OTA 2006 Posters
Scientific Poster #65 Basic Science
Transfixion Wire Variables
Valentin Antoci, MD, PhD (n); Michael Voor, PhD (n);
Valentin Antoci, Jr. (n); Craig Roberts, MD (n);
University of Louisville, Louisville, Kentucky, USA
Purpose: The purpose of this study was to evaluate the influence
of different transfixion wire variables such as wire design (smooth and
olive), olive wire positioning (medially, laterally, posteriorly, and anteriorly),
and tensioning characteristics (tensioning one end or both ends); the relationship
between the crossed wire plane and the bone axis (70, 80, and 90); wire
crossing angles (30-90); wire tension (50-140 kg); wire number (2-5); and
placement of a second level of fixation (2-10 cm) on the stiffness of fine
wire external fixation.
Methods: This study used the fiberglass composite tibias fixed into
an idealized frame. Load deformation behavior was compared under identical
conditions of central axial compression, medial, posterior, posteromedial
compression-bending and torsion. ANOVA followed by post hoc t tests
(P <0.05) were applied to compare the stiffness corresponding
to different wire variables.
Results: Tensioning both ends of the olive wires and positioning
the olives on the side of bending significantly increases bending stiffness.
A reduction in the angle of intersection of crossed olive wire plane with
the bone axis from 90 to 70 increased the overall stiffness twofold. There
was a trend toward increasing overall stiffness with increasing wire crossing
angle from 30 to 90, except medial bending stiffness. Bending stiffness
was a function of the wire positioning with respect to the loading axis.
The wire tension of 140 kg provided the greatest stiffness (P <0.05).
The addition of a second level of external fixation of the proximal tibia
fragment with maximum possible distance between the two levels increases
bending stiffness, while increasing the number of transfixion wires increases
overall stiffness.
Conclusions/Significance: These variables should be used to control
the stiffness of external fixation. Adequate olive wire positioning and
tensioning, adequate crossed olive wire plane with the bone axis, adequate
wire tension, the widest possible wire crossing angle and the wire positioning
closer to loading axis, the addition of a second level of fixation with
maximum possible distance between the two levels, and an increased number
of transfixion wires have to be used to increase the stiffness of external
fixation.
If noted, the author indicates something of value received.
The codes are identified as a-research or institutional support; b-miscellaneous
funding; c-royalties; d-stock options; e-consultant or employee; n-no conflicts
disclosed, and *disclosure not available at time of printing.
·
The FDA has not cleared this drug and/or medical device for the use
described in this presentation (i.e., the drug or medical device is being
discussed for an "off label" use). · · FDA
information not available at time of printing.