Curejoy Expert Claude C Butler Explains:
If you are a parent concerned that your child’s “knuckle cracking” habit might be a disorder or weakness that might lead to something serious like arthritis, then you need not worry. Painless cracking of joints is not harmful and does not cause arthritis.
Cracking of joints, (natural or deliberate like knuckle cracking) also referred to as “popping”, is a form of joint manipulation and tendons snapping over tissues to adjust their gliding paths, that produces a popping or cracking sound.
Synovial fluid, the lubricant and nutrient source for joint cartilage cells, contains dissolved gases like oxygen, nitrogen, and carbon dioxide. Deliberate cracking of knuckles increases pressure in the joint capsule, forcing the synovial fluid to expand. Since the fluid cannot expand beyond a certain limit the dissolved gases (especially nitrogen) escape out of the fluid rapidly causing the cracking or popping sound.
If cracking is accompanied by pain, there could be underlying abnormalities of the structures of the joint, such as loose cartilage, damage to ligaments that surround the joint, or dislocation of tendons. While cracking your knuckles is not linked to causing arthritis, there may be a connection to soft tissue injuries.