Do you hear a popping noise when bending your knee? If so, you’re certainly not alone. 

Knee crackles, knee cracks, popping sounds, or grating sounds when bending the knee are incredibly common. 

The good news is that, although it sounds horrific, it’s usually nothing to worry about. 

Sometimes, knee crackles happen simply out of chance (for no known reason).

Other times, there may be a cause for the knee crackles, which warrants further investigation. 

Knee Crackles When Bending

Whether it’s conditions such as arthritis, a meniscus tear, cartilage damage, or an old knee injury, the key thing to know is that if pain is present alongside the knee clicks, it needs to be looked into by a medical practitioner. 

In this article, we’ll take a look at what knee crackles are, what commonly causes them, how they’re diagnosed, and even how to prevent them from happening in the first place. 

What is Knee Cracking?

Knee cracking, or knee crepitus as it’s medically termed, is often normal. It happens when bending your knee past a certain point. 

In fact, when squatting down low, most people hear a clicking sound from time to time. It’s just how joints work! 

Knee cracking happens when the two surfaces of the knee joint rub together and create a ‘popping’ sound. I know some people call it ‘creaky knees,’ and for good reason!

But what exactly is it? 

Well, in healthy knees, it’s believed to be tiny bubbles of gas being released from the joint capsule when the knee bends. 

Still, in cases where pain accompanies it, knee crackles can signal a more serious condition, such as arthritis or other degenerative changes.

Common Causes of Knee Crackles

Common causes include:

  • Air bubbles (escaping from the synovial fluid)
  • Osteoarthritis
  • Rheumatoid arthritis
  • Meniscus tears
  • Ligament or tendon movement
  • Age
  • Muscle tightness or weakness
  • Dehydration
  • Repetitive strain from sports activities
  • Runner’s knee

Signs and Symptoms 

When bending your knee, the most common sign of knee crackles is a cracking sound or popping, clicking, or crunching sound. 

It can sound pretty horrific! And loud.

It’s a good idea if you notice the sound to log when it happens, and how frequently too. 

Other times, the sound is quite subtle and may not even be that noticeable. 

The sound you hear may be accompanied by instability, pain, or discomfort in the knee joint. Other symptoms can include swelling, joint pain, stiffness, and restricted motion due to pain or discomfort. 

Visible changes can also happen alongside knee crackles, such as a small bony lump at the front of the knee or perhaps a bulge in the kneecap due to swelling. It all depends on the type of crepitus and what’s causing it.

Visible signs usually indicate a more extensive problem nonetheless, meaning the knee crackles are a side effect – not the main issue. 

Diagnosis of Knee Popping

Diagnosing the cause of noisy knees begins with a physical exam by a doctor. This is to assess the knee’s range of motion, and tenderness, look for potential swelling, and assess joint stability. 

Your doctor might also order imaging tests such as X-rays or MRI scans to determine any underlying causes (if there are any.)

Generally, treatment plans vary depending on what the exam results and imaging tests show. 

To give you some idea, treatments and/or support consist of:

  • Physical therapy exercises
  • Corticosteroid injections
  • Anti-inflammatory medications
  • Knee brace
  • Knee surgery (in extreme cases)

Treatment Options

The most frequently used treatment plan (and least risky) is physical therapy when it comes to a large number of knee problems. 

This includes different exercises and stretches as well as forms of massage with a physical therapist to help strengthen the knee, improving the flexibility and stability of the muscles around the knee joint. 

Surgery may be required for more severe damage or instability in the knee joint, but this is only ever considered after all other treatments have been exhausted. 

Preventing knee crackles

Preventing that crunching sound in the knees is integral to protecting the knee joint and maintaining overall physical health. Crackly knees can be embarrassing, as well as downright uncomfortable. 

Taking preventative steps, like maintaining a healthy weight, performing regular exercise, stretching, and avoiding heavy-impact activities if your joints are injured or susceptible to injury, are all advisable to prevent knee crackles. 

Keeping a healthy weight is probably the most key point here, as it reduces the amount of strain on your joints. This helps reduce the risk of developing knee crackles caused by wear and tear.

Additionally, targeted physical exercise strengthens the muscles and ligaments around the knee joint while improving flexibility. 

Exercising regularly also helps improve balance and coordination, reducing the knee injury risk. 

Make sure you stretch well before any physical activity to warm up the muscles, and never force your body into positions that cause pain or discomfort.


I’d like to end by saying that, more often than not, knee crackles are simply a normal phenomenon of the knee joint – that is when the knee bends in a certain way. 

Bending to extremes (when not properly trained) is often when we hear the knee clicking, say from squatting down low to pick something up from the floor. 

The thing to know is, if it hurts when you do this and you hear knee crackles, that’s when a medical opinion is advised to check out why it’s happening. 

I hope you find this post informative and insightful. 

To read more posts of mine, click here

About the Author

Hi there! I’m Dr. Keagen Hadley, OTD, OTR/L. Straight out of the University of Mary, I’m all about blending my know-how in knee health, well-being, and medical technology. As a licensed occupational therapy doc, I’m here to translate complex concepts into clear, actionable insights – whether it’s knee care or groundbreaking healthcare tech.

Similar Posts