Cracking Your Knuckles: Good or Bad?

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Your joints, including those in your knuckles, are surrounded by a membrane called synovial membrane, which forms a capsule around the ends of the bones. Inside this membrane is synovial fluid, which acts as a lubricant and cushion so that your bones do not rub against each other during movement.
When you “crack” your knuckles, or any other joint, you are expanding the space between your bones, creating a negative pressure that draws synovial fluids into the new space.

The entry of synovial fluid is what causes the popping sound when cracking a knuckle. If you crack your knuckles continuously, the synovial membrane and surrounding ligaments will loosen, making it easier and easier to crack your joints.

More than 20 years ago, I collaborated on an article titled “Fighting Neck Cracking,” which was published in the American Family Physician journal. In it, I argued that self-manipulation can lead to lax ligaments. Personally, I do not believe it is wise to crack your knuckles regularly, and research suggests it could have significant repercussions.

Is Knuckle Cracking Associated with Arthritis?

The biggest concern most people have about cracking their knuckles is that it could lead to arthritis, specifically osteoarthritis. If you have osteoarthritis, the cartilage between your joints is progressively being damaged, and the synovial fluid is typically reduced as well.

The pain and stiffness you feel in your joints is the result of your bones starting to come into contact with each other as the cartilage and synovial fluid decrease. To date, research has not demonstrated a correlation between osteoarthritis and knuckle cracking.

In a study of over 200 people, the prevalence of osteoarthritis in any joint was similar between those who cracked their knuckles and those who did not. The authors reported:

“Beyond the duration (in years) and total volume of (daily frequency x years) of knuckle cracking (KC) of each type of joint, it was also not significantly related to 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 the risk of osteoarthritis, it is typically caused by wear and tear on your joints along with lifestyle and dietary factors, and aging. Repetitive movements often also play a role, but while it seems plausible that cracking your joints is also a type of repetitive movement, no link has emerged so far.

Habitual Knuckle Cracking Could Impair Hand Function

While cracking your knuckles may not lead to arthritis, it seems to have other consequences. In a study of 300 people aged 45 and older, among those who cracked their knuckles, it was not found that they had a higher risk of arthritis in their hands. They were, however, more likely to have hand swelling and less grip strength.

They also found that knuckle cracking seems to be associated with manual labor, in people who bite their nails, smoke, and consume alcohol… they concluded that habitual knuckle cracking tends to impair hand function. The damage was likely the result of repeated stretching and loosening of the ligaments during the repeated cracking of the knuckles.

Interestingly, these researchers observed that cracking your knuckles seems 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.” This does not sound like a completely harmless habit.

In fact, there are reports in the literature of various injuries that have occurred from knuckle cracking, such as overstretching of finger ligaments, dislocated fingers, and a partially torn ligament in the thumb.

Knuckle Cracking Could Be Linked to Calluses on the Knuckles

Calluses on the knuckles are solid nodules 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 (the statue of Michelangelo’s David has calluses on its knuckles).

Calluses are very common, and while they do not cause physical symptoms, they can have psychological and cosmetic effects. Apparently, knuckle cracking 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 in a teenage girl who reported frequently cracking her knuckles daily. In her case, the nodules had elongated over the years, and knuckle cracking was on the list of possible causes.

Are There Benefits to Knuckle Cracking?

When you crack your knuckles, the joints loosen and have more mobility for a short period of time. This positive perception 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” similar to nail biting (with which it is associated).

Ultimately, there are no significant benefits to knuckle cracking, and there is a possibility that it could cause injuries or damage to the joints and ligaments over time, so it is a habit best avoided.