It Is Not Bad to Crack Your Knee: What Happens When You Pop Your Joints

Knee and joint cracking usually do not cause arthritis or other health conditions. Learn more about what happens when you pop your joints.

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When you crack your joints, you may be wondering what the sound means about your joint pain. For example, you may be wondering whether the pops are a sign of a joint condition. As long as you do not have pain or swelling, however, the sounds most likely are not signs of a joint illness or injury. Learn more about the causes and effects of joint cracking.

What Causes Joint Cracking?

Bubbles Between Your Joints

According to a 2018 Clinics in Orthopedic Surgery review and a 2018 review published in Clinical Anatomy, joint cracking could happen because of bubbles between your joints. Scientists generally believe that joint cracking happens in these four phases:

  1. At rest, before you pop your joint: No force is being applied between your bones. Your joint surfaces are touching each other.
  2. Separation starts: When you begin applying force in the move that cracks your joint, your joint surfaces start moving away from each other.
  3. Meeting the cracking threshold: During this time period, you create a bubble in your synovial fluid (the liquid between your joints) and your joints crack. Scientists hypothesize that this bubble forms because you lower the pressure in your joints when you move your bones away from each other.
  4. Refractory period: After cracking your joints, you cannot crack your joints again for several minutes, even if you try. The refractory period for knuckle cracking is about 20 minutes.

However, scientists debate what exactly causes the cracking noise. One common theory is that the collapse of the bubbles creates a loud sound. Other researchers believe that the quick formation of a bubble is what makes the noise.

Cartilage and Ligaments

Alternatively, the non-painful popping could be because of the cartilage or ligaments around your joints, according to Roshini Rajapaska, MD, Health's medical editor and a gastroenterologist at NYU Langone Health in New York. Cartilage that cushions joints can become uneven in places as you wear it down, so you might hear rough spots gliding over one another. Or you may be hearing the ligaments—tissues that connect bones—tightening.

Joint Cracking Does Not Cause Arthritis

Despite common belief, joint cracking likely does not cause arthritis. For example, according to a 2016 Journal of Family Practice article, several studies showed that people who did not pop their knuckles developed hand osteoarthritis at similar rates when compared to people who do.

However, frequent cracking sounds from your knees have been linked to osteoarthritis. A 2018 Arthritis Care & Research study found that research participants with noisy joints tended to develop osteoarthritis in the future, even if they did not have other arthritis symptoms. Even though the action does not cause arthritis, cracking noises could be a sign you may develop it in the future.

Do I Need Treatment if My Joint Cracking Isn't Painful?

If your joint cracking isn't painful and is not linked to swelling, it likely is not a sign of a health condition. Your joints can just crack normally.

However, if you prefer to have fewer cracking and popping noises, talk to your healthcare provider about some stretches and exercises you can try. According to the Clinics in Orthopedic Surgery review, stretching your hip, calves, and shins could be helpful. You can also try doing side steps with a resistance band, inner thigh squats, and squeezing a ball between your thighs.

What if My Joint Cracking Is Painful?

Osteoarthritis

If popping your joints is painful, that can be a sign of osteoarthritis. This type of arthritis occurs when the cartilage cushion between your joints degenerates. This can damage the bones, fat, ligaments, and tissue around your joint as you start having more friction in that joint.

A common risk factor for osteoarthritis is age, but young people can also develop this condition. You may be at higher risk for this condition if you had a joint injury, played sports, have clinical obesity, or have a family history of osteoarthritis. If you are young, you may not notice your symptoms, but they will get worse over time.

There is no treatment for osteoarthritis, but you can work with your healthcare provider to manage your symptoms. Common recommendations include pain medications, nonsteroidal anti-inflammatory drugs (NSAIDS), acupuncture, and weight loss (if you have clinical obesity). At the same time, you can try physical therapy exercises and bracing your joints.

Tear in the Meniscus

Besides arthritis, pain when popping your joint could signal that you are tearing your meniscus. According to the National Library of Medicine, the meniscus is the disk of cartilage that sits in your knee joint. It absorbs the shock of impacts and helps to stabilize your knee.

If you have a meniscal tear, you will have pain and difficulty moving that joint. Follow up with your healthcare provider for an exam and scans of your knee, and to discuss a treatment plan. A mild tear may heal on its own with rest. However, if it keeps hurting, you might need surgery, according to Dr. Rajapaksa.

Health's medical editor, Roshini Rajapaksa, MD, is an assistant professor of medicine at the NYU School of Medicine.

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