Everything you need to know about Runner’s Knee Syndrome

Everything you need to know about Runner’s Knee Syndrome

Runner’s knee syndrome is very common among amateurs and athletes who practice running. We analyse the main causes.

What is it

Runner’s knee is the colloquial name of femoropatelar syndrome, a change in the structure of the knee which leads to the degeneration of the joint cartilage and produces intense pain from the friction between the patella and the femur in the joint flexo-extension.

How it manifests itself

The knee is a complex synovial joint structure (diarthrosis) that has great mobility.


Figure I. Osteo Articular structure of the knee.

This is the main cause why it is a joint that causes us many problems.

As humans, we walk in bipedation, so the lower limbs are in continuous movement and tension, receiving impacts systematically. The knee joins the femur with the tibia and fibula, and as a connection of both segments, take on a great burden in daily activities (walking, climbing stairs, exercising…)

Our knees are adapted to these demands, so normally, and although because of the large number of substructures that the knee has usually cause discomfort to many people, it does not present problems.

Who suffers from it?

However, there is an increased risk of developing this condition in a population group: athletes.

People who exercise, especially those who exercise with high intensity, duration and/or frequency, have accelerated joint metabolism and a much greater risk of developing premature osteoarthritis (Van Dijk et al., 2016; Amoako et al., 2014; Vannini et al., 2016).

Sport as a cause of runner’s knee

This is a widely misused concept, and is that there are direct mechanisms through which we can associate the practice of physical exercise of impact (such as running) with bone and joint degeneration, and therefore with the development of joint disorders, pain and injuries.

However, the relationship is not so simple, and all the causes of developing an injury must be evaluated.

Runner’s knee is not as traumatic of an injury as a ruptured cruciate ligament.

Runner’s knee is a syndrome that occurs when continued overuse degrades articular cartilage (sometimes pain occurs before this process begins), causing exposure of the bone by degeneration of the protective structures and damaging the bone marrow by rubbing the kneecap with the femur.


Figure II. Grades I-IV of cartilaginous damage to the knee joint.

This figure shows the runner’s knee with a structural alteration, classic in middle-advanced athletes, and even in non-athletes, many elderly may suffer this simply from joint degradation over time (Petersen et al., 2014).

However, not whenever there is discomfort and pain there is a structural alteration of the joint, that is, there does not have to be a degradation of the cartilage and damage to the bone to suffer runner’s knee (Van Der Heijden et al., 2016).

Patellofemoral pain syndrome

This is what happens to young people with this condition, and this is called patellofemoral pain syndrome.

Patellofemoral pain

Figure III. Chart Flow of the development of patellofemoral pain.

An untreated patellofemoral pain syndrome will eventually produce a symptom of knee osteoarthritis (Petersen et al., 2017) that will damage the cartilage and expose us to a more serious and serious runner’s knee syndrome.

It is important to detect it and to know how to act before it causes structural damage to the joint, which is a problem because 25% of athletes diagnosed with this syndrome stop exercising.


Tendonitis on the knee

In general, the main causes attributed to the appearance of the runner’s knee are structural changes:

  • Damage to the joint-bone assembly.
  • Osteoarthritis.
  • Tendonitis and insertional tendinosis.
  • Patellar instability.
However this, again, is a problem of approach, since structural changes by themselves do not produce a syndrome of runner’s knee (Petersen et al., 2014).

The real cause

The real cause of runner’s knee appearance is an excess training load to which the tissue is not adapted; which usually leads to poor biomechanical adaptations to the physical exercise being carried out, and which produce structural alterations that worsen with the excess load.

Basically, a vicious circle.

Where is the problem?

The main manifestation of the problem is the knee, is the patellar deviation:

This deviation is observed when we perform physical exercise, for example, in the so-called functional dynamic value, where the femur or tibia (or both) rotate internally and cause the knee to move “inward” (adduction);

A position in which you should not find yourself in, and which dramatically increases friction resistance, degenerating cartilage.


Figure IV. Graphical representation of a functional knee valgus.

The knee joint, that undergoes this position for a long time (e.g. in athletes), ends up displacing the patella outward, hindering muscle control over the joint and producing a greater instability on the knee that increases the risk of acute injury (such as a subluxation or dislocation), and/or chronic (tendinitis, cartilage degradation, osteoarthritis).

This condition is called patellar deviation.


Figure V. Graphical representation of the patellar displacement in front view (A) and axial (B).


Poor foot position during motion can cause a knee disturbance.

The main reported cause through which the feet can lead to developing runner’s knee is the eversion of the back of the foot (pronation of the sole of the foot) that causes the tibia to rotate internally, and with it the knee is “turned inside” (i.e. approaches the longitudinal axis of the body) (Mo et al., 2013; Morley et al., 2010).


Figure VI. Graphical representation of eversion in the stride.


The weakness in the muscles that externally rotates the femur, or that abducts the hip, is key to the development of the corridor knee syndrome.

People who develop the runner’s knee have marked weakness in these muscles.

Strengthening the pelcubantereal musculature is key to preventing this condition and possibly the most important factor we can control as sports people.

Gluteal amnesia is a very prevalent problem in the population, especially in women (Glaviano et al., 2019), who curiously also suffer more from runner’s knee, do you see the connection?

Thigh muscles

A big weakness in the quadriceps (Crossley et al., 2016) as well as an isquiosural dominance (White et al., 2009) are risk factors in the development of runner’s knee syndrome.

However, sometimes detection is not so simple, as balances in the production of strength of the different muscles that form the quadriceps can also alter the patella and produce the effect of patellar deviation.

Q angle

Figure VII. Graphical representation of the different degrees of the Q angle and their consequences on knee displacement.

It is called the Q angle, the angle that is formed by the line of the Superior Iliac spine line with the center part of the patella, and the line of the center part of the kneecap to the tuberosity of the tibia; and determines the force vector of the quadriceps (seen lighter in the following image).


Figure VIII. Graphical representation of angle Q. Fq is the force vector of the quadriceps, Fp is the vector of patellar force, and Rl is the net result of the forces.

A patellar angle of more than 18º increases the lateral force on the patella, again producing the already present patellar deviation.

Normally people with runner’s knee syndrome have strong external vast quadriceps (the front of the outside of the thigh) and a weak internal vast (the opposite).


Figure IX. Myology of the thigh.

Knee-Spine axis

This is a minor cause, but it has been observed that those with runner knee syndrome have a lower inclination of the sacrum that is the welded bone found under our spine.


Figure X. 3 types of pelvis depending on the degree of sacral inclination.

That is, people with runner’s knee tend to have rectified the curvature of the final part of the spine.

Symptoms of Runner’s knee

The most obvious, and only symptom you should worry about with runner’s knee, is the pain.

Since it is the one that appears first and since if there is no pain or difficulty in carrying out your daily activities you should not worry about any type of structural change.

“I have one leg shorter than the other” It doesn’t hurt? Don’t touch it.

How to treat Runner’s knee

There are many treatments to improve Runner’s knee; among them:

Pad or brace for Runner’s Knee

The knee brace is a fabric structure that is located inside the orthotic tools for the joint support.

This accessory helps to center the displacement of the patella, preventing the quadriceps force vector from moving the patella.

Draper et al., (2009) demonstrated that the use of knee pads was effective for the treatment (short-term) of runner’s knee syndrome, increasing the contact surface of the kneecap with the femur and decreasing its displacement.

Knee brace effects

Figure XI. Knee brace effects on the placement angle of the kneecap.

Although the actual evidence is mixed, as there are studies that show no improvements with their use (Smith et al., 2015).

Exercises for Runner’s knee

Physical Exercise is the main physiotherapeutic treatment for the runner’s knee.

It is important to be able to assess what are the specific causes in your case in order to be able to treat it correctly.

It is essential to perform strength exercises (e.g. with resistance bands) involving hip abduction and strengthening of the muscles involved in this movement. Here you hve a great strength training guide for runners.

Hip abduction

Figure XII. Execution model of a hip abduction exercise.

It might also be helpful to make sure your quadriceps are strong and not dominated by the strength of your isquiosurales.

Similarly you should make sure that there is no imbalance in the strength of the different muscles that make up your quadriceps.

For that, it’s best to do a pistol squat as a test and record it from a frontal view.

Test 1

Figure XIII. Different A-D graduated models depending on the dysfunctionality shown in an eccentric unilateral squat test for diagnosing the cause of runner’s knee.

  • If your movements look like A, good work;
  • It if looks like B, you should strengthen your core, you are unstable, friend…;
  • If it looks like C your hips are failing, you have weakness in the pelvic muscles, and you should work them as I indicated above;
  • And if it looks like D… you are quite bad, as you show a loss of control over the knee, hip and eversion of the foot.
In the worst case, you should put yourself in the hands of a good physical therapist and a graduate in physical activity and sport sciences to help you with it, since the case is complex.

Surgical treatment of Runner’s Knee

Surgery is the last option for the treatment of patellofemoral pain.

It should only be applied in very specific cases, such as grades III and IV of osteoarthritis, so in young people it is completely discouraged to operate unless a specialist recommends it and establishes it as the most recommended guideline for treatment.

Surgery usually involves rebuilding the cartilage at the base of the femur, transferring tibial tuberosity and/or rotational osteotomy.

Supplements in the management of runner’s knee syndrome

There are food supplements that we can use to deal with runner knee syndrome, especially the discomfort it generates.

First glucosamine, an aminoglycan that has been shown to be effective in preventing cartilage wear in athletes (Yoshimura et al., 2009).

MSM is a sulfur compound that has been a characteristic of joint pain caused by knee osteoarthritis(Debbi et al., 2011)

The combination of glucosamine and MSM has been shown to be more effective than both compounds separately in the adjuvant treatment of osteoarthritis, so they act in synergy(Usha y Naidu, 2004)

Did you know you have this combination in our Joint Care?

Finally, ginger root extract is a great nutritional supplement to attenuate the inflammatory response thanks to its high content in ginsenosides that act as antioxidant and anti-inflammatory alkaloids(Mazidi et al., 2016).


The runner’s knee is a syndrome that appears with or without alterations in the knees, in fact, the most common diagnosis is patellofemoral functional syndrome, i.e. the pain does not come from any apparent place.

High intensity, duration, and impact physical exercise, with poor load management is a determining factor in the development of the runner’s knee.

Once the pain appears you should control it with rest, cold, compression, and elevation of the joint.

You should retrain as soon as possible, in a controlled manner so that you don’t lose the functionality of the joint.


Training with control is not a problem!

It’s going to help you, so you don’t have to quit sports. Strengthen your muscles External rotators and hip abductors, and your quadriceps.

Make sure your stride is stable and adequate, especially on a run. If you want to know more, visit this link.

Use anti-inflammatory and chondroprotective supplements during the recovery process to be ready as soon as possible!

Bibliography Sources

  1. Amoako, A. O., & Pujalte, G. G. A. (2014). Osteoarthritis in young, active, and athletic individuals. Clinical Medicine Insights: Arthritis and Musculoskeletal Disorders, 7, 27–32.
  2. Barton, C. J., Levinger, P., Crossley, K. M., Webster, K. E., & Menz, H. B. (2012). The relationship between rearfoot, tibial and hip kinematics in individuals with patellofemoral pain syndrome. Clinical Biomechanics, 27(7), 702–705.
  3. Chen, H. Y., Chien, C. C., Wu, S. K., Liau, J. J., & Jan, M. H. (2012). Electromechanical delay of the vastus medialis obliquus and vastus lateralis in individuals with patellofemoral pain syndrome. Journal of Orthopaedic and Sports Physical Therapy, 42(9), 791–796.
  4. Crossley, K. M., Stefanik, J. J., Selfe, J., Collins, N. J., Davis, I. S., Powers, C. M., … Callaghan, M. J. (2016). 2016 Patellofemoral pain consensus statement from the 4th International Patellofemoral Pain Research Retreat, Manchester. Part 1: Terminology, definitions, clinical examination, natural history, patellofemoral osteoarthritis and patient-reported outcome measures. British Journal of Sports Medicine, 50(14), 839–843.
  5. Crossley, K. M., Zhang, W. J., Schache, A. G., Bryant, A., & Cowan, S. M. (2011). Performance on the single-leg squat task indicates hip abductor muscle function. American Journal of Sports Medicine, 39(4), 866–873.
  6. Debbi, E. M., Agar, G., Fichman, G., Ziv, Y. B., Kardosh, R., Halperin, N., … Debi, R. (2011). Efficacy of methylsulfonylmethane supplementation on osteoarthritis of the knee: A randomized controlled study. BMC Complementary and Alternative Medicine, 11, 50.
  7. Draper, C. E., Besier, T. F., Santos, J. M., Jennings, F., Fredericson, M., Gold, G. E., … Delp, S. L. (2009). Using real-time MRI to quantify altered joint kinematics in subjects with patellofemoral pain and to evaluate the effects of a patellar brace or sleeve on joint motion. Journal of Orthopaedic Research, 27(5), 571–577.
  8. Glaviano, N. R., & Saliba, S. (2019). Differences in Gluteal and Quadriceps Muscle Activation During Weight-Bearing Exercises Between Female Subjects With and Without Patellofemoral Pain. Journal of Strength and Conditioning Research, 10.1519/JSC.0000000000003392.
  9. Glaviano, N. R., Bazett-Jones, D. M., & Norte, G. (2019). Gluteal muscle inhibition: Consequences of patellofemoral pain? Medical Hypotheses, 126, 9–14. https://doi.org/10.1016/j.mehy.2019.02.046
  10. Kettunen, J. A., Visuri, T., Harilainen, A., Sandelin, J., & Kujala, U. M. (2005). Primary cartilage lesions and outcome among subjects with patellofemoral pain syndrome. Knee Surgery, Sports Traumatology, Arthroscopy, 13(2), 131–134.
  11. Mazidi, M., Gao, H. K., Rezaie, P., & Ferns, G. A. (2016). The effect of ginger supplementation on serum C-reactive protein, lipid profile and glycaemia: A systematic review and meta-analysis. Food and Nutrition Research, Vol. 60, p. 32613.
  12. Mo, S. W., Xu, D. Q., Li, J. X., & Liu, M. (2013). Effect of backpack load on the head, cervical spine and shoulder postures in children during gait termination. Ergonomics, 56(12), 1908–1916.
  13. Mølgaard, C., Rathleff, M. S., & Simonsen, O. (2011). Patellofemoral pain syndrome and its association with hip, ankle, and foot function in 16- to 18-year-old high school students: A single-blind case-control study. Journal of the American Podiatric Medical Association, 101(3), 215–222.
  14. Morley, J. B., Decker, L. M., Dierks, T., Blanke, D., French, J. A., & Stergiou, N. (2010). Effects of varying amounts of pronation on the mediolateral ground reaction forces during barefoot versus shod running. Journal of Applied Biomechanics, 26(2), 205–214.
  15. Petersen, W., Ellermann, A., Gösele-Koppenburg, A., Best, R., Rembitzki, I. V., Brüggemann, G. P., & Liebau, C. (2014). Patellofemoral pain syndrome. Knee Surgery, Sports Traumatology, Arthroscopy, 22(10), 2264–2274.
  16. Petersen, W., Rembitzki, I., & Liebau, C. (2017). Patellofemoral pain in athletes. Open Access Journal of Sports Medicine, Volume 8, 143–154.
  17. Prins, M. R., & van der Wurff, P. (2009). Females with patellofemoral pain syndrome have weak hip muscles: a systematic review. Australian Journal of Physiotherapy, 55(1), 9–15.
  18. Smith, T. O., Drew, B. T., Meek, T. H., & Clark, A. B. (2015). Knee orthoses for treating patellofemoral pain syndrome. Cochrane Database of Systematic Reviews, 2015(12), CD010513–CD010513.
  19. Usha, P. R., & Naidu, M. U. R. (2004). Randomised, double-blind, parallel, placebo-controlled study of oral glucosamine, methylsulfonylmethane and their combination in osteoarthritis. Clinical Drug Investigation, 24(6), 353–363.
  20. Van Der Heijden, R. A., De Kanter, J. L. M., Bierma-Zeinstra, S. M. A., Verhaar, J. A. N., Van Veldhoven, P. L. J., Krestin, G. P., … Van Middelkoop, M. (2016). Structural abnormalities on magnetic resonance imaging in patients with patellofemoral pain: A cross-sectional case-control study. American Journal of Sports Medicine, 44(9), 2339–2346.
  21. Vannini, F., Spalding, T., Andriolo, L., Berruto, M., Denti, M., Espregueira-Mendes, J., … Filardo, G. (2016). Sport and early osteoarthritis: the role of sport in aetiology, progression and treatment of knee osteoarthritis. Knee Surgery, Sports Traumatology, Arthroscopy, 24(6), 1786–1796.
  22. White, L. C., Dolphin, P., & Dixon, J. (2009). Hamstring length in patellofemoral pain syndrome. Physiotherapy, 95(1), 24–28.
  23. Yoshimura, M., Sakamoto, K., Tsuruta, A., Yamamoto, T., Ishida, K., Yamaguchi, H., & Nagaoka, I. (2009). Evaluation of the effect of glucosamine administration on biomarkers for cartilage and bone metabolism in soccer players. International Journal of Molecular Medicine, 24(4), 487–494.

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Review of Runner’s Knee Syndrome

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Causes - 100%

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About Alfredo Valdés
Alfredo Valdés
He is a specialist in metabolic physiopathology training and in the biomolecular effects of food and physical exercise.
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