After arthroscopic knee surgery, it usually takes 2-4 weeks for the swelling to go down. Arthroscopic knee surgery can treat knee synovitis, knee cartilage injury, knee meniscus injury, knee free body, knee cruciate ligament injury and other diseases. After arthroscopic surgery for knee cartilage injury and joint free body, the postoperative joint swelling usually goes down in about 2 weeks because the synovium is not cleaned. In contrast, after arthroscopic surgery for conditions such as knee synovitis and knee cruciate ligament injuries, postoperative swelling usually takes about 4 weeks to subside due to the treatment of the synovium and the creation of a bony channel. After arthroscopic surgery, it is necessary to cooperate with functional exercises and ice packs for the muscles and joints of the lower limbs in order to promote the swelling of the joints to subside.