Why do my knees crunch when I squat?


Why do my knees crunch when I squat?

At Lane Cove Physio, our musculoskeletal and sports specialist physiotherapists treat thousands of people with knee injuries and patellofemoral pain every year. One of the most common symptoms described by those with and without painful knees is a ‘grinding’, ‘cracking’, or ‘clunking’ of the knee during some activities.

Most people with patellofemoral pain and associated crunching commonly experience the worst of it during running, squatting, climbing stairs and kneeling.

Why do my knees crack so much?

When a joint makes an audible noise in response to movement, this is called crepitus.

Generally, these little noises are age-related changes inside the joint or related to a non-painful functioning of the knee. However, if you are experiencing pain, swelling, or loss of normal motion in the knee, you should make an appointment to have your knee evaluated by one of our physiotherapists.

What exactly is joint crepitus?

That is surprisingly difficult to answer!

Many of our patients worry that the clicking represents the bones rubbing together and causing damage to the joints. This is simply not the case.

Kneecap crepitus is incredibly common and has been found to be present in the complete absence of any joint pathology.[1]

Crepitus can be associated with physiological or pathological causes such as:

  • Gas bubbles building up in the synovial fluid and then popping when you move the joint. This is the noise people hear when they crack their knuckles
  • Cartilage wear or osteoarthritis in the knee associated is usually accompanied by stiffness in the joint, as well as swelling and pain with movement
  • Tendons or ligaments moving over each other or over bony structures in the knee
  • Uneven surfaces of the kneecap creating a grating sound when the kneecap slides up and down
  • A tear in the meniscus that acts as cushioning for the knee joint
  • Patellofemoral pain syndrome that causes the kneecap to track poorly in its groove.

People who receive explanations about their crepitus and how to manage it have better outcomes[2]

Patients often hold negative beliefs about their crepitus and in turn this may negatively affect their behaviour.

“Having spoken with my physiotherapist I know it is not actually an effect of what I am doing, you know that it is a common thing, so I decided to kind of get on with it.”

“The explanation was helpful. Even though obviously I don’t like the noise I now do not stop doing things because of this.”

If you are suffering from clicking or crunching joints, ask yourself –

  • Do I avoid anything because of my knee noise/pain?
  • What words I use to describe the noise in my knee?
  • Have I changed or modified anything because of my knee clicking or pain?
  • How does my knee pain or crunching make me feel?
  • Does pain alter my feelings about my knee cracking?
  • Have I discussed my joint crunching with any health professionals?
  • Has anyone other than a health professional commented on the crunching?
  • Do I have any blood relative with knee problems?

The important thing to remember is that this knee clicking, crunching and cracking is commonly associated with normal knee function and is not something to be concerned about. Knees are complex moving parts and there are a number of structures involved when you bend and straighten the knee, for example when you squat up and down.

If you are worried about your clicking knees and would like to book an appointment or for more information please make an appointment on (02) 9428 5772 or send us an email at info@lanecovephysio.com.au.



[1] Robertson, C.J. (2010), Joint crepitus — are we failing our patients?. Physiother. Res. Int., 15: 185-188.

[2] Robertson CJ, Hurley M, Jones F. People’s beliefs about the meaning of crepitus in patellofemoral pain and the impact of these beliefs on their behaviour: A qualitative study. Musculoskelet Sci Pract. 2017 Apr;28:59-64. doi: 10.1016/j.msksp.2017.01.012. Epub 2017 Feb 2. PMID: 28171780.