Septic Arthritis

Question 1

What are the most common organisms to cause septic arthritis

Answer 1

Staph aureus

Streptococcus spp.

Gonorrhoea (more common in sexually active patients)

Salmonella (especially in those with sickle cell disease).

Question 2

How can bacteria seed into the joint

Answer 2

Bacteraemia eg - recent chest infection, UTI, cellulitis

Direct inoculation

Spread from osteomyelitis leading to irreversible articular cartilage damage leading to severe OA

Question 3

What are the risk factors

Answer 3

Age over 80

Any pre-existing joint disease (e.g. rheumatoid arthritis)

Diabetes mellitus or immunosuppression

Chronic renal failure

Hip or knee joint prosthesis

Intravenous drug use

Question 4

What are the clinical features

Answer 4

single swollen joint causing severe pain. Pyrexia will be in around 60% of affected individuals (although its absence should not rule out septic arthritis).

On examination, the joint will appear red, swollen, and warm, causing pain on active and passive movements. An effusion may also be evident.

Often the joint is rigid and the patient will not tolerate any passive movement at all, and will be unable to weight bear.

Question 5

What are the differential diagnosis

Answer 5

Flare of osteoarthritis

Haemarthrosis

Crystal arthropathies (gout and pseudogout)

Rheumatoid arthritis and other inflammatory arthropathies

Reactive arthritis

Lyme disease

Question 6

What are the investigations needed

Answer 6

Routine bloods - FBC, CRP , Urate, ESR,

Joint aspirate ( sent for gram stain) before Abx given

X ray joint

Question 7

What is the management of septic arthritis

Answer 7

Empirical abx treatment

Once confirmed which bacteria => specific abx treatment which is long term - 4-6 weeks

Initial IV abx given

Question 8

What surgical treatments are available

Answer 8

surgical irrigation and debridement (‘washout’) in theatre to aid in source control.

Question 9

What are the complications

Answer 9

osteoarthritis and osteomyelitis.