Updated: Sep 20, 2021
“What’s that noise my knee keeps making”? Despite several misconceptions floating around regarding joint cracking, research has consistently proven that this is most often a completely normal phenomenon. In the sports medicine world, this is known as “crepitus”
This topic was inspired by the countless clients who have asked “my wrist/ back/ shoulder/ knee cracks, is that bad?” By the end of this blog, you should have a better understanding of why your joints snap, crackle and pop, and how we can distinguish whether it is harmless, or if perhaps, further advice may be indicated.
Here are the main reasons why you might hear your joints click.
1. Synovial fluid gas bubbles popping within the joint
Our joints contain synovial fluid which is a clear liquid found inside our joints that serves to lubricate and provide nutrition to our joints. As the joint surfaces are pulled apart, gas bubbles are formed. When our joints are suddenly stretched or compressed, these gas bubbles pop. The technical term for this is “cavitation” and is the most common reason why we hear pops.
2. Moving tendons and ligaments
Your bones are not always as smooth as what’s shown in pictures and the anatomy of the human body can vary subtly within every individual. Occasionally, your tendons and ligaments may “slip” over a lump or bump on your bone which may produce a click. This is common in joints such as the shoulder, hip and ankle. This isn’t usually a problem but occasionally, it could be due to poor joint positioning or ligament damage.
3. Pathological crepitus
This happens when your clicking or cracking is associated with a pain response. Other signs and symptoms may include swelling, a new click following an injury, and a clicking that causes, or is associated with a locking sensation (more common in the knee and jaw). The good thing is, this can easily be addressed through physiotherapy by sticking to an exercise program that improves your joint alignment through muscle strengthening and flexibility.
Need some reassurance?
Recent research fails to find any strong links to poorer outcomes of knee health for those that have clicking knees. A 2018 study found that women with patellofemoral pain syndrome (PFPS), were 4 times more likely to have knee crepitus. However, this had no relationship with function, pain when climbing stairs, squatting or physical activity levels. Another study in 2018 found that knee crepitus did not mean higher odds of having a total knee replacement. For people with knee arthritis, while they found no deficits in objective functions such as their knee strength, crepitus was associated with lower self-reported function.
To put it simply, despite there being no physical impairments, negative emotions and beliefs may ultimately lead to people altering their behaviour.
So the take home message here is: your joints may be noisy, but if they aren’t bothering you, they are fine!
As always, if you ever do have any concerns, feel free to reach out.
de Oliveira Silva, D., Pazzinatto, M., P
riore, L., Ferreira, A., Briani, R., & Ferrari, D. et al. (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. doi: 10.1016/j.ptsp.2018.06.002
Pazzinatto, M., de Oliveira Silva, D., Azevedo, F., & 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. doi: 10.1016/j.bjpt.2018.09.009
Pazzinatto, M., de Oliveira Silva, D., Faria, N., Simic, M., Ferreira, P., Azevedo, F., & 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. doi: 10.1016/j.bjpt.2018.11.001
Rizvi, A., Loukas, M., Oskouian, R., & Tubbs, R. (2018). Let's get a hand on this: Review of the clinical anatomy of “knuckle cracking”. Clinical Anatomy, 31(6), 942-945. doi: 10.1002/ca.23243
Robertson, C., 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. doi: 10.1016/j.msksp.2017.01.012
Song, S., Park, C., Liang, H., & Kim, S. (2018). Noise around the Knee. Clinics In Orthopedic Surgery, 10(1), 1. doi: 10.4055/cios.2018.10.1.1