One of the biggest sources of questions from patients are those related to the “cracking” or popping sound you frequently hear when a spine is manipulated. Some hate it, some love it, but almost everyone is fascinated by it. So what is it? If you’re not familiar, here’s a compilation put together by someone who clearly enjoys watching.

What’s happening?!

The good news is that it is not bones crunching, muscles snapping, ligaments failing or heads being ripped off! It’s far less exciting, but more interesting than that.

The cause of the sound was a source of great debate for many years, which seems to have finally been put to rest with the publication of this study. The video shows the creation of a bubble in the joint space, and the subsequent collapse of the bubble moments later. Whether the sound is caused by the formation or collapse of the bubble is not precisely known.

Weirdly, we don’t really know what happens within the joint and surrounding tissues following a chiropractic adjustment (also known as a High Velocity Low Amplitude Thrust or HVLAT).

What we do know is that it is complicated. There are four main ideas for what may happen:

1. Some of the joint material may “fold in” to the joint itself and become pinched, and stretched or released by manipulation

2. Adjustments cause a relaxation of hypertonic or “tight” muscle by sudden stretching

3. Similar to a rusty hinge, joints can become “sticky” in the joint itself, and HVLATs can help to break this up

4. The “bone out of place” theory. This one has been all but debunked. Much as it may feel like it, no bones are being “put back in” by chiropractors!

The above are all theoretical and as yet untested. However we do have data on manipulation and pain. This study and this study found that spinal manipulation had an effect on the nervous system, including a reduction in pain sensitivity. Which is good news for patients.

Interestingly, this effect was largest at sites away from the spine, which suggests we may be influencing the brain and central nervous system in general more than the specific site we are adjusting! This is bordering on pain science which will require its own extensive series of blogs but is a fascinating and exciting new area of research.

Is it bad if I “crack” my own joints?

Famously Dr Donald Unger conscientiously cracked the knuckles on only one of his hands for 60 (yes, sixty) years, apparently very keen to prove his mother wrong. On X-raying his hands after all that time, he found no difference whatsoever in the arthritis progression in either hand.

This study published almost twenty years after Dr Unger’s groundbreaking research also found no correlation between knuckle popping and arthritis.

So there's definitely no harm in cracking knuckles, but there have been no studies examining self-manipulation of the neck or back so we can’t really say for sure one way or the other how good or bad it is for you.

And if you're worried because your knees crack, don't. This study found that 99% of people with no knee pain had grinding or cracking knees. If it's not painful, you've nothing to worry about.

The Truth About Cracking Your Own Joints

• You don't need to worry about popping joints. It's a normal part of joint function and isn’t an indicator of joint damage

• Joint popping is not related to arthritis or degenerative changes

• Joint popping on its own doesn’t seem to confer any changes; it is more of a harmless side effect

• We don’t know whether cracking your own neck or back is good for you, bad for you, or none of the above.

One thing that adjusting certainly does do is move you, and movement is medicine. If you’re feeling the pinch, give us a call.