COMPARATIVE BIOMECHANICAL EVALUATION OF DIFFERENT EXTERNAL FIXATION SIDEBARS - STAINLESS-STEEL TUBES VERSUS CARBON-FIBER RODS

Carbon fiber rods were developed to provide radiolucent sidebars for e xternal fixation. In the present study, a single-plane, half-pin, doub le-bar external fixator construct with either stainless-steel tubes or carbon fiber rods was applied on the anteromedial surface of an osteo tomized synthetic human tibia and evaluated for fixation rigidity. Tes ting was performed with the bone fragments in cortical contact and wit h a 5-mm midshaft gap between the fragments. The sidebars then were lo aded to failure in bending. The results of this study show (a) that th e carbon fiber rods were 15% stiffer than the stainless-steel tubes (p = 0.009) and (b) that the external fixator with carbon fiber rods ach ieved similar to 85% of the fixation stiffness of the external fixator with stainless-steel tubes. The loss of stiffness of the external fix ator with carbon fiber rods is most likely due to the clamps being les s effective in connecting the carbon fiber rods rigidly to the Schanz screws.