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Abstract: A novel reconstructive prosthesis was designed with topological optimization (TO) and a lattice structure to enhance biomechanical and biological properties in the proximal tibia. The biomechanical performance was validated through finite element analysis (FEA) and biomechanical tests. The tibia with inhomogeneous material properties was reconstructed according to computed tomography images, and different components were designed to simulate the operation. Minimum compliance TO subject to a volume fraction constraint combined with a graded lattice structure was utilized to redesign the prosthesis. FEA was performed to evaluate the mechanical performances of the tibia and implants after optimization, including stress, micromotion, and strain energy. The results were analyzed by paired-samples t tests, and p < 0.05 was considered significant. Biomechanical testing was used to verify the tibial stresses. Compared to the original group (OG), the TO group (TOG) exhibited lower stress on the stem, and the maximum von Mises stresses were 87.2 and 53.1 MPa, respectively, a 39.1% reduction (p < 0.05). Conversely, the stress and strain energy on the tibia increased in the TOG. The maximum von Mises stress values were 16.4 MPa in the OG and 22.9 MPa in the TOG with a 39.6% increase (p < 0.05), and the maximum SED value was 0.026 MPa in the OG and 0.042 MPa in the TOG, corresponding to an increase of 61.5% (p < 0.05). The maximum micromotions in the distal end of the stem were 135 μm in the OG and 68 μm in the TOG, almost a 50% reduction. The stress curves of the biomechanical test coincided well with the FEA results. The TO approach can effectively reduce the whole weight of the prosthesis and improve the biomechanical environment of the tibia. It could also pave the way for next-generation applications in orthopedics surgery.

吉林大学第二医院王金成、韩青、张奥博等 | 基于拓扑优化技术的3D打印胫骨重建假体治疗胫骨近端严重骨缺损

本研究论文聚焦于胫骨近端严重骨缺损患者的关节重建假体的设计与验证。目前对于此类患者，临床上通常选择铰链膝关节假体进行重建，但术后假体生存率并不理想。本研究提出利用拓扑优化和网格化技术设计一种新型的个体化定制胫骨重建假体，从而提高假体的生物力学性能，为临床假体设计提供新的思路。本研究通过三维重建技术完成胫骨非均质仿真建模；通过步态分析获取完整步态周期内胫骨平台受力依据；通过拓扑优化技术及梯度化网格设计完成定制化假体的结构优化；通过有限元分析技术完成假体与骨系统的生物力学分析；通过3D金属打印完成假体的制造，并利用生物力学实验完成生物力学的验证。根据研究结果显示，优化后假体减重77%，假体柄远端应力峰值下降39.1%，柄远端微动降低49.7%，胫骨应力及应变能峰值分别增大39.6%和61.5%，说明优化后假体与骨之间的应力屏蔽效应显著降低，远期发生假体松动、假体周围骨折及假体柄远端疼痛的风险被有效避免，假体的生物力学性能得到优化。