Point tenderness can usually be elicited over the involved area. At this point, the diagnosis of osteomyelitis must be considered and a rapid diagnostic workup carried out. The sedimentation rate is elevated in ninety per cent of cases, but may be normal on the first day of symptoms. The white blood cell count is normal in forty to seventy five per cent of patients and the initial blood culture is rarely positive. X ray changes in bone are usually not seen for ten to fourteen days after the onset of symptoms although some soft tissue swelling or obliteration of fascial planes may be appreciated at two to four days.
Bone scans are positive in one to two days and are ninety to ninety five per cent accurate.
Subperiosteal or metaphyseal aspiration is the definitive diagnostic procedure. This allows confirmation of the diagnosis, decompression of the abscess, and provides a specimen to determine appropriate antibiotic therapy. The culture is positive in seventy per cent of cases. Staph aureus is the pathogen in seventy to seventy five per cent of all cases. Under age two, H. flu and strep must be considered.