Bone healing and fracture Flashcards
(42 cards)
what does secondary (indirect bone healing involve)?
- hematoma
- fibrous tissue
- cartilage
- mineralized cartilage
- endochondral ossification
What does primary healing of bone involve?
spot welding
What does primary healing of bone require?
close contact and rigid stabilization of bone fragments
What does anatomic repair alow for?
early load bearing by repaired bone
How can anatomic repair slow fracture healing?
disruption of blood supply
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
How much can bone cells stand to be deformed?
2% of their length
How much can cartilage or fibrous tissue handle being stretched?
10-15% of their length
How much elongation can granulation tissue tolerate?
100% elongation
Fractures that have more than a mm gap heal by:
indirect healing
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
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
- fracture
- hematoma
- fibrin
- pluripotent eclls
- granulation tissue
- fibrous tissue
- fibocartilage
- mineralized cartilage
- bone
What are the two flavors of primary healing?
- contact healing
2. gap healing
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
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
What are conditions that favor secondary bone healing?
- external coaptation
- intramedullary pinning
- interlocking nail repairs with incomplete reduction of fragments
- elastic plating
- buttress plating
- external skeletal fixation w/ out perfect reduction
What are conditions favoring primary healing?
- compression plating
- rigid forms of external fixation, with close bone contact
- pin/tension band repairs
- screw repair of condylar fractures
What are the three main roots for blood supply to come in?
- nutrient artery (cancellous bone, 2/3 of cortex)
- blood vessels at metaphysis
- periosteum–nourish outer 1/3 of cortex
- 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)
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
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
what are the two main strategies for fixing fractures?
- anatomic and biologic repair
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
What are the advantages of anatomic repair?
- minimal callus formation–good for joint
2. load sharing between bone and hardware–good if expect healing slow
What are disadvantages of anatomic repair?
- often need a big approach, which disrupts blood supply
2. not all fractures can be put back together again and held that way
