TThe Effect of Dynamic Interfragmentary Movement on the Mechanical Performance of External Fixation Devices for Open Tibial Fractures

Abstract

Interfragmentary movement (IFM) in bone formations during tibial shaft fracture stabilization is known to influence the outcome of fracture healing, as well as the performance of external fixation devices. Theoretically, the construction stiffness of a fixation device, including pin insertion configuration, is associated with tibial fracture stability. The objective of this study is to investigate the effect of interfragmentary movement during tibial fracture healing time using finite element analysis, with particular regard for the construction stiffness of the external fixation device. The effect of the distance between pin insertion and the pin length on the mechanical performance of the external fixation device was also performed, with reference to the ASTM F1541 standard. The mechanical stiffness ratio between the fracture site and skeleton device during each healing phase was calculated. According to the numerical results, the axial stiffness of the device displayed values in the range of 130 -950 N/mm. The effect of the pin length on the construction stiffness was found to be higher than the effect of the distance between pin insertions. It is implied that the load sharing between the stabilization occurred in fixation device and callus during first seven weeks.