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33 Cards in this Set

  • Front
  • Back
What is the principal determinant of fracture healing?
Blood supply
What are the three components of the sequence of changes in blood supply after fracture?
Immediate decrease in blood supply
Increased vascularity fmaximal at 2 weeks)
Return to normal by 3 to 5 months
What is the effect of reaming?
Destroys endosteal blood supply
What are the three effects of nicotine on fracture healing?
Increased time to fracture healing
Increased risk of nonunion
Decreased fracture callus strength
Nicotine use is associated with increased risk of fractures at which locations?
Increases risk of wrist and hip fractures
How does smoking affect lumbar fusion rates?
Increases the pseudarthrosis rate of lumbar fusion by 500%
What is the two-step sequence of callus types formed after fracture?
Bridging (soft) callus within 2 weeks
Replaced by woven bone (hard callus)
Callus is ultimately remodeled over what period?
Remodeled to lamellar bone within 7 years
What two types of bone formation are seen with cast treatment of fracture?
Periosteal bridging callus
Enchondral ossiiication
ls there any difference with intramedullary (IM) nail treatment?
IM nail treatment also results in medullary callus formation late
Under what two conditions can intramembranous bone formation (no cartilage precursor) be seen after
fracture?
Low strain
High oxygen tension
What type of chondrocytes are present in the first 10 days after fracture?
Proliferative chondrocytes
What collagen type do they produce?
Type II
What other collagen type is present in the chondroid phase?
Type IX: cross-linking function
After 14 days, what chondrocyte type is present?
Hypertrophic chondrocytes
What type of collagen do they produce?
Type X
What are the next three steps?
Calcification
Osteoclasts resorb matrix
Osteoblasts lay down new bone
How do hypertrophic nonunions heal?
Mineralization of fibrocartilage
What other treatment modality has a similar mechanism?
Pulsed electromagnetic field treatment (bone stimulator)
Rate the four tissue types from highest to lowest strain tolerances?
Granulation tissue (100% strain tolerance)
Fibrous tissue
Cartilage
Bone
At what phase of fracture healing does direct current exert an effect?
Inflammatory-response phase
At what phase of fracture healing does alternating current exert an effect?
Repair phase (callus)
What is the effect of pulsed electromagnetic fields?
lnitiates fibrocartilage calcification
What is the classic application of this technology?
Nonhealing pseudo-jones fracture
What are the two benefits of pulsed low-intensity ultrasound?
Accelerated fracture healing
Increased callus strength
What are the two detrimental effects of radiation?
Decreased cellularity
Decreased callus strength
How long should the latency phase last?
5 to 7 days
What is the desired rate of distraction during distraction phase?
1 mm/day
What is the duration of the consolidation phase?
Twice as long as the distraction phase
What is the weight-bearing status throughout treatment?
Weight-bearing as tolerated (WBAT)
What changes are seen in blood vessels?
Proliferation of vasa vasorum
What is the oxygen tension with distraction osteogenesis?
High oxygen tension
So what type of bone formation is seen tension conditions?
lntramembranous bone formation (no under these low-strain, high oxygen cartilage precursor)