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Knee Bone or Joint Injury

Knee Clicking

Minute Read


Posted 1 year ago


Last updated: 29/11/2022


by James McCormack

Knee clicking is very common and can happen for many different reasons. A large percentage of the population have a clicking knee at some time in their life. Most common is to have knee clicking when walking, knee clicking when squatting, clicking when bending the knee or, when climbing or walking down stairs. Clicking can occur with or without pain and other symptoms. If there is no pain, and no other symptoms other than clicking, then it is likely to be normal and nothing to worry about. If clicking occurs with symptoms such as pain, instability or giving way, locking and if your knee is swollen, then this is not normal and should be assessed by a medical professional such as a physical therapist or sports doctor.

Photo of woman doing deep squat with weight

Knee Clicking: No Pain

Knee clicking can often occur with no pain, and is common with movements such as squatting, climbing stairs or going down stairs. There are many different noises that knees can make, clicking, grinding, popping, and clunking. If these are experienced with no pain and no other symptoms, then you shouldn’t worry, these are normal noises. Some people just have noisier knees than others.

Why Does My Knee Click or Pop?

Clicking or popping noises can occur in the knee similarly to how some people can click, pop or crack the knuckles of their fingers and thumbs. Cavitation is the cause of the sound. Cavitation is the formation of a bubble of gas from within a liquid. All joints are filled with a liquid called synovial fluid. When two joint surfaces are pulled apart, they will resist separation up until a critical point, it is at this point when cavitation occurs, when the surfaces separate suddenly and form gas cavities. A recent study provides evidence for this through the MRI images of finger joints taken before and after traction, and the desired “pop” or “click” (Kawchuk et al, 2015). These “pops” are not repeatable like other noises of the knee, they may only be repeated after several minutes.

Why Does My Knee Sound Crunchy?

It is extremely common to have knees that make a crunchy or grinding noise with no pain at all. Often people will not notice the noise until they do the action that causes it, in a quiet room. Crunching or grinding can occur when soft tissue structures move across or between the joint surfaces, as the joint is moved. Such as when bending and straightening the knee to climb stairs, sit down or get up from a crouched position. These tissues can be scar tissue or tissues such as the plica that sits in the knee that can fold and make these noises. These are all normal movements in the knee and unless pain or other symptoms like swelling or instability occur, there is no cause for concern. This can be a consistent noise when the movement is repeated.

Why does my knee clunk?

A more structural sounding clunk can often be heard and if pain-free, is likely related to the movement of the patella or tissues such as a tendon or ligament clicking over a boney prominence. The patella sits in a grove of the femur bone and for various reasons, such as tight muscles or patella instability, it can sit out of the groove and drop in suddenly, making a clunk sound. Similarly, tight muscles or very prominent boney points can cause the hamstring tendon or IT band to click and clunk as it moves over these points. It often is felt and heard like something is clicking back into place. These are more likely to be repeatable noises with a particular movement such as bending and straightening the knee or walking.

Knee Clicking and Pain

There are many different potential causes of painful clicking knees. After an injury such as a fall, or after medical procedures such as ACL surgery, knee replacement or meniscus surgery, pain and clicking can occur. Clicking in the knee can come from different parts of the knee.

Often the patellofemoral joint is the cause. This is the joint of the knee cap sitting on the femur bone. The knee cap, like all joint surfaces, has smooth cartilage, this can get worn and damaged making it uneven which can be a cause of knee clicking. Wear of the patella can be called chondromalacia patella, or osteoarthritis of the patellofemoral joint. This will usually be experienced with some pain, often felt behind the patella. A less severe condition is runners 

Image of Chondromalacia Patella diagram

Why is My Knee Clicking and Painful?

Another frequent structure that can cause painful clicking, crunching or clunking in the knee is the meniscus. The meniscus is made up of a different type of cartilage but can also get worn, damaged or torn and can be the cause of of these noises. The cartilage is a thick, solid structure that can fold and bend, the knee joint can click and clunk as the joint moves over these parts.


Physiotherapy with James McCormack

This is not medical advice. We recommend a consultation with a medical professional such as James McCormack. He offers Online Physiotherapy Appointments for £45.

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