Bone Growth And Fracture Healing Flashcards
1
Q
Cortical versus cancellous bone
A
Cortical
- Diaphysis
- Resists
- Bending
- Torsion
- Laid down circumferentially
- Less biologically active
Cancellous
- Metaphysis
- Resists/absorbs
- compression
- Site of longitudinal growth (physis)
- Very biologically active
2
Q
What is a Fracture?
A
a break in the structural continuity of bone
3
Q
Stages of fracture repair
A
- inflammation
- soft callus
- hard callus
- bone remodelling
4
Q
Stage 1 inflammation
A
- Begins immediately after fracture
- Hematoma and fibrin clot
- Platelets, PMN’s, Neutrophils, Monocytes, Macrophages
- By products of cell death - lysosomal enzymes
5
Q
Stage 2 soft callus
A
- Begins when pain and swelling subside
- Lasts until bony fragments are united by cartilage or fibrous tissue
- Some stability of fracture
- Angulation can still occur
- Continued increase in vascularity
6
Q
Stage 3 hard callus
A
- Conversion of cartilage to woven bone
- Increasing rigidity
- Secondary bone healing
- Obvious callus
7
Q
Stage 4 bone remodeling
A
- Conversion of woven bone to lamellar bone
- Medullary canal is reconstituted
- Bone responds to loading characteristics
- Wolff’s Law
8
Q
Strain
A
- Degree of instability is best expressed as magnitude of strain (% change of initital dimension)
- If strain is too low mechanical induction of tissue differentiation fails
- Too high and healing process does not progress to bone formation
9
Q
Delayed union
A
failure to heal in expected time
10
Q
Reasons for delayed union
A
- high energy injury
- distraction (increased osteogenic jumping)
- instability
- infection
- steroids
- immune suppressants
- smoking
- warfarin
- NSAID
- Ciprofloxacin
11
Q
Non union
A
- failure to heal
- failure calcification fibrocartilage
- instability
- excessive osteoclasis
- abundant callus formation
- pain and tenderness
- persistent fracture line
- sclerosis
12
Q
Delayed healing management
A
- different fixation
- dynamisation
- bone grafting
