One of the most feared injuries in all of sports is injury to the Anterior Cruciate Ligament (ACL), yet this continues to be among the most common injuries in active individuals. Even as the latest evidence in injury prevention has decreased the prevalence of some other injuries, ACL tears have continued to be an issue over the years. Many of our friends, family members, and/or favorite athletes have suffered from ACL tears. Thus there have been several studies conducted to get to the core of what actually causes the ACL to tear.
As with any injury, there is not one thing that we can point to and say “Alas! This is what I can do to make certain that my ACL remains intact…forever!” Injuries are multi-factorial and despite the term “injury prevention,” they cannot be completely prevented. As long as people are active, injuries will occur. However, with much thought and intentionality in our workout regimens and treatment planning, we can certainly decrease the frequency of these traumatic injuries. I’m confident that as the field of physical therapy continues to evolve and we continue to uncover various aspects of mechanisms of injury in an ACL tear, clinicians and researchers will develop more and more strategies to decrease the likelihood of ACL injury. Here are some things to consider in your injury prevention efforts:
1. Strong Core = More
“The core” is a complex series of muscles that are responsible for providing proximal stability for the pelvis, hips, knees, ankles, etc. to establish and maintain proper function in sport (and in activities of daily living). Without a stable base (strong core), injury is more likely up and down the kinetic chain.
Decreased core stability can cause:
- Pelvic Drop
- Hip Internal Rotation
- Knee Valgus
- Tibial External Rotation
- Excessive Ankle Pronation
*All of the above are associated with increased risk for ACL injury.
Hip Internal Rotation (IR): Although Hip IR in itself can contribute to an ACL injury, being deficient in available Hip IR can also put an athlete at greater risk for injury. When our bodies don’t have certain available ranges of motion, our brains and central nervous systems are not able to prevent us from going into those ranges. Therefore, if an athlete does not have adequate Hip IR, they are unable to prevent this motion from occurring during functional activity.
Hip External Rotation (ER): This motion is important in helping athletes avoid knee valgus, which is crucial in avoiding ACL injury. Adequate Hip ER mobility will allow the athlete to establish and maintain athletic positions during their performance without harmful valgus stresses to their knee joints.
Hip Extension: It is necessary to be able to activate the posterior musculature to decrease the likelihood of knee collapse with dynamic activity. Inadequate hip extension leads to poor muscular compensatory patterns that could lead to injury.
Dorsiflexion: Dorsiflexion is one’s ability to bring their toes upward toward their shin. Dorsiflexion range of motion is very important in absorbing forces during a landing from a jump, deceleration and sudden changes of direction. The force absorbed at the ankle joint with full dorsiflexion motion decreases stress to knee joint.
3. The Separation in Deceleration
Most competitive athletes develop some level of speed, quickness and agility as it relates to their respective sport. The elite athletes can speed up and slow down better than anyone! One common risk factor we see with ACL injuries is a subpar ability to decelerate. If an athlete is going to stop or change direction, they need to have the necessary skills to control their body in space when going from accelerating, to decelerating, and then back to accelerating again.
In order to assess an athlete’s ability to decelerate, it is important to observe how they do with the following change of direction drills:
Linear Cone Drill: Set up cones 3 yards apart, sprint to the cones, decelerate into a lunge, backpedal to cones. Continue for designated sets/reps.
Lateral Hurdle Run w/ Pause: Set up 3-5 hurdles, laterally run over the hurdles, focus on a deep pause for about 2 seconds when changing direction.
Ickey Shuffle: Set up a ladder, run diagonally across the ladder, 2 feet in, 1 foot out. Focus on proper hip/knee angles on outside of ladder.
*Emphasize the end of the drills –Athletes should come to a complete stop abruptly when ending the drill instead of jogging or coasting. To decelerate, lower the hips and slightly overreach by contacting the ground in front of the hips. This will help enhance deceleration over time.
*Focus on force reduction deceleration technique – Start deceleration drills off with an agility ladder and only perform the drills around 70 percent. Focus on digging the foot into the ground, coming to a complete stop, and maintaining low hips and proper body angle. Progress by increasing speed and more complex agility/plyometric drills.
*Add tempo into strength training – Emphasize the eccentric phase (muscle lengthening phase) of exercise. For example, instead of doing regular squats, descend down into the squat very slowly to work on controlling the load. Isometrics can also improve deceleration. Descend down into the bottom of the squat and hold for 5-10 seconds before exploding back upward.
4. Prepare For Your Landing
Tune in to any football game on any level, it won’t take long for you see a wide receiver jumping up to make a catch or a running back attempting to hurdle a defender. Some level of jumping or hopping is part and parcel to most competitive sports. However, most ACL tears don’t occur in the jumping motion, but in the landing! An athlete absorbs up to 7-10x their own body weight in ground reaction forces upon their landing from a single jump. It is imperative that we are working with athletes to ensure that their landing mechanics and patterns are solid in effort to avoid repetitive stress and traumatic injury.
A quick way to determine an athlete’s susceptibility to injury is to evaluate their ability to absorb eccentric stresses in their landing from a “Depth Drop” or “Step Down Test.”
Depth Drop: The athlete steps down from (or drops) from a 6-18 inch plyobox or step. The athlete is then instructed to land simultaneously with both feet. We’d like to see the pelvis, hip, knee and ankle remain in alignment with very little to no hip drop, hips back and knees bent. Ask the athlete to hold the landing for 3 seconds.
*If the athlete steps down and the hip internally rotates and/or their knee collapses into valgus, this is something that must be corrected to decrease risk for injury.
Please note that this blog is not intended to be an exhaustive list of injury prevention tools. Instead, it is my hope that the reader will be able to gain some insights into ACL injury prevention that aren’t regularly discussed.
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