Septic Arthritis

Question 1

What is the pathophysiology of septic arthritis?

Answer 1

• Haematogenous spread (most common),
• Direct inoculation

Question 2

What are the causative organisms for septic arthritis?

Answer 2

• S. Aureus: Most common
• Streptococci: Second most common and can be associated with GI pathology
• N. Gonorrhoea: particularly in young sexually active patients
• P. aeurginosa: Healthcare associated
• Salmonella: Associated with sickle cell anaemia

Question 3

What are the risk factors for septic arthritis?

Answer 3

• IV drug user,
• Diabetes Mellitus,
• Older age,
• Underlying joint injury/disease,
• Prosthetic joint
• Immunosupression
• Unprotected sex
• PVD
• Alcoholism

Question 4

Explain the presentation of septic arthritis

Answer 4

• Hot, red, painful swollen joint,
• Stiffness and reduced range of movement,
• Systemic symptoms such as fever, lethargy and sepsis

Question 5

What are the investigations for septic arthritis?

Answer 5

• Synovial fluid aspirate (cell count, gram stain, culture and microscopy for crystals) prior to abx therapy
• Blood cultures and tests for inflammatory markers

Question 6

What is the treatment for septic arthritis

Answer 6

• Empirical antibiotics until sensitivities known. Treat for 3-6 weeks.
  1. Flucloxacillin and rifampicin. Vancomycin if MRSA is suspected. Clindamycin if penicillin allergy
  2. Ceftriaxone if gram negative infection is suspected (gonorrhoea)

Question 7

What is the Kocher criteria?

Answer 7

For septic arthritis
- Fever > 38.5,
- Non-weight bearing,
- Raised ESR,
- Raised WCC