Patellofemoral Pain Syndrome
Also known as runner’s knee, or anterior knee pain syndrome, patellofermoral pain syndrome (PFPS) is the most common of running injuries, and according to some studies is the most common injury for which people present to physiotherapists. So, if you’re suffering from it, you can take some comfort in the fact that you’re not alone.
Symptoms of runner’s knee
Generally, you’ll feel a dull, achy pain that’s behind the kneecap, or perhaps around the top of it. It’s usually worse for squatting, running, walking up and downstairs, and sometimes sitting for a long time.
You also probably feel pain when you extend your leg against resistance (so if you’re seated and you straighten your knee with someone pushing against your shin), or if you push against the kneecap itself.
What else could it be?
It’s possible the pain you’re feeling could be patella tendonitis, which is a different injury and therefore needs different treatment. Patella tendonitis is a problem with the tendon that connects your knee cap to your shin, and pain tends to be felt just underneath the knee cap, rather than behind it.
What’s Causing the Pain?
PFPS gets its name from the anatomy around the knee. If you were to peel the patella back to show the underside of it, you’d see a ridge running the length of it. This ridge fits into a groove in the femur (the thigh bone). It’s designed so that the ridge runs smoothly through the groove, if the knee is biomechanically sound.
The cause of the pain is PFPS is the ridge on the back of the patella rubbing against the groove in the femur when you bend and straighten your knee.
Who is more at risk?
- More common in women than men
- People with weak quadriceps (thigh muscle)
- People with poor flexibility in the quadriceps
- People with poor calf flexibility
- People with poor hip biomechanics (weak hip abductors –the muscles that you use to move your leg away from your body out to the side, and weak external rotators-the muscles that help stop your femur (thigh bone) from rotating inwards
Is the kneecap or the thighbone the problem?
There are two ways to look at this. In the past most of the research has been around what’s happening with the kneecap, and how your thigh muscles control how the kneecap tracks in the groove of your femur.
The kneecap appears to be pulled towards the outside of the leg when the knee is bending and straightening under load in people with PFPS, which would point to a strength imbalance in the quadriceps muscles (there are four heads to the muscle). A weak vastus meialis oblique (VMO- which is on the inside front of the thigh above and beside the kneecap), and an overly tight ITB and/or overly strong and/or tight vastus lateralis (the head of the quadriceps on the outside of your leg) was thought to be the cause of the kneecap pulling towards the outside of the leg.
Basically, a strength imbalance in the muscles surrounding the kneecap. Makes perfect sense.
Treatment and rehab surrounding PFPS has traditionally focused on strengthening the VMO, and runners who strengthen their VMO will often recover.
But, more recent research has shown that these gains are probably from overall improvement in quadriceps strength, not just in VMO activation.
The other way to look at what’s causing PFPS is to look at what’s happening to the femur. More recent research has shown that the femur actually rotates underneath the kneecap when the knee is bent and straightened, in people with PFPS. This also makes perfect sense, when you think that people who have poor external rotator strength are more prone to PFPS. Their muscles aren’t strong enough to stop their thighbone from rotating inwards, and causing that groove to be out of alignment with the kneecap.
What to do about it?
Work on getting the hip rotators, abductors and quadriceps strong. Exercises such as the clam for hip rotators, side leg raises and bodyweight squats are a good starting point for anyone who hasn’t done strength work in these areas previously. You should be aiming to move to more functional exercises fairly quickly.
Tape the Knee
The main methods people use to tape the knee are the McConnell Method or
Kinesio Taping ® . Both have been shown to provide some relief for pain. Interestingly though, it seems it’s the mere presence of the tape, rather than the actual taping method employed, that provides some kind of feedback to the brain, that helps with the problem. So even if you can’t get your head around precisely which bit of tap goes where, have a go, because a reasonable approximation of either method appears to do the trick. For this particular problem, I’d be more likely to use a flexible tape such as Kinesio tape, as it’s probably going to stay on sweaty skin which is being stretched when each time the knee bends, for longer.
Taping has found to have only a small benefit for the treatment of long term symptoms of PFPS. It’s effective use is more on a short term basis for the prevention of pain to enable exercise to continue pain free.
Stretching and Foam Rolling
Loosen up tight calves and quads by stretching and foam rollering. If stretching your quads irritates your knee, ease off on it, or put the stretch on hold for a while.
All that friction happening around the knee could be setting up some inflammation, so icing after a run could be helpful in reducing the pain. Rub an iceblock over and around the knee cap for 5-10 minutes, or you can also use and icepack.
Whilst orthotics have helped some people with PFPS, they should probably not be the first port of call. You’re much more likely to get benefit from improving your hip strength.
Should You Stop Running?
This injury can hang around a bit, so you need to be sensible. You don’t want to run through pain, if the pain is persistent or getting worse as your run progresses. Taping your knee before you run can help with the pain, and might keep you running on a reduced workload whilst you treat the injury with strength training exercises.
If you feel you knee’s a bit sore or stiff at the beginning of a run, but gets better as you go along, you’ll generally be right to keep going.
How much time you might need off from running is a very individual thing. Some people might be back on track after a few days or a week off from running, combined with an ongoing strength routine, others may take up to 6 weeks. A good physio will be able to give you a fairly accurate estimate of how long you might be out for, and if you actually need to take any time off at all.
Bolgla, L. A.; Boling, M. C., An Update For The Conservative Management Of Patellofemoral Pain Syndrome: A Systematic Review Of The Literature From 2000 To 2010. The International Journal of Sports Physical Therapy 2011, 6 (2), 112-125.
Prins, M. R.; van der Wurff, P., Females with patellofemoral pain syndrome have weak hip muscles: a systematic review. Australian Journal of Physiotherapy 2009, 55, 9-15.
Peters, J. S.J and Tyson, N.L
Proximal Exercises are Effective in Treating Patellofemoral Pain Syndrome: A Systematic Review
Int J Sports Phys Ther. 2013 Oct; 8(5): 689–700.
Ferber, R.; Kendall, K. D.; Farr, L., Changes in Knee Biomechanics After a Hip-Abductor Strengthening Protocol for Runners With Patellofemoral Pain Syndrome. Journal of Athletic Training 2011, 46 (2), 142-149.