septic arthritis

Question 1

definition of septic arthritis

Answer 1

joint inflammation from intra-articular infection

can destroy joint in 24hrs and mortality of 11%

Question 2

epidemiology of septic arthritis

Answer 2

most common in children and the elderly

Question 3

aetiology of septic arthritis

Answer 3

can be idiopathic

systemic infection = haematogenous spread

recent orthopaedic procedures

osteomyelitis

dm

immunosuppression

alcoholism

Question 4

common bacteria organisms

Answer 4

all ages - staphyloccus aureus, mycobacterium TB

<4yrs - streptococcus pneumoniae, streptococcus pyogenes, Neisseria meningitidis, gram -ve rods

16-40yr neisseria gonorrhoea

Question 5

virus causes of septic arthitis

Answer 5

rubella

mumps

HBV

parvovirus B19

Question 6

fungi causes of septic arthritis

Answer 6

candida

Question 7

symptoms of septic arthritis

Answer 7

fever

excruciating joint pain

redness

swelling and loss of joint function

affect single large joint

TB arthritis is more insidious and chronic

Question 8

signs of septic arthritis

Answer 8

painful, hot, swollen and immobile joint with overlying erythema

severe pain prevents passive movement

pyrexia

signs of cause - small pustules near joint in N gonorrhoea

inflammation might be less overt if immunocompromised or underlying joint disease

knee in >50% cases

Question 9

investigations for septic arthritis

Answer 9

joint aspiration - important

blood - FBC (high WCC and neutrophils), high CRP, ESR. blood cultures, culture and sensitivity. viral serology

plain joint XR - affected joint may initially be normal, useful to assess joint damage in later films

MRI scan - detect associated osteomyelitis

Question 10

results from joint aspiration of septic arthritis

Answer 10

aspirate is grossly purulent

send synovial fluid for cytology, polarising microscopy (for gout or pseudogout crystals), culture and sensitivity

PCR if suspected viral

Question 11

RF for septic A

Answer 11

pre existing joint disease - esp RA

dm

immunosuppression

chronic renal failure

recent joint surgery

prosthetic joints - where infection difficult to treat

IV drug abuse

>80yrs

Question 12

mx of septic arthritis

Answer 12

sepsis 6
iv abx for 2 wks - flucloxacillin 2g QDS / ceftriaxone if gonococcal suspected
joint drainage
if prosthetic joint - surgical arthrocentesis and wash out
native - aspiration, abx