A MR imaging procedure to investigate tarsal bone mechanics

In the current work, a magnetic resonance (MR) imaging procedure to evaluate quasi-static motion of the calcaneus, cuboid, navicular, and talus is presented. It is focused on the applicability of a newly developed foot loading and positioning device. For that purpose, tarsal bone positions of three healthy subjects in a pronated and a supinated foot excursion under bodyweight were repeatedly measured. It was found that the talo-navicular joint showed the largest amount of rotation of up to 20° eversion-inversion in the frontal and abadduction in the transversal plane, followed by the subtalar joint showing nearly half of that motion. Considerably less motion was found between the cuboid and calcaneus (about 2-6°) and the cuboid nearly did not rotate relative to the navicular (on average 1°). Since these results were in agreement with the literature, it is concluded that the applicability of the presented procedure to investigate tarsal bone mechanics is warranted. The estimated necessary differences between tarsal joint motion to distinguish between kinematic behaviour were in the order of 2° (4° related to the talo-navicular joint). Thus, a new feasible MR imaging procedure was presented which enables non-invasive, in vivo 3D evaluations of tarsal joint motion in combination with rearfoot morphology.