An acute or chronic inflammatory, infectious process of bone. Can occur via hematogenous spread or direct innoculation of bone.
Can be diagnosed on plain radiographs but bony changes might not be evident for 14-21 days. By 28 days 90% of patients will demonstrate a bony abnormality.
Initially plain radiographs will show periosteal elevation. Later cortical or medullary lucencies are seen.
Additional tests to help make the diagnosis include:
Three phase bone scan: often not practical for the ED.
CT Scan: better in areas with complex anatomy [i.e.:spine, pelvis, ,mid and hind foot]
MRI: most effective in early detection and to guide surgical approaches. Sensitivity is estimated at 90-100%.
References
King RW, Johnson D: Osteomyelitis. In: eMedicine. WebMd; 2009.