Influence of fracture type and thickness of intramedullary nails on fracture healing – A numerical study

INTRODUCTION: It is common knowledge that the fracture healing process is strongly influenced by the mechanical behaviour of the bone implant complex (BIC) due to the resulting interfragmentary movement (IFM) of the bone fragments at the fracture site. Unreamed intramedullary nailing reduces the disturbance of blood supply in comparison to reamed nailing but leads to a more flexible stabilization due to the distance between nail and endosteal surface. Therefore high interfragmentary movements (IFM) may occur under low shear loads which could result in a delayed fracture healing. To identify the mechanical key factors influencing the healing outcome of intramedullary nailing, we simulated the fracture healing process for typical types of diaphyseal fractures treated with intramedullary nails of various diameters.