[Finite element analysis of the initial stability of subtalar arthrodesis with double-screw fixation].

Objective To assess the optimal configuration of double-screw fixation for subtalar arthrodesis using finite element analysis.Methods Three-dimensional finite element double-screw models of subtalar arthrodesis were reconstructed using Mimicsl3.0,GeomagiclO.O and solidworks software based on the 3-D images of the volunteer's right foot.The external and internal rotation torques of 4 N ? m were applied,and the micromotions at the bone-to-bone interface were measured to evaluate the initial stability of subtalar arthrodisis.Results A neck screw plus an anterolateral dome screw was the most stable model.The peak micromotions at the fusion site of this fixation configuration were 41.67±0.49 and 42.64±0.75 urn in response to the respectively.A neck screw plus a posteromedial dome screw was the least stable model,with peak micromotions at the bone-to-bone interface of 61.76±1.00 and 62.32±0.90 urn,respectively.Conclusion A neck screw plus an anterolateral dome screw is the best fixation configuration while a neck screw plus a posteromedial screw provides the least stability of subtalar arthrodesis.Three-dimensional finite element models allow effective preoperative planning of the screw number and placement.