Finite element analysis of five internal fixation strategies for Schatzker IV tibial plateau fractures

Abstract

BACKGROUND: Schatzker IV tibial plateau fractures are highly challenging due to their involvement of the primary weight-bearing area and high rate of soft tissue complications. Although traditional double plating provides mechanical stability, it violates the minimally invasive principle and is associated with more postoperative complications, especially in elderly patients or those with high-energy trauma. Currently, there is a lack of an internal fixation strategy that can meet both mechanical stability and minimally invasive requirements. OBJECTIVE: To establish a three-dimensional model of Schatzker IV tibial plateau fractures using the finite element method and compare the biomechanical stability of five fixation methods to provide an optimal surgical option for the treatment of Schatzker IV tibial plateau fractures. METHODS: A healthy male volunteer underwent knee CT scanning, and a Schatzker IV tibial plateau fracture model was constructed using finite-element software. Five internal-fixation configurations were defined as Groups A, B, C, D, and E. Group A: isolated medial plate; Group B: medial plate plus two posteromedial tension screws; Group C: medial plate plus two lateral tension screws; Group D: posteromedial double plating; Group E: medial-lateral double plating. Under identical boundary and constraint conditions, finite-element analysis software was employed to evaluate the biomechanical performance of five internal fixation models. RESULTS AND CONCLUSION: Finite element analysis showed that minimally invasive combinations (Groups B and C) had comparable overall biomechanical performance to traditional double plating. Group B was an ideal choice for elderly patients, as it had the lowest fracture fragment stress (9.0392 MPa), which could effectively prevent osteoporosis-related collapse, and the percutaneous screw technique reduced the risk of soft tissue complications. Group C showed potential in young patients, benefiting from the smallest implant displacement (4.388 mm), providing excellent stability, and the lateral tension screws avoided neurovascular injury associated with the posteromedial approach.

1. Introduction

As a common intra-articular injury, tibial plateau fractures exhibit a bimodal age distribution: young individuals often sustain high-energy trauma (e.g., traffic accidents, falls from height), while elderly populations mainly suffer low-energy injuries (e.g., falls) closely related to osteoporosis [1-3]. This evolution of age distribution and injury mechanisms imposes differentiated requirements on clinical treatment strategies—meeting the high demand for mechanical stability in young patients while addressing the need for minimally invasive approaches and low complication rates in the elderly.

Schatzker IV tibial plateau fracture is a specific high-energy injury type, accounting for 10%-30% of all tibial plateau fractures [4-6]. It is characterized by splitting or collapse of the medial plateau, often caused by varus and internal rotation forces applied during knee flexion, leading to depression of the medial tibial plateau by the femoral condyle and producing a coronal fracture line perpendicular to the long axis of the tibia [7]. Unlike Schatzker I-III types (lateral plateau injuries), type IV fractures involve the primary weight-bearing area of the knee (the medial plateau bears approximately 60% of body weight) and are often combined with coronal knee dislocation, significantly increasing treatment complexity [8-9]. Moreover, the most severe challenge of Schatzker IV fractures lies in the extremely high rate of soft tissue complications [10-12]; imaging and intraoperative exploration confirm ligament injury rates of 77%-100%, meniscal tear rates exceeding 80%, and a high risk of neurovascular injury [13-15].

However, treatment strategies for Schatzker IV fractures remain controversial [16-18], with the core conflict centered on balancing mechanical stability and minimally invasive principles [19]. Traditional concepts hold that plate-screw systems provide greater stability than screws alone, and combined plates offer excellent mechanical stability through multiplanar fixation; hence, double plating (posteromedial or medial-lateral) is commonly used clinically. Nevertheless, extensive surgical exposure increases intraoperative blood loss by 40% and elevates wound complication rates to 18%-25%, particularly adverse for elderly patients or those with high-energy trauma and poor soft tissue conditions [20-21]. Therefore, to address the clinical dilemma of 'mechanical stability versus minimally invasive' in Schatzker IV fractures, this study introduces finite element biomechanical analysis to systematically evaluate the comprehensive efficacy of five internal fixation strategies: isolated medial locking plate (Group A), medial plate plus posteromedial tension screws (Group B), medial plate plus lateral tension screws (Group C), posteromedial double plating (Group D), and medial-lateral double plating (Group E).