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Osteomyelitis

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Overview

Osteomyelitis is the inflammation of the bone due to infection, which can lead to progressive bone loss and destruction. It can be divided based on its causes of infection:

  • Haematogenous osteomyelitis – common in children:
    • Due to bacteraemia, most commonly causes vertebral osteomyelitis
  • Non-haematogenous osteomyelitis – common in adults
    • Due to infections spreading from adjacent tissues

Inflammation in the bone marrow can increase pressure, leading to interrupted periosteal blood supply, which can cause necrosis.

Causes

Haematogenous osteomyelitis tends to be monomicrobial:

  • Staphylococcus aureus is the most common organism
  • Salmonella species are common in sickle-cell disease as they can infiltrate bone marrow

Non-haematogenous osteomyelitis is often polymicrobial.

Risk Factors

Risk factors for haematogenous osteomyelitis include:

  • Immunocompromised states – such as HIV and immunosuppressive drugs
  • Bacteraemia (e.g. infective endocarditis)
  • Intravenous drug use
  • Sickle-cell disease

Risk factors for non-haematogenous osteomyelitis include:

  • Diabetes mellitus and diabetic foot (e.g. ulcers)
  • Peripheral arterial disease

Presentation

Overview

Osteomyelitis can present subacutely with:

  • Tenderness, warmth, and erythema over the affected site
  • Reduced range of motion/inability to weight bear
  • Systemic upset – such as fever and malaise

Investigations

Osteomyelitis can be suspected clinically and tests are to confirm the diagnosis. Some key tests include:

  • Full blood count (FBC): may show leukocytosis
  • C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR): may be elevated
  • Blood cultures: should be taken before antibiotics, but do not delay them, identifies organism
  • MRI: diagnostic test of choice

Management

Overview

Management involves the use of intravenous antibiotics for 4-6 weeks. Options include:

  • 1st-line: flucloxacillin
  • If allergic/inappropriate: clindamycin

Complications

Sepsis – due to haematogenous spread.

Neurological damage – may occur in vertebral osteomyelitis.

Bone damage – including fractures, the requirement for amputation, growth plate disturbance and premature closure in children, and joint stiffness.

Prognosis

  • If diagnosed and treated early, osteomyelitis often recovers with no long-term complications

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