Given the rising occurrence of ACL injuries mentioned in last week’s ACL awareness post, I’m confident you’ve heard, known, or seen someone with an ACL injury. It’s an unfortunate and sad truth of today’s world. Having said that, I strongly believe it doesn’t have to be this way. And the research supports it.
CONTACT versus NON-CONTACT INJURIES
A contact injury results from direct contact to the body by another person or object during the course of activity – like a football tackle at the legs that causes an injury to the person being tackled. A non-contact injury results from your own movements – like landing awkwardly from a jump, causing an ACL tear.
Can you guess which type of injury is more common for ACLs?
If you answered “non-contact”, you’re right. A comprehensive 2022 study on ACL injuries by researchers in Australia found that 55% of ACL injuries are NON-CONTACT. This high percentage may come as somewhat of a surprise for many, because this means that we can still suffer a significant and serious injury, despite our conscious efforts to avoid contact or dangerous activities or belief that we are in full control over our bodies. How can this be?
NEUROMUSCULAR RISK FACTORS PROMOTE NON-CONTACT ACL INJURIES
We attribute this phenomenon to the presence of neuromuscular risk factors. “Neuromuscular” simply relates to the nerve sending signals to the muscle to produce a certain contraction and overall movement. The research supports four neuromuscular risk factors for ACL injury, which I’ll cover below.
Risk Factor #1: Landing in knee valgus
 Even the untrained eye can tell the position of the legs in this photo doesn’t look right or “good.” The knees are pointing inward, which puts increased stress and tension on the knee (ACL) and increases the risk of rupture. While one may get away with this form without injury for a while, it only takes one time – when you’re a little more fatigued, lifting a little heavier, or jumping/cutting a little harder – for an ACL injury to occur. Proper placement would be to have the knees straight forward and directly over the feet. For some, achieving this form consistently takes repetition and hard work. |
Risk Factor #2: Landing with a straight knee
 As active people, we’ve all probably heard it at some point: “land softly.” There are many reasons why landing softly and with control is a good idea. One important reason is to reduce stress on the knees and ACL. When you land softly, you’re bending your knees and hips to safely absorb force that would otherwise be concentrated in your knees and ankles, putting them at risk for injury. Get those hips and knees bending! |
Risk Factor #3: Landing on a single leg or unevenly distributed between legs
 People who favor one leg over the other or have imbalanced movements may land or lean to one side during jumping, jogging, or even walking, causing more stress to the favored knee and putting the ACL at risk. If you have two legs, we want you to use them! Equally. |
Risk Factor #4: Trunk Lean
 “Trunk lean” refers to the movement pattern in which the pelvis and trunk (or torso) excessively shift over to the side of the weight-bearing leg. Imagine standing on your right leg and your shoulders end up leaning outside of your right foot and slumping downward to the side. That’s a trunk lean. These images show the variation in force on the knee when the trunk and hip are straight (figure A) versus when the trunk and hip are tilted and leaning to one side (figure B). The trunk lean in figure B causes more force and stress to the ACL, making it much easier to tear or rupture during non-contact activity. |
To us, as doctors of physical therapy, ALC injuries resulting from these four neuromuscular risk factors would not be classified as freak accidents. We are heavily focused on treating these risk factors in our office. Our experience – along with clinical research has shown that when these risk factors are trained and worked on correctly, one can REDUCE their risk and PREVENT ACL injuries.
A WORD ON CONTACT ACL INJURIES
So what about the CONTACT ACL injury? These injuries are also on the rise. Some might think they are completely out of their control and could be universally categorized as a “freak” accident.
I beg to differ.
Similar to the non-contact injuries, if we can identify our areas of weakness, lack of mobility, and inadequate motor control, particularly pertinent to the types of activities we do regularly for sport – and even in daily life or leisure – we can strengthen and train them to withstand stronger external forces (like a tackle) and take on more stress. The sooner we get to work on identifying areas of stress and weakness now, the better off we’ll be tomorrow and deep into the future.
SO, HOW DO I KNOW IF I’M AT RISK FOR ACL INJURY?
At our office, we use some of the following tests to determine if someone is at risk for an ACL injury:
Squatting
- Do you lean to one side?
- Do your knees cave inward?
Single leg squatting and hoping/jumping
- Does your trunk lean outside of your foot?
- Can you stay balanced throughout the movement?
- Does your knee wobble or move inward?
- Do you land on a straight or rigid leg?
Double leg jump
- Do you land evenly on both feet?
- Do your knees cave inward?
- Do you land on a straight or rigid leg?
Cutting/agility
- Do you push off and stop evenly on both legs?
- Does your trunk excessively move over the weight bearing leg?
It’s not uncommon to require a physical therapist’s help identify whether you’re at risk for an ACL injury and come up with a plan to get you moving the right way, automatically. At P3 we are trained to help individuals move and feel better. It’s our mission to get you moving, playing, and living your best life. Please reach out at any time for a complimentary discovery session if you’re interested in an assessment on your individual risk factors or other concerns.
Like I’ve mentioned before, we are seeing an influx of ACL injuries and we believe that in many cases they are preventable. Check back for next week’s post in this series to learn our 5 must-do exercises to prevent ACL injuries.