Axis of ankle movement
| The ankle dorsiflexes and plantarflexes through an axis that passes through the tips of the malleoli. As the lateral malleolus is longer and more posterior than the medial, the axis is not quite parallel to either the ground or the coronal plane. In addition, the instant axis of rotation of the ankle moves from moment to moment. Hence, as the ankle dorsiflexes, it rotates externally and vice versa. |
Axis of ankle movement |
Right talus from above |
The talus is also wider anteriorly than posteriorly, so the lateral malleolus has to rotate externally by about 11deg in the course of full dorsiflexion. Damage to the syndesmosis may interfere with ankle dorsiflexion or make it painful. The rotation of the ankle (and proximal limb) in relation to a fixed foot an the ground are accommodated by the rotation of the subtalar joint. Stiffness of the subtalar joint interferes with ankle movement and smooth gait. |
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