Noisy joints: What is normal and what is not-By: Heather Stewart, PT, MSPT
Have you ever wondered if popping or cracking in your joints is okay? Does it cause arthritis? Why does it make these sounds sometimes but not others? Joint sounds can have many different causes. People can experience these symptoms and it’s not usually a cause for concern. Exactly what causes the noises has been the subject of many studies dating back to the 1900s but is still not completely understood. Read on to find out more!
People can forcefully cause a joint, such as your knuckles, to crack or pop. One long held theory determined it was a release of gas from the synovial joints of your fingers that made the sounds. A synovial joint is one that is filled with synovial fluid, has a fibrous joint capsule, and connects long bones. In this theory, when a person bends or straightens a joint to the end of motion, the pressure changes inside it releasing gases, such as nitrogen and carbon dioxide. As a result, a bubble is released that makes a popping or cracking sound. It takes at least 20 minutes for the gases to be re-absorbed therefore you can’t crack the same joint multiple times in a row. This theory, called cavitation, has been challenged by recent research.
In 2015, another study found a slightly conflicting reason for cracking or popping sounds. They determined through real time MRI visualization of joint cavitation; the sounds are due more to the joint resisting separation rather than collapse of a bubble or gases escaping. This process, called tribonucleation, is found when opposite surfaces of the joint resist separation until a point where they separate rapidly creating a cavity, thereby creating a sound.
Some internal causes of joint noise are:
Sounds from muscle or tendon movement- Muscles are connected to bones by tendons. As they contract, the tendon tightens and may snap in and out of place over an area of bone. These sounds are fairly predictable when you move a joint a certain way. Muscle imbalance and swelling within a joint can cause these sounds to worsen.
Cartilage loss- This can occur as a normal process of aging. It causes roughening joint surfaces, like pot holes that deepen in time. This is a Velcro like sound, called crepitus, most commonly heard from the knees when people push through the knee joint to go
upstairs.
Arthritis- Arthritis can cause a more severe form of cartilage degeneration usually accompanied by pain and joint noises. There are many types of arthritis with varying forms of presentation as well.
Popping secondary to traumatic force- higher load injuries can cause tendon, ligament, meniscal, or muscle tearing. These injuries have sounds with subsequent intense pain and are cause for follow up with a medical professional.
The common myth that cracking your knuckles causes arthritis is not supported by scientific evidence. In 2011, a study compared joints of those who regularly cracked their knuckles to those who did not and found that knuckle-cracking did not cause hand osteoarthritis, no matter how many years a person cracked their knuckles 3 . It did however find increased mobility of the joints and decreased grip strength. So, while the joint sounds may annoy others around you, it is not harmful to your joints.
It is important to differentiate between painful popping and swelling, and joint noise without pain. Joint noises without pain are very normal and not generally a cause for concern. If you are having pain with popping joints, it is best to consult a healthcare provider, such as your physical therapist from Advanced Rehabilitation.
References:
1) Unsworth A, Dowson D, Wright V (1971). "'Cracking joints'. A bioengineering study of cavitation in the
metacarpophalangeal joint". Ann Rheum Dis. 30 (4):
348–58. doi:10.1136/ard.30.4.348. PMC 1005793. PMID 5557778.[1]
2) Kawchuk GN, Fryer J, Jaremko JL, Zeng H, Rowe L, Thompson R (2015) Real-Time Visualization of Joint
Cavitation. PLoS ONE 10(4): e0119470.https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0119470
3 Deweber K, Olszewski M, Ortolano R (2011). "Knuckle cracking and hand osteoarthritis". J Am Board Fam
Med. 24 (2): 169–174. doi:10.3122/jabfm.2011.02.100156. PMID 21383216.