Have you ever had or still have noisy knees? Are you concerned that those strange noises in your knees might be causing you damage? Possibly you might have even avoided certain exercises or activities because of the noises? Maybe you have even imagined “bone-on-bone” rubbing within your knee. In this blog I will try to relieve some of those fears regarding the extremely common occurrence known as knee crepitus.
What makes the noise?
Noise coming from a joint is called crepitus or joint crepitations. These can be described as sounds and feelings such as grinding, popping, clunking and clicking within a joint when movement occurs. Whilst these noises and sensations can come from separate causes, they are all grouped together under the term ‘crepitus’. These noises may or may not be associated with pain. McCoy et al., (1987) investigated 247 symptomatic, and 250 normal knees and found that 99% of normal subjects had patellofemoral crepitus – that means it is extremely normal.
The actual cause of these noises is not completely understood and has no definitive answer as of yet. Several theories have been proposed including:
- Synovial fluid gas bubbles popping within the joint (just like cracking your knuckles)
- Fluid movement within the joint and particularly through the patellofemoral joint
- Snapping of ligaments/ tendons over bony prominence’s
- Hyper-mobile or discoid meniscus
Should I be worried?
Most likely not! But this can be hard for people to understand as they often hold extreme beliefs about their noisy knees. Usually they link the crepitus to some sort of tissue damage within the knee joint. It doesn’t help that you can use Google and find articles and YouTube videos telling you these are early signs of “big problems to come!”.
Fortunately for us, more recent research fails to find any strong links to weaker outcomes of knee health for those people who have knee crepitus. In 2018, de Oliveira Silva et. al. found that women with patellofemoral pain were four times more likely to have knee crepitus however, the noisy knees had no relationship with function, physical activity level, pain climbing stairs or squatting. The same author in a separate study also found there was no difference in objective or subjective findings in women with patellofemoral pain whether they had crepitus or not – meaning the crepitus itself didn’t influence their condition.
It should also be comforting to know that a large study observing over 4000 knees was also published in 2018 showing that knee crepitus gave no indication that a person would need a total knee replacement in the following three years. For people who have knee osteoarthritis , knee crepitus is associated with lower self-reported function and worse quality of a life however it is not related to deficits in objective function such as knee extensor or flexor strength. In reality, peoples perceptions of their knees doesn’t match their function. And the obvious assumption is that despite their being no physical impairment due to the crepitus, people are limited by their own negative beliefs surrounding their noisy knees.
What should I do about it?
The quick and easy answer is nothing! Keep moving and do not be scared of a few knee noises here and there.
Our bodies can not be likened to an old car or van, just because there is a new noises it doesn’t mean there is something wrong. Unfortunately, this isn’t the message people often receive and shows a poor understanding of knee crepitus which in turn causes negative emotions, inaccurate beliefs and ultimately leads to altered behaviour.
If there isn’t any pain occurring with the knee crepitus than it is more than likely completely harmless and needs no intervention from health professionals. If there is pain or history of trauma associated with the noise in your knee than the noise isn’t the problem, it’s the underlying pathology and this should be treated with best-practice, evidence-based treatments.
In reality 99% of us have noisy knees!