

Objective: To examine foot involvement in rheumatoid arthritis (RA) and to characterize structural alterations in patients with anti-cyclic citrullinated peptide (CCP) antibody-positive and -negative disease. Methods: Seventy-eight patients with RA with foot pain were consecutively enrolled. The Manchester Hallux Valgus (MHV) rating scale was used to evaluate the hallux valgus deformity degree. The Foot Posture Index (FPI6), a novel, foot-specific outcome measure, was adopted in order to quantify variation in the position of the foot. The findings were correlated with disease duration and presence or absence of anti-CCP antibodies. Results: About 84.6% patients had different degrees of hallux valgus and 65.4% subjects had a pronated foot. These two foot alterations were prevalently found in patients with long-standing disease and circulating anti-CCP antibodies. On the contrary, RA patients without anti-CCP and early disease essentially displayed a supinated foot without relevant hallux valgus deformity. Conclusion: Our findings allowed to identify different anatomic foot alterations in RA patients according to disease duration and negative prognostic factors such as anti-CCP antibodies. Our findings support the role of an accurate analysis of foot structural damage and may suggest the usefulness of a correct plantar orthosis prescription also in early phases of the disease.