Grinding knees, should I be worried?

Nov 2, 2023

Do you ever hear a strange noise coming from your knee when you move it? perhaps a grinding noise? Some describe it as a snap, or crackle or pop.  Don’t worry, you’re not alone. In fact, 99% of knees make some sort of noise, according to a study by McCoy et al. This noise, known as knee crepitus, can be characterized as a grinding or popping sound with a palpable vibration. But what causes it and should you be concerned?

First of all, it’s important to differentiate between pathological and physiological knee crepitus. Pathological crepitus is typically linked to a specific injury or incident, such as an ACL tear or meniscal tear. It may also be caused by degenerative changes, patellofemoral instability, or post-surgical complications. Patients with pathological crepitus may experience pain, swelling, or joint effusions, and should seek physiotherapy to manage their symptoms.

On the other hand, physiological knee crepitus is much more common and has no correlation to pain or function. It’s simply just a noise. People who experience physiological crepitus often cannot accurately describe their knee noises and will not have a specific trauma related to their noises. While these noises may be distressing for patients, they are not harmful or damaging.

So what causes the noise in the first place? Some believe that a build-up and bursting of air bubbles causes cracking sounds. However, more recent evidence from real-time magnetic resonance imaging (MRI) suggests that cracking sounds are related to cavity formation, not bubble collapse. Snapping of ligaments or tendons over bony prominences, such as the bicep femoris over the lateral knee, may also contribute to knee crepitus. This Ted talk video will provide more information on why joints “pop”

It’s important to note that knee crepitus may also be a symptom of patellofemoral osteoarthritis. A study by Pazzinatto found that the presence of knee crepitus may be the first symptom of this condition. If you experience knee crepitus along with other symptoms such as pain or swelling, it’s best to consult with your physiotherapist at the JSSC and Book now for an accurate diagnosis and treatment plan.

Trusted physiotherapy colleagues at La Trobe University are studying this very condition Noisy knees affects 70 per cent of population, News, La Trobe University. We also highly recommend additional reading of the excellent research carried out by Claire Robertson who has been to the JSSC to deliver her training course on patellar pain. Do you have noisy knees? – Musculoskeletal Science & Practice (

In conclusion, knee grinding noises or crepitus is a common occurrence in most people’s knees and is typically harmless. However, if you experience additional symptoms or have concerns about your knee noises, it’s always best to seek medical advice from one of our great physiotherapists at the Jersey Sports & Spinal Clinic. Don’t let knee crepitus cause unnecessary worry or anxiety – it’s just another quirk of the human body!