The ACL Injury Epidemic: Causes and Protection

By Matthew A. Midkiff PT, DPT, CSCS

The anterior cruciate ligament (ACL) is an important stabilizer of an athlete’s knee and it is a ligament that the active female cannot compete without. Injuries to the ACL of the knee have become an epidemic in female sports that involve jumping, rotating, and changing directions. These sports include basketball, soccer, volleyball, and gymnastics. A female in these sports is 4 to 6 times more likely to injure their ACL than males in the same sports and the majority of ACL injuries occur in non-contact situations, where the athlete may be changing directions or landing from a jump. The athlete may feel or hear a pop which is followed by immediate swelling into the knee and loss of motion.

Rehabilitation results in the athlete not being able to play or compete in their sport, with a range of absence from 5.5 to 9 months. Studies show that the surgically-repaired knee may take up to 12 to 18 months to respond in a similar way as the non-repaired knee. A vast amount of thought and research has been spent to determine the reasons females are more at risk for ACL injuries and what measures need to be taken to reduce the startling amount of female knee injuries.

Both intrinsic and extrinsic factors increase the female athlete’s risk of ACL injury. Intrinsic factors (such as how the athlete’s knee is built) are not controllable, but extrinsic factors are controllable and can be changed. Intrinsic factors that increase the female athlete’s risk of ACL injury include the fact that females have a smaller notch in the knee that the ACL runs through, increased laxity in a female’s knee, hormonal differences from the menstrual cycle, and the larger hip to knee angle (Q angle). Extrinsic factors include the type of sport played, the type of shoe worn and the surface played on, weak hamstrings, and decreased body control with jumping and landing. 

Promising research has shown that number of ACL injuries can be reduced by up to 80% if there is a focus on the extrinsic factors for ACL injury, such as increasing hamstring and gluteal strength, balance, flexibility, and body control during sport-specific activities. These ACL prevention programs teach female athletes how to squat, lunge, and land from jumps with proper body control in order to train the body to handle those situations during practices and games. Better body control will keep the female athlete’s knee out of dangerous positions which may lead to knee injury. 

With this exciting research in mind, it is our goal as professionals to educate young female athletes that although obtaining an ACL injury is a concern, steps can be taken to reduce your own risk.  Coaches and parents must become proactive with their young female athletes and begin training them to meet the demands of their sport.  My presentation at the upcoming Girls in Sport Symposium will further explain how ACL injuries occur and what you the athlete can do to prevent ACL injuries.