Mao Chengzheng, Huang Xiaodong, Lu Guoxing, Choong Peter F M, Tse Kwong Ming
Department of Mechanical Engineering and Product Design Engineering, School of Engineering, Swinburne University of Technology, Australia.
Department of Surgery, The University of Melbourne, Australia.
J Mech Behav Biomed Mater. 2025 Oct;170:107031. doi: 10.1016/j.jmbbm.2025.107031. Epub 2025 Apr 29.
Total joint replacement is a cost-effective surgical operation performed in orthopaedics in which a damaged joint is replaced with a medical implant. This can relieve pain, improve motion, and allow patients to return to normal daily activities. However, there are a lot of issues with regard to the conventional solid implantation, such as high potential risk of stress shielding, customised design for different purposes or patients, specific anisotropic and heterogeneous microstructures to restore biological functions.
A Floating Projection Topology Optimisation (FPTO) algorithm with ersatz material model and multiple constraints is used in this paper for implants design. The algorithm develops with a global volume constraint to control total volume fraction, a local porous infill volume constraint to generate porous infill and the objective of maximising stiffness constrained by lower volume fraction for reducing stress shielding effect. The novel FPTO-finite-element-musculoskeletal modelling and analysing pipeline allows weight factors for considering multiple loading cases in accordance with varieties of postures in gait cycle. Validations and simulation-predicted testing are conduct by finite element analysis (FEA) under varieties of loading cases to investigate the performance of the porous implant design.
FPTO is feasible in designing medical implants with lower stiffness for reducing stress shielding effect. Smooth boundary of implants by FPTO can be obtained directly without post-processing, and multiple constraints are allowable. Compared with conventional design, the proposed implant can approximate natural bone structure and load transmission path. Finite-element-based FPTO design provides tailored anisotropic and heterogeneous topology based on host bone and muscle conditions for better biomechanical performance and durable serviceability whilst being lightweight.
This paper proposes a Floating Projection Topology Optimisation (FPTO) algorithm with ersatz material model and multiple constraints for smooth boundary implant design to reduce stress shielding effect. With FPTO technique, it is expected to shed new light on design of porous implant considering tailored biomechanical environment.
全关节置换是骨科中一种具有成本效益的外科手术，通过医用植入物替换受损关节。这可以缓解疼痛、改善活动能力，并使患者能够恢复正常的日常活动。然而，传统的实体植入存在诸多问题，例如应力遮挡的潜在风险高、针对不同目的或患者的定制设计、恢复生物功能的特定各向异性和非均匀微观结构。
本文采用具有替代材料模型和多重约束的浮动投影拓扑优化（FPTO）算法进行植入物设计。该算法通过全局体积约束来控制总体积分数，局部多孔填充体积约束来生成多孔填充，并以在较低体积分数约束下最大化刚度为目标，以降低应力遮挡效应。新颖的FPTO - 有限元 - 肌肉骨骼建模与分析流程允许根据步态周期中各种姿势考虑多种加载情况的权重因子。通过有限元分析（FEA）在各种加载情况下进行验证和模拟预测测试，以研究多孔植入物设计的性能。
FPTO在设计具有较低刚度以降低应力遮挡效应的医用植入物方面是可行的。通过FPTO可直接获得植入物的光滑边界，无需后处理，并且允许多重约束。与传统设计相比，所提出的植入物可以近似天然骨结构和载荷传递路径。基于有限元的FPTO设计基于宿主骨和肌肉状况提供定制的各向异性和非均匀拓扑，以实现更好的生物力学性能和持久耐用性，同时减轻重量。
本文提出了一种具有替代材料模型和多重约束的浮动投影拓扑优化（FPTO）算法，用于设计光滑边界植入物以降低应力遮挡效应。借助FPTO技术，有望为考虑定制生物力学环境的多孔植入物设计提供新的思路。
