Abstract
Aim
The aim of the present study was to compare the primary fixation stability and initial
fixation stiffness of two established fixation techniques, the tension band wiring
technique and interfragmentary screw fixation, with a mini-screw fragment fixation
system in a model of transverse patella fracture. It was hypothesised that the biomechanical
loading performance of the fragment fixation system would not significantly differ
from the loading characteristics of the two established methods currently investigated.
Materials and methods
Ninety-six calf patellae were used in this biomechanical model. A standardized transverse
patella fracture was induced and three different fixation methods, including the modified
tension band wiring technique, interfragmentary screw fixation, and the mini-screw
fragment fixation system, were used for fragment fixation. Specimens were mounted
to a loading rig which was secured within a material testing machine. In each fixation
group, eight specimens were loaded to failure at a simulated knee angle of either
0° or 45°. Another eight specimens were submitted to a polycyclic loading protocol
consisting of 30 cycles between 20 N and 300 N at a simulated knee angle of 0° or 45°. The residual displacement between the first
and the last cycle was recorded. Differences in the biomechanical performance between
the three fixation groups were evaluated.
Results
No significant differences between the three fixation groups were observed in the
parameters maximum load to failure and linear fixation stiffness with monocyclic loading.
Specimens being loaded at 45° showed significantly lower maximum failure loads and
linear stiffness when compared with 0°. During polycyclic loading, no significant
differences in the residual displacement were observed between the groups at 0° loading
angle, while at 45°, residual displacement was significantly higher with tension band
fixation when compared with interfragmentary screw fixation or the fragment fixation
system.
Conclusion
The biomechanical performance of the fragment fixation system was comparable to interfragmentary
screw fixation and superior to the tension band wiring technique. Given the advantages
of a system which provides interfragmentary compression and which simplifies fracture
fixation after open or closed reduction, we believe the fragment fixation system to
be an adequate alternative in the osteosynthesis of transverse patella fractures.
Keywords
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Article info
Publication history
Accepted:
July 13,
2009
Identification
Copyright
© 2009 Elsevier Ltd. Published by Elsevier Inc. All rights reserved.
