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2014-02-15 15:33:30
Osteomyelitis NRO
Osteomyelitis notes flashcards
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  1. Definition
    Infection of the bone, typically affecting the cortex, medulla and periosteum
  2. Peak age
    • Typically children <12 years 
    • Adult onset usually due to compromised host resistance (e.g. immunosuppression, severe debilitation)
  3. Causative Organisms
    • S. aureus - 80% of identified cases
    • M. tuberculosis
    • E. coli - especially infants and the elderly
    • Salmonella spp - especially in patients with sickle cell disease
  4. Pathogenesis
    Gain access to the medullary cavity of bone via 2 main routes:

    • 1. Direct access: through an open wound, especially when #s are involved; also in post-op orthopaedic patients (especially joint replacement)
    • 2. Blood bourne spread: following bacteraemia from a focus of infection elsewhere
  5. Clinical Features
    • Abrupt onset of severe pain at the site of bone infection
    • Fever
    • Malaise
  6. Diagnostic investigations
    • Blood culture
    • Isotope Scan
  7. Management
    • Analgesia
    • Antibiotic therapy
    • Potential surgical drainage of abscesses
  8. Complications and sequelae:
    • Resolution
    • Pathological fracture
    • Adjacent sepsis
    • Chronicity
  9. Osteomyelitis Resolution
    With appropriate antibiotic therapy, ideally based on blood cultures or aspiration material
  10. Complications: pathological fracture
    Purulent acute inflammatory exudate formed in closed compartment of the marrow cavity --> compression of vessels --> necrosis of medullary bone and trabeculae --> increased predisposition to fractures
  11. Complications: Adjacent sepsis
    Destruction of cortical bone --> discharge of pus into extraosseuous CT --> infection my track through to skin surface and cause a discharging fistula

    • Malignant osteomyelitis - spreads to other bones
    • Septic arthritis: spreads to neighbouring joints
  12. Complications Chronicity
    • Organisms remain viable within the marrow cavity for many years
    • Leads to extensive bone destruction, marrow fibrosis and recurrent focal suppuration (Brodie's abscess)
    • Reactive new bone formation, particularly around inflamed periosteum leads to a thickened and abnormally shaped bone
    • Growth disturbace may occur if the physis is damaged in children