Three-dimensional Finite Element Analysis Of Fixation Of Tibial Plateau Fractures With New Network External Fixator

Background and ObjectiveTibial plateau fractures are common, complicated intra-articular fractures, often due to severe injuries. They may also be seen in seniors with minor injuries. With the rapidly aging population, increasing high-speed traffic accidents, and the development of construction industry, cases of severe tibial plateau fractures are increasing.Tibial plateau fractures have several different categories with various kinds of treatment methods. The treatment of tibial plateau fractures has always been a difficult key issue. Inappropriate treatment may result in traumatic arthritis, instability of knee joints and dysfunction of knee joint. Over the past several decades, national and international researchers have had different opinions about the treatment and prognosis of tibial plateau fractures; and there has been no agreed best treatment method. It has been reported in the literature that open reduction and internal fixation may result in high complications because of extensive soft tissue dissection. The development and application of external fixator provides a promising solution for this problem. High infection rate and soft tissue complications can decrease remarkably with the micro invasive technique of reduction and percutaneous fixation and assistant of arthroscopy. However, the external fixators currently used usually have a complicate design with a unwieldiness shape and limited small tensioned wires. Hence,we designed a new external fixator that not only supports the collapsed fragments for dispersion of stress, but also serves as an elastic biological fixation with it's network wire structure. Biomechanical tests showed that the new external fixator has superior mechanical properties compared to fixators with plates and screws. Installation of the new external fixator during the simulated surgery in cadaver and the security evaluation showed it's feasibility in clinical applications.To better estimate mechanical efficiency of the new network external fixtor and compare with the biomechanics study of in vitro sample, a three-dimensional finite element model (FEM) of tibial plateau fractures fixed with the new external fixtor and lateral locking plate is established,to determine if the design is reasonable and how to improve and optimize it in the next step. The results from FEM are analyzed and discussed to evaluate the design of the external fixtor.MethodsA healthy man of 20-30 years old was chosen to obtain images of the middle-upper segment tibia using SCT scan. Normal x-ray photographs were analyzed to make sure he had no bone diseases. A three-dimensional finite element model (FEM) of tibial plateau was then developed using Mimics10.01 digital interactive 3D medical image software and ANSYS10.0 finite element analysis software. Based on this, a fracture model of tibial plateau (type 41-B1) was then established; and the FEM of the new external fixator and lateral locking plate is integrated into the fracture model to set boundary and load conditions for carrying out biomechanical analysis.ResultsThree-dimensional finite element models of tibial plateau fractures and the new network external fixator and lateral locking plate were established. Three-dimensional finite element analysis of biomechanics was carried out. The results indicate that the design of the new network external fixator is consistent with the biomechanics principle and can meet the need of fixation of tibial plateau fractures with good rigidity and stability.ConclusionsIt is effective and feasible to establish a three-dimensional finite element model of tibial plateau based on computer data from a living body with SCT tomoscan. The three-dimension FEMs of tibial plateau fractures and the new network external fixator are realistic and objective, and can reflect geometrical structures. This study represents the first time one was able to estimate the mechanical features of external fixators in tibial plateau fractures in China. The result from this study is consistent with biomechanis principles and the new external fixator has reliable stability, intensity and rigidity and can be used in clinic applications.