幼龄兔及成年兔桡骨骨缺损模型中骨缺损大小的对比研究

目的 探讨不同月龄新西兰兔建立桡骨骨缺损模型时骨缺损大小的选择。方法 选取3月龄(幼龄兔)及6月龄(成年兔)健康雄性新西兰兔各20只,根据兔龄分为A组(3月龄)和B组(6月龄),每组兔前肢采用数字表法随机分为2亚组制备桡骨骨缺损模型,每组20侧。其中A1组、B1组桡骨骨缺损长度为15 mm,A2组、B2组骨缺损长度为20 mm。分别于模型制备术后第4、8、12周行X线检查,并应用X线Lane-Sandhu评分标准评估骨愈合情况。术后12周处死所有实验动物,取桡骨标本进行大体及组织学观察,分析骨愈合情况。结果 制备骨缺损模型术后,所有实验兔均存活。X线检查显示:术后第8周A1组骨缺损基本愈合,至第12周新生骨塑形完全,与正常桡骨形态类似;其余3组至第12周骨缺损均未完全修复,断端及邻近尺侧有少量新骨生成,髓腔封闭。术后各时间点X线Lane-Sandhu评分结果示:组内比较,A1组评分均高于A2组,差异均有统计学意义(P值均<0.05);B1组与B2组评分比较,差异均无统计学意义(P值均>0.05)。组间缺损尺寸相同的亚组间比较:A1组、A2组评分分别高于B1组、B2组,差异均有统计学意义(P值均<0.05)。术后12周标本大体观察显示:A1组断端形成骨性桥接,新生骨塑形良好,其余3组断端髓腔封闭,缺损区由纤维组织填充。组织学结果示A1组修复完全,新生骨骨板排列规则;其余3组缺损空腔可见纤维组织填充。结论 兔龄和骨缺损大小对于术后骨缺损愈合情况有重要影响,在构建兔桡骨骨缺损模型的动物实验中,幼龄兔(3月龄)骨缺损长度宜选择20 mm,成年兔(6月龄)宜选择15 mm。

Comparative study on bone defect size in the radial bone defect model of juvenile rabbits and adult rabbits

Objective To establish radial bone defect model on different month-aged rabbits and to explore bone defect size.Methods Forty healthy male New Zealand rabbits aged three months and six months were included in this study. Based on their age, the rabbits were divided into group A (3 months) and group B (6 months). Before surgery, all the forelimbs were randomly divided into 2 sub-groups by digital table method with a total of 20 sides in each group. The bone defect size of group A1 and B1 was 15 mm, and 20 mm for group A2 and B2. At 4-week intervals postoperatively, X-ray was taken, and the healing of the bone defect was quantitatively evaluated with Lane-Sandhu scores. The rabbits were sacrificed 12 weeks postoperatively and the forearms were harvested for gross observation and histological analysis.Results All the rabbits survived after operation of bone defect model. The X-ray images showed that the bone defect of group A1 almost healed 8 weeks postoperatively. Perfectly plastic bone as normal radius was observed in group A1, but none of the rest three groups were completely repaired 12 weeks postoperatively. Small amount of callus was noticed at both ends and the ulnar side of radius with closed marrow cavity Lane-Sandhu score comparison of intra-group showed that the score of group A1 was higher than that of group A2 with significant difference (all P values<0.05). However, there was no significant difference between group B1 and B2 (all P values>0.05). Inter-group comparison of sub-groups with same defect size showed that the scores of group A1 and A2 were higher than those of group B1 and B2 with significant difference (all P values<0.05) at each time point postoperatively. Continuous bridged callus with a smooth surface were observed in the radii in group A1. However, both ends were closed in other groups, and the defect areas were filled with fibrous tissue. Histological analysis showed that the bone defect in group A1 had been repaired completely, regular arrangement of osteone was also observed. However, the fibrous tissue was seen in the defect area in group A2, B1 and B2.Conclusions The rabbits' age and bone defect size had significant effects on healing of bone defects. To establish an appropriate rabbit radial bone defect model, we can choose 20 mm for juvenile(3 months) rabbits and 15 mm for adult(6 months) rabbits.