低强度脉冲超声对新生骨成熟过程的影响

目的:探讨低强度脉冲超声对兔四肢骨延长模型新生骨成熟过程的影响。方法:60只成年新西兰兔随机分为低强度超声治疗组和空白对照组,所有动物行胫骨中段截骨并以Orthofix M103型迷你外固定架延长器固定,术后7 d后以0.5 mm/12 h延长10 d,超声治疗组在骨延长完成后以超声骨折治疗仪治疗4周,对照组不予治疗。分别于骨延长完成后4周、8周、12周处死治疗组及对照组实验动物,并收集新生骨标本。在骨延长后12周摄X光片,用ImageJ图像分析软件进行影像学分析,比较骨痂生长情况。用双能X线吸收测量法(dual energy X-ray absorptiometry, DEXA)测量兔胫骨中段骨密度。取8周组、12周组双侧兔胫骨标本做扭转生物力学测试。结果:以图像分析软件测量X线片上的12周组新生骨灰度值,发现12周治疗组的灰度值明显高于对照组(P<0.05)。DEXA测量显示8周和12周治疗组新生骨的骨密度大于对照组(P<0.05)。生物力学测试中,8周和12周治疗组的最大扭力、极限扭转强度、破裂能各指标均优于对照组(P<0.05)。结论:低强度超声可作为一种生物物理刺激促使兔胫骨骨折部位成骨。

Effect of low-intensity pulsed ultrasound stimulation on maturation of regenerate bone

Objective To explore the effect of low intensity pulsed ultrasound stimulation (LI-PUS) on the maturation of regenerate bone in a rabbit limb lengthening model. Methods Sixty skeletal mature female New Zealand white rabbits were randomly divided into an LIPUS treatment group and a control group. All rabbits were underwent mid-diaphyseal tibial osteotomy and immobilized in an Orthofix M103 Mini lengther. Gradual distraction at 0. 5 mm every 12 h for 10 d was performed at day 7 postoperatively. A 4-week course of LIPUS treatment group was applied over the distraction site for 20 min daily starting immediately after the completion of the distraction only for the treatment group. Rabbits were euthanized and the mid-diaphyseal tibia was harvested for evaluation at 4, 8, and 12 wk after the completion of the bone lengthening protocol. Radiographic analysis was performed to study the formation of bone callus using the ImageJ software at 12 wk after the completion of the bone lengthening protocol. Bone mineral density (BMD) of regenerate bone was measured by Dual energy X-ray absorptiometry (DEXA) . Torsional testing to failure was performed on the tibia specimens at 8 and 12 wk after the completion of the bone lengthening protocol. Results Radio-graphic measurement showed higher relative gray scale of bone callus in the LIPUS group than that in the control group at 12 wk (P ＜ 0. 05) . BMD in the LIPUS group was significantly higher than that in control group at 8 and 12 wk (P ＜ 0. 05). Biomechanical testing showed that the ultimate torque, ultimate torsional stiffness, and energy absorption at failure of regenerated bone at 8 and 12 wk in the LIPUS treatment group were better than those in the control group (P ＜ 0. 05) Conclusion LIPUS as a biophysical stimulation may accelerate the formation and maturation of regenerate bone in rabbit tibia lengthening model.