低弹应力对钛合金植入物表面新骨形成的影响

目的观察应力作用下低弹β钛合金植入物表面新骨形成过程并探讨其对生物稳定的影响。方法选用20只成年新西兰大白兔,于双侧胫骨近端植入2种弹性模量(110GPa和30GPa)钛合金植入物,其中左侧为低弹组,右侧为高弹组,分别于术后4、8周处死动物,取材标本进行Micro-CT检测,测定BMD,BVF,SMI等指标,采用组织学方法,测定植入物-骨接触率(C)、单位面积新生骨百分比(S)以及生物力学最大拔出力。结果钛合金植入物植入后4周,组织学显示低弹组植入物表面新骨形成量多于高弹组,但2组之间差异无统计学意义;Micro-CT分析显示,2组之间BMD、BVF、SMI差异无统计学意义;生物力学最大拔出力检测低弹组为(74.60±6.59)N,高弹组为(63.30±8.41)N,2组之间差异存在统计学意义(P<0.05)。8周时组织学观察发现,低弹组植入物表面新骨形成量明显多于高弹组,植入物-骨接触率和单位面积新生骨百分比低弹组均优于高弹组;Micro-CTBMD、BVF、SMI分析显示低弹组材料表面成骨明显优于高弹组;低弹组的拔出力明显高于高弹组(P<0.01)。结论金属植入物的低弹特性有利于应力作用下植入物-骨界面的新骨形成,从而有利于提高植入物的生物稳定性。

Influence of low-modulus of elasticity force on new bone formation of titanium alloy implant-bone interface

[Objective] To observe the new bone formation on the surface of low-modulus of elasticity titanium alloy implant under stress and to investigate the effect of biological stability. [Methods] Twenty adult New Zealand white rabbits were selected in this study. Two different kinds of modulus of elasticity titanium alloy implant were inserted to proximal tibia. The left lateral tibia was low-modulus of elasticity group (modulus of elasticity about 30 GPa). The right one was high-modulus of elasticity group (modulus of elasticity about 110 GPa). At 4 and 8 weeks postoperatively, micro-CT, histological analysis and biomechanics evaluation were measured. [Results] At 4 weeks, histological analysis showed that new bone quantity on the surface of nail in low-modulus of elasticity group seemed more than high-modulus of elasticity group. However there was no significant difference between the two groups by micro-CT evaluation. The biomechanical pullout force was higher in low-modulus of elasticity group(P <0.05). At 8 weeks, the new bone formation in low-modulus of elasticity group was obviously more than one in high-modulus of elasticity group by both micro-CT evaluation and histological analysis. The greatest pullout force was obviously higher in low-modulus of elasticity group(P <0.01). [Conclusion] The low-modulus of elasticity of metal seemed to improve new bone formation on the implant-bone interface under stress and enhance the biological stability.