Ilizarov wire tensioning and holding methods: a biomechanical study

Davidson, A.W.; Mullins, M; Goodier, David; Barry, Matthew

doi:10.1016/s0020-1383(02)00045-1

Cited by 19 publications

(10 citation statements)

References 8 publications

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“…Any change in mounting parameters or osteotomy patterns directly influences the biomechanical conditions at the defect site [23,24]. The effects on frame stiffness of various mounting parameters (e.g., ring size, wire/half-pin diameter, number of wires/half-pins/rings) have been analyzed previously [6,12,23,25]. Therefore, the two frames were mounted as they are used in clinical practice with the wires and half-pins positioned with respect to the anatomic constraints of the tibia.…”

Section: Discussionmentioning

confidence: 99%

The influence of a weight-bearing platform on the mechanical behavior of two Ilizarov ring fixators: tensioned wires vs. half-pins

et al. 2011

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BackgroundA weight-bearing platform applied at the distal end of an Ilizarov external frame allows patients with hindfoot transfixations, foot deformities or plantar skin lesions to bear weight. This leads to an indirect loading of the fracture or osteotomy site. However, the effect on the fracture/osteotomy site's motion or compressive loads is unknown. The aim of this study was to analyze the mechanical effects of a weight-bearing platform on the traditional all-wire, four-ring frame in comparison to a two-ring frame consisting of half-pins.MethodsTwo frame configurations, with either anatomically positioned wires or half-pins, were analyzed with and without a weight-bearing platform applied underneath the distal ring. Composite tibiae with a mid-diaphyseal osteotomy of 3.5 mm were used in all the experiments. An axial load was applied with the use of a universal test machine (UTS®). Interfragmentary movements, the relative movements of bone fragments and movements between rings were recorded using displacement transducers. Compressive loads at the osteotomy site were recorded with loading cells.ResultsIndirect loading with a weight-bearing platform altered the force transmission through the osteotomy. Indirect loading of the tibiae decreased the extent of the axial micro-motion by 50% under the applied weight load when compared to direct weight loading (p < 0.05). The half pin frame was 25% stiffer than the wire frame under both direct and indirect loading of the tibiae (p < 0.05). Compressive loads under indirect loading were reduced by 67% in the wire frame and by 57% in the half-pin frames compared to direct loading of the bones (p < 0.05). While axial loading in the wire frames resulted in plain axial movements at the site of the osteotomy, it was coupled with translational movements and angular displacements in the half pin mountings. This effect was more apparent in the case of indirect loading.ConclusionsA weight-bearing platform has substantial influence on the biomechanical performance of an Ilizarov external fixator. Half-pins induce greater stiffness to the Ilizarov external fixator and allow the usage of only one ring per bone segment, but shear stresses at the osteotomy under axial loading should be considered. The results allow an estimation of the size and direction of interfragmentary movements based on the extent of weight bearing.

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Section: Discussionmentioning

confidence: 99%

The influence of a weight-bearing platform on the mechanical behavior of two Ilizarov ring fixators: tensioned wires vs. half-pins

et al. 2011

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“…The biomechanical principle of the Ilizarov external fixator relies on axial compressive loads and micromotions that occur on weight loading [4, 5, 11]. Ilizarov and other authors recommend mobilisation of the patients with full weight bearing when treated with the Ilizarov external fixator [15–17], and the beneficial effects have been shown in vivo during distraction osteogenesis [18].…”

Section: Discussionmentioning

confidence: 99%

Direct and indirect loading of the Ilizarov external fixator: the effect on the interfragmentary movements and compressive loads

Geßmann¹,

Baecker²,

Jettkant³

et al. 2011

Strategies in Trauma and Limb Reconstruction

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The amount of weight bearing and the force transmission to the frame have an important influence on the results of treatment with an Ilizarov external fixator. The frame provides beneficial interfragmentary movements and compressive loads at the fracture site through elastic wires. Mobilisation can be achieved by applying a weight-bearing platform at the distal end of the fixator. The effect on the interfragmentary movements and the compressive loads in indirect and direct loading were analysed in this study using a composite tibia bone model. Displacement transducers were attached to measure the interfragmentary movements and to detect relative movements of the bone fragments and movements between the rings. The compressive loads in the osteotomy were measured with loading cells in the defect zone. The weight-bearing platform had a substantial effect on the biomechanical behaviour of the frame. It led to an indirect force transmission through the fixator with respect to the osteotomy, resulting in lower compressive loads, lower interfragmentary movements and higher mechanical stress on the frame.

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“…Finally, as has been noted throughout previous Ilizarov work, the precise interaction between wire pretension loss, non-90-90 wire positioning, and bolt torque has not been defined (Renard et al, 2005;Vijayakumar et al, 2006;Yang et al, 2003). The effect of wire plastic deformation, wire slippage, frame deformation, and the simple choice between slotted versus cannulated wire fixation bolts are still areas of study (Aronson and Harp, 1991;Davidson et al, 2003;Zhang, 2004).…”

Section: Discussionmentioning

confidence: 99%