Rigidity Comparison of Locking Plate and Intramedullary Fixation for Tibiotalocalcaneal Arthrodesis

Abstract

Obtaining adequate fixation during tibiotalocalcaneal (TTC) arthrodesis may be challenging. Various fixation constructs have been tested biomechanically, but the use of a locking plate has not been reported. We hypothesized that the locking plate with a TTC augmentation screw would provide structural rigidity comparable to that of the intramedullary (IM) nail with a TTC augmentation screw during dorsiflexion testing. Six matched pairs of fresh frozen cadavers underwent TTC arthrodesis. Specimens in each pair were randomized to receive a locking plate or an intramedullary nail. Each specimen had an additional TTC augmentation screw through the calcaneus, talus, and medial tibia. All samples underwent dorsiflexion testing with determination of structural rigidity at the first cycle (initial rigidity) and last cycle (final rigidity) and the torque required to achieve a failure of 10 degrees of dorsiflexion. Statistical analysis was performed using a paired t-test to determine whether any differences were significant (p < 0.05). The locking plate construct showed higher final rigidity (mean +/- standard error of the mean) (27.7 +/- 2.6 N-m/degree versus 17.6 +/- 2.1 N-m/degree, p = 0.01) than the IM nail construct. There were no other differences measured. Rigidity with the the IM nail was inferior to that with locking plate fixation for TTC arthrodesis in one of the four parameters tested. Screw augmented IM nail fixation and augmented locking plate fixation may offer similar rigidity clinically for TTC arthrodesis.