Topology optimisation and lithography-based ceramic manufacturing of short-stem hip prostheses with enhanced biomechanical and mechanobiological performance

Virtual prototyping combined with additive manufacturing technologies are opening new horizons in healthcare and biomimetic medical device personalisation is becoming feasible and competitive. Finite element-based optimisation combined with metallic additive manufacturing has already demonstrated the physical prototyping of interesting topologies for innovative articular prostheses. However, metallic implants are biomechanically and biologically suboptimal and a shift to ceramic materials, for bone replacement and articular implants, could result interesting. To this end, challenges liked to the engineering design of large-sized topology optimised ceramic implants and their additive manufacture still need to be overcome and exemplified. Accordingly, the whole engineering design of innovative short stem hip prostheses is presented here. Different approaches to the virtual prototyping of massive ceramic implants, involving strategies for their topology optimisation, are tested and systematically compared from biomechanical and mechanobiological perspectives. After virtual validation, the selected alternatives are successfully prototyped employing lithography-based ceramic manufacturing of alumina-toughened zirconia, which constitutes a design-enabled manufacturing breakthrough considering the massive implants achieved. Non-destructive evaluation using X-ray computed tomography allows for quantitative quality control and defect detection. Summarising, the study provides a systematic knowledge-based methodology for the engineering of topology optimised ceramic implants for critically sized defects with remarkable biomechanical and mechanobiological performance.