Noisy Knees: Should I be worried?
Have you ever been concerned that those strange noises in your knees might be causing you damage or harm? Possibly you might have avoided certain exercise or activities because of the noises? Maybe you’ve even envisioned “bone-on-bone” rubbing within your knee. In this blog I will try to dispel some fears regarding the extremely common phenomenon known as knee crepitus.
What makes the noise?
Noise originating from a joint is called crepitus or joint crepitations. These can be described as sounds and feelings such as clicking, grinding, popping, clunking and clicking within a joint when movement occurs. Whilst these different noises and sensations can originate from separate causes they’re all grouped together under the term ‘crepitus’ (6). 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’s extremely normal.
The actual cause of these sometimes unsettling noises is actually 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 prominences
- hypermobile or discoid meniscus (6)
Is it bad?
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 Doctor Google and find articles and YouTube videos telling you this is early signs of “big problems to come”.
Fortunately for you, more recent research fails to find any strong links to poorer outcomes of knee health for those people who have knee crepitus. In 2018, de Oliveira Silva et. al. found that women with patellofemoral pain (PFP) were 4 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 sperate study also found there was no difference in objective or subjective findings in women with PFP whether they had crepitus or not – meaning the crepitus itself didn’t influence their condition (1).
It is also may be comforting to know that a very large study observing over 4000 knees was also published in 2018 (a busy year for knee crepitus research) showing that knee crepitus did not predict a person needing a total knee replacement (TKR) in the following 3 years (3). For people who have knee osteoarthritis (OA), knee crepitus is associated with lower self-reported function and worse quality of a life BUT it is not related to deficits in objective function such as knee extensor or flexor strength (4). Simply put, people perceptions of their knees doesn’t match their function. And the obvious speculation 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 don’t be scared of a few knee noises here and there.
Our bodies are not an old car, just because there is a new noise it doesn’t mean there is something wrong. Unfortunately this isn’t the message people often receive and it’s been shown a poor understanding of knee crepitus causes negative emotions, inaccurate etiological beliefs and ultimately leads to altered behaviour (5).
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 (6).
- up to 99% of people have noisy knees
- several competing theories exist as to why knee crepitus occurs
- studies have found very little evidence of crepitus being related to poor function or risk of needing knee surgery
- if you don’t have pain associated with your knee noises, don’t worry about it. If there is pain, seek help from a qualified health professional to treat the underlying cause
Featured in the Top 50 Physical Therapy Blog
- De Oliveira Silva, D., Barton, C., Crossley, K., Waiteman, M., Taborda, B., Ferreira, A. S., & Azevedo, F. M. (2018). Implications of knee crepitus to the overall clinical presentation of women with and without patellofemoral pain. Physical Therapy in Sport, 33, 89-95.
- De Oliveira Silva, D., Pazzinatto, M. F., Priore, L. B., Ferreira, A. S., Briani, R. V., Ferrari, D., Bazett-Jones, D., & Azevedo, F. M. (2018). Knee crepitus is prevalent in women with patellofemoral pain, but is not related with function, physical activity and pain. Physical Therapy in Sport, 33, 7-11.
- Pazzinatto, M. F., De Oliveira Silva, D., Azevedo, F. M., & Pappas, E. (2019). Knee crepitus is not associated with the occurrence of total knee replacement in knee osteoarthritis – a longitudinal study with data from the osteoarthritis initiative. Brazilian Journal of Physical Therapy, 23(4), 329-336.
- Pazzinatto, M. F., De Oliveira Silva, D., Faria, N. C., Simic, M., Ferreira, P. H., Azevedo, F. M., & Pappas, E. (2019). What are the clinical implications of knee crepitus to individuals with knee osteoarthritis? An observational study with data from the osteoarthritis initiative. Brazilian Journal of Physical Therapy, 23(6), 491-496.
- Robertson, C. J., Hurley, M., & Jones, F. (2017). People’s beliefs about the meaning of crepitus in patellofemoral pain and the impact of these beliefs on their behaviour: A qualitative study. Musculoskeletal Science and Practice, 28, 59-64.
- Song, S. J., Park, C. H., Liang, H., & Kim, S. J. (2018). Noise around the knee. Clinics in Orthopedic Surgery, 10(1), 1.
- McCoy, G., McCrea, J., Beverland, D., Kernohan, W., & Mollan, R. (1987). Vibration arthrography as a diagnostic aid in diseases of the knee. A preliminary report. The Journal of Bone and Joint Surgery. British volume, 69-B(2), 288-293