OTA 2006 Posters
Scientific Poster #75 Basic Science
MicroCT Evaluation of Segmental Fracture Healing in Rabbits
Ru Li, MD (n); Herbert vonSchroeder, MD (n); Duncan J. Stewart, MD (n);
Emil H. Schemitsch, MD (n);
St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
Purpose: Although bone regeneration has been evaluated by radiology,
histology, and mechanical testing, three-dimensional structural variation
of new bone formation in fracture segmental defects is not understood. Rabbit
segmental fractures were studied with microCT to evaluate these variations.
The purpose of this study was (1) to evaluate the structural differences
between healing bone and nonunion and (2) to determine how these microarchitectural
differences vary between proximal, middle, and distal fracture locations.
Methods: Using 16 rabbits (after anesthesia), a 10-mm segmental bone
defect was created after excision of 12 mm of the periosteum in the middle
third of the right tibia. The fracture was stabilized with a stainless steel
plate. The bone defects were treated by local injection with cell-based
VEGF gene transfer (n = 8), fibroblasts alone (n = 4), or saline (n = 4),
to stimulate differences in bone healing. The animals were sacrificed and
fracture healing specimens collected at 10 weeks postsurgery.
Results: Fracture healing was defined as bone bridging of the fracture
defect radiologically. Ten tibial fractures healed in total, with six nonunions.
Overall, microCT evaluation of the new bone structural parameters showed
that amount of new bone (volume of bone [VolB] x bone mineral density [BMD]),
bone volume fractions (BVF), bone/tissue volume (BV/TV), trabecular thickness
(Tb Th), number (Tb N), and connectivity density (Euler number) were higher
in the healing than nonunion group, with decreasing levels, respectively,
for proximal, distal, and middle locations. The structure model index (SMI),
bone surface/bone volume (BS/BV) and trabecular separations (Tb Sp) were
lower for healing bone than for nonunion, with increasing levels, respectively,
in proximal, distal, and middle locations. P <0.05 indicated statistical
significance (ANOVA, SPSS) as shown in the table.
| |
VolB |
BMD |
VolBxBMD |
BVF |
SMI |
ConnD |
BV/TV |
BS/BV |
Tb Th |
Tb N |
Tb Sp |
| Healing |
|
|
|
|
|
|
|
|
|
|
|
| Nonunion |
.000 |
.027 |
.017 |
.001 |
.035 |
.021 |
.074 |
.012 |
.011 |
.449 |
.032 |
| Location |
.018 |
.041 |
.001 |
.005 |
.036 |
.998 |
.063 |
.002 |
.375 |
.264 |
.010 |
Conclusion/Significance: MicroCT is efficient, nondestructive, and
accurate for qualitative and quantitative studies of bone microarchitecture
during fracture healing.
If noted, the author indicates something of value received.
The codes are identified as a-research or institutional support; b-miscellaneous
funding; c-royalties; d-stock options; e-consultant or employee; n-no conflicts
disclosed, and *disclosure not available at time of printing.
·
The FDA has not cleared this drug and/or medical device for the use
described in this presentation (i.e., the drug or medical device is being
discussed for an "off label" use). · · FDA
information not available at time of printing.