微波灭活建立兔股骨头坏死模型:最适宜灭活温度和作用时间的筛选

背景:理想的股骨头坏死模型是研究其病因、发病机制及治疗的基础,但到目前为止,仍无一种模型制作方法得到公认.目的:观察不同灭活温度和时间兔股骨头的坏死和修复情况,分析微波灭活建立兔股骨头坏死模型的适宜温度和时间.设计:随机对照动物实验.单位:昆明医学院动物实验中心.材料:实验于2004-09/2005-11在昆明医学院动物实验中心完成.选用健康成年新西兰大白兔48只,雌雄不拘,由昆明医学院动物实验中心提供.实验过程中对动物处置符合动物伦理学标准.微波灭活所用GW-92C型多功能微波治疗仪由格兰德医用设备(天津)有限公司生产.方法:将48只大白兔共96侧股骨头随机分为4组,每组24侧股骨头: 50℃ 10 min微波灭活组,55 ℃ 10 min微波灭活组,50℃ 20 min微波灭活组, 60 ℃ 10 min微波灭活组.应用多功能治疗仪进行微波灭活建立兔股骨头坏死模型,作用温度及时间同分组.主要观察指标:分于术后即刻,1,2,4,8和12周6个时间点进行指标观察,每个时间点2只兔(4侧股骨头).对标本及其周围组织进行大体观察.拍摄骨盆正位片,观察股骨头骨小梁排列、有无囊性变、头塌陷及髋关节破坏等.通过MRI检查,观察股骨头有无坏死及坏死范围.苏木精-伊红染色,光镜下观察股骨头标本坏死及修复情况.结果:50 ℃ 10 min微波灭活组术后1周部分骨髓组织凝固变性,术后8周时坏死骨小梁及骨髓组织完全吸收.55 ℃ 10 min微波灭活组术后1周骨髓组织凝固,术后2周时股骨头出现T1 相信号减低、T2相信号增高区;术后4周时坏死与修复同时进行,术后12周时骨修复停止,骨坏死继续,股骨头开始塌陷.50 ℃ 20 min微波灭活组、60 ℃ 10 min微波灭活组:术后8周所有股骨头塌陷变形.结论:55 ℃作用10 min微波灭活股骨头是制作兔股骨头坏死模型的适宜温度和时间.

Developing a rabbit model of the femoral head osteonecrosis induced by microwave heating: Optimum temperature and time screening

BACKGROUND: An ideal model of osteonecrosis of the femoral head is beneficial to the study on the cause of disease, pathogenesy and treatment. So far there has not been a coherent method to prepare this model. OBJECTIVE: To establish a rabbit model of osteonecrosis of femoral head induced by microwave heating, and to decide optimum microwave temperature and heating time.DESIGN: Randomized controlled animal trial.SETTING: Animal Experimental Center of Kunming Medical College.MATERIALS: The experiment was performed at the Animal Experimental Center of Kunming Medical College between September 2004 and November 2005. Forty-eight healthy adult New Zealand rabbits, either male or female, were provided by the Animal Experimental Center of Kunming Medical College. The animal procedure was accorded with the ethical standards. GW-92C multi-functional microwave therapy apparatus was the product of Grand World Medical Apparatus (Tianjin) Co., Ltd. METHODS: The microwave antenna was inserted into the rabbit femoral head. Ninety-six femoral heads in forty-eight rabbits were randomly divided into four groups (n =24) according to the microwave temperature and heating time: microwave heating at 50 ℃ for 10 minutes group; 55 ℃ for 10 minutes group; 50 ℃ for 20 minutes group and 60 ℃ for 10 minutes group. The models of osteonecrosis of femoral head were induced by microwave heating using multi-functional microwave therapy apparatus according to the temperature and heating time of grouping. MAIN OUTCOME MEASURES: In each group, two rabbits (four femoral heads) were killed immediately, one, two, four, eight and twelve weeks after operation, respectively. A series of examinations were carried out, including gross observation, X-ray to observe bone trabecular arrangement, cystis degeneration, head collapse or hip joint destruction, MRI to observe the necrotic area, and HE staining to observe the osteonecrosis and bone repair. RESULTS: Marrow tissues partially coagulated in the microwave heating at 50 ℃ for 10 minutes group at the end of the 1st week, and the osteonecrosis returned to normality at the end of the 8th week. In 55 ℃ for 10 minutes group, marrow tissues were completely coagulated at the end of the 1st week, and decreased signal on T1 weighted images and increased signal on T2 images were identified at the end of the 2nd week. In the 4th week, bone repair was found simultaneously when osteonecrosis occurred. At the end of the 12th week, the osteonecrosis continued and the repair stopped, and the femoral head collapse occurred. All femoral heads collapsed at the end of the 8th week in 50 ℃ for 20 minutes group and 60 ℃ for 10 minutes group. CONCLUSION: Microwave heating at 55 ℃ for 10 minutes is the optimal choice to develop a rabbit model of osteonecrosis of the femoral head.