By Poppie Human

Snap, Crackle & Pop! The sounds you want to hear from your breakfast cereal…not your knees!

“What is with the snap, crackle and pop in my knee?”

This is one of the most common questions that I get. It is not unusual for people to hear a cracking or a popping sound in their knees.  

This is also known as “Knee crepitus”, which can happen at any age but is more common in older people.  

Should I have concern when I hear crepitus within my knee?

Crepitus is often harmless. If crepitus is recurring and is accompanied by pain and swelling or if it happens after a trauma, it may be an indication of needing further assessment by a Physiotherapist or Doctor.

Common causes of knee crepitus:

Air bubbles:

The popping sound usually comes from air seeping into tissue, causing air bubbles in the synovial fluid. When there is movement of the knee, the bubbles shift around and causes a popping sound.

Damage to the knee due to injury:

This can be caused by acute trauma like falling onto your knee. The popping sound can then be due to a torn meniscus, a torn ligament within the knee or torn cartilage or other torn soft tissue around the knee.

This can also be caused by overload/chronic injuries such as patellofemoral pain syndrome or osteoarthritis.

Scar tissue:

Scar tissue can cause crepitus within the knee.  Scar tissue usually develops after an injury or surgery to the knee.  This can be either pain free or painful.  


When there is an abnormality in the biomechanics within your leg, you may place stress onto your knee with certain movements. This may cause crepitus within the movement if this movement is repetitive.


Treatment of crepitus often depends on the cause. You should have a physiotherapist or doctor evaluate your knee to find the cause of your crepitus.