Septic Arthritis

Question 1

What is septic arthritis?

Answer 1

Infection in the joint

Question 2

Mechanisms of infection in septic arthritis

Answer 2

Traumatic (direct invasion through a penetrating wound)
Pre-existing infection in an adjacent tissue
Haematogenous spread

Question 3

Most common causative organism for septic arthritis

Answer 3

Staph aureus

Question 4

Most common causative organism for septic arthritis in a prosthetic joint

Answer 4

Staph epidermidis

Question 5

Most common causative organism for septic arthritis in a sexually active person

Answer 5

Neisseria gonorrhoea

Question 6

Most common causative organism for septic arthritis in a pre-school person

Answer 6

H.influenzae

Question 7

Most common causative organism for septic arthritis in an IVDU

Answer 7

Pseudomonas aeruginosa

Question 8

Presentation of septic arthritis

Answer 8

Acute onset monoarthropathy
Systemic features of infection
Red, swollen, hot, tender joint
Reduced range of motion

Question 9

Investigations for septic arthritis

Answer 9

Joint aspiration (prior to antibiotics where possible)
Blood cultures (prior to antibiotics where possible)
↑CRP, ↑WCC
MRI

Question 10

What makes up Kochers criteria?

Answer 10

Refusal to weight bare
Fever
ESR 40mm/hr
EBV >12,000 cells/mm3
CRP >2.0
(the more predictors the higher the chance its septic arthritis)

Question 11

Complications of septic arthritis

Answer 11

PVL producing staph aureus

Sepsis

Question 12

Treatment of septic arthritis

Answer 12

Flucloxacillin (for staph aureus)
+ Ceftriazxone for H influenzae if the patient is <5yrs
Clindamycin if penicillin allergic
Urgent open/arthroscopic washout and debridement