Cracking, Clicking and Popping Knee – Should You Worry?

Sep 03, 2018

Have you ever been bothered by the noises your knee makes? For instance, when you stand up, your knee cracks. When you walk down the stairs, your knee pops. With all those cracking, popping or clicking sounds, should you worry?

First off, the knee sounds can stem from two causes. It can be either physiological or pathological.

Physiological Knee Sounds

Physiological noise may vary but commonly, it involves a buildup or bursting of tiny bubbles in the synovial fluid (the fluid that lubricates the joint), snapping of ligaments, catching the synovium or physiological plica (a fold in the synovial membrane), hypermobile meniscus or discoid meniscus, and perception of previous noise after knee surgery caused by emotional concerns.

Usually, when the joint structures rub against each other, joint sounds occur. Ligaments and tendons around the knee joint may stretch slightly as they pass over a small bony lump and then snap back into place, hence the clicking sound.

Pathological Knee Sounds

Pathological noise, on the other hand, involves degeneration, pathological plica, knee instability, pathological snapping knee syndrome and postsurgical knee sounds.

Osteoarthritis, a common cause of knee pain, is characterised by the gradual degeneration of the cartilage accompanied by the development of bony spurs and cysts at the joints. In combination, all these changes may cause knee sounds.

Pathological plica characterises inflammation, thickening, and/or reduced elasticity which can cause pain and sounds. When friction occurs between the plica and the bony end during an activity, it can worsen the changes in the plica and cause pain.

Knee instability is associated with noise as a result of hypermobility of the patella or reduction in the previously subluxated patella during active or passive knee flexion and extension.

The pathological snapping sounds in the knees can also come from various extra- and intra-articular structures. Intra-articular structures can be a ganglion cyst, lipoma and synovial nodule. Extra-articular structures can be fabella, osteophytes, osteochondromas and tendinopathies.

Knee surgery can cause postsurgical noise. Factors may include changes in patellar tendon length, joint line elevation, as well as changes in the thickness of the kneecap, increased tilt and translation, and bone displacement.

What to Do about the Knee Pops, Cracks and Clicks?

Differentiating between physiological noise and pathological noise can help determine the right thing to do to your knee. Physiological noise is common but is more likely to be painless and harmless. If there’s no pathological condition, there’s no need to worry about the sounds. Physiological noise isn’t associated with a history of injury, no aggravation of sounds and combined symptoms.

Pathological noise is often associated with pain and swelling. If there’s a loud pop with pain at the time of injury, it may indicate damage.

So to answer the question if you should worry about your knee sounds, the answer depends on the underlying cause — if it’s physiological or pathological. But either way, you need to work on your knee’s surrounding muscles by increasing strength and flexibility so your body stays functional.

If your popping knee is caused by snapping of the ligaments, for example, you can do various exercises that can stretch and strengthen the musculotendinous structures of your knee joint.

If your knee sounds are pathological, it may require conservative or surgical treatment to fix the cause of the noise. The treatment depends on the underlying cause.

We advise visiting a physiotherapist if you notice anything wrong about your knees – whether it’s a click, clunk, or pop, or if it’s unstable, painful, or swelling.

Your physiotherapist will thoroughly assess your knee to be able to identify the cause and construct an appropriate treatment plan. The treatment may include strengthening, flexibility, and weight loss exercises.

To get help from our expert physiotherapists to ensure your knees are healthy and functioning well – call Happy Physio today on 9272 7359!



Song SJ, Park CH, Liang H, Kim SJ. Noise around the Knee. Clinics in Orthopedic Surgery. 2018;10(1):1-8. doi:10.4055/cios.2018.10.1.1.