Comparison of Two Different Demineralized Bone
Matrices to Autologous Bone Graft in an Athymic
Rat Posterolateral Lumbar Fusion Model
Antonio T. Brecevich, B.A.1; Paul D. Kiely, MCh, FRCS (Tr&Orth)2; B. Victor Yoon, M.S.1; Joseph T. Nguyen,
MPH1; Frank P. Cammisa, M.D., FACS1; Celeste Abjornson, Ph.D.1
1Hospital
2Miami
for Special Surgery, New York, NY
Children’s Hospital, Miami, FL
Introduction

Iliac crest autologous bone graft (ABG) is considered the “gold
standard” graft in spinal fusions.

There is significant harvest morbidity associated with ABG,
which led to the development of alternatives.

Demineralized bone matrix (DBM) is a bone graft substitute.
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Comparison of Two Different Demineralized Bone Matrices to Autologous Bone Graft in an Athymic Rat
Posterolateral Lumbar Fusion Model
Objective
Comparison Groups
3
Novel DBM
putty
Established
DBM putty
“Gold Standard”
• Accell Evo3®
• Integra
LifeSciences
Corporation,
Plainsboro, NJ
• Grafton®
• BioHorizons®,
Birmingham,
AL
• Iliac Crest ABG
Comparison of Two Different Demineralized Bone Matrices to Autologous Bone Graft in an Athymic Rat
Posterolateral Lumbar Fusion Model
Material and Methods

48 mature male athymic rats

Uninstrumented bilateral intertransverse process fusion, using Evo3®, Grafton®, or ABG
Euthanasia at 3 and 12 weeks post-surgery
Evaluation techniques:

Manual Palpation

Radiographic Assessment of Fusion (Post-op, 3 weeks, 9 weeks)
– Graded with Lenke classification

Nondestructive Mechanical Testing
– Lateral bending (both planes), flexion, and extension

Histology
Statistical Analysis

Descriptive statistics (α = 0.05)



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Comparison of Two Different Demineralized Bone Matrices to Autologous Bone Graft in an Athymic Rat
Posterolateral Lumbar Fusion Model
Results – Manual Palpation

Fusion assessment at the time of sacrifice

Three blinded observers

At both the 3-week and 9-week intervals
Fusion Rates
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Evo3
Grafton
ABG
3 Weeks
4/4 (100%)
4/4 (100%)
1/4 (25%)
9 Weeks
8/12 (66%)
12/12 (100%)
4/12 (33%)
Comparison of Two Different Demineralized Bone Matrices to Autologous Bone Graft in an Athymic Rat
Posterolateral Lumbar Fusion Model
Results – Radiograph
Fusion Rates
Evo3 (A)
Grafton (B)
ABG (C)
A
12/16 (75%)
12/16 (75%)
4/16 (25%)
B
4/16 (25%)
4/16 (25%)
5/16 (31%)
C
-
-
6/16 (38%)
D
-
-
1/16 (6%)
Lenke Clasification
A.
B.
C.
D.
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Definitely Solid
Possibly Solid
Probably not Solid
Definitely not Solid
Comparison of Two Different Demineralized Bone Matrices to Autologous Bone Graft in an Athymic Rat
Posterolateral Lumbar Fusion Model
Results – Mechanical Testing

The mean stiffness
(N/mm) for each group
determined and
categorized by the
directional force


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Flexion, extension, and left
and right lateral bends
No statistical difference
between the groups in all
4 directions
100
90
80
70
60
50
40
30
20
10
0
Extension
Flexion
ICGB
Evo3
Comparison of Two Different Demineralized Bone Matrices to Autologous Bone Graft in an Athymic Rat
Posterolateral Lumbar Fusion Model
Left Bend
Grafton DBM
Right Bend
Results – Micro CT

The 3D fusion masses of
Evo3® (A, B), and Grafton® (C,
D) were more mineralized
and appeared more complete
than ABG (E, F)

Evo3® and Grafton® treated
groups had consistent bone
formation

BV/TV was greater than 85 %
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Comparison of Two Different Demineralized Bone Matrices to Autologous Bone Graft in an Athymic Rat
Posterolateral Lumbar Fusion Model
Results - Histology

Significant and coherent bone
formation and remodeling in both
DBM groups

Figure A demonstrates new bone
(green) forming around the
demineralized bone material of
Evo3® (red) 9 weeks post-op

9
A
B
At 10X magnification (Figure B), new
osteoid surfaces are present at a
higher prevalence than osteoclastic
activity highlighting a highly active
phase of bone formation
Comparison of Two Different Demineralized Bone Matrices to Autologous Bone Graft in an Athymic Rat
Posterolateral Lumbar Fusion Model
Discussion

Our results showed that both DBM groups induced fusion at a
substantially and significantly higher rate than ABG at 9 weeks in
this athymic rat posterolateral lumbar spine fusion model, and
that both DBM were able to induce spinal fusion as early as 3
weeks

We placed equal 0.2 cm3 doses of both DBM graft products and
ABG on the intertransverse fusion beds in this study, effectively
eliminating a dosing bias

No adjacent level fusions were seen in this model
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Comparison of Two Different Demineralized Bone Matrices to Autologous Bone Graft in an Athymic Rat
Posterolateral Lumbar Fusion Model
Conclusion

ABG is the “gold standard” graft in spinal fusions

However, there is significant harvest morbidity associated with ABG

DBM putty is an alternative to ABG that eliminates the harvest morbidity

Using an athymic rat posterolateral fusion model, we compared Evo3®,
Grafton®, and ABG

The DBM treated groups achieved a significantly higher rate of fusion than
the ABG treated group at 9 weeks in this model

Successful fusion was also demonstrated in the DBM treated groups at 3
weeks
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Comparison of Two Different Demineralized Bone Matrices to Autologous Bone Graft in an Athymic Rat
Posterolateral Lumbar Fusion Model
Disclosure

12
Nothing to disclose
Comparison of Two Different Demineralized Bone Matrices to Autologous Bone Graft in an Athymic Rat
Posterolateral Lumbar Fusion Model