A simple way to model wires used in ring fixators: Analysis of the wire stiffness effect on overall fixator stiffness

Abstract

The Ilizarov fixator has become widely used in the treatment of complex trauma and deformity correction in the United Kingdom over the last few decades. As such, it has been widely researched. Within this fixator, the characteristic fine wires are the weakest and most flexible component. The wires allow interfragmentary micromotion, which is believed to be beneficial to bone healing. In this paper, a novel and simple numerical model of the stiffness and deflection of the wires when the fixator is subject to axial and torsional loading is presented. A range of wire lengths and pretensions are analysed, and the results compared to the findings of other researchers, with generally good agreement. This indicates that fixator stiffness can be determined simply and without recourse to sophisticated finite element analyses or extensive physical testing. In addition, the model is used to predict the contribution of the wires to the overall stiffness of the fixator.

Rapid pre-tension loss in the Ilizarov external fixator: An in vitro study

“…The Ilizarov system has proven successful for the treatment of complicated fractures and limblengthening procedures (Marsh et al 1997, Arazi et al 2001, Ramesh et al 2004, Nikonovas et al 2005, Sardis et al 2006.…”

Reduction in wire tension caused by dynamic loading. An experimental Ilizarov frame study

“…The wire diameters are relatively small, thereby possessing insufficient transversal stiffness to stabilize the bony structures during healing. Transversal stiffness can, however, be increased by tensioning the wire before clamping it to the ring (Aronson, 1990(Aronson, , 1997Board et al, 2007;Catagni, 1998;Nikonovas and Harrison, 2005;Paley, 1988;Watson et al, 2000;Wosar et al, 2002).…”

Wire tension versus wire frequency: An experimental Ilizarov frame study

“…1.8 mm, thereby holding a relatively low bending stiffness. However, the bending stiffness is increased by tensioning the wires before they are clamped to the ring (Aronson, 1990(Aronson, , 1997Board et al, 2007;Catagni, 1998;Nikonovas and Harrison, 2005;Paley, 1988;Watson et al, 2000;Wosar et al, 2002). This tension is an important factor to maintain fixator stability (Aronson and Harp, Jr., 1992;Catagni, 1998;Ilizarov, 1990;Kummer, 1992;Mullins et al, 2003).…”