A study of calculating Stiffness for an External Fixation side of the Tibia by the Locking Compression Plate Using Finite Element Analysis

Abstract

Surgical treatment for tibia fractures varies based on the fracture's severity and type, with multiple methods available. This article examines the use of locking compression plates (LCP) for external fixation, comparing it to the current unilateral method, which employs a single-sided external fixation device. The study evaluates LCP on three different sides—anterior, lateral, and medial. Using material properties (Young's modulus, Poisson's ratio) as constants and a patient body weight limit of 70 kg, the analysis assesses deformation, stress, and strain via finite element analysis (FEA) to determine the most suitable treatment by evaluating stiffness values and predicting material behavior. In the axial compression test, the anterior installation yielded the best results, with a maximum von-Mises stress of 2,187.00 MPa, a strain of 0.078, and a stiffness of 164.71 N/mm. The torsion test showed a maximum von-Mises stress of 3,705.2 MPa, a strain of 0.104, and a stiffness of 1,759.58 N/mm. The 4-point bending test, with anterior-posterior force applied, resulted in a maximum von-Mises stress of 707.1 MPa, a strain of 0.004, and a stiffness of 2,916.67 N/mm, while the lateral-medial test yielded a maximum von-Mises stress of 356.1 MPa, a strain of 0.018, and a stiffness of 2,258.06 N/mm. These stiffness values were higher than those of the unilateral method, which ranged from 117 to 126 N/mm. Compared to the model by T. Wisanuyotin et al., which showed an average of 10% less deformation, we can conclude that the anterior locking plate installation model is suitable for surgical treatment of tibia fractures. The smaller deformation results in less bone movement, promoting faster healing. This beneficial effect provides a valuable guideline for further treatment.