Patellofemoral Pain Syndrome: What Causes It and How Do You Find the Real Problem?

What does patellofemoral pain syndrome feel like?

PFPS usually causes a dull ache behind or around the front of the kneecap. It tends to come on slowly, not after a single injury. You may also notice a grinding or clicking feeling when you bend or straighten the knee.

If you have sudden swelling, your knee gives way, or you cannot bear weight at all, see your doctor or go to an emergency department. These symptoms may point to a different problem that needs urgent attention.

What causes patellofemoral pain syndrome?

PFPS happens when the kneecap (patella) does not sit or move correctly in the groove at the front of the thighbone (femur). Several factors can play a part, and they often work together.

Notice that several of these causes sit above or below the knee. Your body is a connected chain from feet to head. When one link is out of place, the joints above and below it compensate. Pain then often appears somewhere other than the real problem.

Why does whole-leg alignment matter for anterior knee pain?

The kneecap sits where forces from the hip, thigh and lower leg meet. So how it tracks depends on the alignment of the whole leg. A problem at the hip or ankle can send force through the kneecap unevenly.

Standard tests usually look at the knee on its own, often with the patient lying down. But lying down relaxes the muscles and removes the effect of gravity. The kneecap may sit perfectly in its groove while you lie relaxed on a table. It may then shift when you stand and your full weight presses through the joint.

This is why many people with patellofemoral pain have normal-looking knee scans but still hurt. The problem cannot be seen unless it is measured under real, weight-bearing conditions, with the whole leg in the picture.

How does an EOS standing scan assess patellofemoral pain?

An EOS scan takes a full-length image of both legs while you stand naturally. It captures the hip, knee and ankle in a single exposure. It shows exactly how the bones and joints line up under your own body weight.

Because the image is taken standing, the kneecap is loaded as it is in real life. Your clinician or surgeon can see whether the kneecap sits off-centre, whether the thighbone is rotated, whether the lower leg angles inward, and whether a hip or pelvic tilt higher up is playing a part.

The EOS system uses about 90% less radiation than a standard X-ray, around ten times less. The scan takes only a few seconds. You do not need a doctor's referral to book, and a specialist radiologist reports on the images.

What helps manage patellofemoral pain syndrome?

Most people with PFPS improve with conservative measures guided by a physiotherapist or sports medicine clinician. The focus is usually on strengthening the muscles that control the kneecap. It is also on correcting any alignment or movement patterns that play a part.

Common approaches include targeted exercises for the quadriceps and hip stabilisers, changes to activity to reduce flare-ups, and sometimes orthotic insoles if foot position is part of the problem. In persistent cases, more detailed imaging helps the treating clinician understand exactly what is going on structurally before deciding the next step.

ScanAlign provides the diagnostic imaging that informs these decisions. We do not prescribe exercises or carry out treatment. Your report goes to you and, if you wish, straight to your treating clinician, so they can plan your care with the full picture.

Before you start treatment, or change the one you are on, it is worth getting a detailed diagnosis. Knowing whether the cause sits in the pelvis, the legs or the spine changes what will actually help.

You can learn more about how EOS imaging fits into the assessment of knee problems.

Frequently asked questions about patellofemoral pain syndrome