An ankle sprain refers to a tear of one or more of the ligaments within the ankle joint.
The most common type of ankle sprain occurs with a combined plantarflexion (pointed toes) and inversion (rolled inwards) motion. The most commonly affected ligament is the anterior talofibular ligament (ATFL), followed by the calcaneofibular ligament and the posterior talofibular ligament (PTFL) all of which are located on the lateral (outer) side of the ankle.
A less common type of sprain occurs with an eversion (outwards) motion in which case the most commonly affected ligament is the deltoid ligament on the medial (inner) side of the ankle.
There are three classifications of ankle sprains:
- A mild sprain is a Grade One (I). A grade one sprain involves a slight stretching and minor damage to the ligaments and presents with mild tenderness and swelling around the ankle.
- A moderate sprain is a Grade Two (II). A grade two sprain involves partial tearing to the ligaments and presents with moderate tenderness, swelling and instability.
- A severe strain is a Grade Three (III). A grade three sprain involves a complete tear of the ligaments and presents with significant tenderness, swelling and instability.