Rheumatoid flat foot and deformity of the first ray.

Objective: To study the relationship between flat foot and forefoot deformities in rheumatoid arthritis (RA) in order to improve understanding of the progression of deformity and thus provide more appropriate treatment.

Methods: Anteroposterior and lateral weight-bearing radiographs were obtained of 308 feet of patients with RA and 202 feet of patients with neck pain (control feet).

Results: In women with RA, we observed with disease duration an increased frequency of flat foot that was correlated with first ray deformity (chiefly metatarsus primus adductus) and severe stages of disability. Flat foot increased very markedly after 3-4 years of disease duration. In control women, flat feet were more frequent after the age of 50 years.

Conclusion: In RA the inflammatory and mechanical factors leading to foot deformity must receive early medical treatment to avoid progressive hindfoot deformities that lead to disability.