Learn More About Joints that Crack
Cracking Joints: Disgust and Delight
As part of my work as an osteopath (http://cynthiaosteo.com/fr/osteopathie), depending on the problem encountered (http://cynthiaosteo.com/fr/osteopathie/raisons-de-consulter), I perform various techniques (http://cynthiaosteo.com/fr/l-osteopathe) on several bodily structures: bones, muscles, fascias, nerves, viscera, joints, etc. What I am concerned with working on are joints with muscle energy techniques, trigger points, pumping, and suction cups. Whether during my work or upon standing up from the table, some joints produce a variety of noises, such as cracking and clicking; this sometimes also leads to a “rugged feeling” in the joints. Many patients are intrigued and ask me what these noises are. Some are delighted by these sounds and the relief that they bring, while others are worried… and that’s not counting those who are frankly disgusted from hearing me crack my own fingers several times a day!
What Exactly Does the Famous Sound of Joint Cracking Consist of?
In April 2015, Canadian researchers were finally able to answer this question with certainty using magnetic resonance imaging (MRI). Ten metacarpophalangeal joints (the junction between the finger and the hand) were examined before, during, and after cracking.
What Professor Gred Kawchuk and his colleagues at the University of Alberta observed was “the rapid creation of a cavity in the joint at the time of separation of the two bones that constitute it and the production of a sound; the cavity remaining visible afterwards. The results offer direct experimental evidence that the sound heard during the cracking of the joint is associated with the creation of a cavity rather than the crushing of an air bubble already present in the joint.”
This phenomenon is a form of cavitation known as tribonucleation (a process in which joined surfaces resist separation to a critical point where they subsequently separate rapidly, creating gas cavities that persist for some time). Read the full study, “Real-Time Visualization of Joint Cavitation,” here: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0119470. To see MRI images of a joint cracking, visit https://www.youtube.com/watch?v=_ZNENkkf5Uw.
Is the Repetition of Cracking Joints Dangerous?
I have often heard friends tell me that cracking my fingers repeatedly would lead to osteoarthritis or arthritis… But is this really true?
In 2009, I heard about a silly story that brought a partial answer to this question. Dr. Donald Unger, an American physician, published the result of his research in the Journal of Arthritis and Rheumatology under the title: “Does Knuckle Cracking Lead to Arthritis of the Fingers?” (https://www.bioestadistica.uma.es/baron/bioestadistica/articulos/knucle-cracking.pdf). Dr. Unger won an Ig Nobel (http://www.improbable.com/ig/) of medicine, which are prizes awarded for research and exploits that make people laugh and think.
In order to verify if the repetitive cracking of the joints leads, as popular wisdom predicts, to suffering from arthritis, Dr. Unger proceeded as follows: for 50 years, twice a day, he cracked the joints of the fingers of his left hand, never touching the right. At the end of the 50 years, his hands were compared to judge the presence or absence of arthritis… The result: No sign of arthritis and no difference between hands.
In 1975, physicians Robert L. Swezey and Stuart E. Swezey had already attempted to answer this question by taking X-rays of the hands of 28 patients with an average age of 78 years. Half of the group remembered cracking the knuckles of their fingers all their lives, while the other half were not keen on doing so. The study concluded that there is no link between cracking hand joints and an increased risk of arthritis or degenerative change in the hands. Read the full study, “The Consequence of Habitual Knuckle Cracking,” here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1129752/pdf/westjmed00297-0049.pdf.
In 2011, the study “Knuckle Cracking and Hand Osteoarthritis” (http://www.jabfm.org/content/24/2/169.full.pdf+html) came to the same conclusion. However, in 1990, it was Jorge Castellanos and David Axelrod who questioned the effects of habitual hand joint cracking in their study “Effect of Habitual Knuckle Cracking on Hand Function” (http://ard.bmj.com/content/annrheumdis/49/5/308.full.pdf). Although their results confirm that the habit of cracking hand knuckles is not related to an increased risk of arthritis, they caution that people who crack their joints frequently are more likely to suffer from edema (swelling) of the hands and lose some gripping force.
In short, you can crack your joints at will without fear of developing arthritis; however, like all good things, moderation is key!