Most experts agree that it is probably not harmful to crack your knuckles occasionally. There is no proof that it causes arthritis or increases the likelihood that this condition will develop. If done aggressively, cracking the knuckles — or any other joint — may do some damage to the ligaments and tendons that hold the joint together, but this usually heals on its own. Studies have shown that people who crack their knuckles regularly may experience some swelling in the hands and a weaker grip.
Why Do Knuckles Pop?
When you crack your knuckles, the popping sound you hear is usually a gas bubble bursting between your knuckle joints. The knuckle's bones, ligaments and tendons are surrounded by a thick liquid called synovial fluid. Over time, this synovial fluid becomes filled with tiny bubbles of gas. When you push or pull on the joints, the tendons and ligaments become stretched out and the knuckle bones separate slightly.
The synovial fluid tries to fill in this gap, and the trapped gas bubbles combine to form one large bubble. This bubble pops in order to make room for the sudden rush of synovial fluid into a capsule between the knuckle joints. This gaseous build-up is not harmful to the body if it is not released through knuckle cracking. Cracking the joint releases the pressure that has built up, however, which can make the fingers feel looser and more mobile. It takes about 25 to 30 minutes before the gas builds up again; during that time, you cannot crack the joint again.
In some cases, you may hear the movement of ligaments and tendons in the joint as well. The tendons may be pushed slightly out of position when you crack your knuckles, and you can sometimes hear a snap as they move back into place. Ligaments can also make noise as they tighten and stretch.
When Cracking Does Harm
Although medical studies do not show a link between knuckle cracking and arthritis, there is some evidence that doing it excessively may cause a loss of grip strength or swelling around the joints. When you crack your knuckles, or any other body joint for that matter, you are subjecting the tendons and bones to unnatural pressure; over a long period of time, body tissues do not recover from such manipulations as they once did. This can create the same types of joint pain as professional athletes experience after throwing a football or pitching a baseball for years.
If you are too rough on your knuckles, you can damage the ligaments and tendons in the joint. It's rare to hurt yourself seriously this way, but it can happen. Knuckle cracking should be performed gently, and never forced. If you feel any pain, you should stop immediately.
Pain In or Around Joints
If your knuckles or any other joints hurt when they crack, it could be a sign of a more serious condition. Although knuckle cracking doesn't seem to cause osteoarthritis, if you hear a grinding noise in your joints, it could be a symptom of this degenerative disease. Pain, accompanied by a sudden popping noise, could mean a torn tendon. Very loose or painful joints may have some other type of internal damage. Whenever you experience pain in a joint, you should talk to your healthcare provider to get a complete diagnosis.