Knee Valgus refers to a moment during a squat or jumping movement where the knees cave in toward one another.
Perhaps you're familiar with the images of Robert Griffin III during his Broad Jump at the 2012 NFL Combine, which are a prime example of this valgus collapse:
Many young athletes experience similar valgus collapse during certain movements (perhaps most frequently during heavy Squats), and Griffin is proof that even elite athletes are not beyond this issue.
From a movement perspective, valgus collapse is when the femur or upper leg adducts and internally rotates. This combination of movements is what shows as the knees caving in. However, not every inward movement of the knees is cause for concern. It can become an issue, though, if the knees move past an imaginary line between your ankle and hip. When this happens, some serious issues can arise.
Let's look at what causes knee valgus before addressing the dangers and how to fix them.
What Causes Knee Valgus?
To understand the cause of knee valgus, it's important to note that the knee is a basic hinge joint that primarily flexes and extends. Since this is the case, most knee issues are caused by the ankles and/or the hips. Knee Valgus is no exception.
If you look at the ankle, a certain lack of mobility can contribute to the knees collapsing inward. When we squat, the shin typically shifts forward a bit, allowing us to bring our hips toward the ground. However, when we lack dorsiflexion, which is the ability to bring our toes toward our shin, it causes the ankle to roll inward, which can cause a chain reaction of issues (including knee valgus).
One way to solve this issue is to work on your ankle mobility by incorporating stretches and self-myofascial release to the calves. If you're looking for a simple test to gauge your ankle mobility, try the knee-to-wall test. Get down on one knee with your front foot about 4 inches from the wall. Shift forward and try to get your knee to touch the wall without having your front heel come up off the ground. If you can do it, great. If not, you have some room for improvement in your ankle mobility.
While the ankles could be a cause of knee valgus, it's the hips that are the most likely culprit. In most cases of valgus collapse, the muscles of the hips just aren't strong enough. To be more specific, when the glute muscles that abduct and externally rotate the leg (such as the gluteus medius) are significantly weaker than the muscles that adduct and internally rotate the leg, you've got the recipe for knee valgus.
The Dangers of Knee Valgus
Not all knee collapse is dangerous. But once the knees cave in past that imaginary ankle/hip line during squatting and jumping movements, we want to work to correct it as quickly as possible.
If you continue to fall into knee valgus during such movements, the accumulation of those poor repetitive movements is where injuries can develop. Potential injuries related to knee valgus include ligament damage (particularly of the ACL), ITB syndrome, patellofemoral pain and meniscus damage. Luckily, addressing knee valgus can be as simple as introducing some hip abductor exercises into your routine.
How Do You Address Knee Valgus?
To help solve this issue, we can start to include exercises like Lateral Band Walks, Clamshells and Banded Abduction Exercises to get those posterior muscles primed. Additionally, placing a band around your knees as you squat can give you a tactile cue to push the knees out, helping to strengthen the abductors and prevent valgus collapse.
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