A joint is mobile part of the skeleton any place where the end of two bones come together and meet. The end of the bones where they are in union is covered by a layer of articular cartilage. This is surrounded by a capsule which engulfs the joint and its synovial fluid. This synovial fluid lubricates the joint and nourishes the joint surfaces including the cartilage.
The synovial fluid contains dissolved gases such as Oxygen, Carbon dioxide and Nitrogen. When a quick, precise force is applied to a joint, the space within the joint capsule increases in volume. On the other hand, the increase is restricted by how much synovial fluid is enclosed in the joint itself. The Synovial fluid cannot expand unless the pressure within the joint capsule decreases and the dissolved gases can be set free from the fluid. The audible ‘cracking’ noise is caused by a reaction to this pressure changing within the joint and the gases quickly escaping from the synovial fluid.
A number of clinical trials and research have been undertaken to determine if cracking knuckles causes arthritis. So far there has been no evidence to suggest that there was an increased incidence of arthritis among habitual joint crackers, however, a connection was revealed between knuckle-cracking, hand swollenness, poorer grip strength, injury to ligaments adjoining the joints and dislodgment of muscular tendons.
All in all, the research points towards that even though knuckle-cracking is not linked with arthritis, people who do it too often may cause some damage to other important structures of their joints.
