Rattling of the knee joint is also a relatively common phenomenon, there are two main reasons: 1, when the knee joint activities, the release of gas from the joint fluid will cause a rattle, this rattle will not cause pain, nor will there be any adverse reactions, avoid too fast, too fast, excessive and frequent joint activities can be; 2, abnormal development of the patella, the patella in the femoral carriage in the track of abnormal, in the knee joint activities will The popping sound appears. This condition is not painful in the early stage because the cartilage is not yet damaged to a certain extent. If there is prolonged popping, pain will occur when cartilage damage occurs. If this occurs, it is important to go to the hospital in a timely manner to assess whether there is an abnormality in the patella track, and if so, surgical intervention is required.