Title: A Comparative Study of Wire Fixation and Screw fixation in Arthrodesis for the Correction of Hallux Rigidus Using an In Vitro Biomechanical Model
Authors: Adnan A. Faraj F.R.C.S (orth.),M.Ch. (orth.), Asheem Nareen, F.R.C.S, Peter Twig, Ph. D.
Source: Foot and Ankle International, January 2007; 1:88-91.
PODIATRIC RELEVANCE:
Internal fixation is used in arthrodesis of the great toe joint. Fixation techniques and devices, according to the authors, has become a controversial topic. This study compares methods of fixation for stability and reproducibility. Cerclage wire fixation is compared to screw fixation.
METHODS:
In this article, the bones of the metatarsal phalangeal joint were simulated by using a 25 mm nylon extruded rod. This 125 mm long rod was cut perpendicular to the long axis into a 50 mm long capital fragment and a 70 mm long base. The base was welded to a metal plate for stability. The nylon capital fragment was attached to the base using either a screw or Cerclage wire technique. An Instron 430 Materials testing machine was used to apply a bending moment 20 mm from the fixation site. Stress versus load was measured along the axis of the nylon rod at several positions. The bone analog was tested to failure.
RESULTS:
A Force applied by the materials testing machine was plotted against displacement of the bone analog. The authors describe “elastic stiffness,” the initial straight line segment of the load vs. displacement curve and; “inelastic stiffness,” the curvilinear portion of the curve, as measures of stiffness. Screw fixation was found to be stronger and more rigid than wire fixation. However, the authors argue that Cerclage wiring may be useful less rigidity and greater accommodation to vertical stress is needed.
COMMENTS:
The following were not reported: Diameter of the wire, screw diameter and size, the number of trials conducted with each device, the total number of trails, and the method of wire or screw application. The discussion concludes that wire fixation may be better on speculative grounds.
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Disclaimer:
Scientific Abstract Monthly postings are submitted by podiatric surgical residents. The ideas presented are not the opinions of the American College of Foot and Ankle Surgeons (ACFAS), nor are they presented as facts. ACFAS presents this information without any warranty of any kind, expressed or implied, and is not liable for its accuracy nor for any loss or damage caused by the user's reliance on information obtained in these areas.