Joint deformities: Involved joints mature faster than unaffected ones leading to limb length discrepancy. Narrowing of joint space occurs due to accelerated bone age. Knee flexion deformities, swan necking / boutonniere and subluxation of joints can also occur.
Uveitis: This is a serious complication that can potentially lead to blindness and often requires assessment by an ophthalmologist. Uveitis is screened for in the UK in children presenting with a likely diagnosis of JIA and can be found in up to 30% of cases. It is often insidious in its onset and asymptomatic. Anterior uveitis can be self-limiting in some cases.
Systemic JIA: Can lead to macrophage activation syndrome (hepatosplenomegaly, fever, coagulopathy, encephalopathy, pancytopenia and very high ferritin) and secondary amyloidosis.
In all JIA, joint destruction can lead to joint replacement in later life (50% of cases). There can be educational, social and psychological implications from time missed in school, time away from friends and restriction of activities. If steroid use is prolonged, osteoporosis and growth restriction can become an issue.