Septic Arthritis

Question 1

What is it?

Answer 1

Infection of either a Native or Prosthetic Joint

Question 2

What causes the infection?

Answer 2

Usually Staphylococcus Aureus or Streptococci

Question 3

How is the infection spread to the joint? (3)

Answer 3

1. Haematogenous
2. Contiguous (Spread from an adjacent area)
3. Direct inoculation (trauma or surgery)

Question 4

What is Medullary Arthritis?

Answer 4

Necrosis of the medullary contents

Question 5

What is Superficial Arthritis?

Answer 5

Necrosis of the exposed surface

Question 6

What is localised arthritis?

Answer 6

Stable bone with full thickness cortical sequestation

Question 7

What is diffuse arthritis?

Answer 7

Unstable bone with extensive necrosis

Question 8

Which joints are affected?

Answer 8

Can affect any joint but >50% of cases occur in the knee

Question 9

Is it common?

Answer 9

1.2-2.5% of all joint prostheses become infected, and 20% of revision procedures are infected

Question 10

Who does it affect?

Answer 10

It can affect all age groups

Question 11

Risk Factors (8)

Answer 11

Pre-existing joint disease provides a cement for bacterial attachment, Diabetes, Immunosuppression, Chronic Renal Failure, Recent joint surgery, Prosthetic Joint, IVDU, Above 80 years old

Question 12

Symptoms (7)

Answer 12

Painful joint, hot, erythema, swelling, pain on movement, fever, rigors

Question 13

Signs (1)

Answer 13

Joint effusion

Question 14

Differentials (7)

Answer 14

Rheumatoid, Osteoarthritis, Vasculitis, Gout, Reactive, Viral Arthritis, Infective Endocarditis

Question 15

Investigations (11)

Answer 15

FBC, WCC, CRP, ESR, Joint apsiration for synovial fluid culture and sensitivity, blood cultures, PCR and Immunology, X-ray, USS, CT/MRI, Radionuclide Scan

Question 16

Treatment (4)

Answer 16

Empirical Broad Spectrum Antibiotics IV, if S.Aureus change to Flucloxacilin for 2-3 weeks IV then Oral 2-4 weeks, Surgical drainage/debridement may be needed, limb splinted in position of function then immediate mobilisation once infection under control, Analgesia

Question 17

Complications (4)

Answer 17

Chondral damage, future osteoarthritis, Joint replacement, Amputation

Question 18

Is there a good prognosis?

Answer 18

Mortality is 10-20%, only 45% of patients with S.Aureus infection regain joint function