Hyperextension in the knees, aka Genu Recurvatum, is when the knees are extended backwards and fall behind the line of gravity. This is a super interesting topic to me. In the medical world, hyperextended knees are viewed as a type of structural deformity. In the dance world, especially in ballet, they are viewed as a desirable aesthetic that makes the legs look straighter and higher in the air.
Growing up dancing, I felt jealous of those with hyperextended knees. Whenever I devéloppéd, all I could see was my quad muscles “bulging” out, which made my legs not look straight. Hyperextended-legged people always looked like their quads were slender and their legs just effortlessly rose!! How was this even possible?!
Maybe you have felt this firsthand too. Or maybe you have genu recurvatum and are wondering what to do about it. Either way, understanding hyperextended knees is essential in not injuring yourself, and also keeping your students from getting injured. Also, knees are a little bit important in everyday life, so it would also be nice not to absolutely destroy them by your 30’s, am I right? Here are some considerations for dancers:
Lack of Stability Locally
Where does knee stability come from?
The knee is a relatively unstable joint. When people are talking about the knee they are probably talking about the patella, aka the kneecap. The patella protects the joint from the front, and provides torque to the quadriceps muscles to move the leg. The patella is between the two longest bones in the body- the femur and the tibia. It is responsible for every single movement transaction between the floor and the hip. And we wonder why the knees get injured so much.
The skeleton itself doesn’t really provide a lot of stability for the knee. Compared to say, the hip, which has a very deep joint design that makes it stable, the knee is very exposed. It is the menisci, bursae, cartilage, ligaments, fascia, and muscles that work together to aid in stability.
Where does knee stability come from in hyperextension?
Ligaments
Ligaments are big stabilizers in the body. The cruciate ligaments, more commonly known as the ACL and PCL, prevent excessive forward and backward movement of the tibia in the knee joint. In hyperextended knees there is a constant stretch put on these ligaments, specifically, the ACL. This causes an increase in laxity. Laxity is defined as “the quality or state of being loose”.
So, in hyperextension, the ACL becomes more lax. It is more prone to injury being constantly overstretch. Think of a used hair tie. After you use it over and over, it has way too much laxity and becomes dysfunctional. Similar idea with the ACL, you don’t want the ligament to be in the constantly lengthened position. It will lose its tautness/functionality.
Muscles//Quadriceps
If you are standing in hyperextension, no quad activity is actually necessary to keep standing. People who are in accidents that have lost motor control of the quads can actually still stand! Hyperextension when weight bearing is a passive position. Instead of using the quads to aid in stability, you are sinking into that already unstable knee joint. (See ligaments) This would be an indication of underactive quads.
On the other hand, when non-weight bearing, an overactivation of the quads can cause a muscle induced hyperextended line. If you are sitting on the floor with your legs out in front of you and engage the quads and lift the heels off the floor, you are using the quads to aid in hyperextension. I actually remember doing this exercise to help enhance hyperextension. Maybe you did too? So not #dancescienceapproved. Check out under “Exercise 1” for a better alternative.
Both of these examples of the quads are examples of muscle imbalance, either too much or too little quad activation can attribute to knee hyperextension.
Muscles//Hamstrings&Gastrocnemius
The tendons of the hamstrings and gastrocnemius (calves) cross the back of the knee and help prevent hyperextension. The hamstrings are an antagonist or opposite muscle to the quads. Quick review for the visual people out there:
Muscle | Action |
Quadriceps femoris (Quads) | Extend knee//flex hip |
Hamstrings | Flex knee//extend hip |
Gastrocnemius (Calf) | Flex knee//plantar flex ankle (point) |
When quads are not engaging hamstrings will pick up the slack and overwork to stay balanced. Hamstrings contract to bend the knee and hamstrings extend to straighten the knee. The hamstrings are extra lengthened when the knee is in hyperextension. Same thing with the calves. This makes the hamstrings and gastrocnemius weaken over time- same idea of the increase of laxity with the old hair tie. That leads to super dysfunctional and overcompensated musculature in the legs.
Exercise 1: “pull the knees up” instead of “push the knees back” [2]
Ideally, a co-contraction of the anterior and posterior muscles of the leg while weight bearing will provide stability to the knee joint. Sit on the floor in a long sit position to start. Legs will be out in front of you, and make sure you are in a neutral pelvis. Contract the quads for 5 seconds and try to slide the knee up the femur WITHOUT lifting the heels off the floor. Relax and try it again.
This may be really hard, and require a lot of concentration. Repeat 5 times on each side daily, even before class to help retrain the quads to provide knee stability. If you are feeling good about this, stand up and do the same thing, trying to lift the patella instead of the patella sinking back.
Phew! Lots of info to digest! That is how I felt editing this post! Part 2 will be coming soon to discuss more of the global effects of knee hyperextension! Have any questions//comments? Let me know below!
Sources:
[1] Mushrush, Anne Mercedes, “Genu Recurvatum in Dance Training: Assessing and Addressing the Structural Deformity in Dancers” (2015). Undergraduate Honors Thesis Collection. 258. https://digitalcommons.butler.edu/ugtheses/258
[2] Clippinger, Karen S. Dance Anatomy and Kinesiology. Champaign, IL: Human Kinetics, 2007. Print.