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Patellofemoral Pain Syndrome (PFPS)

Keeping in theme with our last blog on running injuries, I thought that I would discuss one of the most common running injuries that present to us in the clinic. Patellofemoral pain Syndrome (PFPS).

Patellofemoral pain is the term used to describe pain under around or behind the kneecap, it is very common and can cause pain with squatting, stair climbing, walking, running and twisting movements. It can be a frustrating and challenging injury for both the patient and therapist due to the multifactorial nature of the condition. There is not one particular cause for Patellofemoral pain but rather a number of contributing factors. Due to this and individual variance, it is important to have a tailored assessment and a tailored treatment approach.

 

 

 

 

 

 

Let’s explore further some of the issues that may contribute to Patellofemoral Pain particularly as it relates to runners.

  1. The Patella ( kneecap) sits in a groove on the femur ( thighbone) and as the knee bends and straightens the patella has to move within this groove. Some research has indicated that a maltracking of the patella within the groove can contribute to patellofemoral pain syndrome by putting increased stress on the patellofemoral joint. Within this “cause” there are again a number of things which can contribute to maltracking of the patella, particularly when we look at the pelvic and hip control with running.

1.  The opposite pelvis drops which places increased tension on the outside of the patella.

2.  The femur bone internally rotates which causes the femur to roll under the patella.

3.  The quads and gluts may be weak causing poor motor timing.

4.  The foot over pronates or rolls inwards which can lead to the tibia (shin) collapsing under the patella.

 

 

 

2.  Overload – as we discussed in our last blog, training overload is a huge contributor to injury particularly in Patellofemoral pain. For example, increasing distance, speed or hill running can all contribute to increased load on the tissues surrounding the patella which may influence pain. Again a great cue as we discussed in our last blog to reduce loading on the knee structures is to “run lighter and take shorter faster steps”.

3.  Foot mechanics – there is some evidence to suggest that foot mechanics such as landing in pronation (foot rolling inwards) may contribute to patellofemoral pain and in the short term orthotics may be helpful to help unload the painful structures.

4.  Muscle weakness – there is a little evidence to suggest that muscle weakness contributes to patellofemoral pain. However from our last blog, we know that the muscles must be able to deal with the training stresses we put them under, and so if our muscles are not strong, it may contribute to patellofemoral pain. Some of the key muscles that we look at when we are assessing patellofemoral pain are the gluteal muscles as they provide the control around the hip joint and pelvis when we are walking or running. Studies have shown that in patients with patellofemoral pain, there is a delayed onset of glut med activation which can lead to a pelvic drop and internal rotation of the femur. However, it is not clear if this weakness is a CAUSE of PFPS or an inhibition of the muscles DUE to PFPS.

We also can look at Quadriceps strength in relation to PFPS. Again patients often show weakness of the VMO muscle but whether this is due to inhibition or an actual cause of PFPS, we are yet to find out. In this regard, we also speak about the timing of muscles and it has been suggested that altered timing patterns of the outer quads muscles (VL) vs the inner quads muscles ( VMO) can affect the loading of the patellofemoral joint.

So as we can see from the above, there is no one specific cause of patellofemoral pain, and there is a lot of debate in the literature, the only thing we know for sure is that patellofemoral pain is a multifactorial injury demanding a multifactorial approach to treatment.

Watch this space for the next instalment – what we can do to help in the management of your patellofemoral pain!

 

 

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