Why do joints make popping and cracking noises?
A. Joints make many different noises, some can be serious and many are not. Some people learn how to ‘crack their knuckles’, which is the action of pushing or pulling a joint in a certain way. An air bubble can suddenly appear in the joint and can be heard with a ‘pop’. Once the bubble is there the joint cannot be popped again until the air has been reabsorbed. Some joints ‘crack’ as the ligaments and tendons that pass over them slide past bumps on the bones. This is how people can ‘crack their neck’. Other joints lock up intermittently, often with a loud pop because something gets caught in between the joint surfaces. A torn cartilage in the knee or a loose piece of bone or cartilage in the joint can do this. Arthritic joints may also crack and grind. These noises usually occur each time the joint is moved. This noise is due to the roughness of the joint surface due to the loss of the smooth cartilage.
