Morpho-structural characteristics of feet in patients with rheumatoid arthritis: A cross sectional study.

Objective: The aim of this study was to evaluate and classify the types and incidences of foot deformities in patients with Rheumatoid Arthritis (RA). Methods: A cross-sectional study with convenience sample was obtained of 220 patients with foot pain and RA classification criteria (approved by the American College of Rheumatology and the European League against Rheumatism in 2010). A series of outcomes were assessed to measure the morphological characteristics of the feet. The Foot Posture Index (FPI), the Manchester Scale of Hallux Valgus and the Nijmegen classification of forefoot disorders were assessed. Results: The most common foot posture according to the FPI assessment are the pronated position in the left foot (32.7% of participants) and the neutral position in the right foot (34.1% of participants). The disease progression causes more developed and serious foot deformities. 1.82% of patients present a severe level of Hallux Valgus before 10 years of disease evolution whereas 4.09% of patients present a severe level of Hallux Valgus after 10 years of disease evolution. Conclusions: The most common foot type in patients with RA is the pronated foot type with deformities in the MTP joints without Hallux Valgus. However, a percentage of patients with RA presents supinated foot type. The evolution of the disease shows some morphological changes in terms of patient's feet. The presence of more developed foot deformities is increased, such us Hallux Valgus or MTP joints deformity (Grade 3 in the Nijmegen classification scale)