Knee swelling first need to clarify the cause, and then choose the treatment: 1, acute sprain: it is recommended that cold compresses within 24-48 hours, more than 48 hours can be hot compresses, sprained knee swelling because of more blood exudation, cold compresses can reduce the internal exudation of the knee joint, reduce the degree of swelling, reduce pain, while after 48 hours hot compresses can promote local blood circulation, promote swelling receding absorption; 2, inflammatory lesions: can not cold compresses, nor hot compresses, hot compresses will further aggravate the degree of bacterial infection, should promptly go to the hospital for medical consultation.