液氮冷冻法制备兔股骨头坏死模型新方法及效果评估

A new method of building rabbit femoral head necrosis model by liquid nitrogen freezing and the evalu-ation of the effect

目的通过改良的手术路径,应用液氮冷冻法制备兔股骨头坏死模型,建立模拟人股骨头坏死病理变化的实验动物模型,为股骨头坏死的基础研究提供动物模型。方法选取10只健康雌性新西兰大白兔,月龄(3.0±0.2),体重(3.2±0.4)Kg,选取左侧股骨头为实验组,右侧股骨头为空白对照。使用股骨头坏死髓芯减压手术路径,沿股骨颈方向钻入2.0 mm克氏针,将液氮冷冻仪探针插入孔道进入股骨头区域,对股骨头进行冷冻—复温2个循环,冷冻、复温时间均为半分钟,缝合切口后放回原笼位。于术后4周处死实验动物,取出股骨头观察股骨头大体变化,并即刻行股骨头X线等影像学检查,最后行病理切片检查。结果所有实验动物术后均无死亡。通过对实验兔双侧股骨头大体形态观察,实验组股骨头软骨下骨颜色变深,呈暗红色,负重区有小片状坏死灶。X线结果示实验组与对照组相比,股骨头无明显的骨质密度改变。micro-CT示实验组股骨头软骨下骨小梁稀疏、紊乱,出现多处骨小梁连续性中断。MRI示实验组股骨头表现为以高信号为主的片状的高、低混合信号区。病理组织切片结果可以发现软骨变薄、细胞排列紊乱,骨小梁变细、排列紊乱,脂肪细胞融合,空骨陷窝形成等。10只实验兔的左侧股骨头均出现早期坏死的表现,成功率100%。结论本实验通过新的手术路径用液氮冷冻法成功制备了兔股骨头坏死的模型,手术创伤小,无需切开关节囊和脱位股骨头,操作简单,可作为兔股骨头坏死造模的新方法。

Objectives The aims of the this study were establishment of rabbit's ONFH models by liquid nitrogen freezing method that can simulate human's pathological changes.Methods Ten healthy New Zealand female rabbits were used in this study,month-age(3.0±0.2),weight(3.2±0.4)Kg.We selected the left side to be the operated side and considered the right side as the control.The rabbits were anesthetized by ear marginal intravenous injection,then be fixed on the fixation shelf.The skin incision was made on the lateral of left hip joint.And then we chose the appropriate bone landmark as the point for starting drill.Then the hole was drilled toward the femoral head with a appropriate femoral neck anteversion and abduction angle with a 2.0 mm kirschner wire.The femoral head were frozen by liquid nitrogen freezing equipment,followed by re-warming with warm saline two cycle.Ten rabbits were sacrificed post-operation for the fourth week to ob-serve the shape and color of femoral head.Then X-ray,micro-CT,MRI and histopathological sections were performed to test the results.Results All the rabbits survived post-operation.The color of left femoral head gets dark,and we also found sheet necrosis area under the articular cartilage in the weight-bearing area.X ray showed there is no apparent change in bone mineral density.Micro-CT showed thin disorganized trabecu-lar bone.MRI showed mixed-signal of hyperintense signal and hypointense signal in operated femoral head.Histopathological examination showed obvious evidences of ONFH,including empty lacunae,integrated fat cells,disorganized trabecular bone and so on.All the left femoral heads appeared early stage osteonecrosis.Conclusions We have prepared rabbit ONFH model successfully by the new method with smaller trauma and more simply operation that don’t need capsulotomy and dislocating the femoral head,which could be a new standard method of preparing the rabbit femoral head necrosis model.