卵巢切除对大鼠皮质骨结构和力学性能的影响

目的：研究卵巢切除大鼠皮质骨的几何学改变和力学性能改变，探讨雌激素缺乏时皮质骨改变的发生机理。方法：选雌性SD大鼠56只，分为Sham组和OVX组，动物分别在4、12、20和28周时处死7只，取其胫骨备用。左侧于近3/5和远2/5交界部切断，在电镜下摄片，计测截面总面积、皮质骨面积、骨外径周长、骨髓腔面积和骨内径周长。右侧以近3/5与远2/5交界点为加载点进行三点弯曲力学实验。结果：Sham组术后4周至28周胫骨截面总面积和骨外径周长逐渐增加。（P＜0.005)，而髓腔面积和内径周长变化不明显。OVX组截面总面积和外径周长也有逐渐增加趋势。但差异无显性。而内径周长和髓腔面积都明显增加，在相同时期显大于Sham组（P＜0.005)，而皮质骨面积却与Sham组差异无显性。三点弯曲试验结果表明，从4-28周实验对照两组抗弯强度和刚度均逐渐增加，但两组间差异无显性。在各时期骨组织材料力学性能也无显性差异。结论：卵巢切除对皮质骨的影响主要表现在使骨髓控扩大，对骨外膜的影响较小，在短期内皮质骨的力学性能无明显影响。

Effect of ovariectomy onstructure and mechanical properties o f cortical bone in rat

Objective With the aim of studying the changes in geometry,morphology and mechanical properties of cortical bone in ovariectomized rats,the authors tried to find out the mechanism of changes in cortical bone due to estrogenic hormone deficiency. Methods Fifty|six female SD rats,three months old,weighing 240 g,were randomly divided into sham|operated group(sham),and ovariectomined group(OVX).Seven rats each time were killed at the end of the 4 th,12 th,20 th and 28 th week,and tibias were taken out for experiment.The left tibia was excised at the junction of proximal 3/5 and distal 2/5,and was photographed under electron microscope.The total tissue area,cortical area,periosteal perimeter,area of marrow cavity and perimeter of endosteum were measured.For the right tibia,the continuous loading point was chosen at proximal 3/5 and distal 2/5 as place to make three|point bending tests. Results In the sham group,the total tissue area and periosteal perimeter gradually increased from 4 th to 28 th week while there was no distinct change in the area of marrow cavity and perimeter of endosteum.In OVX group the total tissue area and periosteal perimeter also showed a tendency to increase,but there was no significant difference between the two groups.The perimeter of endosteum and area of marrow cavity were significantly larger than those in the sham group,but no distinct difference was found in the cortical area of tibia between the two groups at the same stage of experiment.The three|point bending test showed that from 4 th to 28 th week,the structure strain and stiffness of tibia increased gradually in both groups, but there was no significant difference between the two groups.Neither was in the mechanical properties of tibial cortical bone between the two groups at every stage of experiment. Conclusion The effect of ovariectomy on corticat bone mainly consists of expanded area of marrow cavity while periosteum was little affected and no remarkable change in mechanical properties ensues.;