To what extent is foot pain related to biomechanical changes and ultrasound-detected abnormalities in rheumatoid arthritis?

Objective To investigate the presence of biomechanical abnormalities and ultrasound (US)-detected inflammation and damage in low disease or remission status rheumatoid arthritis (RA) patients with foot complaints. Methods We recruited 136 subjects with foot complaints. Sixty-two were biologic disease-modifying antirheumatic drug-treated RA patients presenting Disease Activity Score-determined remission or low disease activity while the remaining 74 were gender matched controls without rheumatic or musculoskeletal disorders. Both groups underwent a comprehensive podiatric, biomechanical and B-mode and Doppler US assessment of the feet. Results Most RA patients and controls were female (77.4% and 83.8%, respectively). There was no statistical difference in the proportion of obese subjects in either group (p=0.792). Inappropriate shoes were used by 50.0% of RA patients and 33.8% of controls (p=0.080). Talalgia, particularly heel pain, was more frequent in the control group, with associated talalgia and metatarsalgia being more prevalent in the RA group (p<0.05). The RA patient group was also more likely to present greater foot deformity, more limited joint movement and biomechanical abnormalities than the controls (p<0.05). US inflammatory and structural changes were significantly more frequent in RA patients than in controls (p<0.05). US structural involvement was significantly associated with limited joint mobility and pathologic biomechanical tests only in RA patients (p<0.05). Conclusion RA foot complaints seemed to be linked to US-detected RA involvement and biomechanical abnormalities. Podiatric and US assessments can be useful to help the clinician to optimise the management of RA patients in remission/low disease activity with foot complaints.