How Are Bone Infections Diagnosed?
Factors that can increase the risk of osteomyelitis impact its severity are considered during evaluation with an in-depth history (predisposing factors–diabetes, trauma, intravenous drug abuse, vasculitis, etc.) and by a thorough physical exam. A bone probe to investigate the depth of involvement over any suspected soft tissue site of infection is used to identify the need for further testing for bone involvement.
- Laboratory tests can indicate something is occurring: But usually are not any more specific than that. Leukocytosis (white blood cell count elevations as part of the immune response) may not even be present with chronic osteomyelitis.
- The blood test markers for inflammation: Erythrocyte sedimentation rate (ESR) and the C-reactive protein (CRP)–may or may not be elevated.
- Blood cultures are only positive if there is bacteremia: Either the cause of osteomyelitis (hematogenous) or from the osteomyelitis (secondary bacteremia or sepsis from the bone infection).
- X-rays are obtained: If inconclusive or negative, can prompt more involved imaging such as MRI. If a patient has internal metal hardware, CT scans can be used as an alternative.
- Bone biopsy is the standard for diagnosing osteomyelitis: Bacteria can be cultured and the microscopic examination of the bone biopsy tissue can be examined for cellular inflammatory changes and necrosis (tissue death). The biopsy is preferably via an open surgical technique; the alternative is a needle biopsy through the skin, but this often has less reliable findings.
In diagnosing osteomyelitis, other similar clinical presentation should be ruled out, such as soft tissue infection (bone involvement is identified with the bone probe), osteonecrosis from steroids or radiation, gout, fracture, bursitis, malignancy, or synovitis.