Sagittal mobility of the normal ankle.

In children and adults, there is a physiological anterior sagittal displacement of the talus which decreases when the examination is repeated in equinus. The displacement occurs when the examination is performed with or without apparatus, with manual stress or with weights. The diminution of the normal sagittal mobility of the talus when the examination is performed with the ankle in the position of equinus, it attributable to the intact anterior talofibular ligament which becomes taut when the ankle is in a position of flexion. A pathological drawer sign will be noted following an isolated tear of the anterior talofibular; under those circumstances sagittal instability is increased and is not appreciably affected by repeating the examination in a position of ankle equinus.