The quick answer: the pop you hear during an adjustment is gas being released from the fluid inside the joint as the pressure changes. Nothing is cracking, nothing is breaking and it is not bone rubbing on bone. The sound also tells you almost nothing about whether the adjustment worked.
If one thing keeps nervous first-timers out of the clinic, it is the sound. People hear a crack on a video somewhere and imagine something snapping. I have had patients sit in my Wortley Rd treatment room and admit they delayed booking for months over that half-second of audio. So let me spend a whole post on the least understood moment in my profession, because once you know what the sound is, it stops being scary.
What is the popping sound during an adjustment?
It is a small release of gas inside the joint. Your spinal joints are sealed capsules containing fluid, and that fluid holds dissolved gases the way a capped bottle of soda does. When an adjustment quickly changes the pressure inside the capsule, some of that gas comes out of solution and forms a bubble, and that event makes the popping sound. Researchers have watched it happen inside an MRI. The joint surfaces never grind together and nothing structural gives way.
Is a louder pop a better adjustment?
No. The volume of the sound has no relationship to the quality of the adjustment, and I want to be blunt about this because it is where showmanship creeps into my profession. An adjustment is judged by whether the right joint was moved in the right way for the right reason, which is decided by the exam beforehand, not by the soundtrack. At our clinic we never chase the pop, and if you hear a modest click instead of a dramatic crack, nothing went wrong.
Why do some adjustments make no sound at all?
Because the gas needs time to re-dissolve. Once a joint has released, it usually will not make the sound again for around twenty minutes, no matter what you do to it. Beyond that, some joints and some techniques simply produce no sound, and some people's joints are quiet by nature. An adjustment can be entirely effective in silence. If your visits are quiet ones, you are not getting less treatment.
Is it the same as cracking your knuckles?
The sound is the same mechanism, yes. The difference is everything around it. When you crack your knuckles you are moving a joint you can reach in a direction it was already happy to go. An adjustment applies a specific, controlled movement to a specific joint that an exam has identified, after your health history has been screened for reasons not to. And in case your grandmother warned you: the research on habitual knuckle cracking has not shown it causes arthritis.
What if I would rather not hear it at all?
Tell me, and I mean that literally. Some patients never get used to the sound, especially around the neck, and there are approaches that do not involve it. Everything we might do is explained at your report of findings before anything is treated, as laid out in what happens at your first visit, and consent at Anchor Chiropractic covers technique too. Patients coming in about headaches raise this most often, since neck adjustment sits closest to the ear. There is always a plan you can be comfortable with, and if there is not one in our clinic, I will say so and point you somewhere better suited.