Tibiotalocalcaneal arthrodesis: A biomechanical analysis of the rotationalstability of the Biomet Ankle Arthrodesis Nail

We hypothesized that the posterior-to-anterior (PA) calcaneal interlocking screw of the Biomet Ankle Arthrodesis Nail would increase rotational stabil ity secondary to increased bone purchase compared with the standard lateral -to-medial (transverse) screw. Each of 10 fresh human cadaver lower limbs ( five matched pairs) were stabilized with a nail inserted retrograde through the calcaneus, talus, and tibia according to standard technique. One limb of each pair was fixed with a transverse calcaneal screw; the contralateral limb, with a PA calcaneal screw. Each limb was then subjected to torsional testing on an MTS Mini Bionix load frame. The PA screw construct was signi ficantly stiffer than the transverse screw construct: 1.96 and 1.41 Nm/E, r espectively (P < 0.036).