EVALUATION OF A SIMPLE AND LOW-COST EXTERNAL FIXATOR

Simple external fixation is becoming ever move popular for the treatme nt of fractures. Current commercially available external fixation devi ces are complex and expensive, affecting management of injuries in les s developed countries. In this study, a new simple and low-cost extern al fixator called the AG (Alinoor-Goh) fixator, is evaluated biomechan ically by direct comparison with a commercially available fixator devi ce (AO). Four modes of loading were applied to each of the fixators: a xial compression, anterior-posterior bending, medial-lateral bending, and torsion. The loads were applied directly onto a fractured-bone mod el made of perspex, which was immobilized by the fixator through six S chanz pins. From this, stiffness values were obtained by plotting load versus displacement. The results from the mechanical testing indicate d that in axial compression the AG fixator stiffness was 55.7 +/- 0.19 7 N/mm (AO fixator was 57.7 +/- 0.186 N/mm); for anterior-posterior be nding it was 56.8 +/- 0.153 N/mm (57.4 +/- 0.134 N/mm); for medial-lat eral 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/degrees (1.16 +/- 0.003 N.mm/degre es). No significant difference was found in the stiffness of AG and AO fixators, under all modes of loading. A further comparison in terms o f overall design, versatility in application, and cost shows the AG fi xator to be a viable, inexpensive option for the treatment of longbone fractures. (C) 1997 Elsevier Science Ltd.