Why do my fingers crack? Why does my hip pop? Why do my knees crunch?

Do any of you crack your knuckles or your spine on a daily basis? As a child I remember some grown-ups telling me “Hey, you’re going to mess up your joints if you do that enough.” The old thought was that cracking your knuckles enough would lead to early joint degeneration or arthritis formation. These tales have little evidence to back them up however. If you crack your knuckles, you are more than likely doing minimal harm (unless you are a very excessive habitual joint cracker).

But what exactly is happening in the joint when you crack it? The act of cracking a knuckle is a matter of joint science. When we crack our knuckles (or any other joint for that matter), gas bubbles that have built up in the joint’s fluid, overtime, burst. This burst releases the gas into the joint, thereby causing some joint expansion.  Giving you that sense of pressure relief after getting a pop. It takes some time to re-pop the joint because the gas bubbles have to reform within the joint again. Over time, that sensation lessens and your joints begin to feel stiff again, allowing another “crack” or “pop” to happen.

There is no significant research available saying that you are going to cause yourself early arthritis by cracking your knuckles or spine throughout the day.

Let it be said however, that those that do habitually or excessively crack their knuckles or their spine may be increasing the mobility of the joint in the long run, with could lead to problems with joint stability in the future. When you excessively crack your joints, you may be taking the joint through a greater range of motion than it would normally travel though. If, for instance, you did this for years and years, you may be interfering with the long-term joint integrity, which you may comprise a little bit of the stability of the joint. This could potentially lead to an increased chance of dislocation of a joint or tendon. This is not very common though.

If you are cracking your knuckles or your spine often, that may be a sign that you have improper joint mobility or tightness in the tissues surrounding a joint. Performing specific stretches for tight areas around the joint may help to reduce the incidence of the popping and cracking.

Some of you may not be as concerned with cracking your knuckles, but more concerned about the snapping, popping, or grinding that occurs in your knee, hip, or shoulder.  This may be a different phenomenon compared to what’s happening at your joints.

Some of us get these snapping sensations due to the tendons of a muscle, snapping over bony protuberances/edges. You can think about it like plucking a guitar string, where the string is the tissue, and your finger is the bony protuberance.  As a tendon slides over a bump, it can make a snapping sound once it has passed over, leaving an audible sound or physical feeling. This is normal in many people. It may become more common as you get older, so long as you are not having pain when it happens, it should not be something to worry too much about.

Grinding/crunching in a joint may also be felt as you get older, particularly in the knees. This phenomenon is known as “Crepitus”. Commonly, this is due to joint surfaces or tissues that are not perfectly smooth moving across one another. They may rub on each other creating the noise. This can be the case in your knees when you bend them or squat. Rougher cartilage on the underside of the kneecap may rub on the knee joint, leaving behind a crunching sensation. If this is not painful, it is likely something to not worry about. If it is painful when it happens, however, it may worth getting looked into. Painful crunching and grinding could mean that two bony surfaces are rubbing along each other abnormally.