de Bruijn J D, Bovell Y P, van Blitterswijk C A
Laboratory for Otobiology & Biocompatibility, Biomaterials Research Group, University of Leiden, The Netherlands.
Biomaterials. 1994 Jun;15(7):543-50. doi: 10.1016/0142-9612(94)90021-3.
Plasma sprayed coatings of tetracalcium phosphate, magnesium whitlockite and three types of hydroxyapatite, varying in degree of crystallinity, were evaluated with light microscopy, scanning electron microscopy and backscatter electron microscopy (BSE) after implantation periods of 1, 2 and 4 wk in rat femora. BSE revealed that both tetracalcium phosphate and semi-crystalline hydroxyapatite underwent distinct bulk degradation and loss of relatively large particles. Amorphous hydroxyapatite showed a gradual surface degradation, indicated by a transition zone varying in grey level between that of the coating and bone tissue, while degradation was negligible with the highly crystalline material and magnesium whitlockite. Degradation appeared to be related to bone apposition, since more bone seemed to be present on amorphous hydroxyapatite and tetracalcium phosphate, as compared to highly crystalline hydroxyapatite and magnesium whitlockite coatings. At the interface between bone and magnesium whitlockite, a seam of unmineralized bone-like tissue was frequently seen with light microscopy, while few areas with bone contact were present. X-ray microanalysis revealed that both the magnesium whitlockite coating and the unmineralized bone-like tissue contained substantial amounts of aluminium which, in addition to possible influences of magnesium, may have caused the impaired mineralization. The results of this preliminary study indicate that, with regard to early bone formation, amorphous hydroxyapatite coatings seem to be beneficial over highly crystalline coatings. However, further experiments should be performed to give conclusive data on (i) the statistical significance of the differences in bone apposition rate, and (ii) the long-term behaviour of both amorphous and highly crystalline coatings in bone and their relation to implant performance.
将磷酸四钙、镁白磷钙石和三种结晶度不同的羟基磷灰石等离子喷涂涂层植入大鼠股骨1、2和4周后，通过光学显微镜、扫描电子显微镜和背散射电子显微镜（BSE）进行评估。BSE显示，磷酸四钙和半结晶羟基磷灰石均发生了明显的整体降解和相对较大颗粒的损失。无定形羟基磷灰石表现出逐渐的表面降解，涂层与骨组织之间的灰度过渡区表明了这一点，而高结晶材料和镁白磷钙石的降解可忽略不计。降解似乎与骨附着有关，因为与高结晶羟基磷灰石和镁白磷钙石涂层相比，无定形羟基磷灰石和磷酸四钙上似乎有更多的骨。在骨与镁白磷钙石的界面处，光学显微镜下经常可见一条未矿化的骨样组织缝，而骨接触区域很少。X射线微分析显示，镁白磷钙石涂层和未矿化的骨样组织都含有大量的铝，除了镁可能的影响外，铝可能导致矿化受损。这项初步研究的结果表明，就早期骨形成而言，无定形羟基磷灰石涂层似乎比高结晶涂层更有益。然而，应进行进一步的实验，以给出关于（i）骨附着率差异的统计学显著性，以及（ii）无定形和高结晶涂层在骨中的长期行为及其与植入性能关系的确切数据。
