Bio-Inspired lattice-based cranial implants: comparative finite element analysis of topology-dependent mechanical performance, energy absorption, and osseointegration potential

Cranioplasty implants must provide mechanical protection while remaining lightweight and promoting biological integration. This study investigates bio-inspired lattice-based cranial implants incorporating four topologies: body-centred cubic (BCC), cubic, honeycomb and re-entrant. Finite element analysis (FEA) evaluated the quasi-static compressive behaviour of patient-independent cranial implant models made from polyetheretherketone (PEEK) and titanium alloy (Ti-6Al-4V). Compression tests on additively manufactured lattice specimens validated the deformation responses. Eight implant configurations, including designs with honeycomb surface perforations to enhance porosity and potential osseointegration, were analysed. Mechanical performance was assessed through deformation, stress distribution, reaction force, energy absorption and specific energy absorption, evaluated against clinically derived design thresholds under simplified, fully constrained conditions. The results demonstrated that lattice topology significantly influenced implant behaviour. Ti implants exhibited superior stiffness, load-bearing capacity and energy absorption, whereas PEEK implants offered weight reduction. Among the architectures, the BCC topology achieved the highest crush force efficiency and specific energy absorption, while the Ti BCC-H implant outperformed other designs and satisfied all four evaluation criteria, making it the most balanced combination of structural stability, lightweight performance and biological suitability. The findings highlight the importance of topology optimisation in the development of mechanically efficient and biologically favourable cranial implants for patient-specific cranioplasty applications.