大鼠股骨髁临界性骨缺损模型制备及临界值

Preparation and Critical Value of Critical Bone Defect Model of Femoral Condyle in Rats

目的:建立不同尺寸的大鼠股骨髁骨缺损模型,并明确大鼠的股骨髁缺损模型的临界值。方法:8周雄性SD大鼠20只,随机数字表法分为4组,每组各5只,分别在建立股骨髁骨缺损模型,缺损直径分别为2,3,3.5,4 mm,深度均为4 mm,每只大鼠均双侧手术,每组共10侧。在术后28天(4周)进行Micro-CT扫描,并进行三维重建进行观察,并采用CT-Hedberg评分来评价骨缺损的愈合情况。结果:术后无动物死亡,缺损直径为4 mm组大鼠有2只共4侧在手术中出现股骨髁骨折;术后4周大体观察示:直径2 mm组缺损处新生组织填充较多,未见明显凹陷;直径3 mm组缺损处可见部分新生组织填充,有较明显凹陷;直径3.5 mm组缺损处少量新生组织填充,可见明显凹陷;直径4 mm组股骨髁缺损处可见骨折,均出现骨折移位或骨折块脱落,关节周围骨赘形成。CT-Hedberg评分显示,术后4周时,直径2 mm组评分显著高于3 mm组(P < 0.05),直径3 mm组评分显著高于直径3.5 mm组(P < 0.05),直径4 mm组评分最低。结论:当股骨髁缺损直径大于3.5 mm时,骨缺损难以自行愈合,而缺损直径在3.5 mm以下时,股骨髁缺损处可自行愈合,因此直径3.5 mm为大鼠股骨髁临界骨缺损值。

Objective: To establish rat models of femoral condylar defect with different sizes and determine the critical value of the model. Methods: Twenty eight-week male SD rats were randomly divided into four groups with five in each group by random number table method. The models of femoral condylar bone defects were respectively established, with the diameter of 2, 3, 3.5, 4 mm and depth of 4 mm. Each rat was operated bilaterally, with a total of 10 sides in each group. Micro-CT scanning and three-dimensional reconstruction were performed 28 days (4 weeks) after operation, and the healing of bone defects was evaluated by CT-Hedberg score. Results: There was no animal death after the operation. In the group with defect diameter of 4 mm, 2 rats (4 sides in total) had femoral condylar fracture during the operation;The gross observation at 4 weeks after operation showed that the defect in the 2 mm diameter group was filled with more new tissue, and no obvious depression was found;In the 3 mm diameter group, part of the defect was filled with new tissue with obvious depression;In the 3.5 mm diameter group, the defect was filled with a small amount of new tissue and obvious depression was visible;Fracture can be seen at the defect of femoral condyle in the 4 mm diameter group, with fracture displacement or fracture block falling off, and osteophyte formation around the joint. The CT-Hedberg score showed that at 4 weeks after operation, the score of the 2 mm diameter group was significantly higher than that of the 3 mm diameter group (P < 0.05), the score of the 3 mm diameter group was significantly higher than that of the 3.5 mm diameter group (P < 0.05), and the score of the 4 mm diameter group was the lowest. Conclusion: When the diameter of the femoral condyle defect is greater than 3.5 mm, the bone defect is difficult to heal itself, while when the diameter of the defect is less than 3.5 mm;the femoral condyle defect can heal itself, so the diameter of 3.5 mm is the critical bone defect value of the rat femoral condyle.