What Is Knuckle Cracking?
Whether it’s one or all of your knuckles, you may wonder what causes the cracking sound. Although interesting, “cracking joints” and “popping knuckles” are not fully understood. In fact, cracking fingers has been studied for over 60 years.
There are many ideas about why your knuckles crack or pop. Experts have even used math to explain how it happens. But the exact reason is unknown.
“Knuckle cracking is when a person places traction or tension on a joint that can lead to a crack or pop sensation of the joint,” says Daniel J. Gittings, MD, an orthopedic hand surgeon with Hoag Orthopedic Institute in Irvine, California.
Usually painless, knuckle cracking isn’t harmful. But cracking sounds can also occur if your tendons snap over tissues. They glide and adjust as you stretch your knuckles. This can happen as you get older from how your muscles change and work.
Why Do People Crack Knuckles?
Cracking knuckles is an interesting act. Some people never crack their knuckles and couldn’t if they tried. Maybe you do it a little or don’t mean to do it. Or perhaps “knuckle cracking” is a regular part of your day.
If you crack your knuckles more than five times a day, it’s called “habitual knuckle cracking.” In fact, 25% to 45% of people in the U.S. pop knuckles. It’s a common habit.
Gittings says that you may feel relief when you crack your knuckles. Some experts think the inside of your knuckle can release a pleasing feeling. You may also crack your knuckles because you like to:
- Make the sound for fun and find it amusing.
- Do it as a nervous habit, like chew your nails or bite your lip.
- Find it helps relieve stress or tension.
- Feel it helps loosen your knuckles for a short time after cracking them.
What Happens When You Crack Your Knuckles?
What makes the actual cracking sound is up for debate. Experts don’t agree, but there are few knuckle-cracking models.
Cavity joint space and gas bubbles. Cavitation is when bubbles get pulled into a fluid, grow, and cave in. Your knuckles have a slippery fluid inside the joint (synovial fluid). This fluid helps you bend your knuckles smoothly.
There are also gases in this fluid, such as carbon dioxide. After you pull on your finger, a cavity (space) forms with higher pressure.
Tension quickly builds, then caves to pull in the gas bubbles. A large bubble forms and pops to make a noise — that's the cracking sound you hear.
Once the bubble bursts, you can’t crack your knuckles again until the bubbles reform. This usually takes about 20 minutes.
Joint manipulation (movement). This may happen when you pull on your finger. It forms a cavity at the surface of your knuckle joint.
The sound might come from your joint surfaces moving apart. But this can't explain why knuckles crack when you twist your finger.
You may also hear your knuckles crack if your tendons snap over tissues. Tendons (cords) connect your muscles to bone. They may pop to adjust or glide back and forth. This can also occur as you age and muscle mass changes.
Is It Bad to Crack Your Knuckles?
As a rule, cracking of joints isn’t harmful. Common sense may suggest constantly cracking one’s knuckles may be a problem. But painless “knuckle cracking” isn't harmful or beneficial.
For the most part, it’s OK but there are exceptions. If knuckle cracking causes you pain, there may be a physical problem.
Can cracking your knuckles cause arthritis?
Avoid cracking knuckles if youhave arthritis (painful joint inflammation), bursitis, or tendinitis. The “cracking” can mean snapping irregular or swollen joint tissue.
Studies don’t point to knuckle cracking causing arthritis. But osteoarthritis (arthritis from joint tissue breakdown) often happens in joints at the ends (distal) of your fingers. People most often pop their middle finger joints — the second most common place for arthritis to occur.
“Knuckle cracking is unlikely to lead to arthritis in the absence of previous injury or excessive force that can lead to injury,” Gittings says. “If there is a preexisting injury present, knuckle cracking can aggravate symptoms or cause worsening of the injury that can lead to arthritis from repetitive insult to the joint.”
So cracking fingers may make your condition worse. If you already have arthritis or joint damage, talk with your doctor before knuckle cracking.
Does cracking knuckles make them bigger?
In a clinical study, repeated knuckle cracking may have caused some swelling. But another study used sonograms (sound waves) to look at knuckle joints. Researchers couldn’t tell the difference between people who cracked knuckles or didn't.
“It’s possible for your joint’s cartilage (joint tissue) to grow if you put too much pressure on it,” says Gittings. “But if cracking your knuckles causes swelling and it happens often, it might mean you’re injured.”
If you crack knuckles and you notice swelling, ask your doctor about it.
Can cracking knuckles cause ligament sprain?
If you feel pain, you may have a problem with structures inside your knuckle joint. You can get loose cartilage or injured ligaments. Ligaments connect your joints (bones and cartilage) together. Cartilage is a flexible tissue inside your joints, ears, nose, and rib cage.
A few cases reported tendon problems after vigorous knuckle cracking. “Vigorous knuckle cracking can lead to injuries such as muscle strains, ligament sprains, and dislocation,” says Gittings.
If you do crack your knuckles, try to be gentle. And if you have pain, get your joint checked out before popping it again.
Can you pull the finger out of the joint by cracking your knuckles?
In general, knuckle cracking won’t pull your joint out or dislocate your finger.
Some investigators calculated knuckle cracking in “crack years.” It's the number of cracks each day multiplied by years. One person had 50 “crack years” on his left hand. And there wasn’t a visible difference.
It’s not easy to pull a finger out of its joint. But as Gittings says, it is possible if you’re too rough. You could damage your ligaments, too.
How to Stop Cracking Your Knuckles
If you want to stop cracking your knuckles, it can take time and effort. Be patient with yourself and give yourself time to adjust. Here are some tips to get you started:
Triggers. Identify your triggers and make a log. Write down when you crack your knuckles. A good start is to ask why you crack them. Do you just do it without thinking? Or when you’re stressed? How about when you’re bored? Do you do it to keep your hands busy?
Knowing your answers can help you form a plan. It may help change your knuckle-cracking habit. Knowing why you’re cracking fingers can help you stop. Avoid any triggers to help you stop popping your knuckles.
Diversion. Keep a stress ball, fidget ring, or some other small object in reach. If you get an urge to crack your knuckles, squeeze the ball. Or reach for the fidget ring. Think about activities to occupy both your hands.
Finger exercises. Try finger stretches or keep your fingers busy by extending them. Rotate your wrists --- move your hands around in circles. This can keep your mind off knuckle cracking.
Meditation or deep breathing exercises. This might help if you crack your knuckles when you’re stressed or anxious. There are several types of meditation you can try. Look into guided meditation or mindfulness.
Exercise. Whether it’s going for a walk or lifting weights, exercise can help you relieve stress. And it may take your mind off cracking your knuckles.
Reward yourself. Be sure to give yourself a treat. Encourage yourself to not crack your knuckles. It can be small or large. Go out with a friend or your family to celebrate. Keep yourself motivated and talk to others.
If you find your habit is lowering your quality of life, consider talking to your doctor or therapist. There are ones who specialize in helping people change habits.
Takeaways
Experts don’t agree about the popping noise, but it might happen when bubbles get pulled into the fluid inside your joint. They grow and cave in to pop loudly. Knuckle cracking is generally not harmful but if you have pain, ask your doctor to see if there's something else going on. If you want to stop the knuckling-cracking habit, know your triggers, try meditation, and keep yourself motivated by talking to others.
Knuckle Cracking FAQs
Why do knuckles crack?
Doctors aren’t entirely sure why knuckles crack. Most experts think it’s from gas bubbles in your joint bursting after you pull your knuckles apart.
Should I stop cracking my knuckles if it hurts?
In general, knuckle cracking shouldn’t be painful. If there is pain, it could be from damaged ligaments or swollen joints. Talk with your doctor before cracking them if you have pain or swelling.
Why can’t I crack my knuckles anymore?
Experts aren't sure why this happens. Perhaps you just popped your knuckle and the bubbles haven't reformed. After knuckle cracking, it can take up to 20 minutes for them to come back.
Or it may be because the fluid and space in your knuckle joint (making the sound) has gotten smaller. As you get older, this might mean you can't hear a loud sound anymore.
