A finite element model of the Ilizarov fixator system

Mechanical characteristics of orthopaedic fixators, such as stiffness and stability, directly influence the mechanobiological environment in which the bone is healed. A comprehensive understanding of the sensitivity of the Ilizarov Apparatus (IA) to configuration parameters is the key to its biomechanical analysis. In this study, detailed 3D Finite Element (FE) models of two-ring and four-ring configurations of the IA are developed and studied with respect to axial stiffness. A parametric analysis is carried out on the four-ring configuration and the effects of the ring diameter, the wire diameter, and pretension level on the frame stiffness are studied. Both configurations are found to exhibit a non-linear stiffness behavior under axial compression. It is found that the addition of levels of fixations, i.e., rings and wires, augments fixator's stability. The analysis shows that decreasing the rings size and increasing the wires diameter and pretension levels provides greater frame stiffness. The results are in good agreement with the findings reported in literature.