Clicking Joints - Is It Normal?!

Whilst writing this post I've been discussing it with patients and friends and it seems we all have stories about our joints that click! My personal party piece is a clicking temporomandibular (jaw) joint, and in the clinic Physio Rachel has "clicky hips".

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If the definition for "normal" is something which the majority of people agree to having, then clicking joints are indeed normal. But what causes them?

Well, there are 3 main theories about the reasons for joints cracking and clunking away. The first is bubbles of nitrogen being present in the fluid inside a joint and smaller "crackles" can sometimes be attributed to this.

Louder "popping" noises are usually due to bones rubbing and sticking together as we begin a movement and then release with a "pop" as the friction is released and the bones move independently.

Take the thigh bone and knee cap (the femur and patella) for example. When you begin to bend your knee, the patella is pulled upwards (within the quadriceps tendon - more about this in a second) in a groove in the femur. It should move smoothly, however it often moves up the side of the groove as the tendon stretches. Then, as the pressure is increased (the further you bend your knee) it "pops" back into place in the groove.

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Almost everyone I speak to reports clicking in their neck when they turn their head. This is most likely caused by the same sort of “rub and release” as described in the knee, it’s just that the joints in the neck are much smaller, so the sounds are more crackly than clunky.

Usually no damage is done, and the popping causes no harm whatsoever. It can be a little uncomfortable as the structures are stretched, but unless the muscles are very weak or damaged there is little chance of something like a dislocation occurring.

Repeated clicking can sometimes irritate the joint and in order to provide less friction and more shock absorption, the joint fills with extra fluid. This can be inside the joint capsule itself, or into fluid-filled cushions called bursae. Very occasionally with persistent painful cracking of the knee, your GP or physiotherapist might diagnose chondromalacia (or “runner’s knee”), which is irritation of the cartilage on the underside of the patella.

For those of us who love to crack our knuckles (I have to say I'm not one!) there is a very persistent rumour that this leads to larger joints or arthritis, though this is largely untrue. The name given to this kind of popping joint is usually “fixation”. Here's why...

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Most of the joints of the body have two congruent parts, and because one fits so well onto the other, it’s possible for them to “stick” together. This usually happens in joints that have not been moved in a while (like the joints in your spine and neck, or your knuckles). When this happens, the fluid in the joint space creates a vacuum and sucks the two congruent parts together (kind of like the vacuum you’d see if you had two panes of glass stuck together with a film of water in between).

The popping sound in this case, and especially with the knuckles, is the vacuum being released.

The last reason for joints clicking is weakness in muscles which can slacken the tension of tendons crossing your joints, or cause the tendon to cross that joint at a slightly different angle. This means that the bones may meet at the joint at a slightly different angle to normal. So for instance, in the shoulder, if you hear a click when you lift your arm, this is probably due to the joint being in a slightly different position to normal to begin with, then clicking into place as you move and the weaker muscles tighten and correct the position.

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There are obviously a few anomalies with clicking joints too. With regards to the temporomandibular joint, "clicky jaws" are sometimes due to the lower jaw not being far enough forward in the joint.  This can be corrected with a splint but only if the joint is very painful in the first place (in which case, visit your GP or dentist!) 

Clicking thumb joints can sometimes be attributed to a sesamoid bone being present. This is a small bone nestled inside the joint capsule or tendon (interesting fact coming up! The patella, or knee cap, is a sesamoid bone. It is embedded inside the tendon of quadriceps on the front of your thigh). Sesamoid bones are really very rare in thumbs though.  

The upshot here is: unless your joints click persistently with small movements and/or they are painful and swollen, they are probably healthy. And since almost everyone clicks at some point, we must be normal, hurray!