Juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA), also known asjuvenile rheumatoid arthritis, is the most common chronic arthritic disease of childhood and has multiple subtypes.

Epidemiology

The estimated incidence is ~13 per 100,000 per annum³. By definition, symptoms must start before 16 years of age. Females are more affected. F with a F:M ratio= 2 2:1.

Clinical presentation

Oligoarticular or polyarticular arthritis of of a duration of six weeks or longer must be present to diagnose JIA.

Patients may present with an acute onset of symptoms or a more gradual onset. Symptoms are often worse in the morning, but typically persist to some extent throughout the day.

In patients with systemic onset also known as Still disease, intermittent spiking fevers are typically noted, which help distinguish JIA from other diseases such as infection, other inflammatory diseases and malignancy. Migratory light light pink rash involving the trunk and/or extremities and hepatosplenomegaly are also also frequently observed in patients with systemic onset.

Radiographic features

Imaging shows a varied spectrum of involvement, based on the severity and duration of the disease.

RadiographPlain radiograph

Findings on x-ray include soft tissue swelling, osteopenia, loss of joint space, erosions, growth disturbances (epiphyseal overgrowth) and joint subluxation.

Hepatosplenomegaly may be seen on abdominal radiographs, and pericardial or pleural effusions may be seen on chest radiographs.

MRI

MRI shows synovial hypertrophy, joint effusions as well as osseous and cartilaginous erosions. Active synovitis is characterized by enhancement on T1-weighted gadolinium contrast studies.