Kinematics of the ankle/foot complex: plantarflexion and dorsiflexion.

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.