Anterior Knee Pain (Patellofemoral Pain): Causes and Exercises

22.7%Proportion of the general population with anterior knee pain in a given year

28.9%How common it is among adolescents over one year

57%Patients reached 5–8 years after diagnosis who said they had not recovered

Hip + kneeThe exercise combination recommended by the international consensus statement

What is it?

The kneecap glides in a groove on the front of the thigh bone. Pain develops when the load on this joint is more than the tissues can tolerate. Scans often show no obvious damage; the problem is less a structural fault than an imbalance between load and capacity.

Common contributing factors are a sudden increase in activities such as running, jumping or stairs, weakness in the hip and thigh muscles, and growth spurts.

Symptoms

A diffuse, aching pain around or behind the kneecap
Worse when going down stairs, squatting, walking downhill or running
Pain after sitting with your knees bent for a long time, for example at the cinema or on a car journey
A cracking or grinding feeling in the kneecap

What helps in treatment?

A 2018 consensus statement by international researchers recommends exercise therapy, especially hip and knee exercises done together. Combining exercise with other treatments, and foot orthoses (insoles), are also among its recommendations. In contrast, mobilisation of the knee or lower back on its own and electrotherapy are not recommended; for taping, knee braces, dry needling and changing running technique, the evidence is insufficient.

Anterior knee pain does not always go away on its own. In a follow-up study in the Netherlands, 57% of patients reached 5–8 years after diagnosis said they had not recovered; pain that had already lasted more than 12 months at the start was the strongest predictor of a poor outcome. This is why early, regular treatment matters.

Treatment

Hip and knee exercisesThe foundation of treatment is exercise that strengthens the muscles at the side and back of the hip and the muscle at the front of the thigh, and stops the knee from dropping inwards.
Adjusting the loadRunning, jumping, deep squats and stair work that clearly increase the pain are reduced for a while, then built back up gradually.
Foot orthoses (insoles)They can help reduce pain in some people, especially in the short term.
Taping and knee bracesThey can ease pain temporarily; the evidence is limited, and they do not replace exercise.
EducationUnderstanding why the pain happens and how to adjust your load makes treatment more successful.

Exercises at home

Six exercises for the hip and knee

Mild, tolerable pain during exercise is acceptable; carry on as long as the pain is not worse the next day. Make sure your knee stays in line with your toes and does not drop inwards.

Side-lying leg raise

Lie on your side with your bottom knee slightly bent. Lift your top leg, keeping the knee straight and your toes pointing forwards, hold for 2 seconds and lower it slowly. The muscles at the side of the hip help keep the knee stable.

10–15 reps on each side, 2–3 sets

Bridge

Lie on your back with your knees bent and your feet on the floor. Squeeze your buttocks and slowly lift your hips, hold for 3 seconds and lower. As it gets easier, try it on one leg.

10–15 reps, 2–3 sets

Half squat against the wall

Stand with your back against a wall and your feet a step away from it. Keeping your knees in line with your toes, slide down only as far as you can without clearly increasing the pain, hold for a few seconds and come back up.

8–10 reps, 2–3 sets

Seated knee extension

Sit up straight on a chair. Slowly straighten your knee and tighten the muscle at the front of your thigh, hold for 3 seconds and lower slowly. If it hurts, use a smaller range of movement.

10–15 reps, 2–3 sets

Standing hip abduction

Stand upright, holding on to a worktop. Move one leg out to the side, keeping the knee straight and your toes pointing forwards, then lower it slowly. Do not lean your body to the side. As it gets easier, add a resistance band around your ankles.

10–15 reps on each side

Standing on one leg

Single-leg balance

Stand on one leg, holding the worktop lightly, keep your knee slightly bent and make sure it does not drop inwards. As it gets easier, hold on less.

30 seconds, 3 times on each leg

Video

Videos for kneecap pain

From the YouTube channel of US physical therapists Bob Schrupp and Brad Heineck.

Strengthening for kneecap pain

Strengthening exercises to reduce the load around the kneecap.

Five stretches for kneecap pain

Stretches for the thigh, hip and calf muscles.

Videos belong to the Bob & Brad channel.

Frequently asked questions

My kneecap makes noises. Is it causing damage?

Usually not. Painless cracking is common in many people who have no knee pain, and on its own it is not a sign of disease. If the noise comes with pain or swelling, it should be assessed.

Should I stop running?

You usually do not need to stop completely. You can keep running at a distance and pace that do not clearly increase the pain, and build up the load gradually alongside your exercises. Cut back on downhill running and stair training for a while.

Do knee braces or taping help?

They can ease pain in the short term for some people, but according to the international consensus statement the evidence is insufficient. If needed, use them alongside exercise, not instead of it.

Do I need an MRI scan?

Usually not. The diagnosis is made by examination, and scans often show nothing that explains the pain. Imaging may be needed if, for example, the pain started after an injury, or there is locking or obvious swelling.

When to seek help right away

The following can point to a problem other than anterior knee pain. See a doctor without delay:

Obvious swelling, redness or warmth in the knee, or a fever
The knee giving way or locking after an injury, or being unable to put weight on the leg
Pain that does not ease with rest and wakes you at night
Knee pain with a limp in children and adolescents (the pain may be coming from the hip)

Sources

Collins NJ, Barton CJ, van Middelkoop M, et al. 2018 Consensus statement on exercise therapy and physical interventions (orthoses, taping and manual therapy) to treat patellofemoral pain: recommendations from the 5th International Patellofemoral Pain Research Retreat, Gold Coast, Australia, 2017. Br J Sports Med. 2018;52(18):1170-1178.
Smith BE, Selfe J, Thacker D, et al. Incidence and prevalence of patellofemoral pain: a systematic review and meta-analysis. PLoS One. 2018;13(1):e0190892.
Lankhorst NE, van Middelkoop M, Crossley KM, et al. Factors that predict a poor outcome 5-8 years after the diagnosis of patellofemoral pain: a multicentre observational analysis. Br J Sports Med. 2016;50(14):881-886.