Septic Arthritis

Question 1

What is it?

Answer 1

Infection within the synovial fluid and joint tissues

Question 2

What is the pathology of SA?

Answer 2

Joint is invaded by haematological spread/eruption of bone abscess or penetrating wound

Infection spreads throughout wound and destroys cartilage

Pus erupts from joint leading to abscess formation

When healing the articular surfaces are exposed and could fuse together leading to ankylosis

Question 3

What are risk factors?

Answer 3

Extremes of age
Pre-existing joint disease
IV drug users
DM/immunosuppressed
Recent operation
Infection elsewhere
RA

Question 4

What are common causative organisms?

Answer 4

Staph aureus
Disseminated gonococcal infection in young adults
Strep pneumoniae/h.influenzae in young children

Question 5

What are the symptoms?

Answer 5

Hot, swollen, tender joint
Monoarticular
Rapid onset pain
Pain on movement
Decreased range of movement 
Systemic symptoms
-fevers
-rigors
-tachycardia
-tachypnoea

Question 6

What investigations are needed?

Answer 6

Bloods

• FBC= WCC raised
• U&Es, LFTs=look at function
• Uric acid- for CAA
• Blood cultures x2
• CRP

Full septic screen

Joint aspiration

• for gram stain/culture
• can be cloudy/blood stained
• gram stain positive in 50%
• if gonococcal then genital tract culture too
• if joint not easily accessible/prosthetic then aspirate in theatre under image guidance

Joint XR

• must be completed within 2wks to look for structural damage
• initially shows soft tissue swelling and joint space widening due to effusion
• late on narrow joint spaces as cartilage is destroyed

Question 7

What are some differentials?

Answer 7

OA
Crystal Associated arthritis
RA
Seronegative spondyloarthropathies

Question 8

What is the management?

Answer 8

Admit
A-E

Sepsis 6

• High flow oxygen
• urine output
• blood cultures x2
• measure lactate
• IV fluids
• IV abx (after aspiration, 2g fluclox 6hrly)

Inform senior
Pain relief
Early in theatre washout
Rest joint
IV abx for 2-3wks and then oral for 6wks