Dr Beaver's tute - osteomyelitis and septic arthritis

Question 1

commonest areas for osteomyelitis

Answer 1

fast growing areas eg. knee, hip

Question 2

things predisposing to osteomyelitis

Answer 2

HIV immune suppressant
alcoholics
chemo
steroids
substance abuse

Question 3

acute haematogenous osteomyelitis common agents

Answer 3

staphylococcus (aureus commonest)
less often: strep pyogenes, strep pnaumoniae
haemophilus influenza if <4 years old

Question 4

who gets acute haematogenous osteomyelitis

Answer 4

children and immune suppressed adults

Question 5

acute haematogenous osteomyelitis should be considered in presentations of

Answer 5

cold with Pyrexia of unknown origin

Question 6

how to monitor successful treatment of acute haematogenous osteomyelitis

Answer 6

C-reactive protein (more sensitive and responsive)
ESR is not as useful (it is very slow to decline)

Question 7

how to diagnose acute haematogenous osteomyelitis

Answer 7

clinical diagnosis

Question 8

symptoms of acute haematogenous osteomyelitis

Answer 8

pain, malaise, fever
reluctance to use the limb
swelling and erythema if its a superficial joint
warmth
sympathetic effusion in the nearby joint

Question 9

why does acute haematogenous osteomyelitis happen

Answer 9

depositing of bacteria into the bone through blood vessels (may start as bacteraemia)
bacteria lodges in metaphysis
abscess formation

Question 10

what does the x-ray of acute haematogenous osteomyelitis look like

Answer 10

X-rays will be normal until too late
still do an x-ray to exclude other things eg. tumours, child abuse, fracture

Question 11

when will changes be seen on x-rays

Answer 11

after 2-3 weeks (too late)

Question 12

medical term for child abuse

Answer 12

NAI
non accidental injury

Question 13

what happens once you have an abscess

Answer 13

increases intraosseous pressure
toxins from bacteria
pus spreads and can’t get through the growth plate
breakout under the periosteum and sometimes can break into the joint
can become septic arthritis

Question 14

causes of bone necrosis

Answer 14

1. increase of intraosseous preasure
2. toxins from bacteria kill the bone
3. strips blood supply from periosteum

Question 15

sequestra

Answer 15

dead bone

Question 16

periosteal reaction

Answer 16

called onion skin formation
bone forms like the skin of an onion
bone with thicken and encase dead bone which is called an involucrum

Question 17

involucrum

Answer 17

new bone encasing dead bone
can never get better and you can’t get antibiotics into the centre

Question 18

what it is called if dead/infected bone from an involucrum breaks out

Answer 18

cloaca

Question 19

what is it called if dead/infected bone breaks out into the skin

Answer 19

sinus

Question 20

treatment for acute haematogenous osteomyelitis

Answer 20

pain releif
antibiotics - IV at least one week then oral, check local hospital guidelines, may need to notify ID
frequent CRP to monitor progress
splintage

Question 21

drainage for acute haematogenous osteomyelitis

Answer 21

often unnecessary with early treatment
only if no improvement after 36 hours (improvement will be signalled by reduced CRP and fever going down)

Question 22

how do you know if septic arthritis is present

Answer 22

high clinical suspicion - you could aspirate
you can generally move the joint in acute haematogenous osteomyelitis, but not with septic arthritis as the joint is rigidly immobilised

Question 23

what do you do if septic arthritis

Answer 23

aspirate (or just go straight to theatre)
start Iv antibiotics
repeated aspiration
surgical drainage is no response

Question 24

are blood cultures usually positive in osteomyelitis

Answer 24

only positive in 40% of cases
don’t rely on them but still take them
do a PCR of kingell kingae

Question 25

why do you do an x-ray

Answer 25

to rule out fracture, NAI and tumour

Question 26

abscess formation

Answer 26

increases intraosseous pressure
toxins from bacteria, pus spreads, escapes under periosteum into the short tissues
may escape into the joint and cause septic arthritis
hip osteomyelitis should get draained with a lower threshold than other joints because the growth plate is intracapsular so this is more likely to progress to septic arthritis

Question 27

why is septic arthritis important not to miss

Answer 27

pus kills cartilage - it is filled with enzymes that destroy articular cartilage and causes grwoth disturbaance
articular cartilge never recoveers
it does not regnerate
this is why septic arthritis is important not to miss
growth disturbance can also occur