6. Why do we need them???
2.2 million graft procedures done yearly
9 out of 10 involve use of Auto/Allografts
Estimated cost about $2.5 billion per year
7. Properties of an ideal bone graft
Osteoconductive matrix
Osteogenic cells
Osteoinductive proteins
8. Osteoconductive matrix
Acts as a scaffold which supports osteoblasts and
progenitor cells
Provides integrated porous structure through which new
cells can migrate and new vessels can form
10. Osteoinductive proteins
Stimulate and support mitogenesis of undifferentiated cells
into osteoblastic cells
Bone graft substitutes have one or more of these three
properties
11. Autografts
Harvested from the patient
Cancellous, vascularized
cortical, non vascularized
cortical and autogeneous bone
marrow grafts
Commonly taken from iliac
crests
13. Disadvantages
Requires additional surgery
Limited quantity
Non availability for further surgery
Increased morbidity
Infection
Chronic pain
Cosmetic
18. Classification
Laurencin et al, proposed a classification system of material
based groups
Includes:
Allograft based
Factor based
Cell based
Ceramic based
Polymer based
19. Allograft based
Includes allograft bone used alone or in combination with
other material
Available as Demineralized bone matrix, and other forms as
an autograft, Eg- corticocancellous grafts etc.
20. Dimineralized bone matrix
Has osteoconductive and osteoinductive properties
Does not provide structural support
Very good for filling bone defects and cavities
Biological activity - proteins and growth factors present in
the extracellular matrix
Prepared by a standard process- Urist et al, modified by
Reddi and huggins
21. Pulverized allogenic bone (74-420 micrometer)
Demineralization in 0.5N HCL for 3 hours
Extra acid rinsed- sterile water, ethanol and ethyl ether
22. Uses
Excellent for contained stable defects Eg- cysts and cavities
Have been used for non unions and acute bone defects *
Also been used to enhance arthrodesis Eg- spine etc.**
• *tiedmann et al, Orthopedics 1995:18 1153-8
• **Urist MR et al, Clin. Orthop. 1981;154:97-113
23. DBM is available in various forms as
Freeze dried powder
Crushed granules, chips
Paste
Gels
mixture of DBM with autologous bone marrow has also been used as
injection*
* Connolly JF, Clin. Orthop. 1995;313:8-18
24. Product Company Type
Grafton DBM Osteotech DBM as gel, flex, putty
Dynagraft Gensci
Reg.
Process
DBM
Orthoblast DO DBM+ allograft cancellous bone
Osteofil Sofamor
Danek
DBM+gelatin carrier+ water
Opteform Exactech Compacted corticocancellous bone chips
with same material as osteofil
DBX Synthes DBM as putty, paste
25.
26. Disadvantages
Infection
Disease transmission
Variable potency- multiple donors, manufacture processes
No RCT has been done comparing its efficacy
27. Factor based
Involves natural or
recombinant factors
Factors responsible for
differentiation of progenitor
cells and regulation of activity
Mechanism of action based
mostly on activation of protein
kinases
Combined and simultaneous
activity of various factors-
controlled resorption and
formation of bone
28. Factor+ Receptor on cell surface
Activation of protein kinases
Transcription of mRNA Proteins
Regulation of cell activity
29. include TGF-beta, insulinlike
growth factors I and II, PDGF,
FGF, and BMPs
Mostly in research phase
Recombinant BMP2 as
INFUSE bone graft
30. Brief history of rhBMP2
1965- Urist et al, isolated a group of proteins they called
BMPs
2002- FDA approved rhBMP2 for use in lumbar spine
fusion with LT-CAGER device
2004-FDA approved use of rhBMP2 in open tibial fractures
31. rhBMP2/ACS+allograft V/S autogeneous
bone graft in diaphyseal tibial fractures
Study by Jones AL et al
30 patients with diaphyseal tibial fractures with cortical bone loss
Mean length of defect-4 cm
Divided in 2 groups
Short musculoskeletal function assessment administered before and after surgery
10 in autograft group, 13 in rhBMP2 group showed healing
Significantly less blood loss in rhBMP2 group
Comparative improvement in SMFA in both groups
Jones AL et al J Bone Joint Surgery AM 2006 Jul;88(2):1431-41
32. Contraindications to rhBMP2
Hypersensitivity to rhBMP2 or bovine collagen type I
In vicinity of resected tumor
Patients with active malignancy or patients undergoing treatment
Skeletally immature patient
Pregnant women
Patients with active infection at operative site
33. Cell based
Based on in vitro differentiation of mesenchymal stem cells to
osteoblastic lineage
Various additives- dexamethasone, ascorbic acid, b-glycerophosphate
Addition of factors- TGF-beta, BMP2, BMP4, BMP7
They have been used alongwith ceramics
Proposed to be used in bone repair prosthetic setting
34. Ceramic based
About 60 % bone substitutes
involve ceramics- alone or in
combination
Eg-
Calcium sulfate
Calcium phosphate
Bioactive glass
Primary inorganic component of
bone is calcium hydroxyapatite
Property of
OSTEOINTEGRATION- newly
formed mineralized tissue forms
intimate bond with implant
material
35. Ideal ceramic
Chemical structure to promote bone healing
Replaced by native bone
Mechanically strong to provide stability
36. Calcium phosphate biomaterials
Mainly used as osteoconductive matrix
Polycrystalline structure
Crystals of highly oxidised material fused by sintering
Brittle substance with poor tensile strength
Used for filling contained bone defects and areas of bone loss
Placed in rigidly stabilized bone or intact bone- to avoid shear stress on biomaterial
Tightly pack in adjacent host bone to maximize ingrowth
Available as porous/non porous blocks or porous granules
37. Tri calcium phosphate
It is a porous ceramic
Converts partly to hydroxyapatite in the body
More porous and faster rate of resorption than
hydroxyapatite mechanically weaker in
compression
Unpredictable Biodegradation profile not popular
May be used for filling bone defects- trauma, benign
tumors, cysts
38. Coralline hydroxyapatite
Processed by hydrothermal
exchange
Converts coral calcium
carbonate to crystalline
hydroxyapatite
Pore diameter 200-500
micrometer
Structure very similar to
human trabecular bone
Contraindication to use- joint
surface defect, material may
enter joint
39. Study show equivalent result with coralline hydroxyapatite
and autologous bone graft-tibial plateau fractures*
Results less predictable on management of metaphyseal
fractures
* Bucholz RW clin orthop. 1989;240:53-62
40. Calcium collagen graft material
Osteoconductive composite of
hydroxyapatite
calcium phosphate
type I and III collagen
autologous bone marrow
Does not provide structural support
Effective bone substitute/ bone graft expander
Good for use in acute long bone cortical fractures
41. No scientific evidence of benefit in management of non-
unions
Not recommended for use in metaphyseal bone defects due
to articular fractures as provides no structural support
42. Calcium sulfate graft material
Alphahemihydrate crystalline structure
May be used as a bone void filler
Completely resorbs as new bone remodels to fill defect
Potential uses- filling defects including segmental defects,
exapanding grafts as in spinal fusion
May be used to fill bone graft harvest sites
43. Very limited information available regarding use in humans
No published control studies available
44. Injectable calcium phosphate-SRS Norian
Injectable paste of inorganic
calcium phosphate
Hardens quickly to carbonated
apatite of low crystallinity
similar to found in mineral
phase of bone
Within 12 hours, crystallises to
Dahlite, which can be resorbed
and replaced by host bone
Useful to augment cast
treatment or internal fixation of
impacted metaphyseal
fractures
45. Studies have been done in cases of impacted extra articular
distal end radius fractures with good results
Jupiter et al. J Orthop Trauma 1997;11:110-6
Kopylov et al. J Hand Surg [Br]. 1996;21:768-71
Kopylov et al. Acta Orthop Scand 1999;70;1-5
46. Norian SRS in radial osteotomies
study by Logano calderon et al
Retrospective analysis of 6 elderly patients with corrective radial
osteotomies
Fixed with angular stable implants+ Norian SRS
All osteotomies healed
Post op DASH-28 points, Modified Mayo score-68
Logan calderon et al J Hand Surg[Am] 2007 sep;32(7):976-83
47. Norian SRS in knee replacement
Study by Mangotti A et al
Used Norian SRS as substitute of bone graft for tibial bone
defects in TKR
3 unicompartmental TKR, 2 revision TKR, 1 hinged knee
prosthesis
No poor results, improved knee scores, no evidence of post
op deformity
Mangotti A et al Arch Orthop Trauma Surg.2006 Nov:126(9):594-8
48. Other uses:
hip
spine
calcaneal
other metaphyseal fractures
At risk of implant failure or redisplacment due to load
49. Bio active glass
Variation of glass beads
Composed of silica, calcium oxide, disodium oxide and
peroxide
They bind to collagen, growth factors and fibrin to form a
matrix
Provides compressive strength but not structural support
50. Polymer based group
Can be divided into natural/synthetic
Further divided into biodegradable/non biodegradable
Eg:
Healoss(DePuy)- natural polymer based group
polymer-ceramic composite
collagen coated with hydroxapatite
used in spinal fusions
51. Cortoss: injectable, resin based
product for application to load
bearing sites
Rhakoss (orthovita, inc.): Resin
composite available in various
forms for spinal fusion
52. Composite grafts
Rationale most of the graft substitutes are only
osteoconductive
Cinolti G et al J Bone Joint Surg Br. 2004 Jan;86(1):135-42
“Osteoconductive material alone do not give effective fusion
as autologous graft”
54. Rate of fusion was much higher in I, II, IV as compared to
III
Boden SD et al Spine.1999 feb 15;24(4):320-7
“ Coralline Hydroxyapatite+osteoinductive bone proteins give
better results in Posterolateral lumbar arthrodesis than
autograft or bone marrow extracts alone”
55. Kai T et al. Spine 2003 aug 1;28
(15):1653-8
5 groups of rabbits underwent lumbar intervertebral spinal fusion
I- sham operation
II-Porous calcium phosphate ceramic alone
III-autogeneous iliac crest
IV- ceramic + bone marrow stromal derived osteoblasts
V- Ceramic + bone marrow stromal derived osteoblasts + rhBMP2
57. Size of fusion mass and stiffness of fusion segments-
greatest in group V
Conclusions:
rhBMP2 addition may reinforce biomechanical stiffness for spinal
fusion segments
Porous calcium ceramics should not be used alone
58. Choice of graft
What is the expectation? Structure/bone forming function
Availability of graft?
Recipient bed?
Cost?
Remember!!! Stable fixation is required for use of most
grafts
59. New concept
Concept of tissue engineering
Application of biologic, chemical and engineering
principles
repair, restoration and regeneration of tissues
using biomaterials, cells and factors