计算机辅助下低温手术建立三足犬股骨头坏死模型的初步报告

目的建立能模拟人股骨头坏死（osteoneerosis of femoral head，ONFH）病理生理过程的实验动物模型，旨在实验动物水平评价其治疗价值。方法在计算机辅助设计下，采用FLUENT6．2软件对探针置入股骨头后内部温度场分布进行三维有限元分析，设计出可最大化ONFH面积，最小化周围组织损伤的低温手术过程，即在0．5MPa加压液氮下，冷冻6．5min，复温5min至2℃，再次冷冻6．5min。采用上海交通大学生命学院等自主研发的液氮低温冷冻系统，按模拟得到的最佳手术方案建立10只三足犬ONFH动物模型，同时2只假冷冻组作为对照组，通过影像学和病理组织学观察，以确认模型的合理性。结果模拟结果与实验中测股骨头边界的降温曲线基本吻合。于1周后病理组织学观察，实验组股骨头髓腔内有核细胞死亡，局部血管破裂。对照组未见异常改变。实验组余9只继续观察，其中超过3个月的5只X线片和MRI均显示股骨头轻度变形，囊性变，股骨头内部密度不均，呈典型的Ficat Ⅲ期改变，其余4只动物仍在继续观察中。对照组无异常改变。结论应用计算机辅助下的低温手术可建立进展至股骨头塌陷的三足犬ONFH模型。

PRELIMINARY STUDY ON CRYOSURGERY FOR OSTEONECROSIS OF FEMORAL HEAD IN THREE-FOOT CANINE MODEL

OBJECTIVE: To establish a animal model of osteonecrosis of femoral head in canine like human. METHODS: The thermal field of canine's femoral head was three-dimensionally analyzed with fluent 6.2 software so that the best cryosurgery patent could be designed to maximize the osteonecrosis and minimize extra surgery trauma with the cryosurgery system invented by Shanghai Jiaotong University. Liquid nitrogen was pressurized to 0.5 MPa, poured into femoral head for 6.5 minutes, rewarming to 2 degrees C for 5 minutes and then repoured into it again for another 6.5 minutes. Ten three-foot canines were conducted as the animal models of osteonecrosis of femoral head according to the method above. At the end of follow-up, the results were reviewed by radiologic and pathologic check. Two dogs were conducted as control group. RESULTS: In the experimental group, one of the ten canines was testified to occur osteonecrosis of femoral head after one week pathologically, cell death and vessel breakage of cavitas medullaris in the femoral head was obvious under microscope; in other nine canines being still under follow-up, five with three-month follow-up at least progressed to the collapse of femoral head like human (Ficat III). In control group, no osteonecrosis was found. CONCLUSION: Cryosurgery for osteonecrosis of the femoral head in three-foot canine model may become a method to establish the animal model of osteonecrosis of femoral head like human.