Runner's knee (patellofemoral pain): causes and rehab

What runner's knee is

Patellofemoral pain describes pain at the front of the knee, around or behind the kneecap, where the kneecap meets the groove in the thigh bone. It is one of the most common reasons active people see a physio, and it affects runners, footballers, gym-goers, teenagers and people who are not particularly active at all. Despite the name, you do not have to be a runner.

It used to be blamed mainly on the kneecap not tracking properly. The current understanding is broader: the joint and the tissues around it become sensitised because the load going through them has outstripped what they can currently tolerate. That is good news, because load and tolerance are both things you can change.

Common causes and who gets it

It is more common in women and in adolescents and young adults, and often appears after a change in activity. Typical triggers include:

• A jump in running mileage, hills or speed work
• A new training block with lots of squats, lunges, step-ups or wall balls
• Returning to sport after a break at the same volume as before
• Low strength in the quads and hip muscles
• Long periods of sitting with the knees bent, such as a long drive or a cinema trip

Foot shape, knee alignment and running technique may contribute in some people, but they are rarely the whole story, and changing them is usually less important than changing the training load and building strength.

Typical symptoms

The pain is usually a dull ache around or behind the kneecap, sometimes sharp with certain movements. It is often hard to point to one exact spot. It commonly flares with going down stairs, squatting, kneeling, running (especially downhill) and after sitting for a long time, when the first few steps can feel stiff and sore.

Clicking or grinding under the kneecap is common, and on its own it is not a sign of damage. Significant swelling, locking or the knee giving way are not typical of patellofemoral pain and suggest something else is going on.

Symptoms often come and go with training load. A good week followed by a flare after a hilly run or a heavy leg session is typical, and it is a useful signal about how much the knee currently tolerates rather than a sign of damage.

What a physio assessment looks at

Your physio will ask about your training history and recent changes, and check the knee to rule out other causes such as tendon problems, meniscus injuries or ligament damage. They will test strength in the quads and hip muscles, look at how you squat, step down and land, and may watch you run.

They will also look for movements that ease your pain, such as changing squat depth, step height or running cadence. Finding a version of each activity that you can do comfortably keeps you training while the knee settles. Scans are rarely needed for typical patellofemoral pain.

What usually helps

Research consistently shows that exercise therapy combining hip and knee strengthening is the most effective treatment for patellofemoral pain, and that it works better than passive treatments alone. The programme usually starts with exercises in comfortable ranges, such as wall sits and shallow squats, and builds towards deeper, heavier and more dynamic movements.

Load management runs alongside it. For runners, that might mean shorter runs, fewer hills and a slightly higher step rate for a few weeks. For lifters, it might mean box squats to a comfortable depth or swapping lunges for step-ups at a lower height. Taping and foot orthoses may give short-term relief for some people and can make exercise easier, but they are add-ons rather than the main treatment.

What you can start with at home

1. Wall sits at a comfortable depth, 4 to 5 holds of 30 to 45 seconds.
2. Side-lying leg raises or banded side steps for the hip muscles, 3 sets of 12 to 15.
3. Glute bridges, 3 sets of 12 to 15, progressing to single-leg bridges.
4. Box squats to a comfortable height, 3 sets of 10, lowering the box over time.
5. Step-ups onto a low step, 3 sets of 8 to 10 each side, increasing the height gradually.

Once these feel easy, add load and range. Runners should rebuild distance gradually; our guide to returning to running after injury sets out a sensible progression, and our guide to strength training for runners shows how to keep the legs strong long term.

Sitting pain responds well to simple changes. Stretch the leg out straight every 20 to 30 minutes on a long drive or at the cinema, or choose an aisle seat so you can move. These small habits often ease the day-to-day ache while the strength work does its job.

Recovery time and when to get help

Many people notice clear improvement over 6 to 12 weeks of consistent rehab, but patellofemoral pain can be persistent and some people need several months, particularly if it has been present for a long time. Sticking with the strength work after pain settles helps keep it away. The on-site physio at Lycan Strength can build a plan around your running or training, with 20% off for members; book a physio appointment online.

• Go to A&E if you cannot bear weight after an injury, or the knee swelled rapidly after a twist or impact.
• Go to A&E if the knee is hot, red, very swollen and painful, especially with a fever.
• See a GP or physio promptly if the knee locks, will not straighten, or keeps giving way.
• See a GP the same day if a child or teenager has knee pain with a limp, as the problem can sometimes come from the hip.

Questions