20 - Enthesitis-Related Arthritis

Abstract

Enthesitis-related arthritis (ERA) accounts for up to 20% of children and adolescents with JIA. It has a strong association with human leukocyte antigen (HLA)-B27, which is present in 60% to 90% of ERA patients. Enthesitis occurs in 60% to 80% of patients and commonly affects insertions sites of the lower limbs, resulting in common complaints of knee, foot, or heel pain. Peripheral arthritis and less commonly axial involvement in the sacroiliac joint and spine can be seen at disease onset and during the disease course. Studies of genetics, biomarkers, and the influence of microbiota have helped to further uncover the pathophysiology and genes implicated in disease susceptibility and pathogenesis. A comprehensive clinical assessment of articular (peripheral and axial) and extraarticular sites together with imaging modalities (magnetic resonance imaging [MRI] and ultrasound [US]) can be used to detect and monitor disease activity. ERA treatment guidelines are summarized and are typically guided by predominance of peripheral or axial involvement. Peripheral involvement of joints and entheses is initially managed with nonsteroidal antiinflammatory drugs (NSAIDs) and disease-modifying antirheumatic drugs (DMARDs) such as methotrexate and sulfasalazine, with escalation to tumor necrosis factor (TNF) inhibitors with persistent disease activity. In contrast, TNF inhibitors are recommended sooner when there is axial involvement.