A finite element analysis for monitoring the healing progression of fixator-bone system under three loading conditions

BACKGROUND: Unilateral external fixators are widely used in orthopedics to stabilize fractured bones and in the treatment of limb deformities. The main value for evaluation of mechanical stability of the external fixator is fixator stiffness. The fixator stiffness is an important factor as it will influence the biomechanical environment to which fixator and regenerating tissues are exposed. OBJECTIVE: The main objective of this work was to monitor the transmission of stress and the change of displacement generated in fixator-bone system under three loading conditions during healing process. METHODS: In this study, a finite element model with changing Young's modulus of the callus is established, finite element analysis was used to investigating stress and deformation of fixator-bone system caused by axial load, torsional load and bending load during three healing stages. RESULTS: The results reveal that at different healing stages, stress distribution between the fixator and fractured bone is different, the position of displacement is mainly concentrated in the fracture site and proximal bone and with the increase of healing time, the deformation decreased. CONCLUSIONS: This work helps orthopedic doctors to monitor the progression of fracture healing and determine the appropriate time for removal of a fixation device and provide useful information.