Osteomyelitis:

• 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.