Factors that increase your risk of anterior cruciate ligament (ACL) injuries include:

• Playing sports that involve sudden changes in direction or cutting around other players or obstacles, such as skiing, football, soccer, basketball, baseball, and tennis.
• Making accidental movements that may twist your knee, such as falling off a ladder, jumping from an extreme height, stepping into a hole, or missing a step on a staircase.
• Losing muscle tone in legs (from aging or inactivity).
• Having unbalanced leg muscle strength, such as if the muscles in the front of your thigh (quadriceps) are stronger than the muscles at the back of your thigh (hamstrings).
• Previous ACL injuries, especially if your knee sometimes gives out or buckles (chronic ACL deficiency).

Women have more ACL injuries than men. In sports, women injure their ACL up to 8 times as often as men. There are several theories for the increased incidence in women athletes, including differences in men's and women's bodies and how they use muscles, and training that does not help make up for these differences.²³