Diagnosis and symptoms6 min read
Kneecap pain: what is patellofemoral pain syndrome?
Patellofemoral pain syndrome is pain arising from the joint between the kneecap and the thigh bone. It is the most common knee problem in young, active people and is a problem of load distribution rather than structural damage.
Typical symptoms
Pain is felt around or behind the kneecap. Patients usually cannot point to it and instead circle a hand around the kneecap.
Descending stairs, squatting and walking downhill are the most typical triggers. Loading the knee while bent markedly increases pressure on the kneecap.
Pain appearing after sitting with the knee bent for long periods is the most recognisable finding. Stiffness after a film or a long car journey strongly suggests this picture.
Why it develops
The kneecap moves within a groove on the thigh bone. When that movement does not stay centred, pressure at the contact surface concentrates at one point.
Weakness in the hip muscles is the most documented cause. With inadequate hip control the knee drifts inward with each step and the kneecap deviates from the groove.
A sudden increase in load is the second common cause. Rapidly increasing running distance, or returning to heavy activity after a long inactive period, triggers this picture.
How the diagnosis is made
Diagnosis rests on history and clinical examination. The pattern of pain linked to stairs, squatting and prolonged sitting is quite directive on its own.
Examination assesses hip strength, knee alignment under load and kneecap movement. The knee drifting inward during a single-leg squat is a frequent finding.
Imaging is usually unnecessary. It arises where there is locking, giving-way, marked swelling or a history of trauma; those suggest different diagnoses.
Key points
- Pain is around the kneecap and cannot be pointed to.
- Stairs, squatting and prolonged sitting are typical triggers.
- Hip weakness is the most documented cause.
- A sudden increase in load is the second common cause.
- Locking or giving-way suggests a different diagnosis.
Frequently asked questions
Is it the same as chondromalacia?
Not the same. Chondromalacia describes softening of the cartilage under the kneecap seen on imaging. Patellofemoral pain is a clinical picture and can occur with normal cartilage.
Could it be a meniscus tear?
The symptoms differ. In a meniscus tear, pain is felt along the joint line at the inner or outer edge of the knee and sharpens with twisting; locking is common.
Who is most affected?
It is more common in young, active people, particularly in running and jumping sports. It is also frequent in those who sit for long periods and exercise irregularly.
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This content is for information only and does not replace medical diagnosis or treatment. Response to treatment varies between individuals. Please consult a healthcare professional about your symptoms.