Osteomyelitis and osteosarcoma

Question 1

What disease types can relate to bone?

Answer 1

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

Question 2

Define osteomyelitis

Answer 2

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

Question 3

Define osteitis

Answer 3

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

Question 4

Classic acute presentation

Answer 4

• 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

Question 5

Classic chronic presentation

Answer 5

• 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)

Question 6

What are the 2 main reactions to bone disease?

Answer 6

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

Question 7

Diagnostic plans for bone disease

Answer 7

• 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

Question 8

Tx - osteomyelitis

Answer 8

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

Question 9

Most common primary bone tumour - dogs

Answer 9

OSA (very rare in horses and cats)

Question 10

How to investigate a possible bone tumour

Answer 10

• 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

Question 11

Describe bone biopsy

Answer 11

• 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

Question 12

Decision making in OSA tx

Answer 12

• 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)

Question 13

OSA tx

Answer 13

• 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