THREE-DIMENSIONAL ANALYSIS OF THE TIBIOTALAR JOINT OF INTACT MALE FEET UNDER UNLOADED AND AXIAL-LOADED CONDITIONS

Purpose: We investigated the distribution of three-axis rotational directions of the tibiotalar joint in intact feet under axial loading and categorized them according to the combinations of the three-axis rotational directions of the tibiotalar joint as three-dimensional (3D) rotational patterns. Methods: The differences in rotational orientation of the talus relative to the tibia under unloaded and axial-loaded conditions were calculated from the 3D models of the tibiotalar joint that were reconstructed from magnetic resonance (MR) images in 27 intact male feet. Results: In the sagittal plane, the talus rotated into plantarflexion in 63% of the feet and into dorsiflexion in 30%. In the coronal plane, the talus rotated into inversion in 37% of the feet and into eversion in 33%. In the transverse plane, the talus rotated into adduction in 85% of the feet and into abduction in 4%. A total of 10 3D tibiotalar joint rotational patterns were observed under axial loading. There were no significant differences in the frequencies of the 10 tibiotalar joint rotational patterns (p > 0.05). Conclusions: The 3D tibiotalar joint rotational patterns under axial loading were consolidated into 10 directions, which provides insight into the subject-specific kinematics of the tibiotalar joint.