Comparison
of 3.5 mm and 4.5 mm cortical syndesmotic
screw pull out strength.
Hansen, M, Long, Le, Wertheimer, S, Meyer, E, Haut, R.
Abstract:
The purpose of this sawbone study
was to compare the pull out strength of 3.5 mm and 4.5 mm quadricortical
syndesmotic screws under axial loading of the distal sydesmosis. A servohydraulic materials testing machine
was used to test the pull out strength of 18 specimens that were fixated with
one syndesmotic screw. A statistical
analysis was then performed to ascertain if any significant relationship exists
between syndesmotic screw size and pull out strength. The 4.5 mm cortical
syndesmotic screws produced a higher yield load and ultimate load (484.3 ± 93.8
N and 597.7 ± 81.4 N) when compared to 3.5 mm cortical syndesmotic screws
(412.8 ± 55 N and 511.2 ± 64.4 N).
Under circumstances in which patients are unable to be non-weightbearing
post-operatively, this study suggests that a 4.5 mm cortical screw provides
greater strength than a 3.5 mm cortical screw when axial loading is applied to
the distal syndesmosis.
Orthopaedic Biomechanics Laboratories,
College
of Osteopathic Medicine,
Michigan
State University,
East Lansing,
Michigan 48824
Please address correspondence to:
Roger C. Haut, Ph.D.,
Orthopaedic Biomechanics Laboratory,
College
of Osteopathic Medicine,
A414 East
Fee Hall,
Michigan
State University,
East Lansing,
MI 48824,
Tel: (517)355-0320,
Fax: (517)353-0789,
E-mail:
haut@msu.edu