Septic arthritis

Question 1

What is septic arthritis?

Answer 1

Infection of a joint

Question 2

What organisms commonly cause septic arthritis?

Answer 2

Staphylococcus aureus (gram positive cocci)
Streptococcus species
Gonorrhoea
Salmonella

Question 3

How can bacteria reach the joint and cause septic arthritis?

Answer 3

Seeding to the joint from recent
- UTI
- cellulitis
- chest infection
Direct inoculation - e.g. after steroid injections/ trauma
Spreading from adjacent osteomyelitis

Question 4

What are some risk factors for septic arthritis?

Answer 4

Age >80
Pre-existing joint disease - e.g. rheumatoid arthritis
Diabetes mellitus or immunosuppression
Chronic renal failure
Hip or knee joint prosthesis
IV drug use

Question 5

How does septic arthritis present?

Answer 5

Single swollen, red, warm joint
Severe pain
Pyrexia
Joint is often rigid + unable to weight bear / move properly

Question 6

What are the differentials for someone presenting with a single, painful, swollen joint?

Answer 6

Septic arthritis
Flare of osteoarthritis
Haemarthrosis (bleeding into a joint)
Crystal arthropathies - e.g. gout / pseudogout
Rheumatoid arthritis
Reactive arthritis
Lyme disease

Question 7

What investigations are done for septic arthritis?

Answer 7

Bloods - FBC, CRP , ESR,  urate levels
Blood cultures (SEPSIS 6 if septic - lactate levels + monitor urine output)
Joint aspiration (before antibiotics given) - sent for gram stain + culture

Imaging
- XRAY - often nothing is seen early on. Later may so capsule + soft tissue swelling + joint space widening.
Other imaging is rarely needed.

Question 8

How is septic arthritis managed?

Answer 8

SEPSIS 6

• give fluids
• give antibiotics (after aspiration)
• give oxygen if needed

Surgical irrigation + debridement (washout) of affected joint in theatre

Question 9

What are some complications of septic arthritis?

Answer 9

Osteoarthritis (secondary)

Osteomyelitis (inflammation or swelling of the bone)