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Its joints, including those in its knuckles, are surrounded by a membrane called synovial membrane, which forms a capsule around the ends of the bones. Inside this membrane is the synovial fluid, which acts as lubricant and shock absorber so that their bones don't rub against each other when they move.
When you “crack” your knuckles—or any other joint—you’re expanding the space between your bones, creating negative pressure that draws synovial fluid into the new space.
The flow of synovial fluid is what causes the clicking sound when you crack your knuckles. If you crack your knuckles repeatedly, the synovial membrane and surrounding ligaments will loosen, making it easier and easier to crack your joints.
More than 20 years ago, I co-authored an article titled «Combating Neck Cracking,» which was published in the *American Family Physician* journal. In it, I argued that Self-manipulation can lead to loose ligaments. Personally, I don't think it's a good idea to crack your knuckles on a regular basis, and research suggests that it could have significant consequences.
Is Cracking Your Knuckles Linked to Arthritis?
The biggest concern most people have about cracking their knuckles is that it might lead to arthritis, specifically osteoarthritis. If you have osteoarthritis, the cartilage between your joints is gradually breaking down, and the synovial fluid usually decreases as well.
The joint pain and stiffness you feel are the result of your bones beginning to rub against one another as the cartilage and synovial fluid break down. To date, Research has not shown a correlation between osteoarthritis and cracking one's knuckles.
In a study of more than 200 people, the prevalence of osteoarthritis in any joint was similar among those who cracked their knuckles and those who did not. The authors reported:
«Beyond the duration (in years) and the total volume (daily frequency × years) of knuckle cracking (KC) for each joint type, neither was significantly associated with OA [osteoarthritis] in the respective joint. A history of habitual KC—including total duration and total cumulative exposure—‘does not appear to be a risk factor for hand OA.””.
If you are interested in reducing your risk of osteoarthritis, which is typically caused by wear and tear on your joints, along with lifestyle and dietary factors, and aging. Repetitive movements often play a role as well, but while it seems plausible that cracking your joints is also a type of repetitive movement, no link has been established so far.
Regularly Cracking Your Knuckles Could Impair Your Hand Function
While cracking your knuckles may not lead to arthritis, it does seem to have other consequences. In a study of 300 people aged 45 and older, those who cracked their knuckles were not found to have a higher risk of arthritis in their hands. They were, however, more likely to experience swelling in their hands and have weaker grip strength.
They also found that cracking one’s knuckles appears to be associated with manual labor, as well as with people who bite their nails, smoke, and drink alcohol… They concluded that habitually cracking one’s knuckles can impair hand function. The damage was likely the result of repeated stretching and loosening of the ligaments during repeated knuckle cracking.
Interestingly, these researchers observed that cracking one’s knuckles appears to produce «a rapid release of energy in the form of sudden vibrational energy, similar to the forces responsible for the destruction of hydraulic blades and ship propellers.» That doesn’t sound like a completely harmless habit.
In fact, there are reports in the literature of various injuries that have resulted from cracking one's knuckles, such as overstretched finger ligaments, dislocated fingers, and a partially sprained ligament in the thumb.
Cracking Your Knuckles May Be Linked to Calluses on Your Knuckles
Calluses on the knuckles are hard lumps that sometimes form on certain finger joints. They are often associated with trauma or repetitive movements, and have been known to exist since ancient times (Michelangelo’s statue of David has calluses on his knuckles).
Calluses are very common, and while they do not cause physical symptoms, they can have psychological and cosmetic effects. It appears that cracking one's knuckles may play an important role in at least some cases of this condition.
There is at least one reported case of calluses on the knuckles of a teenage girl who reported that she frequently cracked her knuckles every day. In her case, the nodules had grown larger over the years, and cracking her knuckles was listed as a possible cause.
Are There Any Benefits to Cracking Your Knuckles?
When you crack your knuckles, the joints loosen up and become more flexible for a short time. This pleasant sensation may be why some people make a habit of cracking their knuckles.
Another explanation, as reported in a study, is that the movement offers a kind of «therapeutic release.« «Chronic knuckle cracking may stem from habit as a way to relieve tension, although it seems more like a »nervous habit’ such as nail-biting (with which it is associated).”.
Finally, there are no significant benefits to cracking your knuckles, and it’s possible that it could cause injuries or damage to your joints and ligaments over time; therefore, it’s a habit best avoided.
