Investigation on Defect Length in a Model of Radius Critical-size Defect in Adult Rabbits

doi:10.3969/j.issn.1674-5817.2018.03.004

Abstract

Abstract: Objective To establish experimental models with different defect lengths of adult rabbit radius and to determine the optimal length of bone critical-size defects in adult rabbits.Methods Eighteen male New Zealand White rabbits aged 8 months were included in this study.They were randomly assigned into 3 groups,according to the defect lengths of radius:group A (10 mm),group B (12 mm) and group C (15 mm).There were 6 rabbits with a total of 12 sides in each group.These rabbits underwent bilateral radial surgery.Computed tomography (CT) scans were taken immediately after the surgery and at 4-week intervals,respectively.The healing of the bone defect was evaluated with the CT-Hedberg scores.The rabbits were sacrificed at 12 weeks postoperatively and the forearms were harvested for gross and histological observations of new bone formation.Results All rabbits survived after the operation.Twelve (100%) of the radial bones in group A and eleven (91.7%) in group B revealed continuous bridged callus with a smooth surface.In contrast,the defect area was filled with fibrous tissue in group C with the closure of both ends.CT images showed that five out of twelve sides in group C appeared ulnar fracture at fourth weeks postoperatively.We excluded the fracture sides out of the statistical analysis.At twelve weeks postoperatively,recanalized marrow cavity of the bridged radius in group A and group B were observed on CT images.However,a small amount of callus along with closed marrow cavity was found at both ends in group C.Based on the CT-Hedberg scoring system,we found that the scores of group C (1.14±0.38,1.29±0.49,1.57±0.53) were lower than group A (2.42±0.51,3.17±0.58,3.75±0.45) and group B (2.25±0.45,2.67±0.78,3.50±0.67),respectively.There were significant statistical differences among the three groups at each time point postoperatively (P<0.05).However,there were lacks of significant differences at various postoperative time points between group A and group B (P>0.05).Histological analysis showed that the bone defects in group A and group B were perfectly repaired with the recanalization of marrow cavity.It was observed that in group C the ends of the defects were closed and the defect area was filled with fibrous tissue.Conclusions Eight-month-old male New Zealand White rabbits could be selected when radius defect in adult rabbit was established and 15 mm was considered the most appropriate critical-size defect length.However,it should be taken into account that fractures would be one of the complications at such a age of rabbits with heavier weight.

Key words: Adult rabbit, Radius, Critical-size bone defect, Defect length, Animal model

CLC Number:

Q95-33

SONG Zi-Jian, ZHENG Xin, WANG Jin, ZHANG Xing-Chen, GUO Kai-Jin. Investigation on Defect Length in a Model of Radius Critical-size Defect in Adult Rabbits[J]. Laboratory Animal and Comparative Medicine, 2018, 38(3): 182-187.

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