中小功率微波照射对钛合金植入物周围组织的热损伤观察

摘要

Objective To observe the influence of low or middle power microwave radiation on tissues adja-cent to titanium alloy implants. Methods Titanium alloy internal fixation plates were implanted into the upper femur of the right side of New Zealand white rabbits, the left femurs served as the control. Then the femurs were exposed to 20, 40, 60, or 80 W of microwave radiation at a frequency of 2450 MHz for 30 minutes, and real-time temperature of the implants and its adjacent muscles were recorded. The nerve conduction study of the sciatic nerve was performed by stimulating the nerve and recording from gastrocnemius in both groups. Finally, all the rabbits were sacrificed and histo-logical studies were performed on nerve and muscle sections. Results Compared to the control limbs, temperatures of limbs with titanium alloy implants increased significantly when exposed to microwave radiation at 60 and 80 W ( P<0.05) but no significant differences were revealed when exposed to radiation at 20 and 40 W ( P<0.05) . For the sciatic nerve conduction, significantly prolonged distal latency of CMAP ( P<0.05) and slower nerve conduction velocity ( P<0.05) were observed in the experimental limbs when exposed to microwave radiation at 60 and 80 W, but the decrease of CMAP amplitude was not significant (P>0.05). Pathological examination showed obvious congestion and bleeding in the intercellular spaces of skeletal muscle cells in the experiment group when exposed to radiation at 60 W, with no ob-vious pathological changes found in the sciatic nerve. However, when exposed to radiation at 80 W, vacuoles appeared in myocytes, the cellular structure was destroyed and the myelin sheath of the sciatic nerve swelled. Conclusion Ex-posure to microwave irradiation at 20 and 40 W, but not 60 and 80 W exerts no adverse effects on nerves and muscles adjacent to titanium alloy internal fixation plates. Consequently, continuous wave microwave irradiation at low powers (20~40 W) is a safer auxiliary treatment for limbs with titanium alloy implants.%目的：观察中、小功率单次微波照射对钛合金植入物周围组织的热损伤作用。方法通过手术将钛合金内固定物植入兔右侧股骨上段，并将该侧作为实验侧，左侧下肢相同部位作为对照侧。根据微波照射功率将实验兔分为4组，分别是20 W组、40 W组、60 W组及80 W组。各组实验兔经麻醉后分别给予相应功率微波照射(微波频率均为2450 MHz，持续照射30 min)，实时测量微波照射区域钛合金表面及毗邻肌组织温度变化；随后采用肌电图检测各组实验兔坐骨神经复合肌肉动作电位( CMAP )情况；最后处死动物，取股骨旁钛合金周围肌组织、神经组织进行病理学检查。结果与对照侧骨骼肌比较，经20 W、40 W微波照射后实验侧骨骼肌温度升高不显著( P>0.05)，经60 W、80 W微波照射后实验侧骨骼肌温度升高显著( P<0.05)。坐骨神经电生理检查结果显示，经60 W、80 W微波照射后，实验侧坐骨神经CMAP潜伏期明显延长( P<0.05)，神经传导速度显著变慢( P<0.05)，但波幅均无明显下降( P>0.05)。病理学检查结果显示，经60 W微波照射后，实验侧骨骼肌细胞间隙明显充血、出血，坐骨神经无明显病理学改变；经80 W微波照射后肌细胞出现空泡，肌细胞结构遭到破坏，坐骨神经髓鞘肿胀。结论60~80 W微波(频率为2450 MHz)连续照射30 min可引起钛合金植入物周围组织热损伤，20~40 W微波连续照射30 min，钛合金植入物周围组织未见明显热损伤，提示对钛合金植入部位进行小功率微波照射安全性相对较好。