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Do your knees make funny noises?

What causes my knees to crack?

Where knees are concerned, this must be the most popular question that I get asked. So in this blog I am going to explain what these sounds are and why we should not be overly concerned.


Firstly, one of the most important things to get across is that there is no research that shows a link between joint clicking/cracking and joint pathology (injury). A study found that 99% of those with clicky knees were pain free. If however you do experience pain when your knee clicks, I would recommend either coming in to see us or visit your GP.


It is thought that there are 4 causes of the clicking/cracking.


Firstly, it can come from sources outside of the knee joint and be caused by tendons snapping over bony prominences. The most common around the knee is the iliotibial band (ITB) which crosses the outside of the knee joint. On bending and straightening the knee this band flicks across the bony outside of your knee causing a clicking/snapping sound.


Secondly, it can be caused by gas bubbles within the knee joint popping. When the bones around the knee move, they can create a vacuum within the joint. This then leads to the gas bubbles collapsing and causing the common popping sound.


Thirdly the slip/stick phenomenon as the knee cap moves over the bottom of the thigh bone creating a clunky feeling/noise. As the knee bends and straightens, the knee cap glides and slides in a groove.  These movements can sometimes be quite jerky and slip/stick through the movement. This causes vibratory signals which give cause for the clunking noise. These vibrations actually reduce in osteoarthritis of the knee joint. It is thought to be due to reduced range of movement and reduced lubrication as we age.


Lastly is the fine grating that can occur in knees – especially noticeable on going up and down stairs. This is thought to be caused by fluid passing between the roughened surfaces of the back of the knee cap and the thigh bone. This roughening of the cartilage surfaces of the bones is perfectly normal.



So in conclusion, knees do snap, crackle and pop and this is perfectly normal. The only time to be concerned is if this is associated with pain. That is when I would recommend coming to see either ourselves or your GP.


If you have any questions about this or anything else, don’t hesitate to get in touch by email on or call us on 0113 244 0115.


Thanks again for reading!