Dr Beaver's tute - osteomyelitis and septic arthritis Flashcards
commonest areas for osteomyelitis
fast growing areas eg. knee, hip
things predisposing to osteomyelitis
HIV immune suppressant
alcoholics
chemo
steroids
substance abuse
acute haematogenous osteomyelitis common agents
staphylococcus (aureus commonest)
less often: strep pyogenes, strep pnaumoniae
haemophilus influenza if <4 years old
who gets acute haematogenous osteomyelitis
children and immune suppressed adults
acute haematogenous osteomyelitis should be considered in presentations of
cold with Pyrexia of unknown origin
how to monitor successful treatment of acute haematogenous osteomyelitis
C-reactive protein (more sensitive and responsive)
ESR is not as useful (it is very slow to decline)
how to diagnose acute haematogenous osteomyelitis
clinical diagnosis
symptoms of acute haematogenous osteomyelitis
pain, malaise, fever
reluctance to use the limb
swelling and erythema if its a superficial joint
warmth
sympathetic effusion in the nearby joint
why does acute haematogenous osteomyelitis happen
depositing of bacteria into the bone through blood vessels (may start as bacteraemia)
bacteria lodges in metaphysis
abscess formation
what does the x-ray of acute haematogenous osteomyelitis look like
X-rays will be normal until too late
still do an x-ray to exclude other things eg. tumours, child abuse, fracture
when will changes be seen on x-rays
after 2-3 weeks (too late)
medical term for child abuse
NAI
non accidental injury
what happens once you have an abscess
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
causes of bone necrosis
- increase of intraosseous preasure
- toxins from bacteria kill the bone
- strips blood supply from periosteum
sequestra
dead bone
periosteal reaction
called onion skin formation
bone forms like the skin of an onion
bone with thicken and encase dead bone which is called an involucrum
involucrum
new bone encasing dead bone
can never get better and you can’t get antibiotics into the centre
what it is called if dead/infected bone from an involucrum breaks out
cloaca
what is it called if dead/infected bone breaks out into the skin
sinus
treatment for acute haematogenous osteomyelitis
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
drainage for acute haematogenous osteomyelitis
often unnecessary with early treatment
only if no improvement after 36 hours (improvement will be signalled by reduced CRP and fever going down)
how do you know if septic arthritis is present
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
what do you do if septic arthritis
aspirate (or just go straight to theatre)
start Iv antibiotics
repeated aspiration
surgical drainage is no response
are blood cultures usually positive in osteomyelitis
only positive in 40% of cases
don’t rely on them but still take them
do a PCR of kingell kingae
why do you do an x-ray
to rule out fracture, NAI and tumour
abscess formation
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
why is septic arthritis important not to miss
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
