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改变的发生机制。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交界点对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，但差异无显著性，而内径周长和髓腔面积都明显增加，在相同时期显著大于Sham组（P＜0．005），而皮质骨面积却与Sham组差异无显著性，三点弯曲试验结果表明从4－28周实验对照两组抗弈强度和刚度均逐渐增加，但两组间差异无显著性，在各时期骨组织材料力学性能也无显著性差异。结论：卵巢切除对皮质骨的影响主要表现在使骨髓腔扩大，对骨外膜的影响较小，在短期内对皮质骨的力学性能无明显影响。

The effect of ovariectomy on the structure and mechanical properties of cortical bone in rats

Objective To study the changes in geometry morphology and mechanical properties of cortical bone in ovariectomized rats,to find out the mechanism of changes on cortical bone in estrogenic hormones deficiency.Methods Fifty six female SD rats of three months, 240g, were randomly divided into sham-operated group (sham), and ovary resected group(OVX). Seven rats were killed respectively at the end of the 4th, 12th, 20th and 28th week and tibias were taken out for experiment. The left tibia was cut off at proximial 3/5 and distal 2/5, taken a photograph under electric microscope, and then the following were detected: the total tissue area, cortical area, periosteal perimeter, area of marrow cavity and perimeter of endosteal. For the right one, 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 4th to 28th week while there was no distinct change in the area of marrow cavity and perimeter of endosteal. In OVX group the total tissue and periosteal perimeter also showed tendency to increase,but the two groups were not different significantly. The perimeter of endosteal and area of marrow of tibia were significantly higher than that in 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 bend test showed: from 4th to 28th week, the structure strain and stiffness of tibia increased gradually in both group, but there was no significant difference between the two groups.Neither was the material properties of cortical bone in tibia between the two groups at every stage of experiment. Conclusion The effects of ovariectomized cortical bone show that area of marrow is expanded, aventitia is little influenced and the mechanical properties do not change greatly in short time after ovariectomized.