Flashcards in Bone healing and fracture Deck (42)
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1
what does secondary (indirect bone healing involve)?
1. hematoma
2. fibrous tissue
3. cartilage
4. mineralized cartilage
5. endochondral ossification
2
What does primary healing of bone involve?
spot welding
3
What does primary healing of bone require?
close contact and rigid stabilization of bone fragments
4
What does anatomic repair alow for?
early load bearing by repaired bone
5
How can anatomic repair slow fracture healing?
disruption of blood supply
6
How can biologic repair have faster healing?
because even though the apparatus is initially taking all the forces, the fracture may heal more rapidly since the blood supply has been minimally disrupted
7
How much can bone cells stand to be deformed?
2% of their length
8
How much can cartilage or fibrous tissue handle being stretched?
10-15% of their length
9
How much elongation can granulation tissue tolerate?
100% elongation
10
Fractures that have more than a mm gap heal by:
indirect healing
11
How does indirect healing occur?
Cells that can be stretched and squashed bridge the gap and produce matrix. the movement decreases, the next group of cells can come in and produce even stiffer matrix and so on
12
How does indirect healing occur?
Cells that can be stretched and squashed bridge the gap and produce matrix. the movement decreases, the next group of cells can come in and produce even stiffer matrix and so on. eventually bone cells can survive and endochondral ossification occurs
1. fracture
2. hematoma
3. fibrin
4. pluripotent eclls
5. granulation tissue
6. fibrous tissue
7. fibocartilage
8. mineralized cartilage
9. bone
13
What are the two flavors of primary healing?
1. contact healing
2. gap healing
14
What happens in contact healing?
osteoclasts make tunnels across fracture lines (cutting cones with bone multicellular units) and new bone laid down--cutting cone
==>spot welds
15
What is gap healing?
ther eis a thin gap. hematoma forms, followed by CT and blood vessels. Once the blood vessels are present the osteoblasts lay down lamellar bone in the gap, THEN cutting cones come through
16
What are conditions that favor secondary bone healing?
1. external coaptation
2. intramedullary pinning
3. interlocking nail repairs with incomplete reduction of fragments
4. elastic plating
5. buttress plating
6. external skeletal fixation w/ out perfect reduction
17
What are conditions favoring primary healing?
1. compression plating
2. rigid forms of external fixation, with close bone contact
3. pin/tension band repairs
4. screw repair of condylar fractures
18
What are the three main roots for blood supply to come in?
1. nutrient artery (cancellous bone, 2/3 of cortex)
2. blood vessels at metaphysis
3. periosteum--nourish outer 1/3 of cortex
4. extraosseous supply of healing bone--arise from surrounding soft tissues to augment the damaged blood supply coming to the fracture fragments--
(more muscle attachment, better lbood supply)
19
Why do bones heal faster with minimal disruption of soft tissue attachments to bone?
because there is extraosseous supply of healing bone that comes form surrounding soft tissue
20
Why do bones heal faster with minimal disruption of soft tissue attachments to bone?
because there is extraosseous supply of healing bone that comes form surrounding soft tissue
21
what are the two main strategies for fixing fractures?
1. anatomic and biologic repair
22
What is anatomic repair?
involves putting fractured bone back together again like a jigsaw puzzle and holding pieces together so some weight can be transferred through the bone right away--sometimes may allow direct healing
23
What are the advantages of anatomic repair?
1. minimal callus formation--good for joint
2. load sharing between bone and hardware--good if expect healing slow
24
What are disadvantages of anatomic repair?
1. often need a big approach, which disrupts blood supply
2. not all fractures can be put back together again and held that way
25
When is anatomic repair most appropriate?
1. near or involving joints
2. older animals--slow healing anyway
26
What is biologic repair?
pulling bone out to length and spanning fracture with hardware. No attempts to put back together
27
What are the advantages of biologic repair?
1. minimally disruptive of blood supply--encourages rapid healing if blood supply ok to begin with
2. faster than putting all the pieces together
28
What is a disadvantage of biologic repair?
no load sharing between bone and hardware so the hardware is could fail before healing occurs
29
When are biological repairs appropriate?
1. dipahyseal fractures in young animals
2. highly comminuted fractures
30
