What’s the deal with cracking backs?

One of the problems for us chiropractors is that frequently in movies, people are shown murdering other people by twisting and cracking their necks.

See the video attached…although I warn you it’s violent, but total fantasy (and it’s from X-Men, so it’s also totally fabulous!)


Does this stereotype scare you and keep you from trying chiropractic care? Are you afraid or uncomfortable about the sound the adjustment makes? Read on…it’s just gas, people!

You can’t really kill someone this way. But it’s such a cheap and common plot device in movies that many people are terrified of having their necks adjusted. And they avoid chiropractic care as a result.

It is physically impossible for a human being to break another human being’s neck just with his or her hands. Ligaments and bone are so strong they can withstand tremendous forces before they snap. Some studies I found have shown bone taking up to 25,000 lbs of pressure before it fails.

Of course it’s possible to break bones, but chiropractic adjustments have a very, very small risk of that happening. And the areas that are vulnerable are the ribs in the thoracic spine, not the neck. And the neck is the place people are most freaked out about.

It’s normal and natural to be protective of our necks. I always tell patients that if you’re not a little nervous the first time getting adjusted, it’s either not your first time or there’s something a little off!

A patient I had in Boston in the beginning of my career actually said to me “oh…you’re going to break my bones again!” She was not kidding! She thought that’s what I had done the previous session. I couldn’t help but laugh and when I explained the process, she laughed too and we made that joke every time she saw me.

The crack comes from gas escaping from the joint fluid. That all it is. It’s not cartilage snapping, it’s not scar tissue breaking, it’s not the bone.

The crack is not a crack, but a cavitation. The definition of cavitation is the formation of bubbles in a liquid. Propellers on boats do this too, but soda is the best example.

All moveable joints in the body are self lubricating. They have capsules full of lubricant surrounding them. The capsule is elastic in nature as it must stretch as the joint moves. Any joint that has a decrease in motion will have a smaller than normal joint capsule.

Any subluxation in the spine will cause a decrease in the movement of the individual bones. Thus, the joint capsules in the spine shrink and have less fluid in them than is needed for smooth movement. In doing the adjustment, your chiropractor is increasing the range of motion of the b0ne, so the capsule has to stretch.

As a result of the stretched capsule, there is now not enough joint fluid to fill the new capsule volume. There can never be more space than there is stuff to fill it. This is one of the most fundamental natural laws. I learned that in science class in grammar school and it’s more true today than ever. We used to think space was empty. Surprise! It’s not. There are quarks, gamma rays, solar radiation, etc to contend with. That’s why the ships on Star Trek have shields!

So…the crack occurs because something has to fill the new volume of the capsule or we’d be violating fundamental laws of nature. Liquids can release their gaseous components, which we all know if we’ve ever had sparkly water or soda. So when necessary, gas will escape from the joint fluid. That’s what makes the crack. It’s just gas! Nothing more.

And it’s actually very good for the joint, as a joint with limited range of motion and decreased lubrication will begin to degenerate over time. Adjustments make the joints more juicy and that allows for smooth, fluid motion.