Injuries to the knee are the most common type of injury in alpine ski sport and make up about a third of all injuries. The most frequent injury to skiers used to be fracture of the lower leg. With the introduction of improved high cut boots, the most common accidents are now higher up, in the knee. As a result of carve turns, complex knee injuries have also increased, as the ligament system of the knee is put under additional stress by the increased speed in curves and the consequent increase in centrifugal force. Soft tissues of the knee are the most frequently injured structures, primarily the anterior cruciate ligament.