低强度脉冲超声促进卵巢切除大鼠骨折愈合的超微结构研究

Ultrastructure observation of fracture healing in ovariectomized rats treated by Low-intensity Pulsed Ultrasound

目的观察卵巢切除大鼠骨折愈合过程中细胞超微结构的变化,探讨低强度脉冲超声(Low-intensity Pulsed Ultrasound,LIPUS)促进其愈合过程的作用机理。方法60只4.5月龄的雌性SD大鼠,其中48只去势后10周证实已发生骨质疏松,建立双侧股骨中段骨折模型,按标准筛选,共34只接受治疗。造模后第2日起采用自制低强度脉冲超声仪随机对一侧后肢进行连续治疗,每天20min,超声波频率为1.5MHz,脉宽200S,重复频率1KHz,强度为50mW·cm-2;另一侧做对照。分别在骨折后第4天和第1、2、4、6、8周各处死5只大鼠,透射电镜下观察骨痂内细胞超微结构的变化。结果与对照侧相比,治疗侧软骨细胞分化增殖明显,细胞功能活跃;成骨细胞数量增多,细胞合成功能旺盛,胶原纤维致密,矿化明显;破骨细胞极化现象多见。结论LIPUS作用于卵巢切除大鼠骨折愈合过程,促进了软骨细胞的分化成熟,刺激了成骨细胞的合成分泌以及破骨细胞的分化成熟,改善了骨折愈合的质量。

Objective To observe the characteristics and alteration of cellular ultrastructure in fracture healing of ovariectomized rats treated by low-intensity pulsed ultrasound （LIPUS）. Methods 60 female 4.5-month-old SD rats were involved in the study initially, ten weeks after bilateral ovariectomy, 48 were confirmed with osteoporosis and suffered intramedullary nailing and subsequently closed fracture on bilateral femoral shaft. After serious selection only 34 rats finally entered the experiment. From first day after fracture one hind limb was chosen to receive LIPUS as treatment while the other one was taken inactive treatment as control. The LIPUS was done 20 minutes daily with a 200μS, burst of 1.5MHz sine waves repeated at 1KHz and an average intensity of 50mW · cm^-2. At 4 days, 1, 2,4, 6 and 8 weeks after fracture respectively, 5 rats were sacrificed and their bilateral callus were taken for cellular ultrastructure observation by transmission electron microscopy（TEM）. Results Compared with control side, There was more obvious on differentiation and proliferation in chondrocyte, and more active on collagen secretion and mineralization in osteoblast, more osteoclasts were showed in maturation. Conclusion As the treatment on fracture healing in ovariectomized rats, LIPUS can stimulate the proliferation and secretion of both chondrocyte and osteoblast, and the maturation ofosteoclast, finally improve the healing quality of callus.