Septic Arthritis

Question 1

Define:

Answer 1

• Acute joint inflammation resulting from intra-articular infection.
• Can destroy a joint in under 24h
• Usually affects knee

Question 2

Aetiology:

Answer 2

• May be idiopathic

* In most cases there is systemic infection allowing for haematogenous spread

Question 3

Most causative organisms:

Answer 3

o	Bacteria
	All ages 
•	Staphylococcus aureus 
•	TB
	< 4 yrs
•	Streptococcus pneumoniae
•	Streptococcus pyogenes 
•	Neisseria meningitidis
•	Gram-negative rods 
	16-40 yrs
•	Neisseria gonorrhoeae

o	Viruses
	Rubella 
	Mumps 
\:	Hepatitis B
	Parvovirus B19

o Fungi
 Candida

Question 4

Risk factors:

Answer 4

o	Recent orthopaedic procedures 
o	Osteomyelitis
o	Diabetes mellitus
o	Rheumatoid arthritis 
o	Chronic renal failure
o	Prosthetic joints – infection here is particularly difficult to treat
o	Immunosuppression
o	Alcoholism

Question 5

Epidemiology:

Answer 5

• Most common in CHILDREN and the ELDERLY

Question 6

Symptoms:

Answer 6

• Sudden onset
• Fever
• Excruciating joint pain
• Joint redness, swelling and loss of joint function
• Usually a monoarthropathy (usually affecting one large joint)
o NOTE: it may cause a polyarthropathy in the immunosuppressed
• Tuberculous arthritis develops more slowly and is more chronic

Question 7

Signs:

Answer 7

• Painful, hot, swollen
• Immobile joint
• Erythema
• Severe pain prevents passive movement
• Pyrexia
• Look for signs of aetiology

Question 8

Investigations:

Answer 8

• URGENT Joint Aspiration (IMPORTANT)
o In infective arthritis, the aspirate will be grossly purulent
o Send synovial fluid for MC&S
 Microscopy - rule out crystal arthritis
o PCR may be used if a viral cause is suspected

o FBC - high WCC, high neutrophils
o High CRP and ESR
o Blood cultures - MC&S
o Viral serology may be useful
• Plain Joint Radiographs
o Affected joint may look normal initially
o Can show signs of damage following the infection

• MRI Scan
o Useful for detecting osteomyelitis