osteomyelitis Flashcards
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