osteomyelitis Flashcards
(22 cards)
what is osteomyelitis?
infection of the bone marrow that can spread via harversian canals to cortical and calcaneus bone.
what bone is most commonly affected in children and adults?
children: distal femur and proximal tibia. Often involves the metaphysis in children
adults: mainly calcaneus bone and vertebrae and any part of the bone (i.e. not just metaphysis)
what are the sources of infection for osteomyelitis?
skin, respiratory, GI, genitourinary
directly from environment - trauma or surgery
what is the pathophysiology behind osteomyelitis?
infection leads to inflammation and then lifting of the periosteum due to subperiosteal abscess. This compromises the blood supply to the underlying bone and thus there is necrosis and new bone formation underneath.
what organisms can cause osteomyelitis?
90% due to S.aureus
then streptococcus pneumonia and pyogenes
salmonella species are associated with sickle cell and malaria
pseudomonas in puncture wounds
others include E.coli and H.influenzae
what are the risk factors for developing osteomyelitis?
old/young, diabetes, peripheral vascular disease
immunocompromised, HIV,
exposure: IV drug use, trauma , joint replacement and unresolved foot ulcer
TB
how does osteomyelitis present clinically?
localised bone pain, warmth, redness and tender
systemic: fever, malaise, anorexia, weight loss
effusion of near by joint
what investigations should be carried out if you suspect osteomyelitis and why?
FBC - white cells raised ESR/CRP - inflammation U&Es - in case of sepsis blood cultures or sample from source e.g. wound. XRAY - mainly for chronic
what Xray changes are seen in osteomyelitis?
what is the problem with this investigation?
osteolysis cortical thickening periosteal elevation sclerosis metaphysis rarefaction
only seen 2 weeks later and patients are acutely unwell so need to be able to diagnose without Xray
how do we treat osteomyelitis?
IV benzylpenicillin/ flucoxacillin 3 weeks + fluid resuscitation
followed by oral flucoxacillin for further 3 weeks
clindamycin in penicillin allergy
any other Abx based on culture results.
analgesia and NSAIDs
surgery to remove necrotic bone / abscess
what are the complications of osteomyelitis?
septic arthritis may develop bone deformity pathological fracture growth disturbance chronic osteomyelitis abscess formation
what is chronic osteomyelitis?
persistent bone infection. may follow acute osteomyelitis if it is present for >1 month
how does chronic osteomyelitis present?
redness, pain/tenderness, hot
sinus (hole allowing bone to drain of pus etc)
overlying abscess
reduced range of movement
systemically unwell: malaise, weight loss, anorexia and fevers.
how is chronic osteomyelitis diagnosed?
same investigations as acute i.e. bloods
Xray - more useful in chronic because signs appear
MRI - more sensitive and can diagnose accurately.
positive blood cultures - good standard diagnosis
what is a risk factor for developing chronic osteomyelitis?
diabetes
how do we manage chronic osteomyelitis?
long term antibiotics
analgesia / NSAIDs
change lifestyle - better nutrition/control diabetes, stop smoking
limb splinting to protect against fractures
surgically drain abscess’s
what are the complications of chronic osteomyelitis?
pathological fractures
secondary amyloidosis
squamous cell carcinoma of the sinus and surrounding skin.
what is a Brodie’s abscess?
infection is contained within granulation tissue and patient is asymptomatic for years and then eventually infection is released and symptoms show.
What is a Marjolin ulcer?
aggressive ulcerative squamous cell carcinoma that comes over chronically inflamed skin.
can follow burns, osteomyelitis, venous ulcers and radiation
what is a periosteal reaction?
periosteal reaction is the formation of new bone in response to injury or other stimuli of the periosteum surrounding the bone.
can see sclerotic margin at edge of bone.
osteomyelitis can cause this
what does TB infection of bone show on blood results?l
low WCC rather than high
osteomyelitis can be caused by s.aureus, h. influenza, pseudomonas and salmonella. what type of spread is each of these associated with?
H. influenza - haematogenous
s. aureus - haematogenous
salmonella - sickle cell carries
pseudomonas - haemodialysis and IV drug use
