Septic arthritis

Question 1

Define infective arthritis

Answer 1

Joint inflammation resulting from intra-articular infection. Also known as SEPTIC ARTHRITIS

Question 2

Explain the aetiology/risk factors of infective arthritis

Answer 2

May be idiopathic
In most cases there is systemic infection allowing for haematogenous spread

Risk Factors:
Recent orthopaedic procedures
Osteomyelitis
Diabetes
Immunosuppression
Alcoholism

Question 3

Common causative organisms septic arthritis?

Answer 3

Bacteria
All ages - Staph aureus, TB
< 4 yrs - Strep pneumoniae, Strept pyogenes, Neisseria meningitidis, Gram-negative rods
16-40 yrs - Neisseria gonorrhoeae

Viruses
Rubella
Mumps
Hepatitis B
Parvovirus B19

Fungi
Candida

Question 4

Summarise the epidemiology of infective arthritis

Answer 4

Most common in CHILDREN and the ELDERLY

Question 5

Recognise the presenting symptoms of infective arthritis

Answer 5

Fever
Excruciating joint pain
Joint redness, swelling and loss of joint function

Usually a monoarthropathy (usually affecting one large joint) NOTE: it may cause a polyarthropathy in the immunosuppressed

Tuberculous arthritis develops more slowly and is more
chronic

Question 6

Recognise the signs of infective arthritis on physical examination

Answer 6

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

Question 7

Identify appropriate investigations for septic arthritis

Answer 7

Joint Aspiration (IMPORTANT)

In infective arthritis, the aspirate will be grossly purulent
Send synovial fluid for MC&S

Microscopy-rule out crystal arthritis
PCR may be used if a viral cause is suspected

Bloods
FBC - high WCC, high neutrophils
High CRP and ESR
Blood cultures - MC&S
Viral serology may be useful

Plain Joint Radiographs - Affected joint may look normal initially, Can show signs of damage following the infection

MRI Scan - Useful for detecting osteomyelitis