Osteomyelitis is, literally, an inflammation of the bone and its marrow. It is typically used to describe an infectious process. Osteomyelitis usually occurs secondary to hematogenous spread from another source of infection, or from a non-hematogenous source, by introduction through a wound of direct extension of a local infection.
When occurring in Children, 1-16 years, the most common site is in the metaphysis of the bone with subsequent diaphyseal and subperiosteal extension. Staphylococcus is the usual organism responsible.
Diagnostic radiographs are not effective in the first 7-10 days. The first radiographic sign is often a generalized soft tissue swelling. Later, Subperiosteal elevation and bone lesions become visible. However, lytic bone lesions are not visible on radiographs until 40% of the bone substance has been destroyed. Thus it is important that the diagnosis frequently be made from the history and physical exam, since radiographs will not be helpful early.
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