5 Reasons Why Your Knees Make Cracking Noises

We’ve all heard it happen at least a few times in our lives, from bending down to pick up something we’ve dropped, squatting during an exercise, or even walking down the stairs. The sound of crepitus, or your knees making cracking noises, has often been associated with old age, a lack of exercise, or dismissed as a side effect of fatigue.















Is there an exact explanation on why your knees produce such sounds? Is it something that happens in your body naturally? Or an early signal that there’s a serious health issue in your joints? Whatever the case, let’s get cracking on the reasons why your knees are that noisy.

1. Dissolved Air Bubbles

In your knee joints, there are fluids that circulate around the space which helps to lubricate and provide nourishment to the body cells in the area. These fluids also happen to contain dissolved gases from the surrounding air, including carbon dioxide, nitrogen and oxygen.

When you stretch your knee joints accidentally, such as by kicking an object, or on purpose with aerobic exercises, the pressure in the joint area rapidly changes. This will cause the dissolved air in the fluid to quickly form little bubbles due to the sudden force. When these bubbles eventually burst, the sound it produces will make the cracking noise that we’re accustomed to.

Don’t worry, your knee suffers no harm from the bursting air bubbles or the changes in pressure. It’s a natural process which happens to almost everyone in the world.

2. Snapping Ligaments

The cracking noises that you hear from your knee joints may actually not originate from your knee itself. In fact, the surrounding muscles around the knee joint could be the culprit for the unwanted sounds.

This is because when you’re in movement, the nearby tendons and ligaments located near your knee joints will temporarily shift out of position to compensate for the changes in posture. When the muscles return to their original position, they snap back, which causes the cracking noise. That’s why your knees crack after you’ve risen from a sitting position for a while.

This doesn’t cause any harm for your knees, as it’s a normal occurrence in your body. However, should you feel any pain during the snaps, it may be a good idea to get yourself checked.

3. Patellofemoral pain syndrome

Are you a big fan of marathons? Your knee cracks might be a sign of patellofemoral pain syndrome (PFPS). Also fondly known as “runner’s knee”, PFPS is the eventual wear and tear of the knee cartilage, which is essentially a smooth rubber-like tissue which protects the bones in your joints.

Commonly diagnosed among athletes, PFPS is often the result of overuse of the knee joint during strenuous exercise such as jogging and climbing stairs.

While PFPS produces the same cracking noise in the knee joints when your legs are in movement, the poor condition of the protective cartilage also causes an increase in friction between the bones. Affected individuals may suffer from mild to severe pain, swelling and stiffness in their knees as they move.














4. Meniscus Tears

The meniscus plays an important role in keeping you steady on your knees. Being a part of the knee cartilage, any form of damage towards this soft tissue may not only cause cracking noises in your knee joint, but bring about other health consequences as well.

Meniscus tears are the most common complaint amongst the general populace This happens when you twist and turn your knee too quickly during vigorous activity. These tears have a higher chance of occurring amongst the elderly, or anyone who does frequent heavy lifting.

Depending on the severity of the injury, it can range from a slight discomfort in the knee joint, to a painful swelling and difficulties in general movement.

5. Osteoarthritis

A form of arthritis that affects the joints, osteoarthritis refers to the degeneration of the joint cartilage that occurs throughout a person’s life. While PFPS is brought upon by physical activity, osteoarthritis takes place more naturally as a person ages.

While osteoarthritis progresses much more slowly than other knee-related medical conditions, it worsens much more over time and if left without treatment, can cause further complications to your health. Symptoms usually include joint aches and soreness, swelling and even developing a bow-legged limp.

Should you suspect something amiss in your cracking knees, especially if you’re above 50 years old, it’d be best to check with a doctor on the possible signs of osteoarthritis and tackle it at an early stage.

Hopefully, this has put your mind to rest on the mysterious cracking noise that goes on in your knees. If you’re still worried that the sounds may be a sign of an underlying medical condition, the best way to diagnose your problem is to see a doctor as soon as possible.

And if should you ever find the need for a physiotherapist to help you recover from your knee joint issues, we have a few freelance therapists that can provide the right care for you.

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Written by Teo Youliang Hakim

A CaregiverAsia writer, Hakim loves nothing better than to spruce up informative content for the readers, especially if it helps to make the world a better place. Other than that, he also enjoys the occasional chocolate chip cookie or catching reruns of F.R.I.E.N.D.S on the telly!