Effects of wire tension on the biomechanics of asymmetric four-ring circular external skeletal fixator constructs

A. R. Cross; D. D. Lewis; S. Rigaud; G. B. Mackinzie; A. J. Rapoff

doi:10.1055/s-0038-1632712

Veterinary and Comparative Orthopaedics and Traumatology, Table of Contents

Vet Comp Orthop Traumatol 2002; 15(01): 44-50
DOI: 10.1055/s-0038-1632712

Original Research

Schattauer GmbH

Effects of wire tension on the biomechanics of asymmetric four-ring circular external skeletal fixator constructs

Authors

A. R. Cross

¹Department of Small Animal Clinical Sciences and the Centre for Veterinary Sports Medicine, Gainesville, FL, USA
D. D. Lewis

¹Department of Small Animal Clinical Sciences and the Centre for Veterinary Sports Medicine, Gainesville, FL, USA
S. Rigaud

²The department of Aerospace Engineering, Mechanics and Engineering Science, University of Florida, Gainesville, FL, USA
G. B. Mackinzie

¹Department of Small Animal Clinical Sciences and the Centre for Veterinary Sports Medicine, Gainesville, FL, USA
A. J. Rapoff

²The department of Aerospace Engineering, Mechanics and Engineering Science, University of Florida, Gainesville, FL, USA

Abstract

Summary

This study evaluated the effects of fixation wire tension (0 kg, 30 kg, 60 kg, and 90 kg) on the biomechanics of a four ring asymmetric circular external fixator construct in four testing modes (axial compression, medio-lateral bending, craniocaudal bending, and torsional loading) using a gap fracture model. Wire tension had a significant direct effect on gap stiffness in all of the testing modes. Axial compression load-deformation curves exhibited non-linearity, characteristic of the self-tensioning effect observed with fine wire fixation. Bending loaddeformation curves had two discrete linear segments, attributable to slipping of the bone models on the fixation wires, once a critical bending moment was exceeded. Torsional loading caused a gradual ‘windup’ of the construct which was followed by a linear load-displacement curve. Increasing wire tension had a small but significant effect on gap stiffness, which generally diminished as higher tensions were applied, thus demonstrating the need for adequate initial construct design to achieve sufficient stability during fracture healing.

Keywords

llizarov - Circular External Skeletal Fixator - Biomechanics

Full Text

References

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