For the past few weeks we’ve been discussing knee pain. We started with an article on IT Band syndrome and followed it with another on patellar tendon pain. Today, we’re going to examine another common knee injury sustained by barbell athletes, patellar compressive syndrome.
This injury can be broken down into two categories.
- Excessive lateral pressure syndrome (ELPS)
- Global compressive syndrome
Excessive Lateral Pressure Syndrome (ELPS)
Your kneecap (patella) travels within a small notch in your femur called the patellar groove. As your knee bends and straightens the tissues (muscles and fascia) that surround the joint keeps the patella traveling in a stable position.
If the tissues of the lateral leg become stiff they can pull excessively on the kneecap, tilting it on its side and causing it to track laterally in the groove. Think of it like a train being pulled off the train track.
If left untreated, this movement causes the kneecap to rub unevenly against the femur, leading to erosion of the cartilage on the underside of the bone (called chondromalacia). Many will complain of pain around the sides of the kneecap with ascending/descending stairs and squatting with possible popping and grinding noises in the knee (called crepitus).
When your leg is straight and your quads are completely relaxed, your kneecap should move around fairly easily. Most people are able to move their kneecap ~1 cm to the left and right without any pain.2 With ELPS the stiff tissues on the lateral side of the knee limit the ability to of the kneecap to move medially (towards the inside of your leg). This constant stretch of the tissues on the medial side of the kneecap can lead to pain as well and in some cases also cause atrophy (decrease in muscle size) of the inner quads (vastus medialis oblique).
Global Compression Syndrome
When someone has global compression syndrome, they have tissues on both sides of the kneecap that have become excessively tight. This problem usually develops after a direct blow to the kneecap (such as falling or running into something). It can also develop if your knee has been immobilized (placed in a cast/brace) for many weeks following a knee surgery or bone fracture.
For most athletes who complain of pain surrounding the kneecap, the problem will be due to excessive lateral pressure rather than global compression syndrome.
How Do We Fix It?
1. Reduce Swelling
It’s common to see a small amount of swelling in the knees of those who have compression syndrome as a result of repetitive microtrauma. Science has shown that swelling at the knee joint can cause the quad muscles to shut down and stop firing correctly.
In 1984, a group of researchers found that the VMO (the small “tear drop” on the inside of your knee) can shut down with 20-30 ml of swelling, while it takes 50-60 ml to do the same to the rectus femoris and vastus lateralis.12 This means reducing swelling is crucial to restoring normal function of the quad muscle. The best way to reduce swelling in the knee is ice, compression and relative rest.
2. Decrease Soft Tissue Stiffness
The main objective when treating compression syndrome is to decrease the stiffness in the lateral tissues of the knee (vastus lateralis, lateral retinaculum and IT Band). One efficient way to do this is with a self-myofascial release using a lacrosse ball.
Lie on your stomach and place a ball on the lateral quad, just above and to the side of the kneecap. Make sure to stay off the IT Band tendon of the lateral knee as compression here can create pain by irritating the fat pad that lies beneath!
Search out stiff spots in these tissues, pausing for a few seconds when you find a painful area! I recommend doing this for 1-2 minutes at a time.
For some athletes, self treatment with a lacrosse ball or foam roller will not be enough to loosen up these restrictions and they will require some hands-on mobilization of the kneecap from a physical therapist.
3. Addressing Muscular Imbalances (Enhancing Patellar Stabilization)
After mobilizing the stiff and shortened tissues that pull the kneecap off-track, we need to address weakness that occurs as a result of the constant tension, pain and swelling. Many physical therapists today believe we should focus on strengthening the VMO (inner quad muscle) based on the research showing inhibition of the VMO in compression syndrome.
Due to the way the fibers of the VMO run, it works in sync with the lateral quads (vastus lateralis) to stabilize the kneecap and keep it tracking in proper alignment. For this reason, if it isn’t firing correctly it can cause tracking problems for the kneecap and eventual pain.
However, when you look at all the available research on this topic there is a ton of disagreement as to whether VMO problems always occur with those who have ELPS compression syndrome.
Even if the VMO was shut down (relative to the other quad muscles), research shows that it can NOT be strengthened in isolation! For years, many believed certain quad exercises (straight leg raises or short arc knee extensions) selectively strengthened the VMO. Contrary to what you may have read in the past, the VMO is NOT capable of independently firing.3-9 When you contract your quad, the entire quad contracts.
Research is very clear that strength based exercises are however key for successful rehabilitation of this type of injury.10,11,13 It then comes down to choosing the RIGHT exercises.
What we don’t want to do is perform any exercise that increases compression and causes irritation at the knee joint. Let me explain why.
Many people assume the entire kneecap is constantly in contact with the femur during movement. However, nothing could be further from the truth! As the knee flexes the amount of contact between the back of the kneecap and the femur is constantly changing.9 The more your knee bends, the more contact there is between these two bones and any force placed on the knee can therefore be distributed over a greater surface area.
If you’re doing an exercise like a seated knee extension (open chain), your knee is moving from a flexed to an extended position. This means the amount of contact between the kneecap and femur in the groove is constantly getting smaller. The contraction of the quads to extend the lower leg pushes the kneecap into the femur (causing more compression). Therefore the contraction of the quads places a high amount of compressive force on the joint that is distributed it over a very small area under the kneecap. If the area underneath the kneecap is already eroded and/or inflamed due to ELPS, an exercise like this will only make things worse.
For this reason, we want to stick with exercises that can strengthen the quads but also spread the force of the joint compression across a greater surface area under the kneecap. These will include closed chain exercises as they have been shown in research to allow for better positioning of the kneecap in the femoral groove and therefore less joint irritation when performing exercises to strengthen the VMO.13 Rehab exercises can include leg-press with light weight and bodyweight squats to a limited depth.
During the initial recovery period we want to avoid deep squatting, as there is more compression placed on the joint the deeper you squat. While your body dissipates compressive forces over a wider surface area during the squat compared to a seated knee extension, a deep squat still places a considerable amount of force on the joint. Research has shown that compression of the patella increases as the knee bends, maxing out around 90-100° of knee flexion.14 For this reason, we want to start with bodyweight squats to around 30° of knee flexion (a mini squat) and progressing to 60° (and greater as symptoms decrease). When you can eventually squat to full depth without knee pain, the barbell can be slowly introduced back into training.
When it comes to the type of stance to take while performing these squats, research has shown that taking a narrower stance is better than a wide stance in order to minimize excessive compressive forces.15 However when it comes to foot angle, there appears to be no difference in the amount of compression that is generated when the feet are either straight forward or turned out up to 30°.15
The single leg touch down squat will also be a good addition to rehabbing from this injury as well. I want to share with you today a simple progression to perfecting this movement. The process is simple. It starts by breaking down the full pistol into small pieces.
The first thing you need to learn how to do is hinge from the hips. The box touch down is a great way to learn this movement. Start by standing on a small box or weighted plate (usually 2-4 inches in height). Before you begin the squat, drive your hip backwards and bring your chest forward. This movement engages the powerhouse to your body (the posterior chain) and keeps you balanced. Your bodyweight should feel completely balanced over the middle of your foot.
Once the hip hinge is complete, begin to squat until the heel of your free leg taps the ground. After you have made contact, return to the start position. Make sure your knee stays in direct alignment with your toes during the entire movement. It should not rotate inwards whatsoever.
During this small squat, your shin should remain fairly vertical. To perform a full pistol the knee must eventually move forward. However, this is not the time. Even though the distance of the squat is small, you should feel a considerable amount of fatigue in your glutes after a few repetitions. This limited depth should not increase compression enough to aggravate current symptoms.
The next step is the building block of the touch down squat. As the movement becomes easier to perform, increase the difficulty by making the height of the box progressively higher. As the box height grows the movement will become more difficult to complete with good technique. This step will take the longest to master, and your goal should be to work up to a depth of 10 inches.
Make sure the knee does not start to move forward until the bottom of the squat. The longer you can wait to keep the knee from moving toward your toes, the better.
It is crucial during this step that the jumps you make in box height do not cause pain in the knee. We want these touch downs to be as pain free as possible.
Eventually you will reach a touch down height of 12-14 inches. While this single leg squat is much deeper than what was required at stage 1, a full pistol from the ground may still be difficult.
This step introduces a single leg squat that looks more like a full pistol but is much easier to complete. Start with your free leg held out in front of you. Don’t raise it very high. This allows you to focus on the depth of your squat and less on keeping your free leg elevated.
The rehabilitation from compression syndrome is quite simple: improve the mobility of the excessively stiff tissues on the lateral side of the knee and then decrease the imbalances that often present as a response to pain, swelling and excessive tension.
During the recovery phase, make sure to avoid deep squatting and any explosive work (such as running, box jumps, etc.) as the forces generated during movements will likely increase compression at the knee joint and limit healing. If the above exercises are unable to help decrease the pain in your knee, I recommend going to see a physical therapist for a comprehensive evaluation.
Until next time,
- Wilk KE, Davies GJ, Mangine RE, et al. Patellofemoral disorders: a classification system and clinical guidelines for nonoperative rehabilitation. JOSPT. 1998;28(5):307-322
- Fulkerson JP (ed): Disorders of the Patellofemoral Joint (3rd Ed), Baltimore, MD: Williams & Wilkins, 1997.
- Cerny K. Vastus medialis oblique/vastus lateralis muscle acivity ratios for selected exercises in persons with and without patellofemoral pain syndrome. Phys Ther. 1995;75:672-683
- Jackson RT, Merrifield HH. Electromyographic assessment of quadriceps muscle group during knee extension with weighted boot. Med Sci Sports Exerc. 1972;4:116-119
- Lieb FJ, Perry J. Quadriceps function: An electromyographic study under isometric conditions. J Bone Joint Surg. 1971; 53A:749-758.
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- Grabiner MD, Koh TJ, von Haefen I. Effect of concomitant hip joint adduction and knee extension forces on quadriceps activation. Eur J Exp Musculoskl Res. 1993; 1:121-124
- Laprade J, Culham F, Brouwer B. Comparison of five isometric exercises in the recruitment of the vastus medialis oblique in persons with and without patellofemoral pain. J Orthop Sports Phys Ther. 1998; 27:197-204
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- DeHaven KE, Dolan WA, Mayer PJ. Chondromalacia patellae in athletes: clinical presentation and conservative management. Am J Sports Med. 1979; 7:5-11
- McConnell J. The management of chondromalacia patellae: a long term solution. Aust J Physiother. 1986; 32:215-223
- Spencer JD, Hayes KC, Alexander IJ. Knee joint effusion and quadricps reflex inhibition in man. Arch Phys Rehabil. 1984;65:171-177
- Doucette SA & Child DD. The effect of open and closed chain exercise and knee joint position on patellar tracking in lateral patellar compression syndrome. JOSPT. 1996;23(2):104-110
- Escamilla RF, G.S. Fleisig N, Zheng S, W. Barrentine KE, et al. Biomechanics of the knee during closed kinetic chain and open kinetic chain exercises. Med. Sci. Sports Exerc. 1998;30:556-569
- ESCAMILLA, R. F., N. ZHENG, G. S. FLEISIG, et al. The effects of technique variations on knee biomechanics during the squat and leg press. Sci. Sports Exerc. 1997;29(5):S156.