Septic Arthritis

Question 1

Cause

Answer 1

most common organism overall is Staphylococcus aureus

in young adults who are sexually active Neisseria gonorrhoeae (gram negative diplococcus) should also be considered (can present with necrotic pustules on extremeties)

Other causes: E.coli, Haemophillus Influenzae, Strep pyrogenes

Question 2

Diagnosis

Answer 2

The Kocher criteria for the diagnosis of septic arthritis:
fever >38.5 degrees C
non-weight bearing
raised ESR
raised WCC

Synovial fluid aspirate: culture, crystal microscopy, gram staining and antibiotic sensitivity

Question 3

Presentation

Answer 3

Single joint (usually knee)

Red, hot joint

Reduced range of movement

Signs of sepsis

Question 4

Differential Diagnosis

Answer 4

Gout (negatively bifringent needle shaped crystals)

Pseudogout

Reactive arthritis

Question 5

Management

Answer 5

Synovial fluid should be obtained before starting treatment

intravenous antibiotics which cover Gram-positive cocci are indicated: flucloxacillin or clindamycin if penicillin allergic
(6-12 weeks)

needle aspiration should be used to decompress the joint
arthroscopic lavage may be required

Question 6

Xray isn’t part of diagnosis

But what would you see on one?

Answer 6

Focal Corticol Loss

Periosteal reaction

Regional osteopaenia