Septic Arthritis

Question 1

Mechanism of Infection

Answer 1

Haematogenous
Trauma
Iatrogenic (post aspirate etc)

Question 2

Causative organisms

Answer 2

S.aureus
Strep
Gram negatives (elderly, IVDU)
N.gonnorrhoea (young, ATSI)

Question 3

Risk factors

Answer 3

IVDU
Alcoholism
Prosthetic implant
Intervention previously (arthroscopy, intra-articular injections)
Diabetes
Immunocompromised
Chronic skin infection
Adjacent osteomyelitis

Question 4

History

Answer 4

Fever
Joint pain, swelling, tenderness, erythema
Monoarticular- usually knee, sometimes hip
Decreased ROM

Question 5

Ix:

Answer 5

Biochem:
- leucocytosis and WCC
- Blood cultures to rule out sepsis

Arthrocentesis:
- >50 000 WBC
- Bacteria in the aspirate
- Gram stain to identify causative agent

Imaging:
rule out osteomyelitis
USS
X-ray: takes 2 weeks to show up on X-Ray

Question 6

Mx:

Answer 6

• Surgical drainage either with lavage or open debridement
• Aspirations
• Antibiotics (+ fluxcloxacillin, MRSA Vanco, - ceftriaxone)

Take ABx for 2 weeks
Continue drainage PRN
NSAIDs and pain relief
Physio!!

Question 7

Complications

Answer 7

Sepsis
Osteomyelitis
Joint destruction