Prominent midfoot involvement in children with enthesitis-related arthritis category of juvenile idiopathic arthritis

Foot involvement is common in juvenile idiopathic arthritis (JIA) but is often unrecognized and difficult to treat. This study was done to assess clinical and radiological involvement of the feet and its impact on function in Indian children with enthesitis-related arthritis (ERA). We enrolled consecutive children with ERA with disease duration of less than 5 years. All patients underwent clinical examination of the feet and filled the juvenile arthritis foot index (JAFI) questionnaire. Ultrasound (US) of foot joints and entheses and extremity magnetic resonance imaging (MRI) scan of one foot were done. Fifty-five patients (53 boys), with median 14 years and disease duration 1.9 years, were included. Thirty-seven of 46 were HLA-B27-positive. Mean juvenile spondyloarthritis disease activity (JSpADA) index and juvenile idiopathic arthritis disease activity scrore-10 (JADAS10) scores were 4 and 14.25. Forty-six had history of foot pain, 36 had foot involvement on examination (15 ankle, 8 subtalar, 24 midfoot, 10 forefoot, and 21 tendoachilles), and 7 had plantar fascia involvement. On US (N = 55), 16 had ankle involvement and 8 had subtalar involvement, and 19 patients had midfoot arthritis, 24 had tendoachilles enthesitis, and 11 had plantar fasciitis. On MRI (N = 50), 27 had midfoot involvement. Thirty-three had bone edema. Fourteen had midfoot enthesitis and 17 had tenosynovitis. Clinical and US had 82% concordance at the midfoot and 90% at the ankle. MRI had 74% concordance with examination and 72% with US at the midfoot. The median JAFI scores were as follows: total JAFI = 4 (0–11), impairment = 1, activity limitation = 2, and participation restriction = 1. JAFI total and individual domains correlated with JADAS10, JSpADAS, and childhood health assessment questionnaire (CHAQ) but not duration of foot disease. JAFI was higher in children with midfoot arthritis on US. Foot joints and entheses are involved in a substantial proportion of patients with ERA patients and the midfoot is commonly involved. Foot disease produces significant functional limitation.