A biomechanical analysis of the Ilizarov external fixator

The objective of the present study is the construction of a reliable numerical model of the standard Ilizarov fixator that will permit a detailed parametric investigation of various factors influencing the effectiveness of the technique. Mechanical tests of a standard Ilizarov frame were performed under axial and torsional loads. To eliminate the pretension loss due to wire slippage metal nuts with M1.8 thread were manufactured. A numerical analysis followed based on the Finite Element Method. The model constructed simulated accurately all the geometrical details of the experimental model, the load application mode (axial and torsional) and the mechanical characteristics of the materials used to assemble the frame. Comparison of the predictions of the model with the respective experimental data yields excellent agreement for the case of tension and rather satisfactory one for torsion.