Subacute osteomyelitis.

Subacute osteomyelitis is a chronic low-grade infection of bone characterized by a lack of systemic manifestations. The onset is insidious. Pain is the most common symptom, and has usually been present for several months before the initial evaluation. Swelling and tenderness over the area of involved bone may also be seen. Laboratory evaluation is unrevealing, with a normal white blood cell count and differential. The erythrocyte sedimentation rate may also be normal. The most common organism cultured from a subacute osteomyelitis is a staphylococcus species. Twenty-five percent of subacute bone infections are sterile. The most common manifestation of a subacute osteomyelitis in a child is a geographic lytic metaphyseal lesion (Brodie's abscess). Treatment of a culture positive infection includes surgical debridement and antibiotic therapy. A sterile abscess can be treated conservatively without antibiotics, provided the patient's symptoms are improving and the lesion is regressing radiographically.