Inflammation of the joint space caused by infection

Aetiology

Causative organisms

• Staphylococcus aureus ‐ the most common cause in adults
• Streptococci ‐ the second most common cause
• Haemophilus influenzae ‐ was the most common cause in children but is now uncommon in areas where Haemophilus vaccination is practiced
• Neisseria gonorrhoea ‐ in young adults (now thought rare in Western Europe)
• Escherichia coli ‐ in the elderly, IV drug users and the seriously ill

Pathophysiology

• Haematogenous spread (most commonly)
• Can be an extension of local infection
• Suppurative
• Orthopaedic emergency due to rapid irreversible damage to hyaline articular cartilage

Clinical features

Symptoms

• Typically presents as an acute monoarthropathy - single warm, red, painful joint with pain whenever the joint moves
  • Any joint that is hot, red and tender is a septic joint until proven otherwise - must aspirate
• Knee most commonly affected joint

Signs

• Reduced ROM +/- swelling
• Patients may have systemic fever