The ACL, or anterior cruciate ligament, is one of the four major ligaments that support the knee. This ligament prevents forward motion of the tibia (shin bone), especially during sports-specific movements. Female athletes are eight times more likely to sprain or tear their ACL. Several theories have been presented to explain why women are not as lucky as their male counterparts: hormones such as estrogen, size and strength of the ligament, size and strength of the female knee, sports specific skills of females versus males, and so on. One of the most researched and trusted theory is the Q-angle theory. The Q-angle, or quadriceps angle, is the angle that is created between the femur (upper leg bone) and the tibia. Females, because of their tendency to have wider hips than men, in turn have larger Q-angles. This larger angle can put unwanted stress on the knee join, making them more prone to ACL injury.
Recently, a great deal of research has focused on ACL injury prevention. Athletes reduce the risk of a knee injury by adding balance and agility drills to their training during each season, at least two times per week. Proper fitness, form and techniques can also decrease the risk, as well as appropriate gear for the sport being played.