Paediatrics: Oligoarticular juvenile idiopathic arthritis

Oligoarticular juvenile idiopathic arthritis

• Commonest subtype (previously known as pauciarticular JCA/JRA). 40% of patients.

• Two subsets are recognized: persistent and extended. If the number of joints increases to more than 4 within the first 6mths of illness, it is termed extended oligoarticular JIA.

• Children may develop silent, blinding iritis (anterior uvertis). It is usually ANA-positive patients (40–75% of this form of illness) who are at risk of developing iritis.

Clinical features

• Diagnosis of exclusion; rule out infection.

• Milder symptoms than reactive arthritis; no constitutional symptoms.

• Often present with joint swelling or limping rather than pain.

• 2/3 single joint; 1/3 only 2 joints; often asymmetrical; knees, ankles, elbows, wrists common, but any joint possible.

• Careful examination may reveal more extensive disease as the child may be too young to express pain.

• Elbows and knees may lack full extension, but not be painful.

• Affected leg may overgrow; measure leg lengths and check pelvis is level.

• Observe gait for circumduction to compensate for limb overgrowth.

Investigations

• FBC; CRP (usually normal); ANA (prognostic value for uveitis).

• X-ray: exclude fracture, tumour; look for overgrowth and damage.

Management

• Regular review to assess joints, eyes, and general growth.

• NSAIDs for pain and stiffness: full dose for 8wks (ibuprofen, diclofenac, naproxen, or piroxicam).

• Intra-articular steroid injections: may settle inflammation for years.

• If not controlled with oral NSAIDs and intra-articular steroids, MTX oral or SC is used in resistant cases.

• Rarely etanercept (anti-TNF therapy) is needed.

• Screen for uveitis: initially 3-monthly, by ophthalmologist.

Disease course and prognosis

• 80% normal at 15yrs. ‘Extended’ subset have worse prognosis.

Uveitis is most important extra-articular complication.