液氮冷冻兔股骨头坏死模型制备新方法及可靠性评价

目的 建立一种可靠的并可用于治疗和研究新的液氮冷冻法制成的兔股骨头坏死动物模型。方法 采用成年新西兰大白兔21只，无菌条件下手术分离臀肌，切断股骨头圆韧带，显露股骨头。用医用棉签蘸取液氮，对股骨头进行3次冷冻3次复温，制备兔双侧股骨头坏死模型。于术后3、7d及2、4、6、8周进行X线摄片，股骨头大体形态和组织病理学观察。结果 X线摄片结果显示，制模2周时股骨头密度增高；4周时出现密度不均影像；6周时外形出现不规则变化，边缘有透亮区；8周时开始塌陷，关节间隙增大，骺板模糊。股骨头大体形态随时间推移，其受损程度呈加重演变特点。制模3 d的股骨头组织切片可见软骨细胞和骨细胞坏死；2周见骨小梁断裂、排列紊乱；4周见髓腔脂肪细胞坏死，内有新生血管及增生纤维组织；6周时出现匍行附着；而8周可见新骨沉积性生长，骺板处细胞挤压、变形。结论 本实验中建立的液氮冷冻股骨头坏死模型新方法具有创伤性小、贴近人股骨头坏死病理演变规律的优点，为干细胞移植等治疗和研究提供了一种新的模型制备方法。

Novel liquid nitrogen freezing method for establishing a rabbit model of femoral head osteonecrosis and its reliability evaluation

Objective To establish a reliable and therapeutic available rabbit model of osteonecrosis of the femoral head（ONFH）using a novel liquid nitrogen freezing method. Methods Twenty-one New Zealand white rabbits were recruited in this study.Aseptically, gluteus muscles were bluntly separated, the bilateral round ligaments of the femur were cut off and the femoral heads were exposed. Medical cotton stickers were dipped in liquid nitrogen and then used to frozen the bilateral femoral heads by three times alteration of freezing and rewarming. The femoral heads of the model were examined by gross morphology, X-ray photography, and histopathology at 3 days, 7 days, 2 , 4 , 6 and 8 weeks post-operation, respectively. Results X-ray photography showed that the bone density of femoral heads increased at 2 weeks, and was not uniform at 4 weeks post-refrigeration. After 6 weeks, the femoral heads presented irregular shape and a marginal lucent area.Then collapsed joint surface, widened joint space, and blurred epiphyseal plate were observed at 8 weeks post-refrigeration. Gross morphology manifestly demonstrated an aggravating cartilage and bone injury of femoral heads with time elapsed. Histopathologic results showed that necrosis of chondrocytes and osteocytes occurred at 3 days after freezing,and bone trabeculae of femoral heads were collapsed and disarranged at 2 weeks post-refrigeration. Adipocytes necrosis, angiogenesis, and proliferation of fibrous tissue appeared in bone marrow cavity at 4 weeks. Creeping substitution was visible at 6 weeks. Depository growth of new bone was seen and cells dwelled in epiphyseal plate became crushing and deformation at 8 weeks. Conclusion The novel rabbit model of ONFH by liquid nitrogen freezing method presented here has lower trauma,and approximates to pathological changes of human ONFH, and may be used in ONFH therapeutic related studies including stem c