Cracking or Popping Sounds
When you bend and then straighten your knee, you may hear popping or cracking sounds or feel a grinding sensation. Doctors call this crepitus. [3]
You may feel these symptoms when you’ve lost some of the cartilage that allows smooth range of motion. Both RA and OA can damage the cartilage. The damaged cartilage causes the surfaces to become rough and bone spurs develop. These surfaces rub against each other when you move the joint.