The knee is the most common joint to be injured in runners, and ‘Runners Knee’ or ‘Patellofemoral Pain Syndrome’ (PFPS) is the most common knee injury (1). So, if you are a runner, the chances are that you have had it, or have it now, or may one day experience it! This article describes PFPS, what it is, how it arises and what you can do for yourself to help overcome it.
So, what is it?
‘Patellofemoral Pain Syndrome’ is sometimes simply referred to as ‘anterior knee pain’. It’s a general term describing diffuse pain around or behind the patella (kneecap). PFPS is something that usually comes on gradually as a result of repetitive overload.
What causes it?
One theory is that certain biomechanical conditions can cause the patella to ‘track’ differently. Biomechanics is very individual but, put simply, you might have a ‘caving inwards’ of the knee, due to issues at the hip or foot. When the knee bends and straightens, the patella glides up and down along grooves (the ‘trochlea groove’) on the femur. If the knee ‘caves in’, then the patella will be pulled a little bit outwards and doesn’t glide so smoothly in its tracks. This puts some extra stress on the outside edge of the patella which over time might cause irritation (2).
“Loss of tissue homeostasis”
Or it might just be that repeated load going through the patellofemoral joint means that tissues in and around the joint become out of balance in their physiological processes. The knee has two joints – the tibiofemoral joint and the patellofemoral joint (PFJ). The PFJ is the one affected by PFPS and is the joint between the patella and femur underneath it. Certain parts of the PFJ have a bigger sensory nerve supply and therefore are more likely to be a source of pain. These include:
- the subchondral bone that lies just beneath the cartilage
- the peripatellar synovial membrane that lines the joint
- the hoffa’s fat pad underneath and slightly below the kneecap
- joint cartilage doesn’t have a nerve supply so is not on this list! (3).
Reduced strength in the quadriceps has been associated with PFPS, as has reduced strength in the glutes (NB PFPS is also quite common in adolescents, but they don’t seem to show the same muscle strength imbalances) (2).
How do I know if I have it?
If you have pain around or behind your kneecap which is aggravated by running, squatting, hopping, jumping or going up and down stairs – then you might have PFPS. These activities involve weight bearing on a flexed (bent) knee which puts greater load through the patellofemoral joint (PFJ). It is unlikely to be painful at rest, but your knees might complain when you get up after sitting for a while.
Sometimes there might be ‘crepitus’ of the knee i.e. clicking or grinding sensations from the patellar joint. There may or may not be some tenderness if you poke around the kneecap and possibly some slight swelling (4). Locking or giving way of the knee is also not really a symptom of PFPS.
I think I have Patellofemoral Pain Syndrome, what can I do?
I’ve demonstrated all the exercises I’ve described here in a video (below) so make sure you check that out!
Allow it to calm down
Adjust your ‘training load’
You will probably need to make some changes to your training load i.e. the amount and intensity of your running. You’ll have to experiment to find a level of training where your knee is not getting flared up. You want to keep the pain level below around 4 out 10 both during and after a run. You can try reducing some combination of frequency, distance and speed. Hills tend to be more stressful for your knees than flatter surfaces.
Taping your knee can often help to reduce the pain of PFPS. This video shows you one method using kinesiotape that’s easy for you to do on yourself. Try it and see if it helps. Bear in mind that taping doesn’t fix anything, but it could help you to keep running and get stuck into your rehab with less pain.
Balance and control
Single leg exercises are great for improving balance and control of movement. These exercises are best done little and often – several times throughout the day. If you do them in front of a mirror, at least sometimes, you can make sure that your leg stays in good alignment and your knee isn’t caving inwards.
Start off with simply balancing on one leg and work up to a minute of that on each leg. Then you can make it more challenging by closing your eyes or performing toe taps. Single leg dips are a bit more tricky but also a great exercise, combining balance, alignment and increasing confidence in your knee in a state of ‘loaded flexion’. Start with a small movement and just a few reps and build it up.
Quad strengthening is the corner stone of PFPS rehab (5). Below is a progression of quadriceps exercises starting with least stressful to the PFJ. If your knee is very painful, start gently with the first exercise and move on when you’re ready. If your knee is not so bad, you can move through the initial exercises more quickly.
Static quads exercise: sit with both legs straight out and lean back on your hands or elbows. Put a rolled-up towel or pillow under the affected knee. Engage the quads, straightening the leg, pushing the knee into the towel and hold for around 10 seconds.
Straight leg raises: Start in the same position (minus the towel) and simply lift and lower the leg.
Do the above exercises twice a day if you can to get the quads firing up. Start with as many reps as feel comfortable and work up from there.
When you are ready, move on to the following exercises. Start slowly and build up. If your pain levels go over around 4 out of 10, either during or after exercise, then you may need to back up a bit. Do these exercises 2 or 3 times a week.
Wall sits: ‘sit’ with your back against the wall and shins at 90 degrees. Start sitting up higher, so that your knees are less bent if you need to. Eventually you can progress to knees at 90 degrees. Work up to a minute and repeat 3 or 4 times.
Banded knee extensions: Lie on your back with a band hooked around your foot and push your leg out straight. You can adjust the resistance by using different strength bands. Do 3 sets of 10-15.
Bulgarian split squats: Stand on one leg with the other foot resting on a chair behind you and squat down on your standing leg. Hold weights to make it harder. Start with 10-12 reps and as you add weight, reduce the reps to around 8-10. 3 sets.
There is good evidence that hip strengthening combined with quadriceps rehab is better at reducing pain and gives better long-term outcomes (6). If your knee is very irritable you can start with just hip strengthening. This is a great routine (skip anything that irritates your knees).
Adjusting your running gait
If your knees do cave in a bit when you run, strength work is unlikely to change movement patterns. For this you would need feedback from a gait retraining program. However, one thing you can do yourself is to adjust your cadence or step rate. Increasing your cadence when you run results in less bending of your knee when you land. This means less load going through the patellofemoral joint (7). The simplest way to do this is just to focus on taking slightly quicker and shorter steps for some portions of your run. You don’t want to make any huge changes, just a small shift can make a difference.
Don’t expect an overnight fix, but if you persevere with these exercises you will hopefully get your knee pain under control. And if you need any help, then get in touch!
1.Taunton JE, Ryan MB et al (2002) A retrospective case-control analysis of 2002 running injuries. Br J Sports Med 36: 95–101.
2. Lack S, Neal B, (2018) How to manage patellofemoral pain e Understanding the multifactorial nature and treatment options. Physical therapy in sport 32:155-166.
3. Dye, Scott F. MD. (2005) The Pathophysiology of Patellofemoral Pain A Tissue Homeostasis Perspective. Clinical Orthopaedics & Related Research 436: 100–110
4. Crossley KM, Stefanik JJ, Selfe J, et al (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 Medicine50:839-843.
5. Kooiker L, Van de Port, I et al (2014) Effects of Physical Therapist–Guided Quadriceps-Strengthening Exercises for the Treatment of Patellofemoral Pain Syndrome: A Systematic Review. JOSPT 44(6) 391-402.
6. Barton C, Sohan, O et al (2015) Proximal muscle rehabilitation is effective for patellofemoral pain: a systematic review with meta-analysis. British Journal of Sports Medicine 49:1365-1376.
7. Lenhart RL, Thelen, DG et al (2014) Increasing Running Step Rate Reduces Patellofemoral Joint Forces. Med Sci Sports Exerc. 46(3):557-564