Osteomyelitis and osteosarcoma Flashcards Preview

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Flashcards in Osteomyelitis and osteosarcoma Deck (13)
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What disease types can relate to bone?

- autoimmunne (unusual in bone)
- developmental
- degenerative (mostlyjoints)
- endocrine
- infectious
- inflammatory - joints (rare for bone itself)
- metabolic
- neoplastic
- traumatic (fractures)
- vascular (specific problems uncommon)


Define osteomyelitis

infection of cortical bone AND medullary cavity (many people call it this even if one structure is affected)


Define osteitis

inflammation of cortex without involvement of the red or yellow bone
- septic or aseptic


Classic acute presentation

- large/small animl
- single limb lameness
- rapid onset, short duration
- often hx of a laceration or sx
- CE: heat, pain, swelling on palpation, joint structures may be normal, febrile
* ensure you distinguish joint from bone


Classic chronic presentation

- large/small
- moderate? intermittemt? lameness of days-wks
- often hx of laceration or sx
- CE: possible heat, pain, swelling on palpation, joint structures may be normal, pain, discharge, sinus tract formation, pathological fracture (becomes acute)


What are the 2 main reactions to bone disease?

- bone lysis (driven by infection)
- bone formation (Reactive)
- combination of both, seen with infxn and bone tumour
- radiographic signature of osteomyelitis


Diagnostic plans for bone disease

- radiography
- culture and sensitivity
- biopsy
- radionuclide scan (v good at determining high levels of bone activity, useful if radiography doesn't show draining tracts)
- similar radiographic appearance b/w osteomyelitis and OSA so take care when making radiographic dx


Tx - osteomyelitis

- early intervention with BS Abs
- change on C+S
- consider local delivery (gentamicin)
- sx debridement, immbolisation, lavage
- rehabilitation of entire limb


Most common primary bone tumour - dogs

OSA (very rare in horses and cats)


How to investigate a possible bone tumour

- clinical evaluation: LNs, degree of disability
- Radiography - local and thoracic
- Swab tracts, culture and sensitivity on samples
- Biopsy: Jamshidi, # of planes
- definitive diagnosis - biopsy or culture
- Staging/evaluation of prognosis


Describe bone biopsy

- Jamshidi needle or Michelle trephine
- trough the centre of lesion (not margins)
- sample both cortex and medulla
- multiple samples (through same skin incision)
- cytology and culture


Decision making in OSA tx

- unremittingly painful (analgesia won't do)
- must tx primary successfully
- must consider primary spread (nearly all OSAs have micro mets in lungs at time of dx)
- must build client communication into tx time (high emotional impact, very serious very quickly - lameness to life ending disease dx may occur in 3 wks)


OSA tx

- amputation (4 months)
- amputation (remove whole LN chain with it) + chemo (12-14mo)
- limb sparing and chemotherapy (12-24 mo)
- radiotherapy (palliative only)
- NSAIDs/ bisphosphonates (palliative)
- euthanasia