大段仿生活性人工骨修复兔长骨缺损的实验研究

Experimental research on repairing long bone defects of rabbit with large segments of simulated-bioactive bone substitute

目的观察以聚左旋乳酸、磷酸三钙、重组人骨形态发生蛋白-2(rhBMP-2)制备的大段仿生活性人工骨对骨缺损的修复效果。方法利用快速成形技术制备多孔状的聚左旋乳酸-磷酸三钙大段人工骨载体材料,负压复合rhBMP-2后制备成大段仿生活性人工骨。将36只新西兰大白兔随机等分为三组,手术造成右前臂桡骨中上段15mm骨缺损。实验组植入15mm仿生活性人工骨,对照组a为材料对照,对照组b为空白对照。通过影像学、组织学、骨密度检查及图像分析技术观察骨缺损的修复效果及材料的降解情况。结果①影像学结果表明,实验组术后12周新生骨痂将缺损修复,修复率100%,术后24周骨痂塑形良好。两对照组术后24周内均无骨痂形成,缺损未修复。②组织学显示:实验组术后12周骨痂外层为皮质骨,中央为含有骨岛的载体材料,术后24周骨痂皮质骨与材料之间形成贯通的髓腔;材料对照组术后12周缺损区为纤维组织包裹的载体材料,空白对照组形成纤维连接。③实验组术后12、24周的骨密度值分别为正常值的70.6%和96.8%。④术后12周实验组和材料对照组的降解率分别是38.3%和31.4%,术后24周分别为54.2%和43.4%。结论以聚左旋乳酸、磷酸三钙和rhBMP-2制备的大段仿生活性人工骨对骨缺损具有良好的修复作用。

Objective To observe the effects of large segments of simulated-bioactive bone substitutes made from PLLA （poly-left-lactic acid）, TCP （tricalcium phosphate） and rhBMP-2 （recombinant human bone morphogenetic protein 2） on repairing long bone defects of radius in rabbits. Methods Large segments of PLLA-TCP porous carrier were made with a rapid forming machine. Then rhBMP-2 was compounded through negative pressure to produce large segments of simulated-bioactive bone substitute. 36 New Zealand rabbits were divided into 3 groups randomly. Operations were done to make a 15 mm bone defect at the middle-superior segment of right radius in each rabbit. In the experiment group, a large segment of simulated-bioactive bone substitute was implanted into the defect; in the control group A, a large segmental carrier was implanted; in control group B, nothing was implanted. The results were evaluated by radiograph, histology and BMD （bone mineral density）, and the degrading rate of the carrier was analyzed by an image analysis system. Results （1） Radiography： In the experiment group, by 12 weeks after operation, the defect was repaired by newly-formed callus, and the repairing rate was 100%. By 24 weeks postoperatively, the callus molded well, and the medullary cavity formed. In the 2 control groups, by 24 weeks after operation, no callus formed and the defects were not repaired. （2） Histology： In the experiment group, by 12 weeks after operation, the outer layer of callus was cortical bone, and the central part was the carrier where there were bone islands. By 24 weeks, medullary cavity formed between cortical bone and the carrier. （3） The BMD of the new callus in 12 weeks and 24 weeks after operation were 70.6% and 96.8% of the normal radius. （4） In 12 weeks postoperatively, the degrading rate of the carrier was 38.3% in the experiment group, 31.4% in the control group. In 24 weeks, they were 54.2% and 43.4% respectively. Conclusion The large segment of simulated-bioactive bone substitute has satisfactory effects on repairing the bone defects.