激素诱发兔股骨头坏死发生过程中组织学和影像学动态对比研究

The experimental dynamic study of the relationship between histopathologic and radiologic changes in steroid-induced femoral head osteonecrosis of rabbits

目的研究兔激素性股骨头缺血坏死发生、发展过程中组织学改变和影像学表现之间的关系,探讨股骨头缺血坏死早期最佳诊断方法及治疗。方法健康成年日本大白兔46只,随机分为实验组30只,肌肉注射甲强龙(20 mg/kg,单次),对照组16只肌肉注射相同剂量生理盐水。分别于注射后2、4、8、12周行X线、CT、MRI、股骨头血管动脉造影,以及处死动物前股骨头血管墨汁灌注后进行组织学检查、常规HE染色以及微血栓染色。结果组织学:实验组2周时出现骨髓细胞碎片集聚,骨小梁出现空骨陷窝骨髓造血组织消失,大量脂肪细胞堆积,墨汁灌注,血管数量减少;4～12周时骨髓内脂肪细胞增大,骨小梁开始萎缩、变细,骨细胞核边聚、固缩,空骨陷窝数增多,骨髓造血组织几乎完全消失,被脂肪组织、脂肪细胞替代填充,墨汁灌注血管消失。影像学:2～12周X线、CT均未见异常,MRI在应用激素2周双侧股骨头T1WI显示信号强度明显降低,低信号区呈线样,T2WI和准T2WI呈不均匀高信号,高信号区呈线样,并延续至12周。动脉介入造影2周后即出现股骨头血管管腔变细,4及8周时血管数量减少、尚存在的血管变得纤细。对照组均未见明显异常。结论股骨头缺血坏死发生发展过程中组织学变化和MRI表现密切相关,MRI是早期检查发现、诊断股骨头缺血坏死最具灵敏度、特异性的非侵入性检查方法。

Objective To explore the relationship between the histologic results and radiographic demonstrations in steroid-induced osteonecrosis of rabbit femoral head.Methods Totally 46 adult Japanese white rabbits were randomly divided into two groups and injected once intramuscularly with 20mg/kg of methylprednisolone acetate and saline into the gluteus medius muscle respectively.Histopathologic examination and radiographic examination including X-ray,CT, MRI,and angiography were taken at the time of 2,4,8,and 12 weeks.Results Histopathological findings:osteonecrosis lesions demonstrated an accumulation of bone marrow cell debris,presence bone empty lacunae in the trabeculae at 2 weeks after steroid injection.At the time of 4,8,and 12 weeks,the necrosis areas were larger and bone marrow fat cell were proliferated and hypertrophied,and the numbers of bone empty lacunae increased.Radiographic examination demonstrated that plain radiography and CT had no significantly abnormal findings from week 0 to week 12.MRI showed low spot signal on T1 weight and high signal on T2 weight from week 2 to week 12.Angiography demonstrated the diameter of the circumflex femoral arteries decreased and scaricity.At weeks 4,8,and 12,some of the circumflex arteries disappeared. Conclusions The histopathological findings of steroid-induced temoral head osteonecrosis are closely correlated with the MRI demonstrations from week 2 to week 12.MRI examination is highly sensitive and specific for diagnosing the early osteonecrosis.