Oligoarticular juvenile arthritis is the most common form of juvenile idiopathic arthritis (JIA), representing nearly 50% of cases. Its prevalence is estimated at 1-10 in 6,500 children, with an annual incidence of 1-20 in 1,000,000 children. Oligoarticular juvenile arthritis is more common in girls (80% of cases), with onset occurring between ages 2 and 4. It is usually asymmetrical and affects between one and a maximum of four joints, predominantly those of the lower limbs (knee or foot). Pain is not a constant feature in young children and the most common reasons for seeking medical advice are an increase in the volume of the joint and/or limping. The association of this form of arthritis with nonsymptomatic iridocyclitis (no pain or visible redness) is a specific feature, present in a third of cases. Thus, it is important to perform an initial slit-lamp examination with regular ophthalmologic follow-up. The biological findings associated with the inflammatory syndrome are variable: antinuclear factor tests are positive in 70-80% of cases but their specificity remains undetermined and levels are relatively low. Oligoarticular juvenile arthritis is an autoimmune disorder, but the exact disease mechanism and triggering factors are unknown. However, the disease has been associated with HLA class II antigens, HLA DR3 and DRB1*08. The diagnostic criteria for the disease were established in 2001 at the last international meeting in Edmonton. Oligoarticular juvenile arthritis is defined as the presence of arthritis affecting between one and four joints in the first six months following disease onset. There are two subgroups: persistent oligoarticular arthritis (involvement of less than four joints) and extensive oligoarticular arthritis (involving more than five joints or more, after the first six months since onset). The exclusion criteria are: the presence of systemic arthritis or psoriasis in the patient, or a family history of psoriasis in one of the parents or first-degree relative; HLA B27-positivity in males with onset of arthritis after 6 years of age; and detection of rheumatoid factor IgM in two test samples taken three months apart. Other exclusion criteria include: the presence of ankylosing spondylarthritis, enthesitis and arthritis, sacroiliitis with an inflammatory enteropathy or acute anterior uveitis in the patient or a family history of one of these conditions in a parent or first-degree relatives. The presence of iridocyclitis and/or antinuclear factors (without fever or psoriasis) are strong diagnostic indicators. The differential diagnosis should include infectious arthritis and other inflammatory diseases, as well as haematooncologic diseases that may lead to arthritis (e.g. connective tissue diseases and acute leukaemia). Treatment is best managed by a paediatric rheumatologist in collaboration with physiotherapists and ophthalmologists. Initial treatment revolves around administration of NSAIDS. In cases resistant to NSAIDS, intraarticular injection (under sedation or general anaesthesia in children under 3 years of age) of delayed-action corticoids (triamcinolone hexacetonide) is required and gives good results. The use of disease-modifying antirheumatic drugs (salazopyrine or tumour necrosis factor (TNF)-alpha) is only recommended in cases with extensive involvement or those that are refractory to other forms of treatment. The ophthalmologic manifestations should be treated with mydriatic eye drops and corticosteroids, or with general corticotherapy for very severe forms. In total, 50% of cases are non-progressive by adulthood. Joint sequelae are minor (possible asymmetry in the length of the lower limbs). In half of the cases, the joint disease and eye manifestations remain progressive (often with polyarticular extension, a risk of cartilage/bone damage and reduced visual acuity). In 10% of cases, the iridocyclitis causes amblyopia.
Last update: January 2007