The axis of the talo-crural joint was analysed by roentgen stereophotogrammetry in eight healthy volunteers. Examinations were performed at 10#{176} increments offlexion and pronation/supination of the foot as well as medial and lateral rotation of the leg. Results indicate that the talo-crural joint axis changes MD, Lecturer

In an in vivo investigation of eight healthy volunteers, three dimensional ankle/foot kinematics were analyzed by roentgen stereophotogrammetry in 10 degrees steps of motion from 30 degrees of plantar flexion to 30 degrees of dorsiflexion of the foot. The study included all of the joints between the tibia and the first metatarsal, as well as the talocalcaneal joint, and was performed under full body load. Although the talocrural joint was found to account for most of the rotation around the transverse axis occurring from 30 degrees of plantar flexion to 30 degrees of dorsiflexion, there was a substantial contribution from the joints of the arch. This was seen particularly in the input arc from 30 degrees of plantar flexion to the neutral position, where the dorsiflexion motion of these joints amounted to 10% to 41% of the total transverse axis rotation.

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.

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