A multi-domain computational framework investigating the short- and long-term viability of bioabsorbable magnesium fixation for tibial fractures.

This study presents a multi-domain computational framework to investigate the long-term performance of permanent and bioabsorbable magnesium fixation devices in orthopaedic fracture applications. The framework integrates a coupled model for bone fracture healing and remodeling, with an enhanced surface-based corrosion model to predict the performance of bioabsorbable magnesium devices. It was found that plated fracture fixation enabled fracture healing outcomes compare to non-plated models by facilitating direct fracture healing. During the fracture healing phase, it was found that the stiff titanium plate provided a better healing response compared to the less stiff bioabsorbable magnesium plates. However, in the longer-term remodeling phase, the titanium plate showed evidence of stress-shielding and inhibited bone remodeling. On the other hand, the magnesium plates showed that there was continued remodeling, which meant that the bone tissue gradually returned to the pre-fracture stress state. While the corrosion rate and pit severity heavily influenced the mechanical support provided by the corroding magnesium fixator, the results showed that fixation was only required to provide mechanical stability to the fracture region for approximately the first 30 days for successful fracture union to occur. This coupled computational framework provides a platform to investigate the role of a wide range of magnesium fixation devices and their design and optimisation in orthopaedic applications.