Topology optimization and biomechanical evaluation of bone plates for tibial bone fractures considering bone healing

Implant designs highly influence their biomechanical performances when fixed with load-bearing long bone fractures. In this research work, the topology optimisation technique was used to obtain different shapes and designs of the bone plates according to three different loadings, e.g. lateral bending (LB), axial compression (AC), and physiological loads (PL), and solid volume fractions V_f of 30% and 70%. Bi-phasic mechano-regulation algorithm was used to investigate the callus healing for a given bone plate design, and stresses in screws and bone plates were monitored. To further validate the bone plate designs, fatigue analyses using Fe-safe and three-point bending tests were performed using additively manufactured plates. Topology-optimised bone plate PL with V_f 70% showed the maximum bending stiffness (peak load of 138 N and bending stiffness of 29 N/mm) among the optimised bone plates, with the best callus healing normalised stiffness of 0.6 and 0.7 in iterations 21 and 42, respectively. Thus, the bone plates produced using actual loading conditions (PL) outperformed other loading conditions during the biomechanical evaluation of fractured bones.