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Committee and the Ethics Committee of the Medical 2 (25‑50% NB formation), 3 (50‑75% NB formation) or
Training and Research Center. The rabbit bone defect 4 (more than 75% NB formation). The score assigned to the
model was established as described previously. [11,13] The assessment of union was 0 (nonunion), 1 (possible union)
rabbit was anesthetized with a combination of intravenous or 2 (radiographic union). The proximal and distal unions of
sodium pentobarbital at 20 mg/kg and intramuscular ketamine the bone graft were separately evaluated. The remodeling
at 50 mg/kg. The anterolateral side of the forelimb was score assigned was 0 (no evidence of remodeling)
shaved and sterilized with 10% povidone‑iodine. The radius 2 (intramedullary remodeling) or 4 (cortical remodeling).
was exposed through a longitudinal incision by gentle The maximum number of points, which could be achieved,
retraction of the muscles. An osteotomy gap of 1.5 cm was 10 for each reconstructed bone.
was created in the diaphysis. Periosteum from the excised
bone was preserved in the group that would later receive Histological analyses
periosteal encapsulation of scaffolds. The ulna was left Fifty‑two specimens from the bone graft sites of the
intact for mechanical stability [Figure 1]. The bone defect radius were successfully fixed with 10% paraformaldehyde,
was created on both forelimbs of the animals. A total of 56 decalcified with sodium formate and embedded in paraffin.
bone defects within the 28 rabbits were randomly assigned Four specimens in Group 1 experienced technical failures.
to one of the four groups for scaffold implantation: Three sagittal sections were cut with a slow speed saw
Group 1: HDCB graft only; Group 2: periosteum‑wrapped from each site at the distal, proximal and middle lines of
HDCB graft; Group 3: HDCB graft seeded with BM‑MSCs; the bone graft. Sections were then prepared and stained
and Group 4: periosteum‑wrapped HDCB graft seeded with hematoxylin and eosin. The micrographic images
with BM‑MSCs. After implantation, muscle, fascia and skin from the light microscope were quantified. Images from
were separately closed over the defect and no internal or each section were taken to evaluate the bone formation
external fixation was used. Forelimbs were postoperatively ratio by a qualified pathologist blinded to the study. The
supported by a carton splint for one week. Each rabbit was NB formation ratio was calculated by the percentage area
administered 400,000 units of penicillin preoperatively on of bone tissue within the defect site, and a mean value
the 1st postoperative day to prevent infection. All rabbits was determined for each section.
from each group were sacrificed 12 weeks after surgery Biomechanical analysis
for gross observation of the growth of callus, radiological The specimens of the radius of each group were loaded onto
assessment, histological analyses and biomechanical a multifunctional mechanical tester (Instron 5582 Universal
measurements. Tester, USA) for the performance of a uniaxial compression

Gross observation test. The specimen was placed between compression
Following sacrifice, both reconstructed radiuses were plates. Force was applied to the specimens at a constant
harvested and completely cleared from the soft tissues. speed of 1 mm/min until fracture occurred. Compressive
The status of callus growth, degradation, bone healing stress and strain were calculated and plotted. Stress value
and NB formation at the bone graft in the radius were at the point of yield (load‑to‑failure) was determined.
observed. Statistical analysis

Radiological assessment The data were presented as mean and standard deviation.
Radius bone specimens in each group were X‑rayed for the The Student’s t‑test was performed to compare the
evaluation of bone formation and remodeling (Titan 2,000, difference between the mean values of two groups using
COMED Medical Systems CO. Ltd., Korea). Assessment of Statistical Product and Service Solutions version 15.0
NB formation and remodeling was based on the modified (SPSS, Inc., USA). Differences at a level of P < 0.05 were
[1]
Lane and Sandhu radiological scoring system. Three considered to be statistically significant.
experts blindly assessed the radiological scores, which
were the sum of the scores of bone formation and RESULTS
remodeling. The score for NB formation was assigned
as 0 (no NB formation), 1 (less than 25% NB formation), The wounds healed completely after one week and the
rabbits were noted to regain full movement within
two weeks. All the rabbits survived with normal behavior.
No complications such as infection or necrosis were
recorded prior to sacrifice.
Gross observation
At 12 weeks after surgery, radii implanted in Group 1
showed a small amount of callus and fibrous‑like tissue
in the interspaces between the defects and grafts. Partial
degradation of the HDCB grafts was found. There was
a significant amount of callus and bony union filled
more than half of the defects in Groups 2 and 3. The
HDCB grafts in these groups were almost degraded. In
Figure 1: The procedure for the transplantation of cancellous bone graft Group 4, good bony union was observed. Bone defects
into the segmental radial defect were almost completely remodeled with NB tissue and
342 Plast Aesthet Res || Vol 2 || Issue 6 || Nov 12, 2015