低强度超声波结合组织工程修复长骨节段性骨缺损

Low intensity ultrasound combined with tissue engineering in repairing segmental defects of long bone

目的:观察低强度超声波结合组织工程技术对长骨节段性缺损的修复效果。方法:实验于2003-05/2004-10在青岛大学医学院附属医院创伤外科完成。取健康成年大白兔48只,建立兔桡骨1.5cm节段性骨-骨膜缺损模型,于骨缺损处植入磷酸钙人工骨和骨髓基质干细胞复合物后随机分为两组,每组24只,实验组局部接受低强度超声波刺激1次/d,15min/次,对照组未给予超声波刺激。于术后4,8,12周麻醉状态下处死动物获取标本。通过生物力学测定、组织学染色分析、X射线摄片及骨密度测量等手段观察新骨形成和材料降解情况。结果:48只兔均进入结果分析。①兔血清碱性磷酸酶含量:术后随着时间的延长,两组动物血清中碱性磷酸酶浓度逐渐升高,实验组6周时达到最高水平(2284nkat/L),对照组8周达到最高水平(1834nkat/L),实验组总体水平高于对照组。②兔桡骨缺损区骨密度测量结果:12周时实验组新骨密度明显高于对照组(0.217,0.153g/cm2,P<0.01)。③兔桡骨生物力学测定结果:12周时实验组的桡骨最大扭转强度明显大于对照组(0.675,0.298Nm,P<0.01)。④兔桡骨缺损区X射线检查:实验组8周时材料体积变小,12周时新骨大量形成并钙化,可见到连续性骨膜骨痂,骨缺损范围变小;对照组12周时骨端新骨形成,长入材料,但材料体积无明显减少。⑤兔桡骨缺损区组织形态学观察结果:实验组12周时新骨多为板层骨,长入材料并与之相互分割包裹;对照组12周时新骨继续增生,边缘处材料被降解成较小的颗粒。结论:低强度超声波不仅有效地促进了新骨的形成,同时也加速了新骨的钙化,明显地促进组织工程对骨缺损的修复作用。

AIM： To observe the effect of low intensity ultrasound conabined with the technique of bone tissue engineering in repairing segmental defects of long bone. METHODS： The experiment was carried out in the Department of Traumatic Surgery, Medical School Hospital of Qingdao University between May 2003 and October 2004. Forty-eight healthy adult white rabbits were made into models of 1.5 cm long rabbit radial segmental osteo-periosteum defects. All defects were implanted with the composite of calcium phosphate cement and bone mesenchymal stem cells, and tben randomly divided into 2 groups： experimental group （n=24） and control group （n=24）. The rabbits in the experimental group were given local ultrasound exposure stimulation, once a day, 15 minutes for each time, but those in the control group were not given. The animals were sacrificed at 4, 8 and 12 weeks respectively after operation and specimens were harvested. The new bone formation and material degradation were observed with biomechanical determination, histologicat staining, radiography and bone density detection. RESULTS： All the 48 rabbits were involved in the analysis of results. ① Contents of alkaline phosphatase in serum： The contents of alkaline phosphatase in serum gradually increased with the prolongation of time in both groups, it reached the highest level at 6 weeks in the experimental group （2 284 nkat/L） and at 8 weeks in the control group （1 834 nkat/L）, the general level was higher in the experimental group than in the control group. ② Bone mineral density in radial defected region of rabbits： It was obviously in the experimental group than in the control group at 12 weeks （0.217, 0.153 g/cm^2, P 〈 0.01）. ③ Radial biomechanical detection： The maximal torsion intensity at 12 weeks was obviously greater in the experimental group than in the control group （0.675, 0.298 Nm, P 〈 0.01）. ④ Radiographic examination of radial defected region of rabbits： In the experimental group, the volume of material became smaller at 8 weeks, there was plenty of formation and calcification of new bones at 12 weeks, continuous periosteal bony callus could be observed, the defected range of bone became smaller. In the control group, new bone formed at extremities and grew into the material at 12 weeks, but the volume of material did not reduced obviously. ⑤Histomorphologacal observation of radial defected region of rabbits： At 12 weeks, most of the new bones in the experimental group were lamellar bone, grew into the material and packed with each other; the new bones in the control group continued to proliferate, and the materials on the margin were degraded into small granules. CONCLUSION： Low intensity ultrasound cannot only effectively promote the formation of new bones, but accelerate calcification of the new bones, and evidently promote effect on the bone defect repaired by bone tissue engineering.