In Vitro Kinematics of the Axially Loaded Ankle Complex in Response to Dorsiflexion and Plantarflexion

Abstract

The rotational movements of the tibia and calcaneus that occur with dorsiflexion-plantarflexion and axial loading were studied in cadaver foot-leg specimens using an unconstrained testing apparatus. Independent of the foot flexion position, significant internal rotation of the tibia and eversion of the calcaneus were noted after the ankle complex was axially loaded. Independent of loading, 10° of dorsiflexion resulted in 0.1° of eversion and 2.1° of internal rotation of the tibia. Conversely, 10° of plantarflexion resulted in 1.6° of inversion and 1.3° of external rotation of the tibia. The induced rotational movements of the tibia and the calcaneus differed significantly between the specimens. These results suggest that the foot “axes” did not change by axially loading the ankle complex and they support previous reports that the ankle complex uses different axes for dorsiflexion and plantarflexion.