负重对生物活性骨水泥与骨结合界面微力学及化学成分的影响

Effect of weight- bearing on micromechanics and chemical components of interface between bioactive bone cement and bone

目的探讨负重对含锶羟基磷灰石(Sr-HA)生物活性骨水泥与骨结合界面微力学及化学成分的影响。方法12只兔随机分为两组,将Sr-HA活性骨水泥注入其中一组兔的髂骨内(非负重状态),另一组中,Sr-HA活性骨水泥被用于单侧半髋关节置换(负重状态)。术后6个月,我们分别对两种状态下骨与Sr-HA活性骨水泥界面的组织学、化学成分及力学特性等进行了研究和比较。结果组织学观察可见,在两种状态下,骨与Sr-HA活性骨水泥均能紧密结合。但负重组的骨-骨水泥界面可见活跃的新骨形成及骨的重建。能谱(EDX)分析的结果显示:负重组界面的钙与磷含量明显高于非负重组。此外,两种状态下,界面的力学性能表现出不同的特性:负重组界面的杨氏模量及硬度高于骨及骨水泥;而非负重组界面的力学性能介于骨与骨水泥之间。结论负重有利于骨的代谢及骨-骨水泥界面的力学特性。

Objective To examine the effect of weight-bearing on the bone-bonding behavior of the strontium-containing hydroxyapatite （Sr-HA） cement. Methods 12 rabbits were randomized into 2 groups. In one group, Sr-HA cement was injected into rabbit ilium （non-weight-bearing conditions）. Unilateral hip replacement was performed with Sr-HA cement （weight-bearing conditions） in the other group. 6 months later, all the rabbits were sacrificed. The histological examination, scanning electron microscopy （SEM） with energy-dispersive X-ray （EDX） analysis, as well as nanoindentation test were taken and cancellous bone-Sr-HA cement interfaces under non-weight-bearing and weight-bearing conditions were compared. Results Intimate contact between bone and Sr-HA cement was observed in both groups. However, increased bone formation and remodeling was suggested under weight-bearing conditions. EDX analysis also showed that the contents of calcium and phosphorus under weight-bearing conditions were considerably higher than those under non-weight-bearing conditions. Results of nanoindentation test revealed that both the Young＇s modulus and hardness of the interface were higher than those of either cancellous bone or Sr-HA cement under weight-bearing conditions, and lower than the cancellous bone＇s but higher than the Sr-HA cement＇s under non-weight-bearing conditions. Conclusion Weight-bearing has positive effect on the bone metabolism and mechanical properties of bone-cement interface.