Osteonecrosis & Infection Flashcards
What term describes the calcification of normal tissue due to increased serum calcium or phosphorus?
Metastatic calcification
What term describes the calcification of damaged/diseased tissues in a localized fashion?
Dystrophic calcification
What term describes the intramembranous bone formed in response to stress on bone or soft tissue?
Reactive bone formation (periosteal reaction)
Name 4 types of periosteal reaction
solid
laminated
spiculated
Codman’s triangle
What occurs in a solid periosteal reaction?
- slow growing, non-aggressive
- as periosteum is lifted slowly, it fills in completely
What occurs in a laminated periosteal reaction?
- aggressive process
- lifts periosteum, stops, lifts again, etc., (allows layering/onion effect)
- lays down bone during rest phase
What occurs in a spiculated periosteal reaction?
- aggressive process
- periosteum lifted rapidly
- bone growth along Sharpey fibers creates hair-on-end (parallel) or sunburst (outward) appearance
What occurs in a Codman’s triangle periosteal reaction?
- aggressive pattern
- strips periosteum away from adjacent uninvolved bone
What term describes the death of bone and bone marrow in the absence of infection?
Osteonecrosis
What is the most common cause of osteonecrosis?
Infarction (loss of blood supply)
Osteonecrosis of the epiphyseal region is called ____
avascular necrosis (AVN)
Osteonecrosis in the metaphyseal/diaphyseal region is called ____
bone infarct
The inflammation of bone due to a bacterial infection is called?
Osteomyelitis
What is the most common etiology of osteomyelitis?
Staphylococcus aureus
What are the 3 routes of spread for osteomyelitis? Which is most common?
- Hematogenous spread (MC)
- Lymphatic
- Contiguous (direct/implantation)
In the case of hematogenous osteomyelitis, bacteria spread from inside the bone to the subperiosteal space using the ____ and ____ canal systems
Haversian
Volkmann’s
What factors play a role in the severity of a bacterial infection?
- Virulence of the bacteria
- Pre-existing health complications
- Patient’s age
What is the most common form of osteomyelitis that comes from skin pustules or infected teeth or gums?
Hematogenous osteomyelitis
What areas does osteomyelitis most commonly affect?
- metaphyseal regions (most metabolically active)
- lower extremity and hands (blood pooling)
When using the term “osteomyelitis” on its own, the implication is…
acute pyogenic osteomyelitis
What pattern of necrosis is found in tissues undergoing osteomyelitis?
Liquefactive necrosis
What type of edema is produced by the tissue necrosis in osteomyelitis?
Purulent exudate
Describe the pathogenesis of osteomyelitis
- bacteria escape vasculature & proliferate -> local necrosis
- edema results in ^medullary pressure
- ^osteoclast activity in infected area
- necrotic debris lifts periosteum -> reactive bone formation
- periostitis -> loss of blood supply -> necrosis of cortical bone