This document discusses bone grafts and bone morphogenic proteins. It defines bone grafts as the transfer of bone tissue from one site to another. There are several types of bone grafts including autografts, allografts, and synthetic grafts. Autografts are obtained from the patient and provide osteoinduction, osteoconduction and osteogenesis. Allografts are obtained from donors and provide osteoconduction and variable osteoinduction depending on processing. Synthetic grafts like calcium phosphate and hydroxyapatite are osteoconductive. Bone morphogenic proteins can be produced recombinantly and are osteoinductive. The document compares the properties and uses of different graft types.
2. Overview
Definition
Properties of bone graft
Indication of bone graft
Type of bone graft
◦ Autograft
◦ Allograft
◦ Synthetic bone graft
Graft incorporation
3. Definition
Graft – tissue transfer from one site to
another
Bone graft – transfer of bone from one
site to another
4. Properties of bone graft
Osteoconductive
◦ Provide integrated porous structure through
which new cell can migrate and new vessel
form
– acts as a framework/scaffold for bone growth
Osteoinductive
– stimulate and support mitogenesis of
undifferentiated cells to osteoblastic cell
Osteogenic
– presence of progenitor cell for bone
formation (osteoblast/osteoblast precursor)
5. Indication of bone graft
To promote union
Bridging of joint and provide
arthrodesis
To fill defect in
◦ Fracture
◦ Osteotomies
◦ Cavities resulting from cyst/tumours
6. Type of bone graft
Autograft
◦ Cancellous bone
◦ Cortical bone
◦ Bone marrow aspiration
Allograft
◦ Demineralized bone matrix
Synthethic bone graft
◦ Calcium based bone graft
◦ Bone morphogenetic protein
7. Autograft
Bone transfer from one site to another
in the same individual
◦ Cortical bone
◦ Cancellous bone
◦ Bone marrow aspirate
Autograft have osteoinductive,
osteoconductive and osteogenesis
properties
8. Site of harvest
Cortical bone Cancellous bone
Iliac crest
Fibula
Rib
Iliac crest
Proximal tibia(Tibial
Plateau)
Greater Trochanter
9. Advantage Disadvantage
No antigenicity
No potential for disease
transmission
Provides
osteoconduction,
osteoinduction and
osteogenic cells.
Limited quantity
Requires additional
surgery
Donor site morbidity
◦ Risk of infection
◦ Pain over surgical site
10. Bone marrow aspirate
Osteogenic property
◦ Provides mesenchymal stem cells
(osteoprogenitor cells)
◦ Can be used in combination with an
osteoconductive matrix
11. Allograft
Bone transferred from one person to
another
◦ Fresh – highly immunogenic
◦ Fresh frozen – less immunogenic, BMP
preserved
◦ Freeze dried – least immunogenic, loses
BMP
Allograft have osteoinductive and
osteoconductive properties
12. Advantages Disadvantages
Eliminate donor site
morbidity
Abundant supply
Immune reaction
(antigenicity)
Risk of infection
Disease transmission
Reduce osteoinduction
and osteogenicity
Variable osteoinduction
based on processing
13. Demineralised bone matrix
Acid extractraction of allograft bone
leaving
◦ Collagen
◦ Noncollagenous proteins
◦ Bone growth factors
Offer some osteoinductive potential,
mainly act as an osteoconductive
agents
14. Synthetic bone graft
Calcium based synthetic bone graft
are primarily osteoconductive
◦ Calcium phosphate
◦ Calcium hydroxyapatite
◦ Calcium sulphate
17. Calcium suphate
Osteoconductive
Low compressive strength
Rapid resorption (6-9 weeks)
Can be used as autogenous graft
expander
Usually used in conjunction with
gentamicin to provide local antibiotic
delivery in treatment of cavities in
osteomyelitis
18.
19. Bone Morphogenetic Protein
Osteoinductive – targets the
perivascular messenchymal cells
Originally extracted from allograft
bone
Recent advance in technology allow
manufacturing of BMP using
recombinant technology
rhBMP-2 and rhBMP-7
20. Graft Osteoconductiv
e
Osteoinductive Osteogenic
cells
Structural
integrity
Others
Cancellous
bone
Excellent Good Excellent Good Rapid
incorporation
Cortical bone Good Good Good Excellent Slow
incorporation
Bone marrow
aspirate
Poor Poor Excellent Poor
Allograft Good Fair None Good Variable
osteoinduction
based on
preparation
Demineralize
d bone matrix
Good Fair None Poor
Calcium
based
synthetic
bone graft
Good None None Good
BMP Poor Good None Poor
Differences between bone
graft/substitutes
21. Incorporation of graft
Inflammation
◦ At graft site, hematoma develop, which
provides heamatopoetic cells that secrete
growth factor
Reparative
◦ Autograft undergo necrosis, which stimulate
inflammatory respons with fibrovascular
stroma, and stimulus for bone growth
◦ The dead autograft provide passive scaffold
for new bone formation (creeping
substitution)
Bone remodelling
22. Reference
Miller’s review of orthopaedics 7th
edition
Apley’s system of orthopaedic and
fractures 9th edition
Campbell operative orthopaedics 11th
edition