Causes of Knee Popping or Snapping

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It's common to feel your knee popping when you bend or straighten it. Knee popping noises can be a normal part of having aging bones. It can be also caused by problems with the knee joint or the supporting structures around the knee.

If you hear or feel a popping or snapping in your knee, whether or not you have pain as well will help you narrow down the cause of the knee noises. Hearing knee popping with no pain is probably not a serious problem. If your knee pops and it hurts, it can be a sign of a condition that needs treatment.

This article will discuss why you might feel a popping or snapping sensation in your knee. It will also talk about when it's time to see a doctor if you're having knee problems.

Common Causes of Knee Popping or Snapping

Verywell / Emily Roberts

Mechanical Popping

Knee popping can happen when there's something wrong with the knee joint. Patients may experience a symptom of popping called a "mechanical symptom." This may feel as though something is caught within the knee and is popping as the knee bends back and forth.

This type of popping symptom is often a sign of a meniscus tear or a loose piece of cartilage within the joint. These are tissues inside the knee that help cushion and protect the joint. The torn meniscus or loose cartilage may catch in the knee as it moves back and forth. This causes a popping sensation.

While some meniscus tears heal on their own, those involving deeper tissue don't have the blood vessels they need to help in the healing process. They may require a procedure called arthroscopic debridement to trim and repair the tear.

Crepitus

Knee popping can also be related to the supportive structures around the knee. Crepitus is the word used to describe a crunching sensation as the knee bends back and forth. Crepitus can be seen in patients with cartilage irritation. This occurs when you have chondromalacia, which is damage or loss of cartilage. It can also be seen in patients with cartilage wear, such as knee arthritis.

Unlike a mechanical popping where there is a sensation of something getting caught in the knee, the sensation of crepitus is a more constant problem.

You often feel crepitus more than you can hear it. To see if you may have crepitus, sit on the edge of a table with your knee hanging down. Then gently extend and lower your knee with your palm resting over the front of the knee. When you have crepitus, it feels like a crunching sensation under your hand.

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Click Play to Learn About Crepitus

This video has been medically reviewed by Anju Goel, MD, MPH.

Tendon Snapping

Knee popping can also be caused by a problem with the tendons of the knee. There are times when swelling of the tendons that surround the knee can cause the tendons to catch on the knee as the knee bends. The most common type is called iliotibial (IT) band tendonitis.

The iliotibial band is a tendon that runs from your hip to just beneath your knee. When this band becomes swollen or irritated, it can get stuck on the end of the thigh bone as the knee bends back and forth. 

Unlike mechanical popping where the problem is deep inside the joint, this type of popping is felt just below the skin. Often you can feel the tendon by simply moving the knee as you rest your hand on the affected tendon.

When to See a Doctor

Knee popping by itself is not always a reason to worry. However, if you feel pain when your knee pops, have a doctor look at your knee as soon as possible. Doing so may prevent a more serious knee injury including anterior cruciate ligament (ACL) injuries. They affect between 100,000 and 200,000 Americans each year.

Even if the knee popping isn't painful, you may still want to have it checked out. In some cases, it may be an early warning sign of an overuse injury. This may require weight loss, a change of footwear, or knee-strengthening exercises to protect the joint.

The best treatments are targeted directly at the specific problem that is causing the abnormal popping or snapping inside the knee joint. You can ease crepitus and tendon problems with treatments to reduce inflammation in the knee joint, such as rest and anti-inflammatory medications.

Most mechanical problems are best treated with arthroscopic knee surgery. This is a procedure in which a camera and tools are passed through small incisions into the joint to repair any damage.

Summary

Knee popping can be a sign of a problem with your knee, especially if the sound comes with pain or discomfort. However, knee popping can also just be a normal part of getting older and having aging joints.

When you feel a popping or snapping sensation in your knee, various problems may cause it. If you have pain along with snapping and popping, you need to see your doctor as soon as possible. But even if you aren't experiencing pain with the snapping or popping sensation, you may want to see your doctor anyway.

Having a doctor examine your knee can help you figure out if it's a serious issue or something that you don't need to worry about.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Hauser RA, Sprague IS. Outcomes of prolotherapy in chondromalacia patella patients: Improvements in pain level and function. Clin Med Insights Arthritis Musculoskelet Disord. 2014;7:13-20. doi:10.4137/CMAMD.S13098

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By Jonathan Cluett, MD
Jonathan Cluett, MD, is board-certified in orthopedic surgery. He served as assistant team physician to Chivas USA (Major League Soccer) and the United States men's and women's national soccer teams.