Focus on a condition: Runner’s knee

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Patellofemoral pain syndrome (PFPS), also known as runner’s knee, is one of the most common running injuries.

PFPS is characterised by pain “around” or “behind” the patella (knee cap). The pain comes from the tissues surrounding or within the joint between the patella and the femur (thigh bone).

In today’s blog we will look into the symptoms and causes of PFPS and what can be done to reduce this pain.


PFPS can be in one or both knees.  It normally affects younger runners and occurs in twice as many women as men.

Pain is normally felt at the front of the knee, where the patella lies. It is often aggravated by activities that increase the load at the patella-femoral joint (PFJ), such as squatting, lunges, descending stairs, running – especially downhill. It can also be aggravated by sitting for long periods with the knee flexed (bent).

Normally, there is no swelling, locking or giving way but sometimes the knee may feel stiff and there may be clicking.


Identifying a single cause for PFPS is difficult and more often than not there are a few things that could be contributing to the pain.

  • Biomechanics – the shape and position of the patella and how it sits in the femoral groove can alter the load through the knee joint. Also the biomechanics of the foot and ankle can have a part to play, e.g. overpronation of the foot. Some of this can be changed with taping or orthotics but often there is little that can be done. No two people are exactly the same and a lot of the people may have biomechanical changes with absolutely no pain. The best thing to do is to get an assessment from and physiotherapist to see what changes can be made.
  • Muscle weakness – the two main muscle groups to consider here are the quads (the muscles at the front of the thigh) and glutes (the muscles around the buttock/hip). If the quads are weak they can affect how the patella tracks and weak glutes can alter your running form.
  • Muscle tightness – tight calves and hamstrings (the muscles at the back of the thigh) can increase the load through the knee and tight quads will directly affect the way the patella moves.
  • Poor movement control and running form – having good muscle strength is not enough, you need the muscles to contract at the right time. If the muscles “kick in” later than they should this could mean that the knee doesn’t have the support it needs to complete the movement with good control. Running form is linked with movement control, muscle strength and biomechanics but there also other changes that can be made which may help – stride length, cadence, foot strike, foot position and hip position.
  • Training error – one that often gets overlooked by runners but actually it is probably one of the main causes of PFPS or any other running injury! Sometimes it’s simply because you’ve not taken enough rest and a lot of the time it’s caused by an increase in distance, speed or hill work.

How to reduce symptoms:

Firstly, if the pain is quite severe and very irritable the best thing you can do is REST. Sometimes the pain can be managed by reducing the amount you are doing. This means running when it is pain free and not continuing to run when the pain starts. Running may not be the only thing aggravating your knee and so it is important to consider the other everyday tasks you do and see if you can reduce or modify them to help calm the pain down. This won’t be forever but it is important that you don’t continue to aggravate the knee.

Once you’ve identified the likely causes, it’s time to address them in order to reduce the symptoms. Strengthening muscles that are weak, working on your flexibility, making changes to your running form, and setting out a good training plan. A physiotherapist will be able to help you with this.