FE parametric analysis of nonlinear mechanical behaviour of Ilizarov external fixator

The study describes a computational approach for predicting the mechanical response of different configurations of the Ilizarov external fixation system. The Ilizarov type fixators are now being used to an increasing extend to stabilize bone fractures and for limb lengthtening [5,6] and its functions are investigated using numerical [e.g. 3,7] and experimental [e.g. 1,2] techniques. The device is a specialized form of external fixator, modular in construction. Stiff rings are fixed to the bone via wires (called pins or Kirschner wires). The rings are connected to each other with adjustable rods. The circular construction and tensioned wires of the Ilizarov apparatus provide better structural support than the traditional monolateral stabilizers. This allows early weightbearing. The stabilization enables a degree of movement between the connected bone parts, and , under some conditions, this is considered as beneficial to the healing process. The stiffness characteristics of the device are , therefore, crucial to bone healing [3,5,7]. Computational parametric modelling used in the work can provide some information about the influence of different configurations of the fixator and its parameters on the mechanical behaviour of the device without the need for a laborious and time-consuming experimental testing.