Title of the study: finite element analysis of five internal fixation modalities for Schatzker type IV‒C tibial plateau fractures.

Background: This study aims to evaluate the biomechanical performance of five different internal fixation strategies for Schatzker type IV-C tibial plateau fractures using three-dimensional finite element analysis. By analyzing stress distribution and displacement patterns under physiological load, we seek to identify optimal fixation modalities for clinical application.

Methods: We established a three-dimensional finite element model of Schatzker IV-C tibial plateau fractures and evaluated five internal fixation modalities via finite element analysis. These modalities included a medial plate (Model 1), a medial plate with two posterior tension screws (Model 2), a medial plate with two lateral tension screws (Model 3), a posterior medial double plate (Model 4), and a medial lateral double plate (Model 5). To simulate the biomechanics of unilateral knee axial compression during normal adult gait, an axial force of 1,200 newtons (N) was applied, with 60% of the force distributed to the medial plate. We comprehensively analyzed equivalent von Mises stresses, displacements, and equivalent stress-displacement plots for each fixation.

Results: Model 5 demonstrated the best overall performance in terms of internal fixation stress (91.46 MPa) and fracture block stress (10.826 MPa), suggesting optimal stress distribution and fracture block protection. Model 3 performed best in terms of internal fixation displacement (4.391 mm), suggesting an advantage in fracture block stability. While the models performed well in several areas, the double plate fixation scheme was superior in terms of stress distribution and fracture stability. It is ideal for managing complex fractures.

Conclusions: A single medial plate (Model 1) provides adequate fixation and stability for fractures without the lateral intercondylar ridge. Lag screws with the medial plate (Models 2 and 3) effectively reduce stress and minimize trauma. Double plate on the posterior medial side (Model 4) significantly enhances fixation and prevents displacement for complex fractures. Medial-lateral double plate fixation (Model 5) provides the most favorable biomechanical stability for fractures with extensive lateral plateau comminution. However, balance the benefits against increased complexity, particularly in patients with compromised soft tissue or high functional demands. Selecting internal fixation based on the fracture line can optimize outcomes and speed recovery.