Patello-Femoral Pain Syndrome

Hello and welcome back to the ThreeSpires Physiotherapy blog where we take a look at all things physiotherapy and health related. In the last two blogs we have looked firstly at the anatomy of the knee and secondly at the structures that might cause pain and some of the possible reasons that they may become injured. In this blog post I thought it would be good to look at a common knee problem that can be extremely difficult to resolve - patella-femoral pain (PFP).

What is Patello-Femoral Pain Syndrome (PFPS)?

This condition affects a large number of people and is known by a few names: runner's knee, anterior knee pain and patella-femoral pain syndrome (PFPS). Patello-femoral pain is a subject of a large amount of research and considerable debate amongst physiotherapists, athletes and researchers and a full review of the subject would be beyond the scope of this article. Instead all I hope to achieve is to illustrate how it presents and some ideas surrounding its causes.

What are the Symptoms of Patello-Femoral Pain Syndrome (PFPS)?

In general people with patello-femoral pain will have pain around the front of the knee in the area of the knee cap itself, commonly it will be feel sore below the patella but in bad cases the whole of the knee can be sore. As can be guessed from the name Runner's Knee, it is common in runners.

Who is at Risk of Developing Patello-Femoral Pain Syndrome (PFPS)

Pretty much anyone of any age and gender who is mobile and is on their feet a fair bit can develop PFPS however there are some people and categories of peoplewho are more at risk of developing PFPS:

• Runners: anyone who does a large amount of running or especially those who have either taken up running recently or have started training for a specific event are at risk of developing PFPS. This does not mean that all runners are going to get PFPS but there is a fairly clear linkage between PFPS and running especially when you consider another common name for PFPS is runner's knee. Runners most likely to be at risk of PFPS are those who have been rapidly increasing distance or speed recently.

 

• Walkers: obviously most people walk to some degree but in this case here I am considering people whose hobby is walking long distances or walking in the hills. Again as with running doig a lot of hill or mountain walking does not mean that you are going to develop PFPS if this is something that you have been doing for a long time. Those most at risk here are those who have recently started and are rapidly building up the distances that they walk.

 

• People who walk as part of their work: postman, policeman and potentially people working in a distribution plant such as Amazon who walk a large amount each day as part of their work can develop PFPS. This is due in general to the large amount of walking and time that these people spend on their feet and anyone only recently starting a job such as this is at risk of overloading their knee and developing patello-femoral pain.

What Causes Patello-Femoral Pain Syndrome (PFPS)

This is a thorny and difficult question and is currently (and has been for a long time) the subject of research. I think it is reasonable to say that most people would agree that patello-femoral pain syndrome (PFPS) is mainly an overuse and overload injury. Working out what the key factors that are driving the overload and the pain is the difficult part. Below are some common and generally accepted causes of patello-femoral pain syndrome (PFPS) be aware though that apart from the first two there is a large amount of debate about their importance and each one could form a lengthy article in its own right.

1. Going too Far or too Fast: for many of the other potential reasons listed below for PFPS I think there can be a large amount of debate but going too far or too fast is quite clearly the underlying reason for the majority of PFPS. New runners are especially prone to falling foul of this by building up both distance and speed way too quickly. Areas such as the patello-femoral joint take time to strengthen and adapt to new stimuli and if you keep building up speed and distance without giving your knee time to adapt then eventually it will get overloaded. 
2. Hip weakness- much of the control of the lower limb comes specifically from the muscles at the hip and the hip muscles are responsible for control of internal and external rotation of the majority of the leg. Lack of strength here can produce consequences further down the kinetic chain of the leg and certainly if a patient's knee is deviating inwards on walking, squatting or running there is a fair chance that this is a weakness of the hip muscles rather than the knee muscles themselves. Strengthening of this area in patients with runner's knee can produce good results in terms of improved control, gait and reduced pain. 
3. Leg length discrepancy - the first two causes of patello-femoral pain syndrome (PFPS) are I think fairly well accepted by most clinicians for the next set of reasons there is  lot of debate and each one could be a blog topic in its own right. However to varying degrees they do all contribute to PFPS and I think as a physiotherapist I always like to eliminate potential underlying causes of problems. Differences between the length of each leg in most people are common and in fact some would say that this is the norm. Certainly the majority of people will have a difference of at least 5-10 mms between sides and have no problems and in fact be completely unaware of this difference. The importance of leg lengh discrepancy increases with the size of the difference and the amount of running or weight-bearing activity someone is doing. Potentially with some one doing a lot of running or a large amount of walking a difference of over 10mms is thought to be significant and certainly anything over 20 mms would in my opinion need to be addressed. The reasons that this potentially causes PFPS are easy to understand: if you have a shorter leg it is very likely that one leg (most likely the shorter) will take more load and more impact. This difference in load will not be felt when wlking normally but the further you walk or the longer you run the more this adds up. 
4. Foot posture: this potential cause of patello-femoral pain syndrome (PFPS) has been the subject of a large amount of research with some evidence suggesting that those with flat feet are at more risk of developing PFP. However it would be fair to say that most of the research has been inconclusive and it is difficult to say how much of a factor foot posture truly plays in likelihood of developing PFPS. This is not to say that foot shape and posture does not play a role in developing PFPS in some people (in my opinion it does) but that instead you should address the more obvious issues such as overload and hip weakness first before considering foot posture. That having been said some people have well developed medial arches of the feet and others have very flat feet, sometimes when walking or running those with flat feet can display quite a clear over-pronation at the ankle and foot which in turn clearly deviates the knee. There is a good argument to be made that this in turn then overloads the knee through gait and can cause PFPS. As I said there is a large amount of debate on this topic but certainly my experience is that for some patients with very flat feet and who are heavily pronating in their gait a medial arch support orthotic can produce good results in reducing pain and allowing patients to return to running. 
5. Ankle instability: the stability and strength of each of the joints in the leg is clearly going to affect the load through the other joints or potentially the joints on the opposite side. As such ankle instability can sometimes cause an overload of the knee joint. I would say that in my experience this is less common than the other isses identified earlier but still occasionally I see some patients who have a normal medial arch but have an unstable ankle on one side. This can cause them to overload the structures of the knee when running and lead to patella-femoral pain. With these patients some balance work and ankle proprioception exercises tends to work well in eliminating their patello-femoral pain syndrome (PFPS)
6.  Patella position and the angle of the patella tendon: for a long period this was thought to be one of the most important factors in PFPS and identifying the Q angle and other measurements were thought to offer a way of gettng rid of PFPS. The idea was (and is) that if the patella is "out of position" it will rub and cause pain in that area. I think it is now widely accepted that the angle of patella and its tendon are anatomically very variable in people and as such it is extremely difficult to be certain of what importance this plays in developing PFPS. Ceryainly knowing when to address this if as a physio you can see that when running the patella on one side does seem to be out of skew is very tricky and a matter of opinion and current research. Personally for some patients with whom I have eliminated the other more basic causes of patello-femoral pain sydnrome (PFPS), such as overload or weakness I have found that taping of the patella can be effective potentially as a way of  providing feedback to the muscles that control movement of the patella and knee.
7.  Quadriceps weakness: as with the angle of the patella a weakness in one of the quadricep muscles (VMO) was thought to be weak in patients with PFP. The idea was that a weakness of this muscle caused the patella to be pulled out of line by a stronger quadrceps muscle and this cause rubbing and eventually pain. Again as with the patella angle I think it is fair to say that both research and experience has moved away from this being a significant contributor to patello-femoral pain syndrome (PFPS) in the majority of people. Most research has suggested that it is not possible to isolate the quads muscles individually and it is not possible to simply gain strength in VMO and thus get that to pull the patella into line. That is not say that quads strengthening does not work in a large number of PFPS patients (my experience is that it does) instead it simply means that by having stronger quads you are likely to have better general stability and control over your knee and thus be less likely to overload it.  

How is Patello-Femoral Pain Syndrome (PFPS) Diagnosed?

Usually this is done based on clincial symptoms during an assessment with a patient by a physiotherapist. Occasionally there is a need for imaging to rule out something like arthritis but in general the diagnosis will be made by taking a good and thorough history and in combination with the results of a physical assessment. Often patients will have attended their GP with knee pain and then been referred to a physio who will make the diagnosis. If you think that you may have PFPS then it is important that you get an assessment and diagnosis early so that you can start upon an effective treatment and management plan as soon as possible. 

Treating Patello-Femoral Pain Syndrome (PFPS)

So, as with the underlying causes of PFPS there are also a large array of potential treatment options. I have tried to start with the most widely accepted and most (usually) successful options; it would be wise to be aware that I have made this section fairly personalised and it very much reflects my own treament methodology for PFPS. This is because there is a large amount of uncertainty in the literature about what is best to do for PFPS and therefore a large amount of the choice of treatment options comes down to clinical decisions with specific patients. Please remember that it is important to be certain of the diagnosis and I would always recommend a full assessment of your knee pain. 

• Hip Strengthening: I would say that hip weakness and a lack of ability to control the position of the knee due to weakness at the hip is one of the most common factors I see when treating patients with patello-femoral pain syndrome (PFPS). When asked to do an activity where the muscles of the glutes and hip are primary movers and controllers such as a static lunge they struggle to maintain control. As such hip strengthening exercises that concentrate on the ability to control position of the knee and femur are a clear first step to elimninating PFPS.

• General Leg Strengthening: as well as specific hip strengthening and stabilising exercises I have often found general leg strengthening exercises aimed at improving overall leg strength to be very effective in reducing the symptoms of patello-femoral pain syndrome (PFPS). Often patients with PFPS will have quite a marked weakness in one leg generally and increasing this leg strength often gives great results.

• Core and Pelvic Strengthening: with anyone with patello-femoral pain syndrome (PFPS) I work hard to identify any specific weaknesses in their overally kinetic chain as it is very difficult to be certain which part is causing the difficulties. I often find (especially with runners) that their general pelvic control and core strength is poor and as such I think that core and pelvic strengthening exercises can be helpful here as an adjunct to the hip and general leg strengthening exercises. 

• Reducing Load: undoubtedly with any runner or person who is training for a long-distance walk and has developed anterior knee pain this is the most difficult bit to ask them to do. As discussed earlier, it is widely accepted that PFPS is mostly an overload issue and as such one fo the key components in the early days of treatment is reducing the load upon the knee. Exercises and strengthening work should help but they will work slowly and will not be effective if the patient continues to hammer their knee with a large volume of miles each week. Basically it is necessary to reduce the amount of running or walking to a point that the knee pain becomes manageable and clearly symptoms are reducing. 

I think it is worth stating that my opinion (and experience) has been that the vast majority of patients with patello-femoral pain syndrome (PFPS) would get better just from doing the 4 factors above. The difficulty with most patients with PFPS is that usually they are training for something specific and want a quick fix that will allow them to complete their objective which leads them to be unwilling to do the 4 key treatments above and therefore their PFPS tends not to improve. Occasionally though I do find that there are some significant bio-mechanical issues that need addressing such as a significant leg length discrepancy or potentially a large amount of pronation at one foot. In these cases I then consider the following (but only after first doing the above)

• Patella Taping: as mentioned some patients are unable to reduce their  enorunning or potentially walking enough to get their symptoms under control. This can be for a variety of reasons that are perfectly udnerstandable such as they have an event such as a marathon in a few weeks and they do not want to stop training for it. For these patients the priority is symptom control and getting them through their event and as such I sometimes find that taping the patella to reduce potential pinching of the relevant fat pad or bursa near the patella can help reduce pain. 

• Orthotics: some patients quite clearly have an issue at the foot in terms of either over pronation because of lack of ankle stability or through having a reduced or collapsed medial arch. In these cases I generally recommend an off the shelf medial arch support orthotic which if successful I then ask the patient to see a podiatrist for a custom made orthotic. 

• Leg Length: if after the assessment it is clear that there is a significant and real leg length discrepancy then addressing this through either orthotics or a heel wedge can be useful. 

• Footwear: this is a particularly difficult issue and many runners will want specific advice on this subject, unfortunately though the research is extremely uncertain on what shoe is best for what kind of person. However there are some basics that seem to work: in general if I think a change of running shoes might help: e.g. the patient's shoes are very worn out and they clearly have a large amount of pronation during gait. Then I will suggest that they may need a slightly more supportive shoe. However the key here is not to move too far away from the stye of shoe that they are currently wearing as this may change too many things for the patient and give them even more problems. 

Okay, I think that we have covered the bulk of the treatment options out there for patello-femoral pain syndrome. One thing to note for readers of other blogs on this website is that you may have noticed that I have not discussed any surgical options or having a steroid injection. This is because in the case of patello-femoral pain syndrome (PFPS) there is very little that these two options can do to help. 

How Long Will My Patello-Femoral Pain Syndrome Last?

This is a very difficult question to answer and depends upon a number of factors not least of which is how willing are you to reduce the amount of running or walking that you are doing? Adherence to and compliance with both restrictions in terms of running or exercise and being dilligent with the exercises prescribed are the main factors in determining how well you will recover from your PFPS and how long it will last. Certainly though I would expect a time frame of a minimum of 8 weeks to be a good recovery depending upon how severe things were. My experience as a physiotherapist has been that more than most conditions improvements in PFPS rely upon the patient being very consistent with their exercises and also reducing the load that they are putting through the joint. 

Are There Any Specific Exercises That I Should Avoid for My Patello-Femoral Pain Syndrome (PFPS)?

As PFPS is generally an overload issue the main thing that you need to do is reduce the load through the joint by backing of your training, however there are some key aspects of especially running training that you might want to avoid:

• Speed Work: in general I think it is reasonable to say that sprinting, track work or intense interval work should probably be best avoided as this puts a large amount of load through the knee joint and control of the knee is one of the major isues in PFPS. This doesn't mean that you can't do speed work forever rather that you need to allow your leg time to strengthen, gain control and for your knee pain to subside. One of the most common issues I see with people who can not get rid of their knee pain is that they have returned to high level speed work or intense loading too soon and not done enough rehab first.

• Hills: this does not mean that you can only walk or run on the flat and must avoid even the most minor of up or downhill sections. I simply mean that if one of your runs is particularly hilly then I would swap that one out for a flatter and easier run. The same goes for those doing long distance walking: if one of your walks is very hilly and involves a large amount of ascent and descent then potentially consider avoiding that one initially. 

How Can ThreeSpires Physiotherapy Help With My Patello-Femoral Pain Syndrome (PFPS)?

I think I can confidently assert that gaining access to a physiotherapist, especially in the early period of your PFPS is hugely important and as such here at ThreeSpires Physiotherapy we can help in a number of ways: 

• Assessment & Diagnosis of PFPS: potentially this is the most important aspect of the help that we are able to provide as understanding what is happening with your knee and why will guide you as to what you can do about it. Our physiotherapists are experienced at assessing and diagnosing the causes of knee pain and will be able to determine any underlying causes of your PFPS.
• Management Plan: having a clear management and treatment plan is vital to get you back on the right track to getting rid of your PFPS. Our physios have a large amount of experience at devising effective management plans for PFPS.
• Treatment for PFPS: In conjunction with load management, exercises and the other options described above your physio will be able to use soft tissue and hands on techniques to treat any areas of your legs that have become overloaded and tight.

Patello-Femoral Pain Syndrome Case Study:

Okay, as with most of the conditions that I have written about in these articles I like to use a case study to illustrate some fo the issues we have discussed and see what treatment options are best and how how we might be able to help if you think you might have PFPS.

In this case study the patient was a female in her mid 40s who had taken up running a year ago and had slowly built up the mileage until she successfully completed a half-marathon last year with no ill effects. After resting for a few months and not doing much running (1 gentle run per week) she decided to aim for a full marathon and began training in earnest in the November. She built up her running well and was doing 3-4 sessions per week with a long run once per week. On her last long run in December she felt a niggle at the front of her knee at the start of the run but ignored this and continued to run for another 6 -7 miles, the pain slowly got worse in her knee and after 6 or so miles she was forced to walk and hobble the last mile or so. She rested for a few days and then tried to run again later in the week but needed to stop after only a few miles as the knee was extremely sore.

So she got in touch with us here at ThreeSpires Physiotherapy and booked an assessment. During the taking of her history it became clear that although she had managed to do a half-marathon last year she had only really been intermittently running since then and when she started training again in November for her marathon the enxt year she was only doing 3 miles once a week. At this point she really ramped up her running and within a couple of weeks was doing 3 sessions per week of 5-6 miles and a longer run of about 9-10 miles at the weekend. As a physio this rang alarms bells for me in terms of overload and made me immediately consider that she had PFPS/ anterior knee pain/runner's knee. On examination a week the patient had no swelling or raised temperature at the knee, only minimal pain on palpation (touching) of the knee and full range of motion. Further physical testing showed a lack of control at her knee (she struggled to control position during squats and lunges) caused mostly by weak hip muscles Her leg length was roughly equal and her feet and ankles were unremarkable with no clear overpronation. At the end of this assessment in my mind this patient had a reasonably clear cut case of patella-femoral pain/runner's knee due mostly to a large increase in mileage, lack of control and strength at her hips and also due partially to fairly poor injury management - she continued to run through the pain instead of stopping quickly.So, I discussed the diagnosis with the patient and explained the underlying issue of weakness at the hips that she needed to address with strengthening work which she was very keen to work on. We then discussed the overload and the overly rapid build up in mileage that she had undertaken and made a plan for both resting more often in each week and also lowering both the distances and speeds she was running.Over the next 6 - 8 weeks the patient completed all her exercises and slowly built up her running until she was able to run 8 miles at a steady pace with no pain and was very slowly increasing her mileage further. Later that year (about 4 months later) she was able to successfully complete her marathon which was a great result. 

I hope the above case study illustrates the overload nature of PFPS and also the importance of having an assessment with a physiotherapist in order to best manage the injury and return to full fitness as soon as possible.  

I hope you have enjoyed this article about patella-femoral pain and If you or someone you know has knee pain and you would like to understand the cause and how you can improve things then please get in touch. We are a home visit physiotherapy service based in Lichfield and serving surrounding areas such as Sutton Coldfield, Tamworth, Walsall, Rugeley and Burton. We can be contacted on 0788 428 1623 or via email enquiries@threespiresphysiotherapy.co.uk