ACL Injuries and New Guidelines for ACL and Knee Injury Prevention

The anterior cruciate ligament, or “ACL”, is an important knee stabilizer especially for athletic activities like cutting, pivoting, and changing direction.  It is estimated that 100,000 to 250,000 ACL injuries occur every year in the United States. ACL injuries can be costly including surgery, rehab, and time lost from sports, exercise, or work. There are 2 main types of ACL injuries that are important to understand, Contact Injuries and Non-Contact Injuries.

Contact Injuries occur when someone’s knee is impacted by an external object. Think of a soccer player getting slide tackled or a football player getting his knee taken out on a block. These types of injuries account for approximately 30% of ACL tears. These injuries are difficult to prevent unless all contact was to be eliminated from sports.

Non-contact injuries can occur during deceleration and acceleration especially when making a sharp cut or change of direction. Think of these as a player making a sharp cut to avoid a defender, their knee buckles, and it gives out with no one ever running into them. These types of injuries account for approximately 70% of all ACL tears.

There are a number of risk factors for ACL injuries. Some of them we can’t change or work on. These are non-modifiable risk factors. They include female gender (2-8x more likely to sustain an ACL injury than males!), previous ACL injury, anatomical factors, genetics, and hormonal influence among others.

The good news is there are risk factors that can be addressed in an attempt to decrease the risk of ACL injury. These modifiable risk factors include body mass index, movement patterns/mechanics, core control and loading strategies. Physical therapists are movement experts who can help athletes identify their potential risk and work with athletes, parents, and coaches to develop a plan and strategies to address these risk factors.

The most powerful predictor of future ACL injury has been identified as a previous ACL injury. So as the saying goes “an ounce of prevention is worth a pound of cure”. Recently new clinical practice guidelines were published with the most up to date research on ACL injury prevention.

ACL prevention programs should include some basic components based on these guidelines:

  • Exercise-based programs should be implemented during the preseason as well as throughout the season.
  • The program should be 20 minutes or longer in length and performed multiple times per week
  • Programs should include multiple components including:
    • Dynamic Flexibility, Running, Strength, Core, Plyometrics
  • Clinicians, Parents, Coaches, and Athletes all need to be involved in the development and compliance of these programs.
  • All athletes should participate, not just those with increased risk for ACL injury. Especially in athletes 12-25 years old.

If you have questions about ACL injuries, have had an ACL injury in the past, or want to learn how to prevent ACL injuries come and see us! We work with people all the time before and after ACL injury. We focus our treatment on optimizing movement and mechanics to help prevent ACL and knee injuries in all patients and athletes we work with. As physical therapists, we can assess your movement patterns, strength, and landing mechanics and put together a plan to help you.


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Hewett TE, Myer GD, Ford KR, Paterno MV, Quatman CE. Mechanisms, Prediction, and Prevention of ACL Injuries: Cut Risk With Three Sharpened and Validated Tools. Journal of orthopaedic research : official publication of the Orthopaedic Research Society. 2016;34(11):1843-1855. doi:10.1002/jor.23414.

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Snyder-Mackler L, Axe MJ, McDonough CM. Knee Stability and Movement Coordination Impairments: Knee Ligament Sprain Revision 2017. J Orthop Sports Phys Ther. 2017 Nov;47(11):A1-A47.

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