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CNSLF Bone Path 1&2 (iv) - Osteomyelitis (Comps (Brodie abscess…
CNSLF Bone Path 1&2 (iv) - Osteomyelitis
Inflamm of bone + marrow due to infection
Pathogens
pyogenic bacteria - most common
mycobacteria
fungi
viruses
parasites
Pyogenic osteomyelitis
organisms gain access to bone via...
blood from an extra-osseous site (haematogenous) - accounts for most cases - mostly S aureus
direct extension from a contiguous site
direct inoculation (traumatic or surgical) of the bone
E coli, pseudomonas + klebsiella in patients with GUT infection + IVDUs
Pseudomonas a/w DM
patients with sickle cells disease are prone to osteomyelitis common due to salmonella
group b strep most common in neonates
many non-haematogenous cases caused by mixed flora +/or anaerobes
Pathogenesis
initial focus of inflamm is in metaphysis (best vasc part of bone in children) or vertebrae in adults
necrosis of bone sequestrum
reactive new bone formation (involucrum)
fever, mailaise, bone pain, tenderness, reduced movement of limb
Dx
blood cultures
blood tests (high WCC, ESR, CRP)
radiography
lytic lesions surrounded by zone of sclerosis
bone changes are late
US
MRI
bone scan 'hot spot'
Comps
Brodie abscess formation (subacute)
continuous bone formation (Garré sclerosing osteomyelitis)
drainage of pus + necrotic debris (sinus formation)
chronic osteomyellitis
fractures
amyloidosis
bacteraemia
Tx
IV antibiotics, then PO (for wks)
may require surgical drainage
TB osteomyelitis
rare in developed countries but still occurs in developing countries where pul + GI TB are still prevalent - hence a/w pul + GI symptoms
occurs by haematogenous seeding from these extra-osseous sites
TB infection of the spine (Pott's disease) can cause compression fractures + spinal deformities
granulomatous inflamm (necrotising granulomas) of the affected bone
can be v difficult to tx