Rheumatologic conditions in children who may present to the orthopaedic surgeon.

Juvenile idiopathic arthritis, formerly known as juvenile rheumatoid arthritis, is a heterogeneous group of diseases characterized by onset of chronic arthritis in childhood. Diagnosis requires onset of disease by age 16 years, persistent arthritis in any joint for ≥ 6 weeks, and exclusion of other conditions that cause arthritis (eg, infection, malignancy, acute rheumatic fever, inflammatory bowel disease). Most patients with juvenile idiopathic arthritis present with subacute arthritis with minimal pain and few constitutional symptoms. Laboratory evaluation and imaging are useful to exclude other diagnoses and establish the presence of systemic inflammation. However, these modalities are of limited value in screening for rheumatic diseases, and they may be misleading because of the high rate of false-positive results. Most rheumatologic conditions are diagnosed based on pattern recognition, which is established with a thorough history and physical examination.