My Knee Pops, Clicks, or Cracks… Should I Be Worried?

You stand up from a chair and hear a crack.

You bend down and feel a click.

You climb the stairs and notice a grinding or crunching sound coming from your knee.

It can be unsettling, especially when the noise seems louder or more frequent than it used to be. Many people immediately assume the sound means the joint is wearing out.

Fortunately, knee noises are common, and the sound alone usually does not tell you whether something is wrong. What matters more is what happens along with the noise.

Why Do Knees Make Noise?

The general medical term for popping, crackling, or grinding around a joint is crepitus.

Your knee contains bones, cartilage, ligaments, tendons, muscles, and fluid. All of these structures move together as you bend and straighten your leg. Because the knee has so many moving parts, it is not unusual for it to make noise. (Hospital for Special Surgery)

One common explanation involves small gas bubbles within the joint fluid. As pressure changes during movement, those bubbles may form or release, creating a pop or crack.

A tendon or ligament may also shift slightly as it moves across nearby tissue or bone. That movement can produce a snapping or clicking sensation without causing harm. (Hospital for Special Surgery)

You may also hear rougher sounds when surfaces within the knee do not glide as quietly as they once did. That can occur for several reasons, including changes around the kneecap or age-related joint changes.

When Is Knee Popping Usually Harmless?

Knee popping is generally less concerning when it:

• Does not hurt.
• Is not accompanied by swelling.
• Does not limit your movement.
• Does not make the knee feel unstable.
• Occurs occasionally during bending, standing, or exercise.
• Has been present for a long time without getting worse.

For example, you may hear crackling when you stand after sitting for a while or when you squat. You may notice a single pop when you stretch your leg. You might even be able to reproduce the same sound repeatedly without discomfort.

These sounds can be surprising, but sound and tissue damage are not the same thing. Hospital for Special Surgery notes that most knee popping is harmless, particularly when it occurs without other symptoms. (Hospital for Special Surgery)

You do not necessarily need to stop exercising just because your knee makes noise. Pay attention to how the joint feels during the activity and how it responds afterward.

When Does a Noisy Knee Deserve More Attention?

The sound becomes more important when it appears with other changes.

Consider having the knee evaluated when popping, clicking, or cracking is accompanied by:

• Pain.
• Swelling.
• Catching or locking.
• Buckling or giving way.
• Difficulty fully bending or straightening the knee.
• A recent fall, twist, or impact.
• A sudden loss of confidence in the leg.

Catching or locking can sometimes occur when tissue interferes with smooth movement inside the joint. Meniscus injuries, for example, may cause pain along with catching, locking, swelling, or a sense that the knee could give way. (Hospital for Special Surgery)

A painful pop during an injury is also different from the familiar crack you hear while standing up. A sudden pop followed by swelling, instability, or difficulty bearing weight should be assessed promptly.

The combination of symptoms matters more than the volume of the sound. A very loud but painless crack may be harmless, while a quiet click with repeated locking may deserve attention.

Does Grinding Mean You Have Arthritis?

Not automatically.

Grinding or crackling around the kneecap can occur with patellofemoral pain, which is discomfort involving the area where the kneecap moves against the thigh bone. Popping or crackling may be noticed while climbing stairs or standing after prolonged sitting. (OrthoInfo)

Crepitus can also occur with osteoarthritis, particularly when joint surfaces have changed over time. However, the presence of noise does not tell you how much pain a person should have or how well the knee can function. Some people have noticeable joint sounds without meaningful limitations.

That is why it is usually unhelpful to hear grinding and immediately conclude that the knee is “bone on bone.” Determining whether arthritis is contributing requires more context, including symptoms, movement, history, examination, and sometimes imaging.

We will discuss arthritis in greater detail later in this series.

Knee noise may occur with arthritis, but noise alone does not prove that arthritis is the cause.

Should You Try to Stop the Popping?

You usually do not need to eliminate painless sounds.

Repeatedly testing, twisting, or forcing the knee to make the sound may irritate it and increase your worry. Instead, focus on whether the knee can comfortably perform the activities that matter to you.

If the sound comes with discomfort, the goal is not simply to silence the joint. The better goal is to understand why that movement has become sensitive.

A physical therapist may examine:

• Where and when the sound occurs.
• Whether it is painful.
• How the kneecap moves.
• Knee strength and mobility.
• Balance and control.
• How the hip, ankle, and foot influence the movement.
• Whether the knee catches, swells, or feels unstable.

The same clicking sound can mean different things in different people. An evaluation helps separate a harmless noise from a movement problem that deserves attention.

The Good News

A knee that pops, clicks, or cracks is not necessarily failing.

If the noise is painless and your knee remains strong, stable, and fully functional, reassurance may be all you need.

If symptoms are present, many contributing problems can be addressed without assuming surgery is necessary. Physical therapy may help improve strength, mobility, balance, and movement control based on the findings of an individual evaluation. (ChoosePT)

You should seek prompt medical care after a significant injury or when the knee is badly swollen, visibly deformed, unable to support your weight, locked in one position, hot and red, or accompanied by fever.

For ongoing clicking or popping with pain, swelling, catching, or instability, an evaluation can help you understand what the noise means in your situation.

If your knee sounds are making you nervous or changing how you move, a FREE Discovery Visit can help you determine whether the noise is harmless or worth addressing.