PT Classroom - ACL Injury Prevention in the Female Athlete ׀ by Elisa Suchy, DPT

Importance
Anterior cruciate ligament (ACL) injuries are amongst the most common season or career ending knee injuries for athletes. Unfortunately, ACL injuries can impact the athlete both emotionally and psychologically in addition to the obvious physical limitations they place on training and performance. However, the economic implications of ACL injuries in the United States are as staggering as they are overlooked. ACL patients requiring surgery account for 1.5 billion dollars annually in health care costs (1). Physical therapists and coaches must be attentive in their design of practices and strength training routines to include exercises that can help to prevent ACL injuries if only to keep their athletes healthy and happy. However, it is imperative that preventative measures are taken with female athletes for reasons beyond keeping them healthy and happy. Female athletes are four to six times more likely to injure the ACL than males (1, 2). As a result, females account for a huge portion of the 1.5 billion dollars in health care costs associated with ACL injuries mentioned earlier. The best treatment for an ACL injury is prevention. Studies have shown that prevention programs focused on neuromuscular training and proprioceptive training decreases the risk for an athlete 3.6-3.7 times than the control groups (1, 3). Physical therapists play a large role in the development of these programs and the ability to rehabilitate athletes from any type of knee injury while decreasing the risk of ACL injuries.

Anatomy
The anatomy of the ACL and the surrounding structures is an important factor to consider when developing programs to prevent ACL injuries in athletes. Female athletes have a greater Q angle than males, which increases the amount of valgus forces at the knee creating an unstable mechanism (1, 4). The main function of the ACL is to decelerate the lower extremity with movement as the tibia internally rotates and the hip internally rotates (4). This is extremely important in the athletic setting because any weakness during eccentric loading of the lower extremity forces increased strain on the ACL by increasing the load on the ACL (4). Individuals with a high risk of ACL injuries are typically in a position where the pelvis and hip are uncontrolled. This lack of control over the pelvis and hip put the hip abductors and extensors at a disadvantage and eventually force these muscles to shut down (3).

Seventy percent of all ACL injuries are noncontact (4) and the mechanism of injury is as follows: relatively little flexion, with hip internal rotation and adduction on a pronated and externally rotated foot (4). As you can see, many ACL injuries involve not only the biomechanics of the knee but those of the hip and ankle as well. Neuromuscular programs have been developed to improve the stability of the lower extremity with functional close chain exercises at the hip, knee, and ankle.

Prevention
Evidence supports the need for neuromuscular and proprioceptive retraining for the prevention of ACL injuries. Stability training helps to improve the athlete’s ability to co-contract the lower extremity. Additionally, stability training has proven instrumental in providing proprioceptive feedback with unpredictable dynamic activity (2). A study by Paterno et al concluded that a six week neuromuscular training program being utilized three days per week improved total anterior/posterior postural stability in young female athletes (4).

A comprehensive neuromuscular program was described in the article by Paterno. The focus of the preventative program for female athletes included three subgroups. The first subgroup included female athletes engaging in balance training and hip, pelvis, and trunk strengthening. The second subgroup included female athletes engaging in plyometrics and dynamic movement training. The final subgroup included female athletes engaging in resistance training. This study shows that participation in all three groups over a six week period; postural and stability changes occurred. With this evidence, it is important for all therapists and coaches to education themselves on proper form and corrections for athletes to minimize their risk of injury. The importance of ACL prevention programs is to educate the athlete on safe positions, proper posture, and the ability for the athlete to self-correct.

Proprioceptive retraining is important with all dynamic sport-related maneuvers. Cutting, jumping, and quick start and stop motions are of particular importance during proprioceptive retraining. Prevention programs focus on completing these activities with proper biomechanics. All close chain functional activities should be performed using methods to minimize the amount of stress placed on the body. An example would be proper jumping mechanics. Each athlete must land on the balls of their feet before transferring their weight to their heels. Athletes should also be required to land with bent knees and their center of gravity shifted forward (1). Additional cues with which to provide the athlete include having a soft landing with toe to heel rocking in order to decrease the ground reaction forces (1). Many athletes, specifically females, tend to perform plyometric activities in a more upright position. This creates greater force on the knee and maximizes the anterior shear forces of the quad. Ultimately, these greater forces combine to increase the total load on the knee which can lead to ACL injury (1). Proper verbal cuing is important to maximize the benefit of the neuromuscular retraining and begin to teach the athlete how to self-correct.

In conclusion, the evidence mentioned above supports the need for proper training and education for therapists, athletes, and coaches to minimize the risk of season ending knee injuries. Without the proper stability training, postural cuing, and education, athletes will continue to fall into poor biomechanics and increase the load and stress on the ACL. With the proper education, many noncontact ACL injuries can be prevented allowing athletes to have successful and accomplished seasons.