Finite element analysis of tissue differentiation process of a tibia with various fracture configurations when a composite intramedullary rod was applied

Flexible implants for long bone fractures are receiving much attention in modern orthopedic surgery because of their excellent healing potential as biological fixations. In this study, we investigated the healing performance of composite intramedullary rods (IM rods) used for tibial diaphyseal fractures. A three dimensional tibia model was developed for various fracture gap sizes and oblique angles. To evaluate the types and time-dependent material properties of the healing tissues, a mechano-regulation algorithm with deviatoric strain was implemented in the finite element analysis. The results showed that the healing performance of a tibial fracture was affected by the modulus of the IM rod according to the fracture gap size and oblique angle. This study suggested the most appropriate IM rod modulus for bone fractures.