Causes. Formation of bubbles of joint air as the joint is expanded. Cavitation within the joint—small cavities of partial vacuum form in the synovial fluid and then rapidly collapse, producing a sharp sound. Rapid stretching of ligaments. Intra-articular (within-joint) adhesions being broken. May 31, - We’ve all experienced it: Knees that snap when we stand up, a neck that cracks when we turn our head and ankles that pop when we rotate them. Often, joint cracking can be loud – and perhaps a little disconcerting. Creaking and snapping joints might be annoying, but they usually.