Kapitel 48 Bone grafts and substitutes

Question 1

Which type of bone healing does bone grafting rely on?

Answer 1

Embryonic bone formation during secondary bone healing (endochondral ossification)

Question 2

Which cells are the initiators of new bone formation?

Answer 2

Mesenchymal stram cells (+ growth factors)

Question 3

Where is the most accessible source of mesenchymal stem cells in an adult?

Answer 3

• Cambium layer of periosteum
• Bone marrow
• Fat

Question 4

Which growth factor is especially common in bone, platelets and cartilage?

Answer 4

Transforming growth factor-beta (TGF-B)

Question 5

List 5 growth factors important for bone healing

Answer 5

• Transforming growth factor beta (TGF-B
• Bone morphogenic proteins (BMPs). most studies are BMP-2, -4 and -7
• Fibroblast growth factor (mainly FGF-1 and FGF-2)
• Insulin like growth factor (IGF)
• Platelet- Derived growth factor (PDGF)

Question 6

Name the 4 classification strategies of bone regeneration

Answer 6

• osteogenesis
• osteoinducation
• osteoconduction
• osteopromotion

Question 7

What is a osteogenic bone graft and give an example

Answer 7

A graft that directly supplies and supports the bone-formating cells

Best example is fresh autogenous cancellous bones grafts which are the gold standard for bone regeneration material.

Another example is bone marrow

Question 8

What is osteoinduction and give example

Answer 8

Materials that have the capacity to induce bone formation at places where no bone formation will otherwise grow.

Example is demineralised bone matrix

Question 9

What is osteoconduction and give example

Answer 9

Material that provides a scaffold for mesenchymal stem cells.

Can be naturally occurring (trabecular matrix of cancellous bone) or synthetic (porous bio ceramics)

Question 10

What is osteopromation and give example

Answer 10

A material that results in enhancement of regeneration of bone

examples are platelet-rich plasma, hydrogels and biphasic calcium phosphate

Question 11

Name the possible sites for harvesting cancellous bone grafts

Answer 11

• Proximal humerus
• Ilium wing
• proximomedial portion of tibia
• subtrochanteric region of femur
• Femur condyles
• Caudoventral period of mandible
• Ribs

Question 12

What is the optimal size of harvested cancellous particles?

Answer 12

between 3 and 6 mm

Question 13

What is demineralised bone matrix?

Answer 13

Bone that has been ground to specific particle sizes and has been decalcified with the use of acid.