Finite Element Analysis of Von Mises Stress in External Fixators for Open Tibial Fractures: A Comparative Study of ASTM F1541-02 and Tibia-Based Models in Indonesian Patients.

Traffic accidents are the leading cause of traumatic fractures worldwide, with tibial fractures being the most common lower-extremity injury. Open tibial fractures pose significant clinical challenges due to their high risk of infection and non-union, requiring effective stabilisation. External fixators are widely used for this purpose, but their biomechanical performance must be evaluated under both standardised and patient-specific conditions. This study presents a finite element analysis of an external fixator tailored to Indonesian patients, using two frameworks: the ASTM F1541-02 standard protocol and a tibia-based model derived from patient geometry. Von Mises stress distributions were assessed under axial compression, torsional loading, and four-point bending. Results showed that stresses predicted by ASTM F1541-02 were consistently higher than those from the tibia-based model, particularly under torsion and bending, though all values remained below material yield strength. These findings indicate that the fixator design is safe, while emphasising that tibia-based modelling provides more physiologically realistic predictions. The study shows the importance of patient-specific anatomy in computational biomechanics and points to future directions in design optimisation and localized manufacturing.