Why does my knee click or crunch? When it is harmless and when to see a doctor

Reviewed by The Wellness Team. Last reviewed October 2026.

Short answer: a knee that clicks, pops or crunches with no pain, swelling or giving way is usually not a problem. Mayo Clinic describes isolated knee crunching ("crepitus") with no other symptoms as generally not a cause for concern. Noise matters when it comes with pain, swelling, locking or a feeling that the knee gives out.

Why knees make noise

Doctors call the grinding or crackling sound crepitus. A 2025 article in The Conversation notes that we do not know exactly what causes it. You tend to hear it on stairs, when standing from a chair or when squatting. In most people it is harmless and has no link to pain.

When the noise is telling you something

The American Academy of Orthopaedic Surgeons (OrthoInfo) lists the common causes of knee noise alongside other symptoms:

• Arthritis. Cracking or a creaky, Velcro-like sound, with stiffness that is worse in the morning or after sitting.
• Meniscus tear. Clicking, with catching or locking, painful swelling, and pain when you stand up from a low seat.
• Ligament injury. A sudden pop at the time of injury, then swelling and a feeling that the knee is unstable.
• Tendon tear. A pop, painful swelling and being unable to straighten the knee.
• Iliotibial (IT) band syndrome. A snap on the outside of the knee that hurts with running or cycling.
• Plica syndrome. A snap on the inside of the knee with catching under the kneecap.
• Loose bodies. A pop with locking or catching while walking.

See a doctor sooner if

OrthoInfo advises prompt treatment after a fall or injury, or if you have any of these:

• A pop and the knee gave way at the time of an injury.
• Severe pain or swelling.
• You cannot move the knee.
• You are limping or cannot put weight on the leg.

The NHS also advises seeing a GP if knee pain does not improve after a few weeks of self-care. See the NHS guide to knee pain.

What helps a noisy knee that is not injured

Strong thigh and hip muscles share the load across the joint. Regular, gradual exercise is the first step in the NHS and NICE advice for knee problems linked to osteoarthritis. If it hurts when you start, that does not by itself mean you are doing harm. Build up slowly and stay consistent.

Where PRP fits

Platelet-rich plasma (PRP) is made from a small sample of your own blood and injected into the joint. It is not a treatment for a noisy knee that does not hurt, and we would not suggest it for that. If a clicking knee is painful and has been diagnosed as early osteoarthritis or a tendon problem, PRP can be one option to discuss. The research is mixed and results vary. We do not guarantee an outcome.

Our prices are plain: PRP for a joint is £750.

Next step

If your knee noise comes with pain, swelling or locking, we can talk through your history and tell you honestly whether an injection makes sense or whether a different route comes first.

Message us on WhatsApp or read our knee injection guide.

Sources: Mayo Clinic News Network, knee crunching; OrthoInfo (AAOS), Why do knees make noise; The Conversation, "My knee is clicking", September 2025; NHS, Knee pain; NICE guideline NG226. This article is general information and not a diagnosis.