Torsional stiffness of an intramedullary nail versus blade plate fixation for tibiotalocalcaneal arthrodesis: a biomechanical study.

The purpose of this investigation is to compare the rotational stability of intramedullary rod fixation with blade plate and screw fixation in tibiotalocalcaneal arthrodesis. Five matched pairs of cadaver ankles were randomly fixated with a lateral blade plate and screws or a retrograde intramedullary nail. The bone mineral density (BMD) for each sample was ascertained. These samples were tested through internal and external rotation of 0.5 degrees/s until 7 N-m was achieved. The torsional stiffness of each specimen was determined from the linear slope of the torque-rotation curve. No statistical difference in internal (p=.11) or external (p=.36) rotation for the matched pairs was noted. Data were excluded from one intramedullary sample secondary to early failure of the tibia. A trend toward increased rotational stability in the intramedullary group versus plate fixation in specimens with lower BMD was observed. These findings suggest no rotational biomechanical advantage of intramedullary nail compared to blade plate fixation in a cadaveric tibiotalocalcaneal arthrodesis model.