Bone Healing And Grafting (Mod)

Front 1

What is the most important thing to consider for a successful bone repair?

Back 1

Adequate blood supply

Front 2

What are the two types of bone healing? What is the difference? Which takes longer?

Back 2

Indirect- healing by intermediate callus formation
Direct- healing by primary osteonal reconstruction
Direct

Front 3

In what situations does indirect healing occur? What does a larger callus indicate?

Back 3

-Unstable mechanical environment
-Gap > 1mm b/w fragments
-Impaired blood supply
Higher stability

Front 4

What are the three stages of indirect bone healing? How long does each last? What is the main outcome of each phase?

Back 4

1) Inflammatory phase- lasts 3-4 days, with development of clot
2) Repair phase- begins 4-5 , days post break and lasts 6-10 weeks, callus formed
3) Remodeling- can last 6-9 years in humans, bone adapts to regain optimal strength and function

Front 5

When does extraosseous blood supply develop?

Back 5

Within hours of break

Front 6

What are the two types of direct bone healing? What is the difference?

Back 6

Gap- < 1mm
Contact- < 0.01mm

Front 7

How is bone laid down in gap healing? Contact? Are bony union and remodeling separate or combined events in gap healing? Contact?

Back 7

Perpendicular to long axis
Longitudinal to long axis
Separate
Simultaneous

Front 8

Does cancellous/trabecular bone heal by callus formation?

Back 8

No

Front 9

How will a fracture in a the zone of hypertrophy heal? Zone of proliferation?

Back 9

By continued growth of physeal cartilage
Will heal by endochondrial ossification

Front 10

What are the biomechanical approaches to bone healing? What is compromised to achieve this?

Back 10

Anatomical reduction and rigid fixation
Soft tissue

Front 11

What is the more favored approach to fracture repair?

Back 11

Biological osteosynthesis-emphasizes the role of soft tissue integrity

Front 12

With plates and external fixation are you more likely to get direct or indirect healing? With pins, wires, nails and ESF? Casts and splints?

Back 12

Direct
Direct or indirect
Indirect

Front 13

What type of hardware effects blood supply? Which don't?

Back 13

Plates, intermedullary pins and nails
Wires and external fixation pins

Front 14

What are four causes for a bone graft?

Back 14

-Comminuted fractures
-Fractures with bone loss
-Fractures of joints
-Delayed or non-union fractures

Front 15

What are the three types of bone grafts?

Back 15

1) Autogenous- patients own bone
2) Allograft- bone from the same species
3) Xenograft- bone from a different species

Front 16

What are the three osteo functions of bone grafts?

Back 16

1) Osteogenesis- laying down of new bone
2) Osteoinduction- recruitment of host mesenchymal cells to form new bone
3) Ostoconduction- provide a scaffold for the growth of new bone

Front 17

What is the most common type of bone graft? What are the advantages? Disadvantages?

Back 17

Autogenous
Provides osteogenesis, readily available, no rejection (high cellularity if cancellous)
Mechanically weak, pain at donor site, increased surgery time

Front 18

What are the advantages of an cancellous allograft? Disadvantage?

Back 18

Readily available, no donor site problems
Lacks osteogenic properties

Front 19

What are the four phases of cancellous bone graft healing?

Back 19

I- inflammation, hours
II- revascularization and osteoinduction, 2 weeks
III- osteoconduction, 3-4 wks
IV- mechanical support, up to 12 weeks

Front 20

What do cortical bone grafts provide? What "osteo" properties? What do they lack?

Back 20

Structural support
Osteoconductive
Osteogenic properties, b/c acellular

Front 21

What is "creeping substitution"?

Back 21

Osteoclasts reabsorb bone graft, then osteoblasts lay down new bone