Singh Ankush Pratap, Rana Masud, Pal Bidyut, Datta Pallab, Majumder Santanu, Roychowdhury Amit
Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology Shibpur, Howrah, India; Bioceramics & Coating Division, CSIR-Central Glass & Ceramic Research Institute, Kolkata, India.
Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology Shibpur, Howrah, India.
Med Eng Phys. 2023 Mar;113:103959. doi: 10.1016/j.medengphy.2023.103959. Epub 2023 Feb 15.
Loading configuration of hip joint creates resultant bending effect on femoral implants. So, the lateral side of femoral implant which is under tension retracts from peri‑implant bone due to positive Poisson's ratio. This retraction of implant leads to load shielding and gap opening in proximal-lateral region, thereby allowing entry of wear particle to implant-bone interface. Retraction of femoral implant can be avoided by introducing auxetic metamaterial to the retracting side. This allows the implant to push peri‑implant bone under tensile condition by virtue of their auxetic (negative Poisson's ratio) nature. To develop such implants, a patient-specific conventional solid implant was first designed based on computed-tomography scan of a patient's femur. Two types of metamaterials (2D: type-1) and (3D: type-2) were employed to design femoral meta-implants. Type-1 and type-2 meta-implants were fabricated using metallic 3D printing method and mechanical compression testing was conducted. Three finite element (FE) models of the femur implanted with solid implant, type-1 meta-implant and type-2 meta-implant were developed and analysed under compression loading. Significant correlation (R = 0.9821 and R = 0.9977) was found between the experimental and FE predicted strains of the two meta-implants. In proximal-lateral region of the femur, an increase of 7.1% and 44.1% von-Mises strain was observed when implanted with type-1 and type-2 meta-implant over the solid implant. In this region, bone remodelling analysis revealed 2.5% bone resorption in case of solid implant. While bone apposition of 0.5% and 7.7% was observed in case of type-1 and type-2 meta-implants, respectively. The results of this study indicates that concept of introduction of metamaterial to the lateral side of femoral implant can prove to provide higher osseointegration-friendly environment in the proximal-lateral region of femur.
髋关节的加载配置会在股骨植入物上产生合成弯曲效应。因此，由于泊松比为正，处于拉伸状态的股骨植入物外侧会从植入物周围的骨组织中缩回。植入物的这种缩回会导致近端外侧区域出现载荷屏蔽和间隙开口，从而使磨损颗粒进入植入物 - 骨界面。通过在缩回侧引入负泊松比超材料，可以避免股骨植入物的缩回。由于其负泊松比特性，这使得植入物在拉伸条件下能够推动植入物周围的骨组织。为了开发这种植入物，首先基于患者股骨的计算机断层扫描设计了一种针对患者的传统实体植入物。采用两种类型的超材料（二维：类型 - 1）和（三维：类型 - 2）来设计股骨超植入物。使用金属3D打印方法制造类型 - 1和类型 - 2超植入物，并进行了机械压缩测试。开发了三个分别植入实体植入物、类型 - 1超植入物和类型 - 2超植入物的股骨有限元（FE）模型，并在压缩载荷下进行了分析。在两种超植入物的实验应变和有限元预测应变之间发现了显著相关性（R = 0.9821和R = 0.9977）。在股骨的近端外侧区域，与实体植入物相比，植入类型 - 1和类型 - 2超植入物时观察到冯·米塞斯应变分别增加了7.1%和44.1%。在该区域，骨重塑分析显示实体植入物的骨吸收为2.5%。而在类型 - 1和类型 - 2超植入物的情况下，分别观察到骨增生为0.5%和7.7%。本研究结果表明，在股骨植入物外侧引入超材料的概念可以证明在股骨近端外侧区域提供更高的骨整合友好环境。
