Possible causes of cold knees include poor blood circulation, anemia, rheumatoid arthritis and knee synovitis. 1. Poor blood circulation: poor local blood circulation caused by knee trauma, arterial occlusion, etc., individual physical factors or lack of exercise leading to slow blood circulation, etc., can cause cold knees. 2. Anemia: Anemia caused by iron deficiency leads to blood redistribution and reduced blood supply to skin, mucous membranes and other secondary organs, which can lead to coldness of the whole body and cold knees. 3. Rheumatoid arthritis: mostly recurring in winter and spring rainy season, cold and wet environment, with wandering and multiple arthritis, resulting in cold and painful joints. 4. Knee synovitis: Knee synovitis is caused by swelling and congestion of synovial tissues, resulting in poor blood circulation of synovial tissues, which can lead to clinical symptoms of cold knees. There are many reasons for cold knees, you should pay attention to keep warm, seek medical treatment in time, diagnose and treat under the guidance and observation of professional doctors, and follow the doctor’s instructions.