Most physicians agree that if there is no pain associated with the annoying joint cracks or pops, you can assume it is being caused by the soft tissue in a joint, and is not something to worry much about. In the knee, for example, cracking or popping may occur if the patella is slightly out of alignment, and rubs on the adjacent tissues. Other causes of joint noise is the snapping of tendons or scar tissue over a prominence, or something referred to as cavitation. Cavitation frequently occurs in synovial joints when a small vacuum forms in the synovial fluid and a rapid release produces a sharp popping or cracking sound.
Joint Noises That Cause PainAny joint popping or cracking that is associated with pain may indicate damage to the articulating surfaces of the joint. Such pops, cracks, creaks and clicks could be due to tissue damage, such as a tear in the meniscus of the knee, but are sometimes due to an overly large or loose meniscus which may snap over the other structures in the joint as the knee bends and straightens.
If you hear joint pops and clicks with no associated pain in a joint, you don't need to worry, but you may want to begin some conditioning exercises to improve the overall integrity of the joint. Stronger muscles will take the weight off of the joint and help reduce the pressure on the articulating surfaces.
If there is pain along with those joint noises, you may have signs of structural damage building in the joint. It would be wise to see a physician for an appropriate diagnosis and treatment pain to help prevent further damage.