Many people’s knees squeak, crack, or crackle, a phenomenon known as crepitus. Most of the time, it’s no big deal at all. But a loud popping sound accompanied by pain and swelling indicates an injury.

For many, a trip to the chiropractor feels like hitting a reset button—spines snap back into place, joints loosen, and pain seemingly vanishes. But beneath the satisfying pops and cracks lies a ...