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Joint complaints are common in children, and the presentation may vary according to the underlying disease process and the age of the child. An infant may present with a red, swollen joint, decreased use of an extremity, or pain, demonstrated by fussiness with manipulation, such as with diaper changes. A toddler or school aged child may present with a complaint of pain, limp, or swelling noticed by a caregiver or with decreased use of an extremity. An adolescent is more likely to present with a complaint of pain, swelling, or stiffness. Joint complaints may be articular, originating directly from the joint, or nonarticular, arising from surrounding bone, muscles, soft tissue, or organs. This chapter will focus on articular pain.
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Arthritis is defined as inflammation of a joint with two of the following: pain, swelling/effusion, limited range of motion, erythema, or warmth. Arthritis may affect a single joint (monoarticular) or multiple joints (oligoarticular if fewer than five; polyarticular if greater than or equal to five) and may be acute, chronic (6 weeks or more), or acute on chronic. Arthralgia is joint pain without other signs of inflammation. Enthesitis represents tenderness and inflammation of the tendon insertion into bone.
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The causes of joint pain may be classified as infectious, postinfectious, rheumatologic, autoinflammatory, hematologic, oncologic, mechanical/traumatic, and other (including genetic and metabolic) (Table 11–1).
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Infectious and Postinfectious
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Septic arthritis is an infection of the joint space, usually caused by hematogenous spread rather than direct inoculation or spread from contiguous tissues. Septic arthritis is typically bacterial (e.g., Staphylococcus aureus, Streptococcus pyogenes, Neisseria spp.), although the spirochete Borrelia burgdorferi (Lyme disease) may be found in the synovium ...