- Etiology: hematogenous spread from asymptomatic or symptomatic bacteremia, infection starts in marrow space with significant edema with proliferation of excess WBC and bacterial growth and through bony canals the infected fluid permeates outward and elevates the periosteum, most commonly Staphylococcus aureus or Salmonella in sickle cell disease
- Imaging: most commonly occurs at metaphysis and metaphyseal equivalents (apophyses, areas at the junction of bone and cartilage in flat bones) both of which are highly vascular with slow blood flow, physis is relative barrier for spread of infection from approximately 18 months of age until physeal closure, infection can spread into joint space / subperiosteal space / soft tissues / diaphysis of bone, most common regions involved are extremities and pelvis, continuous periosteal reaction, deep soft tissue edema, lack of extra osseous soft tissue mass
- Complications: subperiosteal abscess, intramedullary abscess
- Clinical: multicentric in 10%
Radiology Cases of Acute Osteomyelitis (Greater Than 18 Months)

