There are several reasons why the knee may get cold: 1. If the patient has cold and uncomfortable symptoms in the knee joint or other parts of the lower limbs for a long time, most of them are caused by cold in the lower limbs for a long time, especially in cold and humid environments such as winter or rainy weather, and not paying attention to keeping the lower limbs warm. 2, The cold and humidity invade the knee joint, resulting in edema of the synovial membrane or ligaments in the knee joint cavity, leading to cold symptoms in the knee joint or other parts of the lower limbs; 3. The knee joint will be sensitive to the stimulation of cold wind, and the coldness of the lower extremities will be evident during activities.