Evaluation of a simple and low-cost external fixator

Abstract

Simple external fixation is becoming ever more popular for the treatment of fractures. Current commercially available external fixation devices are complex and expensive, affecting management of injuries in less developed countries. In this study, a new simple and low-cost external fixator called the AG (Alinoor-Goh) fixator, is evaluated biomechanically by direct comparison with a commercially available fixator device (AO). Four modes of loading were applied to each of the fixators: axial compression, anterior-posterior bending, medial-lateral bending, and torsion. The loads were applied directly onto a fractured-bone model made of perspex, which was immobilized by the fixator through six Schanz pins. From this, stiffness values were obtained by plotting load versus displacement. The results from the mechanical testing indicated that in axial compression the AG fixator stiffness was 55.7 +/- 0.197 N/mm (AO fixator was 57.7 +/- 0.186 N/mm); for anterior-posterior bending it was 56.8 +/- 0.153 N/mm (57.4 +/- 0.134 N/mm); for medial-lateral bending it was 11.4 +/- 0.036 N/mm (11.6 +/- 0.053 N/mm); and for torsion it was 1.16 +/- 0.002 N.mm/degree (1.16+/- 0.003 N.mm/degree). No significant difference was found in the stiffness of AG and AO fixators, under all modes of loading. A further comparison in terms of overall design, versatility in application and cost shows the AG fixator to be a viable, inexpensive option for the treatment of long-bone fractures.