Septic Arthritis

Question 1

Define SA

Answer 1

Infection of a joint space and its synovium

Question 2

Who is commonly affected by septic arthritis? (4)

Answer 2

1 Infants 2 children 3 diabetics 4 immunocompromised

Question 3

Common infective agents in SA? (3)

Answer 3

1 S. Aureus 2 Gram -ve (E Coli) 3 anaerobes

Question 4

What is primary SA?

Answer 4

Seeding of synovium

Question 5

What is secondary SA?

Answer 5

Spread to synovium from adjacent metaphysis or epiphysis

Question 6

What causes destruction of the articular cartilage? (2)

Answer 6

1 Protease release from chondrocytes and 2 synovial cells

Question 7

How long for proteoglycan loss from cartilage?

Answer 7

5 days

Question 8

How long for collagen loss?

Answer 8

8 days

Question 9

Normal presenting features? (6)

Answer 9

1 child 2 with history of trauma/infection 3 joint held in most comfortable position 4 acute onset 5 pyrexia 6 irritability

Question 10

Preceding infection in children usually affects which organs? (2)

Answer 10

1 skin or 2 respiratory organs

Question 11

Appearance of affected joint (4)

Answer 11

1 hot 2 swollen 3 erythematous 4 with effusion

Question 12

Common presentation in neonates (4)

Answer 12

1 irritability 2 lethargy 3 off feed 4 affected limb still

Question 13

Examination findings in adult (5)

Answer 13

1 exquisite pain 2 heat 3 redness 4 swelling 5 refuses passive movement

Question 14

Plain XR findings? (3)

Answer 14

1 joint space wider 2 subluxed or dislocated 3 swollen soft tissues

Question 15

Best imaging modality to demonstrate effusion and guide needle aspiration?

Answer 15

Ultrasound

Question 16

Use of MRI/CT in investigation?

Answer 16

None

Question 17

Main diagnostic tool?

Answer 17

Culture of needle aspirate

Question 18

Tests performed on needle aspirate? (3)

Answer 18

1 Gram stain 2 culture 3 sensitivy testing

Question 19

Extra test on needle aspirate?

Answer 19

Crystal analysis

Question 20

Blood tests ordered? (6)

Answer 20

1 FBC 2 CRP 3 Cultures 4 U&Es 5 LFTs 6 CBG

Question 21

Why is rapid diagnosis and management required?

Answer 21

Surgical emergency

Question 22

Surgical treatment of SA? (3)

Answer 22

1 Drainage 2 open or arthroscopic 3 copious irrigation

Question 23

Definitive management of SA? (3)

Answer 23

1 Drainage with washout 2 fluid resuscitation 3 antibiotics

Question 24

Considerations when SA does not settle?

Answer 24

Re-exploration

Question 25

Antibiotic regime for SA? (3)

Answer 25

1 IV broad spectrum 2 IV specific (once sensitivity determined) for two weeks 3 oral for four weeks