When a chiropractor adjusts my spine, what is that “popping” sound?

Adjustment of a joint (or manipulation) often results in a popping sound, but there is no need for concern. The air pressure within the joint has suddenly changed, which causes the gas bubble to be released. It is the same thing that happens when someone cracks his or her knuckles. There is rarely any discomfort involved. An adjustment has no effect on the bones to either side of a joint; the adjustment works on its connective tissue.