Injuries to the lateral ligaments usually occur in a position of inversion and plantar flexion. The ligaments usually tear in sequence, starting with the anterior talofibular ligament (ATFL) progressing to involve the more posterior calcanealfibular (CTFL) and posterior talofibubular ligaments. For this reason, if the ATFL is normal it is likely that all are normal. The ATFL is tightest in plantar flexion and is half as strong as the CTFL. The ATFL is intra-capsular and when torn causes a haemarthrosis.
Injuries to the syndesmosis usually affect the anterior inferior tibio-fibular ligament (AITFL) as a result of forced dorsiflexion, forced external rotation of the foot or eversion of the talus. Deltoid injuries generally occur after forced eversion of the ankle.
An ongoing sense of instability following an ankle sprain may imply a poorly rehabilitated injury, a more significant ligamentous injury, a loose body or a talar dome injury.
In the acute setting, athletes will have a painful and swollen ankle. The Ottawa Ankle Rules are very useful.2 The anterior drawer and talar tilt tests, which are of limited value in evaluating an acute injury, may be used to assess the mechanical stability of the ankle joint in players with chronic issues. Proprioceptive function is reduced in athletes who complain of a feeling of persistent instability following an ankle sprain. A simple single-leg balance test may be used to estimate sensorimotor control.
Weight-bearing plain images are needed in patients suspected of having a syndesmosis injury as it can create result of forced dorsiflexion, forced external rotation of the foot or eversion of the talus that can be missed on non-weight-bearing images. Stress XRs are used by some clinicians to quantify and document the degree of instability, but the large variability in talar tilt values in both injured and non-injured ankles precludes the routine use of these diagnostic tests.3