Runner's Knee: Patellofemoral Pain Explained

Runner's knee is the injury I see most often in people who have recently increased their mileage, and it is also the one most likely to be misunderstood. The pain sits around or behind the kneecap, it builds gradually rather than arriving with a bang, and it has a habit of being fine during the first mile and miserable by the fifth. If that sounds like your knee, this is for you.

The proper name is patellofemoral pain syndrome. It describes pain arising from the joint between the kneecap (patella) and the groove in the thigh bone it slides through as you bend and straighten. It is not a tear, it is not arthritis, and in the overwhelming majority of cases it is not damage in any structural sense.

What runner's knee actually feels like

The classic pattern is a dull, diffuse ache around the front of the knee. Ask someone to point to it and they usually cup the whole kneecap with their palm rather than jabbing one finger at a spot — that vague, "somewhere in there" quality is characteristic.

It typically gets worse with:

• Running, especially downhill or on camber
• Squatting, kneeling or going down stairs
• Sitting with the knee bent for a long stretch — the so-called "cinema sign"
• Getting up after that long sit, easing off once you have moved about

Some people report a grinding or clicking sensation. On its own that is not a worry: noisy knees are extremely common and poorly correlated with any problem.

Why it happens

The honest answer is that patellofemoral pain is usually a load problem rather than an alignment problem. The tissue around and behind the kneecap has been asked to tolerate more than it is currently conditioned for, and it has become sensitised.

The most common trigger I see in Liverpool runners is a training change: a jump in weekly distance, a new hill route, a switch to faster sessions, or coming back after a lay-off at the mileage you finished on rather than the mileage you can currently handle. Merseyside's calendar makes this seasonal — spring race entries and autumn marathon blocks both produce a wave of sore kneecaps about six weeks in.

Contributing factors worth assessing include hip and quadriceps strength, running cadence, and how much of your week is running versus anything else. What matters much less than the internet suggests: the shape of your kneecap, mild differences between your legs, and whether your feet roll in.

What assessment involves

When I assess a runner's knee, I am trying to answer three questions. Is this actually patellofemoral pain, or something else wearing the same disguise? What has changed in your training or your life to bring it on now? And which of your capacities — strength, tolerance, technique — has the most room to improve?

That means a conversation about your training history, watching you squat, step down and hop, testing hip and thigh strength properly rather than by eye, and examining the knee itself. I do not need a scan to diagnose this, and national guidance does not support routine imaging for straightforward anterior knee pain. A scan of a sore kneecap frequently shows findings that are equally present in people with no symptoms at all, which tends to frighten rather than help.

Treatment that has evidence behind it

Exercise is the treatment. Research consistently shows that a progressive strengthening programme targeting the quadriceps and hips outperforms passive treatments for patellofemoral pain, and the effect holds up over the long term.

That usually means:

Load management, not rest. Complete rest settles the pain and then it returns the moment you run, because nothing has changed. Instead I reduce running to a level your knee tolerates — sometimes shorter, flatter, slower, sometimes run-walk — and build from there.

Strength work. Quadriceps and gluteal strengthening, loaded properly and progressed over weeks. This is the part people skip and the part that does the work.

Technique tweaks where useful. A modest increase in cadence reduces load through the kneecap for some runners. It is a tool, not a cure, and it is not right for everyone.

Time. Patellofemoral pain typically responds over weeks to a few months, not days. That is normal and not a sign of failure.

Hands-on treatment, taping and soft-tissue work can help symptoms in the short term and I use them where they earn their place — but as an adjunct that makes the exercise possible, never as the plan itself.

What you can do this week

Keep moving. Drop your running to whatever is comfortable rather than stopping. Add a simple strength session twice a week: sit-to-stands, step-downs and a hip-focused exercise such as a side-lying leg raise, working in a range that does not spike your pain. Expect some discomfort during and shortly after — as a rule of thumb I am comfortable with pain up to about 3 out of 10 that settles within 24 hours.

Avoid the temptation to buy your way out of it. There is no insole, strap or shoe that substitutes for building capacity.

When to seek help — and when to seek it urgently

Book an assessment if the pain is not improving after a few weeks of sensible self-management, if it is limiting more than running, or if you simply want a plan rather than guesswork.

See a doctor urgently, rather than a physiotherapist, if you have any of the following: a knee that gave way completely at the moment of injury, a knee that locks and will not straighten, marked swelling that came on within an hour of an injury, an inability to weight-bear, or a hot, swollen knee accompanied by fever or feeling generally unwell. Those point to problems that need different investigation.

I treat runners across Liverpool and Merseyside, either in your own home with all the equipment brought to you, or by video call if you would rather work through a programme remotely. If you want to read more about how I work locally, there is detail on my Liverpool physiotherapy page, on knee pain specifically, and on sports injury rehabilitation.

If your knee has been grumbling for a while and you would like a clear plan rather than another fortnight of guessing, you can book an appointment at /portal/book or call me on +44 7553 370300. Home visits are £90 and online consultations £60, evenings Monday to Friday, plus Saturday and Sunday daytimes — and you do not need a GP referral to see me.