Preparing an animal model of critical femoral defect in
rabbit femoral condyle and the critical bone defect size

doi:10.3969/j.issn.2095-4344.2614

Abstract

Abstract:

BACKGROUND: Rabbit model of distal femoral bone defect has been widely used to test bone tissue engineering materials for bone defects. However, there is no uniform standard for the size of the cylindrical bone defect model of the rabbit femoral condyle, which ranges 5-9 mm in diameter and 8-12 mm in depth.

OBJECTIVE: To establish the bone defect model of adult rabbit femoral condyle with different sizes and to determine the critical bone defect size of the femoral condyle

METHODS: Eighteen male New Zealand White rabbits aged 6 months were randomly divided into three groups according to the diameter of bone defect: 5 mm diameter group, 6 mm diameter group, and 7 mm diameter group. The defect depth was 10 mm. These rabbits underwent bilateral radial surgery, a total of 12 sides. Computed Tomography (CT) scan and three-dimensional reconstruction were performed at 1 day, 4, 8, 12 weeks after surgery. The CT-Hedberg score was used to evaluate the healing of bone defects. The rabbits were sacrificed at 12 weeks after surgery, and the femoral condyle specimens were taken out. Healing of the defect was analyzed by gross observation and hematoxylin-eosin staining. The study protocol was approved by the Animal Ethics Committee of Xuzhou Medical University.

RESULTS AND CONCLUSION: All rabbits survived after surgery. The gross observation showed that the defect of 5 mm diameter group was filled with new bone tissue, the femoral condyle was well shaped, and the bone defect was completely repaired. In 6 mm and 7 mm diameter groups, depressed deformation was obviously observed in the defect area, with less new bone tissue, and the defect was was not repaired. The CT images showed that the defect area of 5 mm diameter group gradually decreased, and the broken ends of the defect were bridged. In the defect area of 6 mm and 7 mm diameter groups, only a small amount of new bone tissue was implanted, and the defect area was slightly reduced. At the 12^th week after surgery, the cortical bone structure of 5 mm diameter group was intact and continuous, the femoral condyle was well shaped, and the bone defect was completely repaired. The defects of 6 mm and 7 mm diameter groups were partially or not repaired, and the defect cavity was still visible in the 7 mm diameter group. The CT-Hedberg scores of 6 mm diameter group were significantly lower than those of 5 mm diameter group at different time points (P < 0.05), and there was no significant difference in the CT-Hedberg scores between 6 mm and 7 mm diameter groups (P > 0.05). Histological results showed that there were irregular trabecular structures in the defect area of 5 mm diameter group, with a large amount of new bone tissue. In the other two groups, there were some new bone trabeculae around the bone defect, but the defect area was less filled with new bone tissue. During the 12-week observation period, the femoral condyle defect with a diameter of > 6 mm and a depth of 10 mm could not heal spontaneously, while the defect with a diameter of < 6 mm could be completely repaired, which met the criteria of critical bone defect. Therefore, the diameter of < 6 mm could be used as the critical bone defect size of rabbit femoral condyle.

Key words: rabbit, femoral condyle, critical bone defect, defect size, animal model

CLC Number:

Xu Shizhuang, Wang Jin, Pan Wenzhen, Liu Lei, Yang Guangjie, Zhao Fengchao. Preparing an animal model of critical femoral defect in rabbit femoral condyle and the critical bone defect size[J]. Chinese Journal of Tissue Engineering Research, 2020, 24(20): 3191-3195.

Figures/Tables 4

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