< 16 years

> 6 weeks of disease

Seronegative - 70%

Pauciarticular most common (60% of cases), typically affects young girls, involves the larger peripheral joints such as the knees, ankles, elbow and wrists and affecting one to four joints.  When a single joint is involved, it is most commonly the knee.Polyarticular disease (20% of cases), commonly affecting bilaterally the hands, wrists, knees, ankles and feet

Seropositive -  (5% to 15%)

Juvenile-onset adult type rheumatoid arthritis -  onset during adolescence, a strong female predominance, and polyarticular distribution.  Sites of involvement in order of decreasing frequency are the hands, wrists, feet, knees, and hips.

Others - juvenile-onset ankylosing spondylitis, psoriatic arthritis, arthritis of inflammatory bowel disease, other seronegative spondyloarthropathies, and miscellaneous arthritis

Common radiographic features of arthritis in Still disease include soft-tissue swelling and osteopenia

There are several distinct differences when compared with adult rheumatoid arthritis. These differences include delayed joint space narrowing and erosive changes, possible periostitis, growth disturbances, and, later, joint fusion.

The presence of periostitis is due to the relatively loosely adherent periosteum in children compared with that in adults. Growth disturbances include osseous overgrowth of the epiphyses due to chronic hyperemia and bone undergrowth due to premature growth plate fusion with limb length discrepancy, brachydactyly and  temporomandibular hypoplasia.

Hips -

Knee -