Joints are areas within the body where two or more bones meet. Most joints have some degree of mobility which allows the bones to move. Joints consist of a cartilage, which covers the surface of the bone at the joint which reduces friction as well as the synovial membrane which lines and seals the joint to the joint capsule. The synovial membrane secretes synovial fluid which lubricates the joint. The ligaments surround the joint and limit the joint’s movement, and these connect the bones together. Then there are tendons which are found on each side of the joint which control the movements of the joints, and these connect the muscles to the bones. 

Joints emit a variety of different noises. The technical term for these noises is crepitus, which comes from the Latin term ‘rattle’. The clicking/cracking sound is actually a gas bubble ‘popping'. The gas bubble explanation is normally the most spoken about, and it is essentially when the gas bubbles inside the liquid that surrounds our joints pop producing a clicking/cracking noise. However, research has shown that it’s the formation of these bubbles that actually causes the noise and not, in fact, the popping of them. 

 

In 2015, scientists used a real-time MRI to look at the joint capsule to determine what actually causes joints to click. It was found that when the joint surfaces move and separate, the gas bubbles form in the synovial fluid inside the joint capsule. By observing the MRI images, they pinpointed exactly what happens inside the joint at the exact moment an audible click occurred. The scientists concluded that the gas pockets formed as the joint moved, remained visible after the noise, therefore proving that it was their formation that was responsible for the clicking sound. 

 

Sometimes, there is an anatomical cause for the clicking noise. This tends to happen when the tendons move over bony protrusions and then quickly go back into place. This noise is commonly heard when moving from position to position, for example, the knee can click when going from a seated to a standing position or when climbing the stairs. This does increasingly occur the older we get as the structures around the joint (ligaments, tendons and muscles) degenerate. 

Clicking joints are generally never a cause for concern if you click your joints without experiencing pain. 

 

However, if you crack your joints and do experience pain then there could be a number of different causes. These tend to range from arthritis (damage to the cartilage covering the joint surface) to meniscus tears. Other injuries can cause swelling and issues with bone alignment which may cause certain joints to click. In cases like this, it is usually advised for you to see a professional. 

 

A professional will be able to check it out and advise you on the best way to relieve your issue. This could include a referral to another healthcare professional e.g., doctor, osteopath, physiotherapist, or a rehabilitation programme focusing on the strengthening of the surrounding structures to provide more support for the joint.