Characteristics

• Majority of primary osteomyelitis occurs in children. Usually occurs in adults secondary to debilitation or immune compromise (diabetes, drugs, disease).

• Organism seeding is usually haematogenous or direct implantation from trauma (accidental or iatrogenic).

• Causal organisms include Staphylococcus aureus, Group B Streptococcus and enteric species. In drug addicts Pseudomonas is common. Salmonella infection is associated with sickle-cell disease.

• The metaphysis is the commonest site in children (e.g. proximal femur). In adults the spine is commonly affected. The lower extremities of diabetic patients are particularly at risk.

• Pathological sequence usually follows inflammation, suppuration, necrosis, new bone formation ending with resolution.

Clinical features

• Characteristically the patient is feverish and complains of severe pain associated with malaise. Local erythema, oedema and warmth tend to be later signs. In adults beware new-onset back pain associated with systemic upset.

• Lymphadenopathy is usually present but non-specific.

• Infants may simply present with failure to thrive with only a mild constitutional upset.

• In the elderly and immuno-deficient patient, systemic features can again be mild. Take a full history – even an uncomplicated catheter change may be causative.

Radiological features

• Initial plain films are often normal.

• In the early stages look for distortion of fat planes signifying soft tissue swelling or adjacent fluid accumulation. Lucency may be visible after 5–7 days.

• After approximately 10–14 days, bony necrosis and periosteal reaction become evident.

• MRI – more sensitive in the early stages. Bone marrow is hypointense on T1WI + hyperintense on T2WI.

• Nuclear medicine – high sensitivity with gallium or diphosphonate bone scans.

Management

• Traditional management involves general supportive therapy for pain and dehydration.

• Exclude septic arthritis in children with a reactive effusion.

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