Abstract
Background
The biomechanical effect of indirect weight loading with the Ilizarov ring fixator
using a weight-bearing platform has not yet been investigated. The problem of wire
loosening and breakage occurs more frequently when patients are mobilised with a weight-bearing
platform. Therefore, the aim of this research was to compare the influence of direct
and indirect weight loading on the tensioned wires.
Method
A universal testing machine (UTS, Germany) was used in this study. A composite tibia
model with a standard four-ring Ilizarov fixator and 1.8-mm wires in anatomical position
was used to simulate a clinical situation. Wire strain was measured with two strain
gauges positioned at the ring–wire interface of each wire. After a standardised 2-mm
mid-diaphyseal osteotomy, an axial load of up to 1000 N was applied to the bone; the different methods of weight loading were evaluated
in two experimental set-ups.
Results
A higher axial load was necessary to achieve an osteotomy gap closure at indirect
loading. Mechanical stress on the tensioned wires was 400% higher on the proximal
wires and 250% higher on the distal wires at a maximum axial loading of 1000 N. Mechanical stress remained on the wires in indirect loading, even after bone end
contact, and led to excessive stress under higher weight-bearing amounts.
Conclusion
There is a substantial change in the biomechanical characteristics of the Ilizarov
ring fixator when mobilising a patient with a weight-bearing platform. The considerable
higher mechanical stress on the wires needs to be considered when patients are mobilised
with a weight-bearing platform.
Keywords
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References
- Mechanical considerations in using tensioned wires in a transosseous external fixation system.Clin Orthop Relat Res. 1992; : 23-29
- Stability of external circular fixation: a multi-variable biomechanical analysis.Clin Biomech (Bristol, Avon). 1998; 13: 441-448
- Mechanical validation of whole bone composite tibia models.J Biomech. 2000; 33: 279-288
- Ilizarov wire tensioning and holding methods: a biomechanical study.Injury. 2003; 34: 151-154
- Mechanical performance of external fixators with wires for the treatment of bone fractures—Part II. Wire tension and slippage.J Biomech Eng. 1993; 115: 37-42
- Mechanical behavior of Ilizarov ring fixators. Effect of frame parameters on stiffness and consequences for clinical use.Unfallchirurg. 2000; 103: 839-845
- A biomechanical analysis of the Ilizarov external fixator.Clin Orthop Relat Res. 1989; : 95-105
- Arthrodesis of the infected ankle joint: results with the ilizarov external fixator.Z Orthop Unfall. 2010;
- The yielding of tensioned fine wires in the Ilizarov frame.Proc Inst Mech Eng H. 1998; 212: 37-47
- Clinical application of the tension-stress effect for limb lengthening.Clin Orthop Relat Res. 1990; : 8-26
- The biomechanics of wire fixation in the Ilizarov system.Injury. 2003; 34: 155-157
- Relationship between locking-bolt torque and load pre-tension in the Ilizarov frame.Injury. 2006; 37: 941-945
- Biomechanics of the Ilizarov external fixator.in: Bianchi Maiocchi A. Aronson J. Operative principles of Ilizarov. Medi Surgical Video, Milano1991: 33-41
- Treatment of malunion and nonunion at the site of an ankle fusion with the Ilizarov apparatus. Surgical technique.J Bone Joint Surg Am. 2006; 88: 119-134
- The Ilizarov fixator in trauma: a 10-year experience.J Orthop Sci. 2000; 5: 108-113
- Mechanical performance of Ilizarov circular external fixators in comparison with other external fixators.Clin Orthop Relat Res. 1993; : 61-70
- The Ilizarov external fixator: what remains of the wire pretension after dynamic loading?.Clin Biomech (Bristol, Avon). 2005; 20: 1126-1130
- Yielding of the clamped-wire system in the Ilizarov external fixator.Proc Inst Mech Eng H. 2003; 217: 367-374
- Geometric and material nonlinearity in tensioned wires of an external fixator.Clin Biomech (Bristol, Avon). 2004; 19: 513-518
Article info
Publication history
Accepted:
February 8,
2011
Identification
Copyright
© 2011 Elsevier Ltd. Published by Elsevier Inc. All rights reserved.
