Septic Arthritis

Question 1

Define septic arthritis

Answer 1

infection of a joint

Question 2

What is the most common causative organism of septic arthritis?

Answer 2

S. aureus

Question 3

What is the most common causative organism of septic arthritis in sexually active young adults?

Answer 3

Neisseria gonorrhoeae (disseminated gonococcal infection)

Question 4

What are the routes via which bacteria can seed infection causing septic arthritis?

Answer 4

Bacteraemia (e.g. recent cellulitis, UTI, chest infection)
Direct inoculation
Spreading from adjacent osteomyelitis.

Question 5

What is the most common route and location of septic arthritis in adults?

Answer 5

Haematogenous spread
Knee

Question 6

List 7 RFs for septic arthritis

Answer 6

Age
Pre-existing joint disease (RhA)
DM
Immunosuppression
CKD
Joint prosthesis
IVDU

Question 7

symptoms of septic arthritis

Answer 7

Severe pain + swelling in single joint
Fever (60%)

Question 8

4 signs of septic arthritis

Answer 8

Red, hot, swollen joint
+/- effusion
Restricted ROM
Inability to weight bear

Question 9

Ix for septic arthritis

Answer 9

Bloods: FBC, CRP, U+Es, LFTs
Blood cultures x 2
Synovial fluid sampling (prior to abx if possible)

Question 10

How do symptoms often differ in native vs prosthetic joint septic arthritis?

Answer 10

Native: Sx more florid + obvious
Prosthetic: can be subtle

Question 11

What imaging may be performed in septic arthritis?

Answer 11

Plain XR
USS: guide aspiration esp in hip

Question 12

Describe Mx for septic arthritis in a native joint

Answer 12

IV Flucloxacillin
If pen allergy IV Clindamycin
Analgesia

Native: surgical irrigation + debridement
Prosthetic: irrigation + revision (acutely or staged)

Question 13

Describe antibiotic delivery in septic arthritis?

Answer 13

4-6w abx
IV for first 2w

Question 14

Name 2 complications of septic arthritis

Answer 14

Osteomyelitis
Joint destruction: Osteoarthritis