(Clinical Imaging) (Infection)

Overview

• Inflammatory condition of the bone caused by an infective organism, most commonly Staphylococcus aureus (except in SCA patients → salmonella species more common)
  • Haematogenous Osteomyelitis
    • Results from bactaraemia and is usually monomicrobial
    • Most common form in children
    • Vertebral osteomyelitis → most common form of haematogenous osteomyelitis in adults
    • Risk Factors → sickle cell anaemia, IV drug use, immunosuppression, infective endocarditis
  • Non-Haematogenous Osteomyelitis
    • Results from contageous spread of infection from adjacent soft tissues to the bone or from direct injury/trauma to bone
    • Polymicrobial, most common form in adults
    • Risk Factors → diabetic foot ulcers/pressure sores, diabetes mellitus, peripheral arterial disease
• Usually involves a single bone, may occur in the peripheral or axial skeleton
• Risk Factors → previous osteomyelitis, penetrating injury, IV drug misuse, diabetes, HIV infection, recent surgery, distant or local infections, sickle cell anaemia

Making Diagnosis

Clinical Features:

• Limp or Reluctance to weight-bear → common presentation fo acute osteomyelitis in children
• Non-specific Pain at site of infection
• Malaise, Fatigue, Fever, Chills
• Local inflammation, tenderness, erythema, or swelling
• Local Back Pain with systemic symptoms → native vertebral osteomyelitis

Investigations:

• Bone MRI → most definitive imaging modality
• Bone Biopsy → should be performed whenever feasible, before administering antibiotics. Gold standard for accurate identification of infection and the causative microorganism, allowing appropriate antimicrobial treatment to be chosen.