The human knee is a large joint and individual patients may experience some ringing when walking, which is normal. A significant number of people may have ringing between bones, between bones and ligaments, and between ligaments and ligaments during activity, just like the popping that occurs when wrenching a finger. However, if there are no painful symptoms, it should be considered normal. The knee joint is the largest joint in the body and mainly plays a weight-bearing role in physical activities. When the knee joint is flexed at 90°, it can be rotated internally and externally by about 25°, but when it is straightened, it cannot be rotated internally and externally because it needs the stability of the joint. If the knee is snapping and painful, consider whether there is synovitis, bursitis, or ligament damage, patellofemoral arthritis, or osteoarthritis, if it is patellofemoral arthritis, the pain is usually in front of the knee, especially when going down the stairs or squatting up. If there is a popping sound and no symptoms of pain, it should be normal.