The effect of clamping a tensioned wire: implications for the Ilizarov external fixation system

Michael Andrew Watson, K. J. Matthias, David William Laurence Hukins, N. Maffulli

    Research output: Contribution to journalArticle

    25 Citations (Scopus)

    Abstract

    This study demonstrates that clamping a tensioned wire can cause a reduction in wire tension. Tension (about 1275 N) was applied to a wire that was subsequently clamped, using cannulated bolts, to the steel half-ring of an Ilizarov external fixator. The tension in the wire was monitored before, during and after clamping. The apparatus was disassembled and the deformations in the wire caused by the clamps were measured. This experiment was repeated 15 times. When the wire was clamped to the frame, the wire tension was reduced by 22 +/- 7 per cent (mean +/- standard deviation, SD). The drop in wire tension was linearly correlated (r = 0.96; p < 0.001) with the deformation caused by the bolts. A finite element (FE) model of the wire was also constructed. The model was pre-stressed (tensioned), and the clamping effect replicated. This analysis showed that clamping the wire could be considered to squeeze the wire outwards (like toothpaste from a tube) and so reduce its tension during fixator assembly. To assess the magnitude of this effect in the clinical situation, the FE model analysis was repeated to replicate clamping a 1.8-mm-diameter wire to a 180-mm-diameter steel Ilizarov ring component. The analysis showed that for these conditions the tension reduced by 8-29 per cent. The results of this study highlight a general engineering problem: how can a tensioned wire be secured to a structure without an appreciable loss of tension?. If the performance of the structure depends on the wire tension, this performance will change when the wire is secured.

    Original languageEnglish
    Pages (from-to)91-98
    Number of pages7
    JournalProceedings of the Institution of Mechanical Engineers. Part H, Journal of Engineering in Medicine
    Volume217
    Issue number2
    DOIs
    Publication statusPublished - 2003

    Keywords

    • Ilizarov
    • external fixation
    • wire tension
    • FIXATORS
    • FRACTURES

    Cite this

    The effect of clamping a tensioned wire: implications for the Ilizarov external fixation system. / Watson, Michael Andrew; Matthias, K. J.; Hukins, David William Laurence; Maffulli, N.

    In: Proceedings of the Institution of Mechanical Engineers. Part H, Journal of Engineering in Medicine, Vol. 217, No. 2, 2003, p. 91-98.

    Research output: Contribution to journalArticle

    Watson, Michael Andrew ; Matthias, K. J. ; Hukins, David William Laurence ; Maffulli, N. / The effect of clamping a tensioned wire: implications for the Ilizarov external fixation system. In: Proceedings of the Institution of Mechanical Engineers. Part H, Journal of Engineering in Medicine. 2003 ; Vol. 217, No. 2. pp. 91-98.
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