Which ankle ligament is most commonly injured?

• A. Deltoid ligament
• B. Posterior talofibular
• C. Anterior talofibular
• D. Calcaneofibular

Answer: (C)

When the ankle is sprained from an inward twist (inversion) with the foot often in a bit of plantarflexion, the ligaments on the outer side are stressed. The anterior talofibular ligament is the first to give way because it is the weakest of the lateral ligaments and is stretched the most in that position. Its fibers connect the front of the talus to the fibula, and in plantarflexion the talus moves forward against the fibula, placing maximal strain on this ligament. Because of this mechanical setup, it ends up being the most commonly injured part in these sprains, sometimes with involvement of the calcaneofibular ligament if the injury is more severe. The deltoid (medial) ligament is much stronger and less frequently damaged in typical inversion injuries, and the posterior talofibular ligament is usually the last to be affected. This pattern underlies tests like the anterior drawer test, which assesses ATFL integrity.