How to Fix Patellar Compressive Syndrome

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 to use an NMES device (read more about that here:

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

Toe Out angle

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.

Step 1

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.

Step 2 

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.

Step 3

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.

Final Thoughts

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,

Dr. Aaron Horschig, PT, DPT, CSCS< USAW


Kevin Photo
Dr. Kevin Sonthana, PT, DPT, CSCS


  1. 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
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  3. 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
  4. Jackson RT, Merrifield HH. Electromyographic assessment of quadriceps muscle group during knee extension with weighted boot. Med Sci Sports Exerc. 1972;4:116-119
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  7. 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
  8. 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
  9. Powers CM. Rehabilitation of patellofemoral joint disorders: A critical review. JOSPT. 1998; 28(5): 343-354
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  11. McConnell J. The management of chondromalacia patellae: a long term solution. Aust J Physiother. 1986; 32:215-223
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16 thoughts on “How to Fix Patellar Compressive Syndrome

  1. I’ve been diagnosed with Chondromalacia about 6 years ago and had two surgeries (Arthroscopy). Everything you described on the article, from knee pain under/side of the knee cap and reduction on the quad muscle size (specially the lateral) is like describing my knee. I’ve difficult trying to gain muscle on the quad over the years and still feel be pain. Would you recommend then to follow the same steps from above (lacrosse ball, foam roller, ice) and limit the depth of my squats to focus on excercises that do not generate more compression? Thanks for your response.

  2. Hi Dr. Aaron. Thank you for all the free content and advice you give. So I think I’ve had ELPS in one of my knees for 6 years and possibly starting to develop it in my other knee. I first noticed something different when I would feel a strange rubbing/catching sensation on the lateral/lower part of my patella while doing lunges. Since then I’ve had a job that has me kneeling and squatting constantly. Also I took up mountain running and because of my growing discomfort i neglected strength training as it seemed if I trained lifting and running simultaneously my knees would constantly ache. Over the last year I’ve tried several times to get back lifting but keep giving up because I thought i had developed arthritis. But once I saw the location of pain and symptoms you describe I believe this is what it has been. Like I said Running doesn’t necessarily produce pain, but mostly lifting. I did the test and could definitely feel pain without even having pressure on my patella when I flexed my quad with my knee flexed at 60-70 degrees. How long does this condition typically take to repair and get to pain free lifting? Also would you recommend I stop running and maybe see a Doctor? Again thanks for what you do and for giving me hope that I can have pain free knees one day soon!

    1. Josh! Great questions – so healing time really depends on a number of factors. I would personally recommend going to get some hands on treatment from a sports physical therapist. This is an issue that can at times be very multi-factorial and require a hands on approach to fixing. So start with some of these exercises I explain (as long as they’re pain free) and see if you can get with a sports physical therapist that lives near you and you should be on a good road to recovery!

  3. Sets-reps recommendation for each step pistol variation? How many weeks is recommended before starting to squat again?

    Thanks in advance.

  4. Great article!

    I have noticed during the initial decent in a squat, knee angle at around 20 degrees, a painless pop which seems like it’s coming from my patella.

    I’ve read about cavitation being the cause of sounds like this, but am more concerned about patellar compressive syndrome. I know it’s hard to offer thoughts without an exam, but any queues to know whether this is compressive syndrome vs. cavitation?


  5. Hi Aaron.
    Would you give us some insight on the touch-down exercise. I am trying to understand the anatomical difference between :
    1. touch-down on an incline board, trunk leans forward (a test to trigger and evaluate pain associated with tendiopathy)
    2. touch down on a regular box, trunk is vertical (a treatment for compression syndrome)
    As a case study : my training partner, a female, has a bit of a knee valgum, glutes are actice, she easily performs touch-down n°1 from a flat surface while maintaining big toe pressure on ground and hip-knee-ankle alignment. But she is struggling with touch-down n°2 (loosing foot pressure to the outside, loosing alignment, balancing herself by swinging trunk and free leg in opposite directions in the frontal plane) ! ?
    So many thanks in advance !

  6. Hi Dr. Aaron Horschig,
    Thank you for the amazing article, very informative. I was wondering how often it is optimal to perform these rehab exercises during the week (assuming a 3 day exercise split), and at what point in the workout should they be performed (start or end)? Also, will barbell glute bridges make the problem worse or better, by increasing glute activation and fixing imbalances in the glutes?

    Thank you in advance,

  7. Didn’t understand the relationship between patellar swelling and quad function. It makes sense, and paints the picture for why reducing inflammation is an essential component to recovery after squats. What are your thoughts on warm-up?

    Brian Ford

  8. Apologies for the Length of this comment. The vast majority of it is for General info for anyone else visiting this site that may have a common experience and find some encouragement.

    To Summarize my problem:
    A few years ago, I experienced a mild aching of the right knee that began with NO CONNECTION TO ANY PARTICULAR INCIDENT. Then, when I squatted deeply to put some clothes in a washing machine, I felt a real high pressure in the knee at almost full deep squat. This Progressed to aching when knee held in one position (When seated for example) and had to adjust (Extend/bend leg) until it began aching again. Progressed to general Pain behind kneecap even with shallow bending when going up and down stairs. Progressed to large swelling around the knee causing a reduced sensation in lower leg and foot.
    Diagnosed with Patellofemoral pain syndrome I followed a Physio program of exercises to strengthen quads and stretch, the swelling significantly reduced over many months and almost no pain or crunching of knees when bodyweight squatting to parallel to floor.
    At this point, I was signed off the physio program of the National Health Service here in UK with no further progression instructions. I assume this level of functionality was considered a success. As such, I would continue to hurt or injure my knee when I had to squat deeper or with more force.
    With no explanation of the root of the problem, I was left scouring the internet periodically for other explanations. I stumbled upon the work of physiotherapist Doug Kelsey who mentioned as a possible root cause of patellofemoral pain, the “weakening” (softening and thinning) of cartilage due to lack of low-force bending of the knee such as walking combined with a “weekend warrior” approach to exercise that the knees can’t handle and are damaged by as a result. This appeared to be plausible pattern of my physical activity.
    The solution? ease off any forceful knee loading and engage in lots of walking, seated leg swings etc. to build the cartilage back up to tolerate the force of deep squats and eventually more intense exercise.
    I have been following these recommendations for a little while but I still had a niggling question of why I experienced crunching of the knees (and later pain) when I did the following that I assume pushed very little force through the knee joint. I discovered this by chance when I was lying in bed and brought my knee to my chest in a full knee bend to scratch my lower shin. When I initially raised my foot to the sky a little before extending my leg back to the resting position I heard the crunching in my knee,

    Having read your post, I considered ELPS might be the problem I am suffering from. As an experiment, I again tucked my knee to chest. This time however, before raising my foot to the sky and straightening my leg, with the base of my hand I forcefully pressed my kneecap medially as I extended my foot. To my surprise a very smooth extension with NO CRUNCHING NOISE. Is this be suggestive of having this ELPS? I am not sure but I am willing to give these exercises a prolonged and progressive effort and report back.

    Thanks in advance for all the effort of creating and sharing this information for free.

  9. Electrical stimulation of the VMO works well for this. With E-Stim you can fire the VMO in isolation, or make it contract harder than the rest of the quad during voluntary contraction. In single leg closed chain exercise it has a big effect on patella position, moving it noticably medial. I’ve been using it for a couple months now and I’m pretty optimistic about it. It’s the only approach I’ve ever tried that actually made me think fixing patellar tracking can actually work.

  10. Hi Dr Aaron

    Thanks a lot for posting these great pieces. I have been having knee pain for around 6 months, and initially thought this may be tedinopathy or IT band syndrome, but the description of patellar compression syndrome seems to ring true more in terms of where the pain is located and general description.

    I’ve been foam rolling and introducing the ball rolling has also seemed to help target closer to the knee rather than just the quad itself. I’ve also been doing side leg lifts to strengthen the VMO and some band work.

    I’ve been advised previously to use a slant board for incline squats for rebuilding strength in the knee for tendinopathy, and to use a bosu ball or wobble board to build knee stability. Are these exercises that you would also recommend for patellar compressive syndrome?

    Best wishes

  11. […] While these forces are unlikely to cause a sudden severe injury like a torn ACL while barbell training, subtle alterations in knee stability over time can have a profound effect on the smooth lining of the underside of the kneecap. If the body loses control of the knee and it starts to wobble or cave in during a lift, it causes the kneecap to rub unevenly against the femur and can lead to erosion of the smooth cartilage on the underside of the bone (similar to the athlete with EPPS compression syndrome). […]

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