Around 30% to 50% of musculoskeletal (tendon/muscle/bone) injuries presenting to physicians are tendon and ligament injures.  Among those injuries, acute ankle injury is one of the most common musculoskeletal injuries in athletes and sedentary people. It has been estimated that ankle sprain occurs at a rate of about one injury per 10,000 people per day.  In the US it accounts for an estimated 2 million injuries per year and 20% of all sports injuries.   
There is no gender difference, but the incidence depends on type of sports or activities.  A study in Australia showed that most injuries presenting to a sports medicine centre were a result of Australian football or distance running.  The most commonly injured region was the knee, followed by the upper arm and shoulder. Partial ligament strain accounted for 4% of injuries at this centre and third-degree ligament tear for 3.5% of case presentations.