Commonest ligament injured in an ankle injury
The ankle is one of the most common sites for acute musculoskeletal injuries.

Sprains constitute 85% of all ankle injuries, and 85% of those involve a lateral inversion mechanism,

Inversion Sprain - Inversion ankle sprains occur when the foot turns in or out to an abnormal degree relative to the ankle.

The most common mechanism of an ankle sprain is a combination of plantarflexion and inversion where the foot is pointing downward and inward.

The lateral ligaments are involved in an inversion ankle sprain and hence most commonly damaged.

These ligaments are on the outside of the ankle, which includes the anterior talofibular {ATFL), calcaneofibular (CFL) and posterior talofibular ligaments (PTFL).
Injury to the ATFL is the most common. When both the ATFL and CFL are injured together, ankle instability will be more noticeable.
The PTFL is the strongest of the three ligaments and is rarely injured in an inversion sprain.
Calcaneofibular ligament
Posterior talofibular ligament
Spring ligament
Anterior talofibular ligament