Osteomyelitis refers to inflammation of the bone and bone marrow, usually caused by bacterial infection.
Haematogenous osteomyelitis refers to when a pathogen is carried through the blood and seeded in the bone. Alternatively, it can occur due to direct contamination of the bone, for example, at an open fracture site.
Staphylococcus aureus is the most common cause of osteomyelitis. Kingella kingae is a key cause in children under 5 years old.
Risk Factors
Osteomyelitis is more common in boys and children under 5 years old.
Factors that increase the risk of osteomyelitis in a child include:
- Open fractures
- Orthopaedic operations
- Immunodeficiency (e.g., HIV or immunosuppressive drugs)
- Intravenous catheters
- Sickle cell disease (specifically increasing the risk of Salmonella infection)
Presentation
Acute osteomyelitis presents over days, with localised bone pain and reduced limb use. They may be systemically well or unwell.
Chronic osteomyelitis involves persistent or recurrent bone infection, often with slowly developing or fluctuating symptoms.
Children with osteomyelitis may be afebrile, have low-grade fever, or be systemically unwell with high fever.
Investigations
X-rays are the first-line imaging investigation, but often do not show any changes, particularly in early disease. They cannot be used to exclude osteomyelitis. The potential signs of osteomyelitis on an x-ray are:
- Periosteal reaction (changes to the surface of the bone)
- Localised osteopenia (thinning of the bone)
- Destruction of areas of the bone
MRI is the gold standard imaging investigation for osteomyelitis.
Blood tests often show raised inflammatory markers (e.g., WBC, CRP and ESR), although they can be normal early.
Blood cultures may help establish the causative organism.
Bone cultures can be performed if required to establish the causative organism and the antibiotic sensitivities.
Management
Antibiotics are the main treatment for osteomyelitis, initially intravenous, then oral. Simple osteomyelitis typically requires 3-4 weeks of antibiotic therapy.
Surgery may be required to drain and debride the infected bone where there is abscess formation, necrotic bone or a poor response to antibiotics.
Last updated July 2026
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