Univ Paris Est Creteil, CNRS, MSME, Créteil, F-94010, France.
SUPMECA, EA 7393 QUARTZ Laboratory, Saint-Ouen 93407, France.
J Orthop Res. 2021 Jun;39(6):1174-1183. doi: 10.1002/jor.24840. Epub 2020 Sep 14.
Short and long-term stabilities of cementless implants are strongly determined by the interfacial load transfer between implants and bone tissue. Stress-shielding effects arise from shear stresses due to the difference of material properties between bone and the implant. It remains difficult to measure the stress field in periprosthetic bone tissue. This study proposes to investigate the dependence of the stress field in periprosthetic bone tissue on (i) the implant surface roughness, (ii) the material properties of bone and of the implant, (iii) the bone-implant contact ratio. To do so, a microscale two-dimensional finite element model of an osseointegrated bone-implant interface was developed where the surface roughness was modeled by a sinusoidal surface. The results show that the isostatic pressure is not affected by the presence of the bone-implant interface while shear stresses arise due to the combined effects of a geometrical singularity (for low surface roughness) and of shear stresses at the bone-implant interface (for high surface roughness). Stress-shielding effects are likely to be more important when the bone-implant contact ratio value is low, which corresponds to a case of relatively low implant stability. Shear stress reach a maximum value at a distance from the interface comprised between 0 and 0.1 time roughness wavelength λ and tend to 0 at a distance from the implant surface higher than λ, independently from bone-implant contact ratio and waviness ratio. A comparison with an analytical model allows validating the numerical results. Future work should use the present approach to model osseointegration phenomena.
种植体与骨组织之间的界面载荷传递强烈决定了无骨水泥种植体的短期和长期稳定性。由于骨与种植体之间的材料性能差异，会产生应力屏蔽效应。因此，仍然难以测量骨内的应力场。本研究旨在探讨骨内的应力场对（i）种植体表面粗糙度、（ii）骨和种植体的材料特性、（iii）骨-种植体接触率的依赖关系。为此，开发了一个骨-种植体界面的微观二维有限元模型，其中表面粗糙度通过正弦表面来建模。结果表明，等静压不受骨-种植体界面存在的影响，而剪切应力则是由于几何奇点（对于低表面粗糙度）和骨-种植体界面处的剪切应力（对于高表面粗糙度）的综合作用产生的。当骨-种植体接触率值较低时，应力屏蔽效应可能更为重要，这对应于种植体稳定性相对较低的情况。剪切应力在距界面 0 到 0.1 倍粗糙度波长 λ 的距离处达到最大值，并在距种植体表面大于 λ 的距离处趋于 0，与骨-种植体接触率和波幅比无关。与解析模型的比较验证了数值结果的有效性。未来的工作应该使用这种方法来模拟骨整合现象。
