An estimated 200,000 ACL-related injuries occur annually in the United States, with approximately 95,000 ACL ruptures. Approximately 100,000 ACL reconstructions are performed each year. Knee injuries are the most common cause of permanent disability in female high school athletes accounting for up to 91% of season-ending injuries and 94% of injuries requiring surgery. In the United States as many as 80,000 high school female athletes experience ACL injuries each year, with most in soccer and basketball.
Since the passage of Title IX in 1972 the number of females participating in sports in high school has increased ten fold and by more than five times in college. The speed and power demonstrated by female athletes have dramatically increased over the last twenty years and a more aggressive style of play has led to an increase in musculoskeletal injuries. Female athletes have a 4-6x increased risk of ACL injuries compared to males in similar cutting sports and overall, girls are 8 times more likely to suffer an ACL injury than boys. Year round female athletes who play soccer or basketball have have a 5% chance of tearing their ACL each year they participate in their sport.
At the age of 14 years, girls have 5 times higher rates of ACL tears than boys. The incidence of ACL tears in females peaks at the age of 16. The reasons for females being more at risk for ACL injury have been extensively studied. The increased risk for injury appears to be associated with many factors including a narrower intercondylar femoral notch and smaller ACL, an increase in natural ligament laxity, slower reflex time, an imbalance secondary to a greater quadriceps strength and hamstring weakness, fluctuation in estrogen levels and the tendency for females to land flat-footed. Seventy percent (70%) of ACL injuries in females are non-contact and primarily involve one of two mechanisms: running and cutting sharply with an erect posture; or landing with minimal knee bend on one leg. Both mechanisms result in the knee being forced inward into valgus with rotation as the athlete’s center of gravity is tilted laterally outside of their feet.
Several recent studies demonstrate that the rate of ACL injury among women can be significantly reduced by following a proper neuromuscular training and conditioning program. Two prevention programs Sportsmetrics and PEP have been shown to not only significantly reduced ACL injury rates but also improved athletic performance. PEP, the Prevent Injury and Enhance Performance (PEP) program (www.aclprevent.com/pepexercises.pdf) is a specific exercise program an athlete follows before practices and games. The PEP program consists of a series of 19 warm-up, stretching, strengthening, plyometric, and sport-specific agility exercises that can be completed in less than 30 minutes without any specialized equipment. In general these programs reduce the risk of ACL injury in athletes by stressing: proper leg muscle strength training and core training; proper neuromuscular (balance and speed) training; proper coaching on jumping and landing and avoiding any straight knee landing; and assessing proper footwear and orthotics to determine the necessary amount of traction needed to fall within an optimal range that minimizes rotational friction to avoid injury yet optimizes transitional frictional grip to allow peak performance when cutting and stopping. A physical therapist, coach or trainer who is certified in these programs can assist in teaching them to their patients or teams.