Department of Orthopedic Surgery and Orthopedic Research Institute, West China Hospital, Sichuan University, Chengdu, 610041, China.
School of Mechanical Engineering, Sichuan University, Chengdu, 610065, China.
J Orthop Surg Res. 2024 Aug 22;19(1):499. doi: 10.1186/s13018-024-05006-1.
Unicompartmental knee arthroplasty (UKA) has been proved to be a successful treatment for osteoarthritis patients. However, the stress shielding caused by mismatch in mechanical properties between human bones and artificial implants remains as a challenging issue. This study aimed to properly design a bionic porous tibial implant and evaluate its biomechanical effect in reconstructing stress transfer pathway after UKA surgery.
Voronoi structures with different strut sizes and porosities were designed and manufactured with Ti6Al4V through additive manufacturing and subjected to quasi-static compression tests. The Gibson-Ashby model was used to relate mechanical properties with design parameters. Subsequently, finite element models were developed for porous UKA, conventional UKA, and native knee to evaluate the biomechanical effect of tibial implant with designed structures during the stance phase.
The internal stress distribution on the tibia plateau in the medial compartment of the porous UKA knee was found to closely resemble that of the native knee. Furthermore, the mean stress values in the medial regions of the tibial plateau of the porous UKA knee were at least 44.7% higher than that of the conventional UKA knee for all subjects during the most loading conditions. The strain shielding reduction effect of the porous UKA knee model was significant under the implant and near the load contact sites. For subject 1 to 3, the average percentages of nodes in bone preserving and building region (strain values range from 400 to 3000 μm/m) of the porous UKA knee model, ranging from 68.7 to 80.5%, were higher than that of the conventional UKA knee model, ranging from 61.6 to 68.6%.
The comparison results indicated that the tibial implant with designed Voronoi structure offered better biomechanical functionality on the tibial plateau after UKA. Additionally, the model and associated analysis provide a well-defined design process and dependable selection criteria for design parameters of UKA implants with Voronoi structures.
单髁膝关节置换术（UKA）已被证明是治疗骨关节炎患者的一种成功方法。然而，人工植入物与人体骨骼之间机械性能不匹配导致的应力遮挡仍然是一个具有挑战性的问题。本研究旨在设计一种仿生多孔胫骨植入物，并评估其在 UKA 手术后重建应力传递途径方面的生物力学效果。
使用 Ti6Al4V 通过增材制造设计并制造了具有不同支柱尺寸和孔隙率的 Voronoi 结构，并进行了准静态压缩测试。使用 Gibson-Ashby 模型将机械性能与设计参数相关联。随后，为多孔 UKA、传统 UKA 和自然膝关节开发了有限元模型，以评估具有设计结构的胫骨植入物在站立阶段的生物力学效果。
发现多孔 UKA 膝关节内侧胫骨平台的内部应力分布与自然膝关节非常相似。此外，在所有受试者中，在最加载条件下，多孔 UKA 膝关节内侧胫骨平台的平均应力值至少比传统 UKA 膝关节高 44.7%。多孔 UKA 膝关节模型在植入物和靠近载荷接触点处的应变屏蔽减小效果显著。对于受试者 1 到 3，多孔 UKA 膝关节模型中保留和构建区域（应变值范围为 400 到 3000μm/m）的节点的平均百分比，范围为 68.7%到 80.5%，高于传统 UKA 膝关节模型，范围为 61.6%到 68.6%。
比较结果表明，UKA 后具有设计 Voronoi 结构的胫骨植入物在胫骨平台上提供了更好的生物力学功能。此外，该模型和相关分析为具有 Voronoi 结构的 UKA 植入物的设计参数提供了明确的设计流程和可靠的选择标准。
