“What is that popping noise?”

Picture cracking your knuckle. When you stretch your finger out to the extreme, you are pulling the joint apart. As you do so, you create more space within the joint, thereby increasing the volume, and as a consequence, decreasing the pressure within the joint capsule. In this environment of low pressure, carbon dioxide, nitrogen and oxygen gases that are dissolved in the synovial fluid that lubricates the joint become less soluble and form a gas […]