WHAT HAPPENS IN A SPRAINED ANKLE? A sprained ankle is a common injury said to be up to 20% of all sports injuries. It typically involves the overstretching of the ligaments in the ankle. In most cases, the ligaments on the outside of the ankle are overstretched when the foot is rolled inwards. These ligaments include the posterior talofibular ligament (PTFL), the calcaneofibular ligament (CFL) and commonly, the anterior talofibular ligament (ATFL). The ligament on the inside