实验性骨质疏松性骨折愈合中的骨密度及组织学观察

目的：观察骨质疏松性骨折愈合过程中骨折端骨密度及组织学变化特征,阐明骨质疏松性骨折愈合的特点。方法：60只3月龄,雌性SD大鼠,手术建立骨质疏松性骨折模型组和一般骨折模型组各30只。于骨折模型建立后2、6、12周截取股骨,用双能X线吸收法作骨折端骨密度测定。并同时对骨折端骨痂组织作光镜观察。结果：（1）骨折端骨密度：骨折后2周,两组动物骨折端的骨密度差异不明显（P＞0．05）;而在骨折后6周及12周,骨质疏松性骨折组的骨密度较一般骨折组明显低（P＜0．05,P＜0．01）。（2）光镜观察：术后2周,骨质疏松性骨折组骨折端结缔组织数量多,小梁骨较细小;术后6周,一般骨折组骨折端软骨痂为编织骨取代,而骨质疏松性骨折组骨折端则仍有透明样软骨存在,其软骨痂向骨性骨痂转化缓慢;术后12周,骨质疏性松骨折组原始小梁状骨向成熟小梁状骨转化亦较慢,且原已形成的成熟小梁状骨多吸收、消失。结论：（1）骨质疏松不仅使全身骨密度减少,也使骨折愈合中骨折端的骨密度升高减慢。（2）骨质疏松性骨折愈合质量降低是骨折端骨密度值低的重要原因。

Bone mineral density and histological changes during the healing of experimental osteoporotic fractures

Objective To observe the bone mineral density BMD and histological changes during osteoporotic fracture healing,to highlight the characteristic of healing.Methods 60 female 3 month old SD rats were randomized into two groups of 30 each:the osteoporotic fracutures model and the common fracture model.The fracture site bone was cut out in 2,6 and 12 weeks postoperatively and scanned on Lunar's DPX L's dual X ray absorptiometry.The callus of each rat was examined by light microscope postoperatively at the same time.Results Bone density at fracture site:There was no clear difference of BMD at the fracture site 2 weeks after fracture( P >0 05).However there was a clear difference in 6 weeks( P <0 05)and 12 weeks( P <0 01)after fracture,the BMD of osteoporotic fracture model was lower than common fracture model.Histological results:The callus in the osteoporotic fracture model appeared to have more undifferentiated mesenchymal tissue and thinner trabecular bone 2 weeks postoperatively.By 6 weeks,callus in the common fracture model was composed of mature lamellar bone,although in the osteoporotic fracture model hyaline cartilage persisted,suggesting a delay in differentiation.By 12 weeks,original trabecular bone changed slowly into mature trabecular bone,part of which had already been absorbed and disappeared.Conclusion (1)Osteoporosis did not only cause a decrease in total body decreased BMD but also significantly attenuated the increase in BMD at fracture site after fracture.(2)Poor quality of healing was the main reason of low BMD at fractures site in the rat osteoporotic fracture model. [