Torsional stiffness after subtalar arthrodesis using second generation headless compression screws: Biomechanical comparison of 2-screw and 3-screw fixation.

•Fixation should be optimized for subtalar fusion patients at risk for nonunion.•Two tapered, fully threaded, variable pitch screws resist torsion better than two lag screws.•A third screw placed anteriorly provides additional torsion resistance.