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All too often I have a patient contact me in regards to knee pain during a squat. They say,” Jake, the second I start to bend my knees during a squat I get this sharp achy pain in the front of my knee that won't go away. I don't know what caused the pain, it just hurts.”
Knee pain, especially with squatting, can have several different causes. Whether it's from work related duties, poor load management, lifestyle factors, or sports related it won't just go away on its own.
So the real question is..... how do I fix the problem? To understand this lets develop a solid foundation on the knee and how it functions.
The Knee Joint 101
The Knee joint is a hinge joint consisting of the convex femur meeting the concave tibia. The knee allows for flexion, extension, and a small amount of rotation called the “screw-home mechanism." Between and around these two bones, there are many different structures:
Ligaments: ACL, PCL, MCL, LCL, Medial patellofemoral ligaments and posterolateral corner ligaments
Menisci: Medial and Lateral meniscus
Muscles, Rectus Femoris, Vastus Lateralis (VL), Vastus Medialis Oblique (VMO), Vastus Intermedius, Biceps Femoris (2 heads), Semitendinosus, Semimembranosis, Gracilis, Sartorius, Gastrocnemius, Soleus, and Popliteus
Nerves and Blood Vessels: A CRAP TON!
For the simplicity of this article lets focus on the anterior (front of) portion the knee
PATHOPHYSIOLOGY:
There are two diagnoses that come to mind with anterior knee pain. One being Patellofemoral pain syndrome (PFPS) and patellar tendinopathy.
PFPS is beyond mutli-factorial and hard to truly diagnose. Researchers believe that it can be due to an imbalance of VMO and VL activation and tight lateral structures/weak medial structures. However there is only weak evidence to support this.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4169618/
Overall weakness in all the quadricep and glute muscles, female sex, and chronic overuse are correlated to pain with lateral tracking of the patella within the trochlear groove. This results in irritation behind the patella against the knee joint.
So if you didn't understand any of that, all I ask is that you don't get caught up in the “Oh your VMO is not firing, dude” debate. It's simply not the entire case. Ill explain more about this in a bit.
Patellar tendinopathy is a repetitive overuse injury commonly seen in your younger male jumping athletes (basketball, volleyball, track and field, CrossFit, and more). This overuse injury can develop micro degeneration in the patellar tendon structure which results in inflammation of the surrounding area.
The same principles apply to tendinopathy as we saw with PFPS. Do not get caught up in the big scary terms like dynamic valgus moment and mal-tracking. The evidence is still lacking.
TESTING TIME
What are the limitations/mechanical barriers that could be correlated to the knee pain? Lets dive in.
Here are the three biggest correlations we see most often with chronic achy anterior knee pain during a squat.
Hip mobility
Quad/Glute weakness
Ankle mobility
Hip mobility:
Hip mobility can definitely help you in performing a more efficient squat. However, limitations in hip mobility can force unnecessary stress in various spots of the lower back, knee, and ankle. Lets go over some tests to see if hip mobility is an issue that needs to be addressed.
Hip IR test: start in seated position, place hands behind your back, and without tilting your torso internally rotate (knee inward, foot outward) your problematic side with knee pain. If there is pinching pain in the hip, asymmetries side to side, or reproduction of knee pain this may be a problem we need to address
90/90 hip mobility drill: start in seated position, flex knees to 90 degrees, attempt to touch knees side to side without touching hands behind you. If this is problematic, causes pain, or severely difficult the hip IR may need to be addressed.
FABER test: lie supine and cross your leg with your ankle above your knee cap. Let the knee fall out to the side. Add slight pressure without letting your pelvis tilt to the same side as the raised leg. If this is problematic, causes pain, or severely difficult, then hip ER may need to be addressed.
Thomas test: start seated and pull non problematic knee towards your chest, lower your body down slowly to a supine position while holding your knee. Maintain a flat back on the table and let the problematic side hang off the table. If you notice pain, your back needing to extend, or your problematic side is significantly raised off the table then this may be a problem we need to address.
Glute and Quad Weakness:
Strength can always be used to our advantage with functional training. Weakness in one area can cause other muscle groups to over compensate for lack of force production.
Now the evidence behind “VMO weakness” and “glutes not firing” have been debated in the physio world for sometime. Long story short, it is highly unlikely to isolate one muscle group, see a deficit, and conclude that that muscle is the problem causing your pain,. The squat itself is a multi-joint/multi-muscle movement.
This means that although testing one single muscle is helpful it does not give us the full picture. So what test can we use that incorporates both muscle groups in combination?
Single leg squat test: start by placing a small surface like a chair behind you. Standing on one leg, lower down into a squat position. Try to maintain your knee in line with your toes. If you noticed excessive caving in of the knee, pain in the knee, or pain in the hip we may want to address these issues.
Single leg step down: starting on a raised surface (4-12 inches), hang one leg off the side. Either handing onto support or not bend your knee and lower yourself slowly to the ground. f you noticed excessive caving in of the knee, pain in the knee, or pain in the hip we may want to address these issues.
Ankle mobility: the ankle joint plays a significant roll in regards to a full depth squat. Adequate ankle dorsiflexion and some pronation allows the knee to travel anterior over the foot without compromising hip and knee movement.
To do this we need a few things to be functioning properly. We need a bone called the talus to move posterior, the tibia to travel anterior, and tibial internal rotation to occur. Without these body parts moving as they should we can experience trouble with squat mobility and extra stress placed on the knee joint.
Testing time!
5 inch wall test: start in a kneeling position facing a wall. Place your big toe of the symptomatic side 5 inches was from the wall. Drive the knee towards the wall and stop when you begin to feel your heel lift off the ground. If you can touch your knee to the wall without the heel lifting up congrats. If not, we have some work to do.
* Mind you this test is not fool proof and some individuals anatomy does not require 5 inches of Dorsiflexion mobility. So please don't stress yourself out over this. We can work on it if necessary.
BIG 5 exercises to take home
Side plank glute rock n raise (ER hip mobility/glute strength)
- Start in a sidelying position. Raise hip off the surface forcing pressure onto knee. As you raise up lift the upper leg to the sky. Make sure to maintain an appropriate Valsalva as you lift up into side plank position. Aim for 3-5 sets, 10-20 reps pain free.
Seated straight leg hip IR (IR hip mobility)
- Start in a seated 90/90 positions. Raise back leg off the ground. Begin to swing leg forward while maintaining upright trunk. Finish with a straight leg raised off the surface. Swing the leg back and repeat. Aim for 2-3 sets, 10-15 reps pain free
SL eccentric step downs (glute and quad strength)
- Lucky for you one of our test is an exercises as well. Pick a surface that is challenging but does not raise your pain level above a 5/10. Focus on good control or knee over toe positioning and reducing the knee from caving inward. Aim for 3-4 sets, 8-12 reps pain free.
Wall sits (quad strength)
- Start with back up against a wall with legs straight. Lower your torso toward the floor with knees bent around a 75-90 degree angle like shown. Stick to the less than 5/10 pain in your knee with this exercises. Aim for 3-4 sets, 15-60 seconds holds.
DF mobilization (ankle mobility)
-Place a moderately resisted band around the top of your ankle below the bony prominences on each side. Elevate your leg onto a surface that you can maintain your balance on. Drive your knee over your toe maintaining a good stretch in your calve. Aim for 2 sets, 10-15 reps, 5-15 second holds
Try performing these exercises before squatting and see if they help. Continue to perform them 4-5 times a week while increasing repetitions each week.
We hope that these exercises find you well and add some benefit to your rehabilitation. If you want to access to more exercises/content check out the Nomadic Physical Therapy Patreon page!
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References:
1) Petersen, W., Ellermann, A., Gösele-Koppenburg, A., Best, R., Rembitzki, I. V., Brüggemann, G.-P., & Liebau, C. (2014, October). Patellofemoral pain syndrome. Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4169618/
2) Willy, R. W., & Hoglund, L. T. (n.d.). Patellofemoral Pain: Clinical practice guidelines linked to the ... Patellofemoral Pain. https://www.jospt.org/doi/10.2519/jospt.2019.0302
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