A TPMS-integrated paediatric proximal femoral osteotomy implant demonstrates structural feasibility and improved load sharing: An in silico proof-of-concept study

Additively manufactured (AM)-enabled cellular architectures with tuneable mechanical properties offer new opportunities for design optimisation in orthopaedic implants. In paediatric proximal femoral osteotomy (PFO), conventional implants provide structural integrity and fixation stability, but their high stiffness reduces load transfer to the growing bone (stress shielding). Triply periodic minimal surface (TPMS) lattices exemplify AM-enabled architectures with favourable strength-to-stiffness trade-offs. This study presents a proof-of-concept of a TPMS-integrated Ti-6Al-4V paediatric PFO implant, benchmarked against conventional designs using a patient-specific digital-twin workflow coupling neuromusculoskeletal (NMSK) simulations with finite element analysis (FEA) of bone-implant mechanics. NMSK-derived joint contact and muscle forces were applied to assess von Mises stresses (implant safety), bone-implant micromotion (implant attachment), and cortical mechanical stimulus through strain energy density and microstrain metrics (stress shielding). All implants remained below the relevant material yield-strength range and exhibited micromotion within the accepted threshold. The TPMS-integrated design increased distal cortical strain energy density by 25% relative to the solid plates and reduced the cortical volume falling below the selected microstrain-based disuse threshold. The TPMS implant also generated a more uniform strain distribution near screw interfaces. These engineering metrics suggest that the TPMS design may meet key initial mechanical performance requirements while improving implant-to-bone mechanical compatibility, motivating further fatigue characterisation, experimental validation, and multi-subject studies.