激素性股骨头坏死的细胞学变化

Cytological changes of femoral head necrosis induced by glucocorticoid

目的:观察长期大剂量使用糖皮质激素后兔股骨头组织细胞超微结构的变化,以及激素性股骨头缺血坏死的原因。方法:实验于2002-03/2003-06在西安交通大学第二医院骨病研究所完成。健康雄性日本白兔18只,随机分为两组,实验组为12只,皮下注射醋酸氢化泼尼松8mg/kg,1次/周。对照组6只,皮下注射生理盐水0.32mL/kg,1次/。取股骨头组织苏木精-伊红染色,苏丹Ⅲ染色,周光镜下计量空缺骨陷窝数和脂肪分布。用透射电子显微镜观察股骨头各系细胞超微结构的改变。结果:实验纳入兔18只,实验过程中,实验组死亡2只,进入结果分析16只。①光镜下两组兔股骨头空缺骨陷窝量的改变:实验组第4,8,12周股骨头软骨下区的皮质下骨小梁内空缺骨陷窝较对照组增多犤21.0±2.6)%比(12.0±1.8)%,(24.0±1.8)%比(12.0±1.3)%,(36.0±1.5)%(比(13.0±2.1)%,P<0.01犦8周和12周即可见到小片块状缺失骨;第细胞的区域。②光镜下两组之间股骨头脂肪细胞的改变:实验第8,12周实验组兔股骨头内脂肪细胞明显增大,骨陷窝内有被苏丹Ⅲ染成桔黄色的脂肪沉积,两组间均未见有脂肪栓子。两组间股骨头脂肪细胞大小变化统计学上有显著性意义。③电子显微镜观察两组股骨头超微结构变化:股骨头各系细胞早期(轻者)胞浆和胞核内出现脂质堆积,晚期成骨细胞核膜碎裂染色质溶解,血管内皮细胞胞浆肿胀出现脂滴,毛细血管壁肿胀,质膜结构不完整,可见到明显的裂隙。脂肪细胞核内可见脂滴。小静脉常被异常肥大的脂肪细胞压迫,使管腔骤然变窄。结论:长期大剂量使用糖皮质激素可导致股骨头各系细胞慢性缺血缺氧引起脂肪变性,晚期发生细胞坏死。

AIM： To observe the cellular uhrastructural changes of in rabbits＇ femoral head tissue ＇after long-term glucocorticoid treatment of large dosage, and investigate the reasons for the femoral head necrosis induced by glucocorticoid. METHODS： The experiment was carried out in the Orthopaedic Institute, the Second Hospital of Xi＇an Jiaotong University between March 2002 and June 2003. Eighteen healthy male Japanese rabbits were randomly divided into experimental group （n=12） and control group （n =6）. In the experimental group, the rabbits were treated with subcutaneous injection of methylprednisolone acetate （8 mg/kg）, once a week. In the control group, the rabbits were given subcutaneous injection of saline （0.32 mL/kg） once a week. The femoral head tissues were taken as treated with hematoxylin and eosin （HE） staining and Sudan Ⅲ staining, and the number of defect osteocyte lacunae and fat distribution were calculated under light microscope. The cellular ultrastructure changes of the femoral head were observed under transmission electron microscope. RESULTS： Two rabbits in the experimental group died during the experiment, and finally 16 rabbits were involved in the analysis of results. ①The changes of the number of defect osteocyte lacunae in rabbits＇ femoral head under light microscope in both groups： The numbers of defect osteocyte lacunae in subcortical bone trabecula of the femoral head subcartilage at 4, 8 and 12 weeks in the experimental group were more than those in the control group [（21.0±2.6）% vs （12.0±1.8）%; （24.0±1.8）% vs （12.0±1.3）%; （36.0±1.5）% vs （13.0±2.1）%, P 〈 0.01], and small pieces of block-like deletion osteocytes could be observed at 8 and 12 weeks. ② Changes of lipocyte in femoral head under light microscope in both groups： At 8 and 12 weeks, the lipocytes in rabbits＇ femoral head in the experimental group were obviously enlarged, and there were Sudan Ⅲ stained orange fatty deposition in the osteocyte lacunae, but fat embolus could not be observed in both groups. The change of lipocytes size in femoral head had significant difference between the two groups. ③Ultrastructural changes of femoral head under electron microscope in both groups： Liposome was found in the cytoplasm and nuclei of all kinds of cells in femoral head at early period, and pyknosis, karyolysis and karyorrhexis were observed in the osteoblasts at late period. There was also lipid droplet in vascular endothelial cells, the wall of blood capillary swelled, the structure of plasma membrane was not complete, and obvious crevice could be observed. Lipid droplet could be seen in the nuclear of adipocyte. Venules were often compressed by abnormal hypertrophic adipocytes, which made the venous canal become narrow. CONCLUSION： The long-term glueocortieoid treatment of large dosage can result in the chronic isehemia and hypoxia of cells in femoral head and lead to fatty degeneration, and necrosis occurs at late period.