微波高温处理的人皮质骨生物力学性质的研究

BIOMECHANICS OF HUMAN CORTICAL BONE TREATED BY MICROWAVE INDUCED HYPERTHERMIA

目的 :明确微波高温处理的人皮质骨生物力学性质的变化 ,为预防微波介入式高温治疗的骨肿瘤患者病理骨折提供理论依据。方法 :微波高温加热人皮质骨 ,制备力学试样。进行静态拉伸、静态压缩试验。测定强度极限、断裂功 ,延伸率。结果 :微波高温处理 80℃ ,持续 30min ,皮质骨密度下降 5 .5 1%。在加载应变率为 0 .8～1.6× 10 -4s-1条件下 ,进行静力学试验。微波高温处理人皮质骨静拉伸强度无明显下降 ,压缩强度比正常皮质骨提高约 2 3%。显微硬度比正常湿润皮质骨提高 4 6 %。延伸率下降 4 3.2 % ,断裂功下降。结论 :微波高温损害了皮质骨的韧塑性 ,使骨组织脆性增加 ,易突发断裂。

Objective: The aim of the study is to clarify the changes of biomechanical properties of human cortical bone treated by microwave induced hyperthermia, and to seek the biomechanical factors of the pathological fractures of tumourous bone heated by the hyperthermia. Methods: The human cortical bone was heated by a bone tumor microwave therapy instrument with 2450MHz and 800 watt output. The duration of heating was 30 minutes and the surface temperature of the bone was controlled at 80°C. The mechanical testing of cortical bone specimen was then proceded according to mechanical standards. The microhardness measurement, static tensile test and compressive test were performed. The strain rat of both tests were 0.8-1.6 × 10-4 s-1. Results: The microhardness of bone treated by hyperthermia increased by 23%. The tensile stretching rate decreased by 43.2%, and tensile strength reduced slightly. The compressive strength of bone treated by microwave-intervening hyperthermia increased by 23%. The fracture work of bone reduced greatly in compressive and tension tests. Conclusion: The hyperthermia induced by microwave worsens the flexible capacity of cortical bone and thus makes the bone fragile.