What is the “Popping Sound”

The “pop” sound during an adjustment, arises from inside a joint after moving the joint past a restricted range of motion (ROM). These sounds are called a cavitation.

What is a cavitation? 

Cavitation sounds result from the separation of joint surfaces, which results in a rapid decrease in intra-articular pressure (cavitation), which results in degassing of synovial fluid (mostly carbon dioxide), the creation of a cavitation bubble within the joint, and the sound itself is the result of bubble collapse. An Adjustment Separates the spinal joints call facets joints. There is synovial fluid in the inside the facet joints. The following happens to create the cavitation.

1. Resulting in a rapid decrease in intra-articular pressure (cavitation)
2. Degassing of synovial fluid (mostly carbon dioxide)
3. Creation of cavitation bubble within the joint
4. The sound itself is either the result of bubble collapse (like popping a balloon) or bubble formation/tribonucleation (like pulling a suction cup off of a window).