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The influence of pronation and supination of the foot on the joints of the ankle/foot complex was analyzed three dimensionally by roetgen stereophotogrammetry in eight healthy volunteers. Radiopaque markers were introduced into the tibia, talus, calcaneus, navicular, medial cuneiform, and first metatarsal bones. The subjects stood on a platform that was tilted in 10 degree-steps from 20 degrees of pronation to 20 degrees of supination. Pairs of x-ray exposure were made in each position. Calculation of resulting joint deviations from the neutral position showed that the largest amounts of motion occurred in the talonavicular joint followed by the talocalcaneal joint, in the latter case mainly in supination. The joints proximal and distal to the medial cunriform also participated substantially in the total motion registered. The tibia showed an average of 0.2 degrees of external rotation for each degree of supination of the foot.

In an in vivo kinematical investigation, the movements of the ankle/food complex induced by external rotation of the leg from an internally rotated position were analyzed by roentgen stereophotogrammetry. Radiopaque markers were introduced into the tibia, talus, calcaneus, navicular, medial cuneiform, and first metatarsal bones of eight healthy volunteers. Rotations occurring between these bones after 10 degrees increments of leg rotation were calculated in three dimensions. Movement of the leg from an internally rotated position to the neutral was found to induce motion mainly as internal rotation of the talus in relation to the tibia. Further external rotation induced motion mainly in the talonavicular and talocalcaneal joints, whereas a smaller amount of motion was seen in the joint between the navicular and the medial cuneiform.

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