The main reason for the cold in the joints is the accumulation of fluid in the joints, mainly due to the following possibilities: 1. Synovitis is the most common disease, often occurring after the joints are cold or cold, manifested as swollen joints, feeling cold, local heat can be significantly improved, mainly caused by aseptic inflammation of the synovial membrane. 2. Chondritis of the joints, excessive joint activity causes wear and tear of the articular cartilage, and the appearance of chondritis. In severe cases, this can lead to widespread cartilage exfoliation, causing edema and fluid accumulation in the joint, which can be relatively cool when the amount is relatively large. 3, joint damage caused by trauma, joint hemorrhage and fluid accumulation, due to soft tissue damage, local bleeding leads to a significant increase in peripheral sterile inflammation, and the appearance of joint fluid, poor blood flow and a relatively cool feeling. 4, in the knee joint there is meniscal damage or Synovial crepitus syndrome, which causes joint effusion, is also prone to such manifestations.