Often, crepitus is harmless. It happens when air seeps into the soft tissues around the joint (such as the kneecap). When you bend the joint, the air bubbles burst, and you hear a cracking sound. While most crepitus is harmless, some forms of crepitus signal a problem.

What is Crepitation caused by?

Crepitus is caused by tissues rubbing together in an abnormal way. The most common cause of crepitus is rough cartilage and bone rubbing together in a joint, and the most common cause of this type of crepitus is arthritis or joint injury.

When does Crepitation occur?

Crepitation is a palpable or audible grating or crunching sensation produced by motion. This sensation may or may not be accompanied by discomfort. Crepitation occurs when roughened articular or extra-articular surfaces are rubbed together by active motion or by manual compression.