Cause of Knee Popping or Snapping

Knowing When It's Time to See a Doctor

knee pain
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The symptom of popping or snapping in the knee can be a sign of a few different problems. One of the key distinguishing factors is whether or not the popping or snapping causes or is associated with pain. Popping or snapping not associated with painful symptoms is often not a sign of a significant problem.

Mechanical Popping

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. The torn meniscus or loose cartilage may catch in the knee as it moves back and forth causing a popping sensation.

While some meniscus tears heal on their own, those involving deeper tissue lack blood vessels to aid in the healing and may require a minimally invasive arthroscopic debridement to trim and repair the tear.

Crepitus

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, as is the case in chondromalacia, or 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.

Crepitus can often be felt more easily than heard. Sit on the edge of a table with your knee hanging down. Then gently bend your knee back and forth with your palm resting over the front of the knee. Crepitus can be felt as a crunching sensation under your hand.

Tendon Snapping

There are times when swelling of tendons that surround the knee can cause the tendons to catch on the knee as the knee bends. The most common type is called IT band tendonitis, and occurs when the iliotibial band becomes swollen and irritated, and then catches of the end of the thigh bone as the knee bends back and forth. 

Unlike the mechanical popping where something is deep inside the joint, this type of popping is felt just below the level of the skin. Often the tendon can be felt by simply bending the knee back and forth with the hand resting on the affected tendon.

Treatments

The best treatments are targeted directly at the specific problem that is causing the abnormal popping or snapping inside the knee joint. Most mechanical problems are best treated with arthroscopic knee surgery, whereas crepitus and tendon problems are more often treated by addressing inflammation in the knee joint.

Even if the knee popping does not cause pain, you may still want to have it checked out. In some cases, it may be an early warning sign of a repetitive use injury, requiring weight loss, a change of a foot wear, or knee-strengthening exercises to better protect the joint.

If there is pain, by all means have your knee looked at as soon as possible. Doing so may prevent a more serious knee injury including anterior cruciate ligament (ACL) injuries which affect between 100,000 and 200,000 American each year.

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