Journal article
Mechanical Analysis of the Factors Affecting Dynamization of the Orthofix Dynamic Axial Fixator
Journal of orthopaedic trauma, Vol.4(4), pp.449-457
12/1990
DOI: 10.1097/00005131-199004000-00014
PMID: 2266452
Abstract
SummaryLoading trials were conducted to identify mechanical factors affecting dynamization of a commercially available external fixator (Orthofix) that is designed to undergo free telescopic motion when axially loaded. Angular variations between the proximal and distal screw clamps and the telescoping fixator body failed to produce fixator binding (failure to dynamize) in any of the loading trials. However, binding was produced by applying external torques in magnitudes that occasionally occur during routine ambulation. The specific torque necessary to induce binding (typically 3–4 Nm) was only a weak function of axial load magnitude, axial loading frequency, or simulated fracture stiffness. Among several geometrical variables of fixator application, only the pre-extension of the telescoping body and circumferential misalignment between proximal and distal pin clusters had an appreciable influence on the threshold binding torque. Axial fixator motions were also monitored in a small adjunct clinical series of 22 dynamized tibial fractures. The fixator dynamized appropriately in 15 cases (68%). Three patients (14%) showed evidence of fixator binding, and another four (18%) had less than predicted slider excursions. The role of several design factors implicated in torque-induced fixator binding is discussed in light of the benchtop and clinical observations.
Details
- Title: Subtitle
- Mechanical Analysis of the Factors Affecting Dynamization of the Orthofix Dynamic Axial Fixator
- Creators
- Jeffrey Ralston - Department of Orthopaedic Surgery, University of Iowa, Iowa City, Iowa, U.S.AThomas BrownJames NepolaDiana WilliamsJ Marsh
- Resource Type
- Journal article
- Publication Details
- Journal of orthopaedic trauma, Vol.4(4), pp.449-457
- Publisher
- Lippincott-Raven Publishers
- DOI
- 10.1097/00005131-199004000-00014
- PMID
- 2266452
- ISSN
- 0890-5339
- eISSN
- 1531-2291
- Language
- English
- Date published
- 12/1990
- Academic Unit
- Orthopedics and Rehabilitation
- Record Identifier
- 9984040376102771
Metrics
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