What is the involvement of small joints in Oligoarticular Juvenile Idiopathic Arthritis (JIA)?

From the Guidelines

Oligoarticular juvenile idiopathic arthritis (JIA) typically involves the large joints, but small joint involvement can occur in approximately 15-30% of cases, with the most commonly affected small joints including the metacarpophalangeal joints, proximal interphalangeal joints of the hands, and metatarsophalangeal joints of the feet, as noted in the 2021 American College of Rheumatology guideline for the treatment of JIA 1.

Key Points

• Small joint involvement in oligoarticular JIA is more frequently seen in the extended subtype, where the disease progresses to affect more than four joints after the first six months of disease.
• Early recognition of small joint arthritis is crucial for appropriate management, which typically includes NSAIDs like naproxen (10-20 mg/kg/day divided twice daily) or ibuprofen (30-50 mg/kg/day divided three to four times daily) as first-line therapy, as recommended by the 2021 American College of Rheumatology guideline 1.
• For persistent arthritis, intra-articular corticosteroid injections (triamcinolone hexacetonide for larger joints, methylprednisolone acetate for smaller joints) may be used, with triamcinolone hexacetonide being the preferred agent due to its superiority in achieving and maintaining remission in children with JIA 1.
• Disease-modifying antirheumatic drugs (DMARDs) such as methotrexate (10-15 mg/m² weekly) are often added for extended oligoarticular disease with small joint involvement, with methotrexate being conditionally recommended as a preferred agent over leflunomide, sulfasalazine, and hydroxychloroquine 1.
• For refractory cases, biologic agents like TNF inhibitors (etanercept 0.8 mg/kg weekly or adalimumab 24 mg/m² every 2 weeks) may be necessary, with biologic DMARDs being strongly recommended if there is inadequate response to or intolerance of NSAIDs and/or intra-articular glucocorticoids and at least one conventional synthetic DMARD 1.

Management Considerations

• Regular ophthalmologic screening is essential as children with oligoarticular JIA, particularly ANA-positive patients, have an increased risk of uveitis regardless of joint pattern involvement.
• Consideration of risk factors for poor outcome, such as involvement of key joints (e.g., TMJ, wrist, sacroiliac, hip, and ankle) and other features (e.g., erosions), is conditionally recommended to guide treatment decisions, as noted in the 2021 American College of Rheumatology guideline 1.
• Patient/caregiver input is instrumental in creating treatment recommendations, with patients/caregivers stressing the need for individualizing treatments and shared decision-making that considers patients' and caregivers' values, goals, and preferences 1.

From the Research

Involvement of Small Joints in Oligoarticular Juvenile Idiopathic Arthritis (JIA)

• The involvement of small joints in oligoarticular JIA is a significant aspect of the disease, with studies indicating that it can affect the prognosis and treatment of the condition 2.
• A study published in 2024 found that small joint involvement was observed in 10% of patients with oligoarticular JIA, with 5.5% having small joint involvement at the time of diagnosis and 4.5% developing it during the follow-up period 2.
• The frequency of small joint involvement was found to be significantly higher in extended oligoarticular JIA compared to persistent oligoarticular JIA 2.
• Patients with small joint involvement were found to have higher erythrocyte sedimentation rate and C-reactive protein values at admission, as well as higher Juvenile Arthritis Disease Activity Score at 3,6, and 12 months 2.
• The need for conventional disease-modifying antirheumatic drugs and biologic disease-modifying antirheumatic drugs was significantly higher in patients with small joint involvement 2.
• Another study published in 2024 found that involvement of small joints at diagnosis was more prevalent among patients who did not respond to DMARD therapy 3.

Clinical Characteristics and Treatment

• Oligoarticular JIA is a subtype of JIA that is characterized by the involvement of fewer than five joints within the first six months of disease onset 4.
• The disease is often accompanied by anti-nuclear antibody positivity and anterior uveitis, particularly in young female patients 4.
• Intra-articular corticosteroid injection is a common treatment for oligoarticular JIA, with triamcinolone hexacetonide being a effective treatment option 5, 6.
• The treatment of oligoarticular JIA often involves a combination of disease-modifying antirheumatic drugs, corticosteroids, and biologic agents, with the goal of eliminating active disease, normalizing joint function, and preserving normal growth 4.