Many people have noisy knees. Noises without pain are usually not a problem. Crepitus is a medical word which means a crunching that can be felt (palpable crepitus) or heard (audible crepitus) when a joint moves. Joint noises often persist for years without any significant problems developing.
In the knee, cracking or popping may be heard if the patella (kneecap) tracks slightly out of the groove it is supposed to run in. This can happen with muscle wasting which alters the ‘tracking’ or pathway the patella follows or because of an underlying biomechanical abnormality. Other causes of noises in the joint are the snapping of tendons or scar tissue over a prominence or the meniscus clicking in and out of place when it is torn.
Most commonly the cracking is either scar tissue or a rough area between the kneecap and the femur where the kneecap rubs.
Any joint popping or cracking that is associated with pain may be a sign that you have damage to your joint lining surfaces. If the knee swells as well then you can be fairly sure you have significant damage in the knee.
While many causes of cracking in the knee can be helped by an exercise programme a certain number of patients will require a knee arthroscopy. If joint lining damage is found during the surgery recovery from the operation is not always complete.