🔑 Key Learning

  • Acute osteomyelitis is a bone infection typically caused by Staphylococcus aureus.
  • MRI is the gold standard investigation.
  • Treat with IV antibiotics for a minimum of 6 weeks - 1st line: Flucloxacillin

🧬 Pathophysiology

  • Infection of the bone
    • Adults - Usually contiguous spread
    • Children - Typically haematogenous spread
  • Most common cause: Staphylococcus aureus
  • Sickle cell patients - salmonella is the most common cause 

👀 Clinical Features

  • Acute bone pain
  • Fever and systemic features (e.g. malaise, rigors)
  • Localised tenderness, swelling, warmth over affected area
  • Refusal to weight bear or use limb (in children)

🧪 Investigations

  • Bloods: FBC (↑WCC), CRP/ESR raised
  • Blood cultures
  • X-ray: May show soft tissue swelling, periosteal elevation (late sign)
  • MRI: Gold standard — detects early marrow oedema and abscess

💊 Management

  • Empirical antibiotics:
    • Flucloxacillin IV for 6 weeks
    • If penicillin allergic: Clindamycin
  • Tailor antibiotics once cultures return
  • Consider surgical debridement if abscess, necrotic bone, or poor response

📝 Exam Clues & Clinchers

  • Sickle cell + bone pain + fever → suspect Salmonella osteomyelitis
  • Child with fever and limp, ESR/CRP raised → consider MRI for early detection
  • Chronic wound + exposed bone + localised pain → contiguous spread in diabetic foot