Walking Disabilities in Association With Tenosynovitis at the Metatarsophalangeal Joints: A Longitudinal Magnetic Resonance Imaging Study in Early Arthritis

OBJECTIVE: The relationship between functional disability and magnetic resonance imaging (MRI) inflammation has been studied for the hands, but has not been well established for the feet, even though walking difficulties are common. Therefore, our objective was to study whether walking difficulties were associated with MRI inflammation at metatarsophalangeal (MTP) joints in early arthritis patients, at diagnosis and during 24 months of follow‐up. METHODS: A total of 532 consecutive patients presenting with early arthritis reported on the presence and severity of walking difficulties (Health Assessment Questionnaire question 4a, scale 0–3), and underwent unilateral contrast‐enhanced MRI of MTP joints 1–5 at baseline. In total, 107 patients had clinical and MRI data at follow‐up (4, 12, and 24 months). MRI inflammation (synovitis, tenosynovitis, and osteitis) was scored in line with the Rheumatoid Arthritis Magnetic Resonance Imaging Scoring system. At baseline, the association of walking disability with MRI inflammation was assessed using regression. Longitudinally, the association between a change in walking disability with a change in MRI inflammation was studied with linear mixed models. RESULTS: At baseline, 81% of patients with walking disabilities had MRI inflammation at MTP joints, versus 68% without walking disabilities (P < 0.001). Total MRI inflammation (i.e., the sum of tenosynovitis, synovitis, and osteitis) was associated with severity of walking disability (β = 0.023, P < 0.001). Studying the MRI features separately, tenosynovitis, synovitis, and osteitis were all univariably associated with severity of walking disability (P < 0.001, P < 0.001, and P = 0.014, respectively). In multivariable analysis, the association was strongest for tenosynovitis. During follow‐up, a decrease in MTP inflammation was associated with a decrease in walking disability (β = 0.029, P = 0.001); in multivariable analyses only, tenosynovitis was independently associated (β = 0.073, P = 0.049). CONCLUSION: Of the different inflamed tissues in MTP joints, predominantly MRI‐detected tenosynovitis was associated with walking disabilities. Likewise a reduction in tenosynovitis related to a decrease in walking disabilities. These results increase our understanding of the involvement of tenosynovitis in walking disabilities in early arthritis.