生物活性梯度HA涂层人工关节的生物力学研究

Biomechanical studies on gradient hydroxyapatite-coating

[目的]探讨生物活性梯度羟基磷灰石(HA)涂层人工关节的生物力学性能。[方法]在人工股骨头置换组,将10只健康成年杂交犬随机分成2组,行右侧人工股骨头置换,分别植入钛合金人工股骨柄(Ti关节组)、HA涂层钛合金人工股骨柄(HA关节组);在圆柱体植入组,选4只健康成年杂交犬,麻醉后在股骨内外髁关节面垂直植入1个种植体,左腿植入钛合金棒(Ti圆柱体组),右腿植入羟基磷灰石涂层钛合金棒(HA圆柱体组),术后12周处死动物取材,进行生物力学测试和界面组织学观察。[结果]生物力学顶出试验显示:Ti关节组、HA涂层关节组的抗剪切强度分别为(2.58±1.56)Mpa和(7.57±1.03)Mpa,HA涂层关节组的抗剪切强度明显高于Ti关节组(P<0.01)。Ti圆柱体组、HA涂层圆柱体组的抗剪切强度分别为(2.36±1.04)Mpa和(21.65±1.48)Mpa。HA涂层圆柱体组的抗剪切强度明显高于Ti圆柱体组(P<0.01)。界面组织学观察显示:HA关节组和HA圆柱体组界面骨结合良好,骨结合率高;而Ti关节组和Ti圆柱体组界面大部分区域钛金属表面与周围的骨小梁之间有纤维组织分隔,界面骨结合率低。[结论]生物活性梯度HA涂层人工关节有良好的生物力学性能,界面较高的骨结合率是HA涂层植入体获得良好的生物力学性能的基础。

[ Objective] To evaluate the interface biomechanical characteristics of a new kind of hydroxyapatite coating. [ Method] Ten dogs underwent hermiarthroplasty of hip joint and were divided into 2 groups. One group was placed in Ti-6AI-4V femoral stem （Ti hip group）, the second group was placed in HA-coated femoral stem （HA hip group）. The second method was rod implant in condyles in both legs of each dog. Four matured dogs were selected. Eight Ti-6AI-4V rods （Ti rod group） were placed in lateral and medial condyle in left leg of each dog and eight HA-coated rods （ HA rod group） were implanted in that of right leg of each dog. The dogs were sacrificed at 12 weeks after operation, and then the interface shear strength and imerface histological changes were evaluated. [ Result ] The Pust-out test showed that the average interface shear strengths of Ti hip group and HA hip group were （2. 58 ± 1.56） Mpa and （7.57 ± 1.03 ） Mpa respectively. The interface shear strengths of HA hip group was significantly higher than that of Ti hip group （P 〈 0. 01 ）. The average interface shear strengths of Ti rod group and HA rod group were （2. 36 ± 1.04） Mpa and （21.65 ± 1.48） Mpa respectively. The interface shear strengths in HA rod group was significantly higher than that in Ti rod group （P 〈 0. 01 ）. The histological examination showed that a good interface osseointergration appeared in the HA hip group and HA rod group. The average rates of osseointegration were high. But in Ti hip group and Ti rod group, the most area of surface of implant was surrounded by a layer of fibrous tissue membrane. The average rate of oseointegration was lower. [ Conclusion] This hydroxyapatite-coating showed good biomechanical bonding strength which obviously improved the stability of the prosthesis in weight loading. The high osseointegration rate may be the foundation of good biomechanical ability.