可降解珊瑚羟基磷灰石兔体内移植后的降解及骨折愈合

Degradation of degradable coral-hydroxyapatite after implanted into rabbit and its effect on bone healing

背景:目前临床所用的多数人工骨在体内不降解,会影响后期骨骼塑形,如受较大外力作用可能会导致再骨折的发生;另外人工骨在体内长期存留可能带来其他不可预测的风险性。目的:观察可降解珊瑚羟基磷灰石人工骨植入兔体内后不同时间的降解情况,及其对骨折愈合的促进效果。设计、时间及地点:自身对照动物观察,于2002-01/2006-12在北京积水潭医院创伤骨科研究所完成。材料:新西兰大耳白兔70只,由北京实验动物中心提供。珊瑚羟基磷灰石人工骨由北京意华健公司提供,批号500R,羟基磷灰石含量为12%。方法:选取一定孔径的块状珊瑚,通过控制热液交换条件,形成可降解珊瑚羟基磷灰石人工骨。70只兔麻醉后,利用磨钻在双侧胫骨近端制造骨缺损,左侧骨缺损内植入与骨槽同样大小的珊瑚羟基磷灰石人工骨;右侧骨缺损作为对照,于右侧髂骨取骨,修成合适大小后植入缺损部位。主要观察指标:移植后不同时间点大体观察、X射线及非脱钙组织切片甲苯氨蓝染色镜检结果。结果:珊瑚羟基磷灰石人工骨移植后3～8周,骨槽周围有大量瘢痕组织和骨痂形成;移植后10周,骨槽部位被新生骨封死,能介导骨缺损部位愈合。X射线显示,随植入时间的延长,珊瑚羟基磷灰石人工骨移植部位的骨密度逐渐下降。非脱钙组织切片镜检显示,珊瑚羟基磷灰石人工骨植入早期与机体相容性良好,4周时人工骨与自体骨交界位置有大量新生骨形成,32～60周人工骨小梁降解后表现为细线状或细环状残迹,降解部位为新生骨所替代,部分位置出现髓腔化。植入髂骨的对照侧4周时移植的髂骨与周围胫骨紧密愈合,部分位于髓腔内的髂骨逐渐降解,但直到60周时仍可在部分髓腔中见到移植的髂骨骨小梁。结论:可降解珊瑚羟基磷灰石人工骨植入体内后,随时间延长人工骨逐渐降解,并介导骨折良好愈合,是一种较理想的新型自体骨移植替代材料。

BACKGROUND： So far, most artificial bones used in clinic can not degrade in vivo, which affects bones shaping. The artificial bones may fracture again when great external force acts on them. Furthermore, the artificial bones which preserved for along term in vivo may induce unpredictable risks. OBJECTIVE： To observe the degradation of degradable coral-hydroxyapatite at different stages after implanted into rabbits and its effect on fracture healing. DESIGN, TIME AND SETTING： A self-control animal experiment was performed in the Traumatic Orthopedic Institute of Beijing Ji Shui Tan Hospital from January 2002 to December 2006. MATERIALS： A total of seventy New Zealand rabbits in the experiment were provided by Experimental Animal Center of Beijing. The coral-hydroxyapatite bones with batch number of 500R were provided by Beijing Yihuajian Science and Trade Co,, Ltd. The content of hydroxyapatite was 12%. METHODS： The coral-hydroxyapatite bones were prepared by massive corals with certain pore size. Under anesthesia, bone defects of the bilateral proximal tibias about 10×5×3 mill3 in the rabbits were prepared by drilling. The coral-hydroxyapatite bones which had same size with bone groove were implanted into the left tibias. The bones drawn from the right iliac crest bones were implanted into the right defects which were as controls. MAIN OUTCOME MEASURE： General observations, X-ray examination and histological examination were performed at different time points after implantation. RESULTS： During 3-8 weeks after implantation of coral-hydroxyapatite, plenty of scar tissues and bone callus formed. At 10 weeks, the bone grooves were filled with new bones, which could mediate bone defects recovery. The X-ray image showed that as the increasing time, bone mineral density of coral-hydroxyapatite bones decreased. Histological examination showed that the coral-hydroxyapatite bones had good biocompatibility in the early stage. Many new bones formed at the junctional zone of coral-hydroxyapatite and autogenous bones at 4 weeks. After degradation at 32-60 weeks, the bone trabeculae showed line and ring shaped vestiges, and the degraded sections were instead of new bones. Some bone trabeculae showed medullary cavity formation. In the control sides, the grafts were fused with tibias at 4 weeks. Some iliac crest bones degraded gradually, but the bone trabeculae of grafts also could be seen in the medullary cavity after 60 weeks. CONCLUSION： As the increasing time after implantation, the coral-hydroxyapatite bone degraded gradually and mediated the good fusion of fracture. The coral-hydroxyapatite could be used as an ideal bone graft instead of autograft.