低强度脉冲超声治疗骨质疏松性骨折的实验研究

Experimental treatment of osteoporotic fracture in rats by low-intensity pulsed ultrasound

目的 通过实验研究评价低强度脉冲超声 (Low intensityPulsedUltrasound ,LIPUS)对大鼠骨质疏松性骨折的治疗作用。方法 实验用 4 5月龄的雌性SD大鼠 2 6只 ,2 0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 ,最后有 9只进入治疗实验。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治疗 ,每天 2 0min ,超声波频率为 1 5MHz,脉宽 2 0 0 μS ,重复频率 1KHz,强度为 5 0mW/cm2 ;另一侧作对照。治疗 6周后处死大鼠 ,取双侧股骨分别行组织学观察、X线摄片 ,并采用 3点弯曲试验比较两侧骨痂的力学性能。结果 实验侧LIPUS治疗 6周后与对照侧比较骨折愈合进程加快 ,软骨性骨痂向骨性骨痂的转化更明显 ,更多的原始骨小梁进入改建期。两者的最大载荷、最大应力和弹性模量分别为 93. 79± 12 . 4 4和 5 3. 13± 11. 6 9(P <0. 0 1) ,32 . 5 7±11 .30和 19. 5 7± 4 . 2 0 (P <0 . 0 5 ) ,5 77 .78± 176. 5 4和 35. 8 77± 14 4 . 2 4 ;实验侧分别比对照侧高76 . 5 3%、6 6 . 4 3%和 6 1. 0 4 %。结论 低强度脉冲超声治疗能明显促进大鼠骨质疏松性骨折的愈合过程 ,改善骨痂的力学特性 ,为临床上治疗骨质疏松性骨折提供新的思路和方法。

Objective To evaluate the therapeutic effect of low-intensity pulsed ultrasound(LIPUS) on osteoporotic fracture in rats. Methods Twenty-six female 4.5-month-old SD rats were involved in the study,20 of which underwent bilateral ovariectomy. Ten weeks later when the osteoporosis was confirmed, the 20 rats had their bilateral femoral shaft closely fractured. After selection only 9 rats finally entered the experiment. The day after fracture a hind limb was chosen to receive LIPUS as treatment and the other one was taken as control. The LIPUS was done 20 minutes daily with a 200 μS, burst of 1.5 MHz sine waves repeated at 1 KHz and an average intensity of 50 mW/cm^2. Six weeks after treatment, the rats were sacrificed and their bilateral femurs taken for histological study, radiography and biomechanical analysis by three point bending test. Results The LIPUS treated femurs showed more rapid bone healing, accelerated endochondral bone formation and more bone remodeling than the control. The three-point bending test revealed that, the peak load, maxinam stress and elastic load were 93.79±12.44 versus 53.13±11.69(P<0.01), 32.57±11.30 versus 19.57±4.20(P<0.05), and 577.78±176.54 versus 358.77±144.24, respectively, with the values in the experimented sides being 76.53%,66.43%, and 61.04% higher than those in the control sides, respectively. Conclusions LIPUS accelerates the healing of osteoporotic fracture in rats, and improves the mechanical strength of the callus, thus providing a new way to treat osteoporotic fractures clinically.