Biomechanical analysis of two external fixation methods for management of AO/OTA 42A3 type tibial fractures using finite element analysis

To compare the biomechanics of two external fixation methods—the externally applied locking plate and the unilateral external fixator—for treating AO/OTA 42A3 type tibial fractures using finite element analysis, and to provide a theoretical reference for clinical application. Using CT data from the left tibia of a healthy male volunteer, a three-dimensional model of a normal tibia was reconstructed using Mimics, Geomagic Studio, HyperMesh, MSC Patran, and MSC Nastran software. Based on this model, modifications were made to construct a tibial fracture model of type AO/OTA 42A3. Using this fracture model, finite element models of an external locking plate and a unilateral external fixator were established and meshed. Four different tests were simulated: four-point bending, axial compression, clockwise torsion, and counterclockwise torsion. The maximum stress and maximum displacement of the two fixation methods under different conditions were compared. Under the four different testing conditions, it was found that the locking plate fixation exhibited a higher peak equivalent stress but a lower peak overall tibial displacement compared to the unilateral external fixator, at the respective maximum loads. The locking plate showed better global deformation control but higher stress concentrations than the external fixator, with both sensitive to torsion. Results highlight mechanical differences and risks, but clinical use requires further validation.